Research ArticleEffect of Modulated Alternating and DirectCurrent Iontophoresis on Transdermal Deliveryof Lidocaine Hydrochloride
Gaurav Bhatia and Ajay K Banga
Department of Pharmaceutical Sciences College of Pharmacy Mercer University Atlanta GA 30341 USA
Correspondence should be addressed to Ajay K Banga banga akmerceredu
Received 9 February 2014 Accepted 1 May 2014 Published 15 May 2014
Academic Editor Sandeep Nema
Copyright copy 2014 G Bhatia and A K Banga This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited
The objective of this study was to investigate the iontophoretic delivery of lidocaine hydrochloride through porcine skin and tocompare the effects of modulated alternating and direct current iontophoresis Continuous and modulated iontophoresis wasapplied for one hour and two hours (0-1 h and 4-5th h) using a 1wv solution of lidocaine hydrochloride Tape stripping wasdone to quantify the amount of drug permeated into stratum corneum and skin extraction studies were performed to determinethe amount of drug in stripped skin Receptor was sampled and analyzed over predefined time periods The amount of lidocainedelivered across porcine skin after modulated direct current iontophoresis for 2 h was 106987 plusmn 12003 120583gsqsdotcm compared to74481 plusmn 12541 120583gsqsdotcm after modulated alternating current iontophoresis for 2 h Modulated direct current iontophoresis alsoenhanced lidocaine delivery by twelvefold compared to passive delivery as 9127 plusmn 1871 120583gsqsdotcm of lidocaine was delivered afterpassive delivery Modulated iontophoresis enhanced the delivery of lidocaine hydrochloride across porcine skin compared to thepassive delivery Modulated alternating current iontophoresis for duration of 2 h at frequency of 1 kHz was found to be comparableto the continuous direct current iontophoresis for 1 h
1 Introduction
Lidocaine hydrochloride is a hydrophilic local anestheticwhich is widely used for topical anesthesia and other medicaland surgical procedures including treatment of skin soreslesions and suturing of wounds [1] It is also used as anantiarrhythmic drug [2] It exerts local anesthetic effect bybinding with voltage gatedNa+ channels at axonalmembraneand prevents the transport of Na+ across the channelsthus inhibiting the postsynaptic neuron from depolarizationand stabilizes neuronal membrane [3] The most commonform of lidocaine administration is through intravenous orhypodermic injection which causes pain and discomfort [4]Transdermal delivery of lidocaine is a potential alternativeroute of administration
However due to poor penetration through intact skinthe percutaneous application of lidocaine is limited [5]Commercial products including EMLA cream (AstraZeneca)
and Lidoderm (Endo Laboratories) are available for trans-dermal delivery of lidocaine However achieving effectiveanalgesia requires the application of EMLA for 1-2 h whichlimits its use during emergency where fast onset of anes-thesia is desired making it less convenient to use duringnormal clinical procedures [6] Several other formulationssuch as liposomes [5] or microemulsions have also beeninvestigated to enhance the transdermal delivery Polymericliposomes have been shown to be effective in enhancingthe transdermal delivery of lidocaine across the mouse skinBacterial cellulose membrane incorporated with lidocainedemonstrated lower permeation than conventional formu-lation through human epidermis [7] A combination ofshort-term iontophoresis and microemulsion formulationsignificantly increased the flux and resulted in accumulationof large skin drug depot and short lag time in delivery oflidocaine through porcine skin Studies have also reportedthat transdermal delivery of lidocaine has a possibility to be
Hindawi Publishing CorporationBioMed Research InternationalVolume 2014 Article ID 537941 6 pageshttpdxdoiorg1011552014537941
2 BioMed Research International
used for local anesthesia and pain management of the skin[8] Therefore there is a need to enhance the transdermaldelivery of lidocaine to achieve rapid onset of action this canbe achieved using physical enhancement techniques such asiontophoresis
Iontophoresis is a widely used technique for the deliveryof neutral and charged drug molecules into and across theskin by using small amount of physiological current [9]The mechanisms of iontophoresis include electrorepulsionwhich is based on the principle of ldquolike repels likerdquo andelectroosmosis where the neutral molecules are transportedfrom anode to cathode along with the bulk solvent flowDirect current (DC) iontophoresis is the most commonlyused form of the transdermal iontophoretic drug deliveryExamples of drug delivery using DC iontophoresis are theNumby Stuff Phoresor system (Iomed Inc UT) LidoSite(lidocaine hydrochlorideepinephrine topical iontophoreticpatch) and the Ionsys E-Trans system for systemic fentanyldelivery (Alza Corp CA) However DC iontophoresis mayhave some adverse effects including electrical burn as a resultof electrode polarization during electrolysis This adverseeffect limits the duration time of DC iontophoresis to lessthan 15min at current density of 1mAcm2 [10] A decrease intransport efficiency is also observed inDC iontophoresis withincreasing duration of the electric application The decreasetransport efficiency is due to the voltage drop in the solutionwhich results from the formation of an electric double layeron the surface of electrode known as electrode polarizationthis phenomenon occurs due to the accumulation of ionizedsubstance with the different charge from that of the electrodeTo overcome these issues alternating current (AC) has alsobeen employed in iontophoretic delivery [11] It has beenreported thatAC iontophoresis can eliminate electrochemicalburn and reduce the skin irritation which occurs duringthe long application time of DC iontophoresis [12] It hasalso been reported that alternating current iontophoresis canreduce the skin electrical resistance thereby increasing theintrinsic permeability of skin [11]
Iontophoresis is also widely used to enhance the deliveryof topical anesthetics [13] Studies have also reported thationtophoresis facilitates the transport of lidocaine moleculesinto the skin under the influence of electric current and canprovide topical anesthesia of intact skin within 5ndash15min [14]Lidocaine iontophoresis has also been found to be effectivein reducing the pain associated with venous cannulation inpatients [15]
The objective of the current study was to enhance thetransdermal delivery of lidocaine by iontophoresis and tocompare the effects of modulated alternating and directcurrent iontophoresis on the permeation of lidocaine inporcine full thickness skin Passive diffusion of lidocaine wasused as the control for the study
2 Materials and Methods
21 Materials Lidocaine hydrochloride silver wire (05mmdiameter) and silver chloride used for preparation ofelectrodes were purchased from Sigma-Aldrich (St Louis
MO USA) Acetonitrile methanol potassium phosphatemonobasic (KH
2PO4) and PBS (phosphate buffered saline)
were purchased from Fisher Scientific (NJ USA) Transporetape for tape stripping was obtained from 3M (St Paul MNUSA) Deionized water was used to prepare all the solutionsrequired in this study and for HPLC analysis Iontophoresispower supply unit (Model 6221) was purchased fromKeithleyInstruments (Cleveland OH USA)
22 Methods
221 Skin Isolation and Preparation Porcine skin wasobtained from a local abattoir Whole skin was excisedfollowed by the removal of subcutaneous fat The skin wasthen cleaned using deionized water and stored at minus20∘C inaluminum foil until use Skin was thawed before permeationstudies cut into appropriate sizes and mounted on theFranz diffusion cells (PermeGear Hellertown PA USA) withstratum corneum side facing the donor compartment andsecured into place using clamps
222 Preparation of Electrodes A planar coil of silver wasprepared manually and used as the anode in the studyThe cathode was custom made by coating a melt of silverchloride on silver wire Coating was done until a uniform andsufficient coat of the silver chloride was obtained
223 Continuous versus Modulated Iontophoresis Contin-uous and modulated iontophoresis were applied for theduration of one and two hours The anode was placedin the donor chamber and the cathode was inserted intothe receptor compartment through the sampling arm toperform anodal iontophoresis A continuous direct current(DC) iontophoresis at current density of 05mAcm2 andalternating current (AC) iontophoresis at a frequency of1 kHz and current density of 05mAcm2 were applied usingKeithley instrument (Model 6221 Cleveland OH USA) forone hour from 0 to 1 h
To determine the effect of iontophoresis on transdermaldelivery of lidocaine continuous direct current iontophore-sis was applied for one hour from 0 to 1 h and modulateddirect current iontophoresis at current density of 05mAcm2was applied for two hours (from 0 to 1 h and from 4 to5th h) while modulated alternating current iontophoresis ata frequency of 1 kHz and current density of 05mAcm2 wasalso applied for two hours (from 0 to 1 h and from 4 to 5th h)respectively on porcine full thickness skin Our group hasalso reported that flux recovers back to the normal level intwo to three hours after iontophoresis [16]Therefore we keptinterim period of 3 h between two iontophoresis applicationsReceptor samples (05mL) were collected at predeterminedtime intervals during the study
224 Permeation Studies In this study the influence ofanodal iontophoresis on the delivery of lidocaine hydrochlo-ride into porcine full thickness skin was investigated andpassive diffusion was used as the control in the study In vitropermeation studies (119899 ge 3) were performed using vertical
BioMed Research International 3
Franz diffusion cells Receptor compartment was thoroughlywashed prior to the study and then filled with receptorbuffer (5mL 1X PBS pH 74) The temperature of the cellswas maintained at 37∘C during the study by using a watercirculation jacket built around receptor chamber Porcineskin was mounted on the receptor compartments (effectivearea of diffusion was 064 cm2) with the stratum corneumfacing the donor chamber Donor chambers were then placedon the mounted skin and secured into place using clampsLidocaine (1wv) solution in deionized water was used asthe donor (05mL) for the study Sodium chloride (23mM)was added to the donor solution to drive the electrochemistryof the silver-silver chloride electrodes Samples (05mL) werewithdrawn from the receptor compartment at predeterminedtime intervals over a period of 24 h and replenished withequal volume of fresh receptor buffer Samples obtained wereanalyzed using high performance liquid chromatography(HPLC) assay After the permeation studies tape strippingand skin extraction studies were performed to quantifydrug levels in the stratum corneum and the stripped skinrespectively
Lidocaine is a small molecule and is categorized phar-macologically as local anesthetic and antiarrhythmic drugIt is lipophilic in base form with a log 119875 of 26 whilethe hydrochloride salt of drug (used here) is hydrophilicin nature with log 119875 le 0 [17] The salt form of drug wasused for the study as active enhancement techniques likeiontophoresis require the drug to be hydrophilic and incharged form for the delivery also salt form of drug has theability to provide the chloride ions which is essential forthe completion of electrochemical reaction at anode whensilversilver chloride electrodes are used for iontophoresis[18]The electrochemistry at anode and cathode is as follows
Anode
Ag + Clminus 997888rarr AgCl + eminus (1)
Cathode
AgCl + eminus 997888rarr Ag + Clminus (2)
For salt form of the drug log 119863 (logarithm of distributioncoefficient) is used which is the partition between organicand buffer phase and is determined by degree of ionization ofmolecule at a particular pHandpKa [19] log119863was calculatedby (3) as follows [20]
log119863 = log119875 minus log (1 + 10 and (pKa minus pH)) (3)
The log 119863 value of compound also determines its abilityto ionize at given pH condition so the effectiveness oftransport by iontophoresis through electrorepulsion can bedetermined Lidocaine hydrochloride has a log 119863 of 157(calculated from (3)) at pH 74 and the drug has pKa of79 hence at pH of 74 it will be positively charged andanodal iontophoresis will actively transport lidocaine byelectrorepulsion
225 Skin Extraction Skin extraction procedure was per-formed to determine the drug levels in skin Skin sampleswere removed from Franz diffusion cells at the end ofpermeation studies The skin surface was then thoroughlycleaned by dabbing it three times with Q-tips soaked inreceptor medium Skin was then tape stripped using 3MTranspore tapes to determine the amount of drug permeatedin stratum corneum The first five tape strips were extractedindividually and remaining tape strips were extracted in agroup of five Kim wipes were used to dry the skin surfaceAfter tape stripping skin samples were minced manuallyusing a pair of scissors and added to scintillation vials PBS(1X pH74) was used as an extraction solvent and was addedtominced skinThe extraction was carried out by shaking thevials overnight on the roller shaker (NewBrunswick ScientificCo Inc NJ USA) The samples were then centrifuged at13400 g for 2min at 200 rpm and the supernatant extract wasfiltered by using 045 120583mfilters (Milipore) and analyzed usingHPLC assay
226 Quantitative Analysis Lidocaine hydrochloride wasquantified using HPLC by using modified assay from litera-ture HPLC analysis was performed on Perkin Elmer System(Waltham MA) with a UV detector operating at 230 nmColumn used was RP-18 Phenomenex column (Luna 5120583C18 100A 250mm times 46mm Phenomenex Torrance CAUSA) Mobile phase consisted of methanol 01M sodiumdihydrogen phosphate (60 40 vv) Isocratic elution wasperformed at a flow rate of 06mLmin after injecting 10120583L ofsample the total run time was 10min and the retention timeof lidocaine hydrochloride was around 604min The Lowerlimit of detection (LOD) was 005120583g and the lower limit ofquantification (LOQ) was 01 120583g Standards were prepared inthe range of 01ndash100120583g The assay was sensitive for range ofinterest
227 Statistical Analysis Statistical significance was deter-mined using one-way analysis of variance (ANOVA) andDunnettrsquos test using GraphPad Prism software (version 50d)All results are reported as mean plusmn SD (119899 = 3) Values wereconsidered significantly different when 119875 le 05
3 Results and Discussion
31 Iontophoretic Drug Transport Mechanism Anodal ion-tophoresis was performed for one or two hours using alter-nating and direct current (Figure 1) to determine the effectof iontophoresis on the delivery of lidocaine hydrochlo-ride through porcine full thickness skin The present studyrevealed that both the DC and AC iontophoreses enhancedthe delivery of lidocaine hydrochloride through porcine skinStudies have demonstrated that the mechanisms responsiblefor the transport of drug substance after DC iontophore-sis are electrorepulsion electroosmosis and increased skinpermeability [21] It has been reported that electrorepulsionand electroosmosis are involved in transport of lidocaineafter the application of AC iontophoresis at low frequencyLidocaine used in the study is dissociated into positively
4 BioMed Research International
Current source+ minus
Figure 1 Iontophoretic setup that was used for iontophoreticstudies of lidocaine silver wire (represented in red) served asthe anode (active electrode) and silver wire coated with silverchloride (represented in black) serve as cathodeThe electrodes wereconnected to a current source to perform anodal iontophoresis
charged lidocaine and hydrogen ions along with negativelycharged chloride ions During electrorepulsion the chargedsubstances are repelled from the electrode of same polarity[22] Positively charge lidocaine ions would be similarlyrepelled during the positive phase of AC iontophoresisTransport mechanism of the substance after the applicationof electric field can be explained by following (4) [10]
119869L = 119869119901 + 119869er + 119869eo (4)
where 119869L is the mole flux of the substance L Jp is thepassive flux 119869er represents electrorepulsive contribution and119869eo depicts the electroosmotic flux Therefore both elec-trorepulsion and electroosmosis are the major mechanismsresponsible for the delivery of lidocaine hydrochloride afterAC and DC iontophoresis
32 Effect of Continuous Iontophoresis on Lidocaine Deliv-ery through Porcine Skin Continuous iontophoresis usingalternating and direct current iontophoresis enhanced thedelivery of lidocaine into porcine full thickness skin ascompared to passive diffusionThe amount of drug deliveredafter continuous DC iontophoresis for one hour was 68476plusmn2481 120583gsqsdotcm compared to 9127plusmn1871 120583gcm2 for passivedelivery (Figure 2) Continuous iontophoresis resulted in asteady rise of drug delivered when the current was appliedand the highest flux was 10659 plusmn 585 120583gcm2h at 2 h forDC iontophoresis after which the flux decreases gradually(Figure 3)
33 Effect of Modulated Iontophoresis on Lidocaine Deliverythrough Porcine Skin To determine the effect of modulatediontophoresis on the delivery of lidocaine modulated anodaliontophoresis (05mAcm2) using direct and alternatingcurrent iontophoresis was performed for two hours (from0-1 h and 4-5th h) on porcine full thickness skin and passivediffusion served as the control for the study
0
200
400
600
800
1000
1200
1400
0 1 2 3 4 5 6 10 12 22 24
Aver
age c
umul
ativ
e am
ount
Time (hr)
Modulated iontophoretic delivery of lidocaine hydrochloride
of d
rug
(120583g
sqcm
plusmnSD
)
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
lowast
Figure 2 Cumulative amount of lidocaine delivered throughfull thickness porcine ear skin after continuous and modulatediontophoresis (lowast119875 lt 005 versus passive mean plusmn SD 119899 = 3)
0
50
100
150
200
250
300
350
400
0 1 2 3 4 5 6 10 12 22 24 Time (hr)
Transdermal flux of lidocaine hydrochloride
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
Flux
(120583g
sqcm
h)
lowast
Figure 3 Flux of lidocaine across full thickness pig ear skin aftercontinuous and modulated iontophoresis (lowast119875 lt 005 versus passivemean plusmn SD 119899 = 3)
Modulated iontophoresis enhanced the delivery of lido-caine significantly (119875 lt 005) from 9127 plusmn 1871 120583gcm2 forpassive delivery to 74481plusmn12541 120583gcm2 forAC iontophore-sis and 106987 plusmn 12001 120583gcm2 for DC iontophoresis Theamount of drug delivered by modulated alternating currentiontophoresis for duration of two hours at frequency of 1 kHzwas found to be comparable to the drug delivered by con-tinuous direct current iontophoresis for one hour as 74481 plusmn12541 120583gcm2 of lidocaine was delivered aftermodulated ACiontophoresis compared to 68476 plusmn 2481 120583gsqsdotcm2 afterone hour of continuous DC iontophoresis at the end of 24 h
BioMed Research International 5
study respectively (Figure 2) Plot of average flux versus time(Figure 3) shows that amount of lidocaine delivered at a par-ticular time point depends on the current appliedModulatediontophoresis (0-1 h + 4-5 h) resulted in increased flux ateach time period of current application during the durationof study that is 8968 plusmn 3578 120583gcm2h at 2 h and 6406 plusmn1661 120583gcm2h at 6 h for AC iontophoresis compared to16296 plusmn 4158 120583gcm2h at 2 h and 24887 plusmn 11695 120583gcm2hat 6 h for DC iontophoresis The study was continued till24 h to observe the postiontophoretic permeation and fluxdecreased gradually during the time period of the study Theamount of drug delivered by modulated alternating currentiontophoresis for total duration of two hours at frequencyof 1 kHz was found to be comparable to the drug deliveredby continuous direct current iontophoresis for one hourThis may be due to the periodic polarity alteration duringalternating current It has also been reported that the drivingforce of the alternating current is less compared to thatwith application of direct current due to periodic polarityalteration [10]
34 Drug Levels in Skin Layers following Iontophoresis StudiesTape stripping was done to quantify the amount of drugdelivered into the stratum corneum After tape stripping thestripped skin was minced and extracted with 1 times PBS pH 74to quantify the drug level in stripped skin The amount ofdrug delivered into the stratum corneum and stripped skinby anodal iontophoresis using alternating current and directcurrent iontophoresis was significantly (119875 lt 005) highercompared to the passive diffusion as demonstrated in Figures4 and 5 The average total amount of drug delivered intostripped skin following iontophoresis was also significantly(119875 lt 005) higher compared to the passive delivery The druglevels delivered into stripped skin following iontophoresiswere 3968 plusmn 111 120583g for AC iontophoresis and 4198 plusmn1309 120583g for DC iontophoresis for two hours which was5-fold higher than passive delivery (885 plusmn 269 120583g) Theseresults demonstrate the presence of rate limiting step whichrestricts the movement of drug into the stripped skin Thisrate-limiting step was however overcome by iontophoresisas the application of current was able to propel higher levelof drug into deeper skin layers as compared to passivediffusion Quantification of lidocaine in the skin establishedthat stratum corneum was the barrier to the delivery of thisdrug as a negligible amount was detected in the skin afterpassive delivery
4 Conclusions
Results of the iontophoretic studies demonstrated that anodaliontophoresis enhanced the delivery of lidocaine hydrochlo-ride into and across the porcine skin Direct current ion-tophoresis enhanced the permeation of lidocaine hydrochlo-ride by twelvefold compared to passive diffusion Direct cur-rent iontophoresis was also found to be more effective thanalternating current iontophoresis in enhancing the deliveryof lidocaine hydrochloride into and across the porcine skin
0
10
20
30
40
50
60
70
80
Aver
age a
mou
nt o
f dru
g
Drug in stratum corneum
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
in st
ratu
m co
rneu
m (120583
gplusmn
SD) lowast
Figure 4 Average amount of drug in stratum corneum followingiontophoresis and passive delivery (lowast119875 lt 005 versus passive meanplusmn SD 119899 = 3)
0
10
20
30
40
50
60
Aver
age a
mou
nt o
f dru
g in
Drug in stripped skin
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
strip
ped
skin
(120583gplusmn
SD)
lowast
Figure 5 Average amount of drug in stripped skin followingiontophoresis and passive delivery (lowast119875 lt 005 versus passive meanplusmn SD 119899 = 3)
Conflict of Interests
The authors declare that there is no conflict of interests
References
[1] D W Smith M R Peterson and S C DeBerard ldquoRegionalanesthesia nerve blocks of the extremities and facerdquo Postgrad-uate Medicine vol 106 no 4 pp 69ndash73 1999
[2] LHu SMC Silva B BDamaj RMartin andB BMichniak-Kohn ldquoTransdermal and transbuccal drug delivery systemsenhancement using iontophoretic and chemical approachesrdquoInternational Journal of Pharmaceutics vol 421 no 1 pp 53ndash62 2011
[3] H R Shah E Reichel and B G Busbee ldquoA novel lidocainehydrochloride ophthalmic gel for topical ocular anesthesiardquoLocal and Regional Anesthesia vol 3 no 1 pp 57ndash63 2010
[4] P J Lee N Ahmad R Langer S Mitragotri and V P ShastrildquoEvaluation of chemical enhancers in the transdermal deliveryof lidocainerdquo International Journal of Pharmaceutics vol 308no 1-2 pp 33ndash39 2006
6 BioMed Research International
[5] Y Wanga W Su Q Li et al ldquoPreparation and evaluationof lidocaine hydrochloride loaded TAT-conjugated polymericliposomes for transdermal deliveryrdquo International Journal ofPharmaceutics vol 441 no 1-2 pp 748ndash756 2013
[6] Y Zhang K Siebenaler K BrownDDohmeier andKHansenldquoAdjuvants to prolong the local anesthetic effects of coatedmicroneedle productsrdquo International Journal of Pharmaceuticsvol 439 no 1-2 pp 187ndash192 2012
[7] E Trovatti C Freire P C Pinto et al ldquoBacterial cellulosemembranes applied in topical and transdermal delivery of lido-caine hydrochloride and ibuprofen in vitro diffusion studiesrdquoInternational Journal of Pharmaceutics vol 435 no 1 pp 83ndash87 2012
[8] J S Yuan M Ansari M Samaan and E J Acosta ldquoLinker-based lecithin microemulsions for transdermal delivery oflidocainerdquo International Journal of Pharmaceutics vol 349 no1-2 pp 130ndash143 2008
[9] AK BangaTransdermal and IntradermalDelivery ofTherapeu-tic Agents Application of Physical Technologies pp 81ndash94 CRCPress Taylor amp Francis Group 2011
[10] S Hayashi S Ogami T Shibaji and M Umino ldquoLidocainetransport through a cellophane membrane by alternating cur-rent iontophoresis with a duty cyclerdquo Bioelectrochemistry vol74 no 2 pp 315ndash322 2009
[11] G Yan S K Li and W I Higuchi ldquoEvaluation of constantcurrent alternating current iontophoresis for transdermal drugdeliveryrdquo Journal of Controlled Release vol 110 no 1 pp 141ndash150 2005
[12] J P Howard T R Drake and D L Kellogg ldquoEffects ofalternating current iontophoresis on drug deliveryrdquo Archives ofPhysicalMedicine and Rehabilitation vol 76 no 5 pp 463ndash4661995
[13] J M DeCou R S Abrams J H Hammond L R Lowderand M W L Gauderer ldquoIontophoresis a needle-free electricalsystem of local anesthesia delivery for pediatric surgical officeproceduresrdquo Journal of Pediatric Surgery vol 34 no 6 pp 946ndash949 1999
[14] W T Zempsky and T M Parkinson ldquoLidocaine iontophoresisfor topical anesthesia before dermatologic procedures in chil-dren a randomized controlled trialrdquoPediatric Dermatology vol20 no 4 pp 364ndash368 2003
[15] M Ashburn M Gauthier G Love S Basta B Gaylord andK Kessler ldquoIontophoretic administration of 2 lidocaine HCLand 1100 000 epinephrine inmanrdquoTheClinical Journal of Painvol 13 no 1 pp 1322ndash1326 1997
[16] V Kumar and A K Banga ldquoModulated iontophoretic deliveryof small and large molecules through microchannelsrdquo Interna-tional Journal of Pharmaceutics vol 434 no 1-2 pp 106ndash1142012
[17] P D Sawant D Luu R Ye and R Buchta ldquoDrug releasefrom hydroethanolic gels Effect of drugrsquos lipophilicity (log P)polymer-drug interactions and solvent lipophilicityrdquo Interna-tional Journal of Pharmaceutics vol 396 no 1-2 pp 45ndash52 2010
[18] Y N Kalia A Naik J Garrison and R H Guy ldquoIontophoreticdrug deliveryrdquo Advanced Drug Delivery Reviews vol 56 no 5pp 619ndash658 2004
[19] V Sachdeva S Siddoju Y Yu H D Kim P M Friden andA K Banga ldquoTransdermal iontophoretic delivery of terbinafinehydrochloride quantitation of drug levels in stratum corneumand underlying skinrdquo International Journal of Pharmaceuticsvol 388 no 1-2 pp 24ndash31 2010
[20] M Kah and C D Brown ldquoLog D lipophilicity for ionisablecompoundsrdquo Chemosphere vol 72 no 10 pp 1401ndash1408 2008
[21] H Haga T Shibaji and M Umino ldquoLidocaine transportthrough living rat skin using alternating currentrdquo Medical andBiological Engineering and Computing vol 43 no 5 pp 622ndash629 2005
[22] A C Sintov and R B Sitton ldquoFacilitated skin penetrationof lidocaine combination of a short-term iontophoresis andmicroemulsion formulationrdquo International Journal of Pharma-ceutics vol 316 no 1-2 pp 58ndash67 2006
Submit your manuscripts athttpwwwhindawicom
PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
used for local anesthesia and pain management of the skin[8] Therefore there is a need to enhance the transdermaldelivery of lidocaine to achieve rapid onset of action this canbe achieved using physical enhancement techniques such asiontophoresis
Iontophoresis is a widely used technique for the deliveryof neutral and charged drug molecules into and across theskin by using small amount of physiological current [9]The mechanisms of iontophoresis include electrorepulsionwhich is based on the principle of ldquolike repels likerdquo andelectroosmosis where the neutral molecules are transportedfrom anode to cathode along with the bulk solvent flowDirect current (DC) iontophoresis is the most commonlyused form of the transdermal iontophoretic drug deliveryExamples of drug delivery using DC iontophoresis are theNumby Stuff Phoresor system (Iomed Inc UT) LidoSite(lidocaine hydrochlorideepinephrine topical iontophoreticpatch) and the Ionsys E-Trans system for systemic fentanyldelivery (Alza Corp CA) However DC iontophoresis mayhave some adverse effects including electrical burn as a resultof electrode polarization during electrolysis This adverseeffect limits the duration time of DC iontophoresis to lessthan 15min at current density of 1mAcm2 [10] A decrease intransport efficiency is also observed inDC iontophoresis withincreasing duration of the electric application The decreasetransport efficiency is due to the voltage drop in the solutionwhich results from the formation of an electric double layeron the surface of electrode known as electrode polarizationthis phenomenon occurs due to the accumulation of ionizedsubstance with the different charge from that of the electrodeTo overcome these issues alternating current (AC) has alsobeen employed in iontophoretic delivery [11] It has beenreported thatAC iontophoresis can eliminate electrochemicalburn and reduce the skin irritation which occurs duringthe long application time of DC iontophoresis [12] It hasalso been reported that alternating current iontophoresis canreduce the skin electrical resistance thereby increasing theintrinsic permeability of skin [11]
Iontophoresis is also widely used to enhance the deliveryof topical anesthetics [13] Studies have also reported thationtophoresis facilitates the transport of lidocaine moleculesinto the skin under the influence of electric current and canprovide topical anesthesia of intact skin within 5ndash15min [14]Lidocaine iontophoresis has also been found to be effectivein reducing the pain associated with venous cannulation inpatients [15]
The objective of the current study was to enhance thetransdermal delivery of lidocaine by iontophoresis and tocompare the effects of modulated alternating and directcurrent iontophoresis on the permeation of lidocaine inporcine full thickness skin Passive diffusion of lidocaine wasused as the control for the study
2 Materials and Methods
21 Materials Lidocaine hydrochloride silver wire (05mmdiameter) and silver chloride used for preparation ofelectrodes were purchased from Sigma-Aldrich (St Louis
MO USA) Acetonitrile methanol potassium phosphatemonobasic (KH
2PO4) and PBS (phosphate buffered saline)
were purchased from Fisher Scientific (NJ USA) Transporetape for tape stripping was obtained from 3M (St Paul MNUSA) Deionized water was used to prepare all the solutionsrequired in this study and for HPLC analysis Iontophoresispower supply unit (Model 6221) was purchased fromKeithleyInstruments (Cleveland OH USA)
22 Methods
221 Skin Isolation and Preparation Porcine skin wasobtained from a local abattoir Whole skin was excisedfollowed by the removal of subcutaneous fat The skin wasthen cleaned using deionized water and stored at minus20∘C inaluminum foil until use Skin was thawed before permeationstudies cut into appropriate sizes and mounted on theFranz diffusion cells (PermeGear Hellertown PA USA) withstratum corneum side facing the donor compartment andsecured into place using clamps
222 Preparation of Electrodes A planar coil of silver wasprepared manually and used as the anode in the studyThe cathode was custom made by coating a melt of silverchloride on silver wire Coating was done until a uniform andsufficient coat of the silver chloride was obtained
223 Continuous versus Modulated Iontophoresis Contin-uous and modulated iontophoresis were applied for theduration of one and two hours The anode was placedin the donor chamber and the cathode was inserted intothe receptor compartment through the sampling arm toperform anodal iontophoresis A continuous direct current(DC) iontophoresis at current density of 05mAcm2 andalternating current (AC) iontophoresis at a frequency of1 kHz and current density of 05mAcm2 were applied usingKeithley instrument (Model 6221 Cleveland OH USA) forone hour from 0 to 1 h
To determine the effect of iontophoresis on transdermaldelivery of lidocaine continuous direct current iontophore-sis was applied for one hour from 0 to 1 h and modulateddirect current iontophoresis at current density of 05mAcm2was applied for two hours (from 0 to 1 h and from 4 to5th h) while modulated alternating current iontophoresis ata frequency of 1 kHz and current density of 05mAcm2 wasalso applied for two hours (from 0 to 1 h and from 4 to 5th h)respectively on porcine full thickness skin Our group hasalso reported that flux recovers back to the normal level intwo to three hours after iontophoresis [16]Therefore we keptinterim period of 3 h between two iontophoresis applicationsReceptor samples (05mL) were collected at predeterminedtime intervals during the study
224 Permeation Studies In this study the influence ofanodal iontophoresis on the delivery of lidocaine hydrochlo-ride into porcine full thickness skin was investigated andpassive diffusion was used as the control in the study In vitropermeation studies (119899 ge 3) were performed using vertical
BioMed Research International 3
Franz diffusion cells Receptor compartment was thoroughlywashed prior to the study and then filled with receptorbuffer (5mL 1X PBS pH 74) The temperature of the cellswas maintained at 37∘C during the study by using a watercirculation jacket built around receptor chamber Porcineskin was mounted on the receptor compartments (effectivearea of diffusion was 064 cm2) with the stratum corneumfacing the donor chamber Donor chambers were then placedon the mounted skin and secured into place using clampsLidocaine (1wv) solution in deionized water was used asthe donor (05mL) for the study Sodium chloride (23mM)was added to the donor solution to drive the electrochemistryof the silver-silver chloride electrodes Samples (05mL) werewithdrawn from the receptor compartment at predeterminedtime intervals over a period of 24 h and replenished withequal volume of fresh receptor buffer Samples obtained wereanalyzed using high performance liquid chromatography(HPLC) assay After the permeation studies tape strippingand skin extraction studies were performed to quantifydrug levels in the stratum corneum and the stripped skinrespectively
Lidocaine is a small molecule and is categorized phar-macologically as local anesthetic and antiarrhythmic drugIt is lipophilic in base form with a log 119875 of 26 whilethe hydrochloride salt of drug (used here) is hydrophilicin nature with log 119875 le 0 [17] The salt form of drug wasused for the study as active enhancement techniques likeiontophoresis require the drug to be hydrophilic and incharged form for the delivery also salt form of drug has theability to provide the chloride ions which is essential forthe completion of electrochemical reaction at anode whensilversilver chloride electrodes are used for iontophoresis[18]The electrochemistry at anode and cathode is as follows
Anode
Ag + Clminus 997888rarr AgCl + eminus (1)
Cathode
AgCl + eminus 997888rarr Ag + Clminus (2)
For salt form of the drug log 119863 (logarithm of distributioncoefficient) is used which is the partition between organicand buffer phase and is determined by degree of ionization ofmolecule at a particular pHandpKa [19] log119863was calculatedby (3) as follows [20]
log119863 = log119875 minus log (1 + 10 and (pKa minus pH)) (3)
The log 119863 value of compound also determines its abilityto ionize at given pH condition so the effectiveness oftransport by iontophoresis through electrorepulsion can bedetermined Lidocaine hydrochloride has a log 119863 of 157(calculated from (3)) at pH 74 and the drug has pKa of79 hence at pH of 74 it will be positively charged andanodal iontophoresis will actively transport lidocaine byelectrorepulsion
225 Skin Extraction Skin extraction procedure was per-formed to determine the drug levels in skin Skin sampleswere removed from Franz diffusion cells at the end ofpermeation studies The skin surface was then thoroughlycleaned by dabbing it three times with Q-tips soaked inreceptor medium Skin was then tape stripped using 3MTranspore tapes to determine the amount of drug permeatedin stratum corneum The first five tape strips were extractedindividually and remaining tape strips were extracted in agroup of five Kim wipes were used to dry the skin surfaceAfter tape stripping skin samples were minced manuallyusing a pair of scissors and added to scintillation vials PBS(1X pH74) was used as an extraction solvent and was addedtominced skinThe extraction was carried out by shaking thevials overnight on the roller shaker (NewBrunswick ScientificCo Inc NJ USA) The samples were then centrifuged at13400 g for 2min at 200 rpm and the supernatant extract wasfiltered by using 045 120583mfilters (Milipore) and analyzed usingHPLC assay
226 Quantitative Analysis Lidocaine hydrochloride wasquantified using HPLC by using modified assay from litera-ture HPLC analysis was performed on Perkin Elmer System(Waltham MA) with a UV detector operating at 230 nmColumn used was RP-18 Phenomenex column (Luna 5120583C18 100A 250mm times 46mm Phenomenex Torrance CAUSA) Mobile phase consisted of methanol 01M sodiumdihydrogen phosphate (60 40 vv) Isocratic elution wasperformed at a flow rate of 06mLmin after injecting 10120583L ofsample the total run time was 10min and the retention timeof lidocaine hydrochloride was around 604min The Lowerlimit of detection (LOD) was 005120583g and the lower limit ofquantification (LOQ) was 01 120583g Standards were prepared inthe range of 01ndash100120583g The assay was sensitive for range ofinterest
227 Statistical Analysis Statistical significance was deter-mined using one-way analysis of variance (ANOVA) andDunnettrsquos test using GraphPad Prism software (version 50d)All results are reported as mean plusmn SD (119899 = 3) Values wereconsidered significantly different when 119875 le 05
3 Results and Discussion
31 Iontophoretic Drug Transport Mechanism Anodal ion-tophoresis was performed for one or two hours using alter-nating and direct current (Figure 1) to determine the effectof iontophoresis on the delivery of lidocaine hydrochlo-ride through porcine full thickness skin The present studyrevealed that both the DC and AC iontophoreses enhancedthe delivery of lidocaine hydrochloride through porcine skinStudies have demonstrated that the mechanisms responsiblefor the transport of drug substance after DC iontophore-sis are electrorepulsion electroosmosis and increased skinpermeability [21] It has been reported that electrorepulsionand electroosmosis are involved in transport of lidocaineafter the application of AC iontophoresis at low frequencyLidocaine used in the study is dissociated into positively
4 BioMed Research International
Current source+ minus
Figure 1 Iontophoretic setup that was used for iontophoreticstudies of lidocaine silver wire (represented in red) served asthe anode (active electrode) and silver wire coated with silverchloride (represented in black) serve as cathodeThe electrodes wereconnected to a current source to perform anodal iontophoresis
charged lidocaine and hydrogen ions along with negativelycharged chloride ions During electrorepulsion the chargedsubstances are repelled from the electrode of same polarity[22] Positively charge lidocaine ions would be similarlyrepelled during the positive phase of AC iontophoresisTransport mechanism of the substance after the applicationof electric field can be explained by following (4) [10]
119869L = 119869119901 + 119869er + 119869eo (4)
where 119869L is the mole flux of the substance L Jp is thepassive flux 119869er represents electrorepulsive contribution and119869eo depicts the electroosmotic flux Therefore both elec-trorepulsion and electroosmosis are the major mechanismsresponsible for the delivery of lidocaine hydrochloride afterAC and DC iontophoresis
32 Effect of Continuous Iontophoresis on Lidocaine Deliv-ery through Porcine Skin Continuous iontophoresis usingalternating and direct current iontophoresis enhanced thedelivery of lidocaine into porcine full thickness skin ascompared to passive diffusionThe amount of drug deliveredafter continuous DC iontophoresis for one hour was 68476plusmn2481 120583gsqsdotcm compared to 9127plusmn1871 120583gcm2 for passivedelivery (Figure 2) Continuous iontophoresis resulted in asteady rise of drug delivered when the current was appliedand the highest flux was 10659 plusmn 585 120583gcm2h at 2 h forDC iontophoresis after which the flux decreases gradually(Figure 3)
33 Effect of Modulated Iontophoresis on Lidocaine Deliverythrough Porcine Skin To determine the effect of modulatediontophoresis on the delivery of lidocaine modulated anodaliontophoresis (05mAcm2) using direct and alternatingcurrent iontophoresis was performed for two hours (from0-1 h and 4-5th h) on porcine full thickness skin and passivediffusion served as the control for the study
0
200
400
600
800
1000
1200
1400
0 1 2 3 4 5 6 10 12 22 24
Aver
age c
umul
ativ
e am
ount
Time (hr)
Modulated iontophoretic delivery of lidocaine hydrochloride
of d
rug
(120583g
sqcm
plusmnSD
)
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
lowast
Figure 2 Cumulative amount of lidocaine delivered throughfull thickness porcine ear skin after continuous and modulatediontophoresis (lowast119875 lt 005 versus passive mean plusmn SD 119899 = 3)
0
50
100
150
200
250
300
350
400
0 1 2 3 4 5 6 10 12 22 24 Time (hr)
Transdermal flux of lidocaine hydrochloride
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
Flux
(120583g
sqcm
h)
lowast
Figure 3 Flux of lidocaine across full thickness pig ear skin aftercontinuous and modulated iontophoresis (lowast119875 lt 005 versus passivemean plusmn SD 119899 = 3)
Modulated iontophoresis enhanced the delivery of lido-caine significantly (119875 lt 005) from 9127 plusmn 1871 120583gcm2 forpassive delivery to 74481plusmn12541 120583gcm2 forAC iontophore-sis and 106987 plusmn 12001 120583gcm2 for DC iontophoresis Theamount of drug delivered by modulated alternating currentiontophoresis for duration of two hours at frequency of 1 kHzwas found to be comparable to the drug delivered by con-tinuous direct current iontophoresis for one hour as 74481 plusmn12541 120583gcm2 of lidocaine was delivered aftermodulated ACiontophoresis compared to 68476 plusmn 2481 120583gsqsdotcm2 afterone hour of continuous DC iontophoresis at the end of 24 h
BioMed Research International 5
study respectively (Figure 2) Plot of average flux versus time(Figure 3) shows that amount of lidocaine delivered at a par-ticular time point depends on the current appliedModulatediontophoresis (0-1 h + 4-5 h) resulted in increased flux ateach time period of current application during the durationof study that is 8968 plusmn 3578 120583gcm2h at 2 h and 6406 plusmn1661 120583gcm2h at 6 h for AC iontophoresis compared to16296 plusmn 4158 120583gcm2h at 2 h and 24887 plusmn 11695 120583gcm2hat 6 h for DC iontophoresis The study was continued till24 h to observe the postiontophoretic permeation and fluxdecreased gradually during the time period of the study Theamount of drug delivered by modulated alternating currentiontophoresis for total duration of two hours at frequencyof 1 kHz was found to be comparable to the drug deliveredby continuous direct current iontophoresis for one hourThis may be due to the periodic polarity alteration duringalternating current It has also been reported that the drivingforce of the alternating current is less compared to thatwith application of direct current due to periodic polarityalteration [10]
34 Drug Levels in Skin Layers following Iontophoresis StudiesTape stripping was done to quantify the amount of drugdelivered into the stratum corneum After tape stripping thestripped skin was minced and extracted with 1 times PBS pH 74to quantify the drug level in stripped skin The amount ofdrug delivered into the stratum corneum and stripped skinby anodal iontophoresis using alternating current and directcurrent iontophoresis was significantly (119875 lt 005) highercompared to the passive diffusion as demonstrated in Figures4 and 5 The average total amount of drug delivered intostripped skin following iontophoresis was also significantly(119875 lt 005) higher compared to the passive delivery The druglevels delivered into stripped skin following iontophoresiswere 3968 plusmn 111 120583g for AC iontophoresis and 4198 plusmn1309 120583g for DC iontophoresis for two hours which was5-fold higher than passive delivery (885 plusmn 269 120583g) Theseresults demonstrate the presence of rate limiting step whichrestricts the movement of drug into the stripped skin Thisrate-limiting step was however overcome by iontophoresisas the application of current was able to propel higher levelof drug into deeper skin layers as compared to passivediffusion Quantification of lidocaine in the skin establishedthat stratum corneum was the barrier to the delivery of thisdrug as a negligible amount was detected in the skin afterpassive delivery
4 Conclusions
Results of the iontophoretic studies demonstrated that anodaliontophoresis enhanced the delivery of lidocaine hydrochlo-ride into and across the porcine skin Direct current ion-tophoresis enhanced the permeation of lidocaine hydrochlo-ride by twelvefold compared to passive diffusion Direct cur-rent iontophoresis was also found to be more effective thanalternating current iontophoresis in enhancing the deliveryof lidocaine hydrochloride into and across the porcine skin
0
10
20
30
40
50
60
70
80
Aver
age a
mou
nt o
f dru
g
Drug in stratum corneum
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
in st
ratu
m co
rneu
m (120583
gplusmn
SD) lowast
Figure 4 Average amount of drug in stratum corneum followingiontophoresis and passive delivery (lowast119875 lt 005 versus passive meanplusmn SD 119899 = 3)
0
10
20
30
40
50
60
Aver
age a
mou
nt o
f dru
g in
Drug in stripped skin
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
strip
ped
skin
(120583gplusmn
SD)
lowast
Figure 5 Average amount of drug in stripped skin followingiontophoresis and passive delivery (lowast119875 lt 005 versus passive meanplusmn SD 119899 = 3)
Conflict of Interests
The authors declare that there is no conflict of interests
References
[1] D W Smith M R Peterson and S C DeBerard ldquoRegionalanesthesia nerve blocks of the extremities and facerdquo Postgrad-uate Medicine vol 106 no 4 pp 69ndash73 1999
[2] LHu SMC Silva B BDamaj RMartin andB BMichniak-Kohn ldquoTransdermal and transbuccal drug delivery systemsenhancement using iontophoretic and chemical approachesrdquoInternational Journal of Pharmaceutics vol 421 no 1 pp 53ndash62 2011
[3] H R Shah E Reichel and B G Busbee ldquoA novel lidocainehydrochloride ophthalmic gel for topical ocular anesthesiardquoLocal and Regional Anesthesia vol 3 no 1 pp 57ndash63 2010
[4] P J Lee N Ahmad R Langer S Mitragotri and V P ShastrildquoEvaluation of chemical enhancers in the transdermal deliveryof lidocainerdquo International Journal of Pharmaceutics vol 308no 1-2 pp 33ndash39 2006
6 BioMed Research International
[5] Y Wanga W Su Q Li et al ldquoPreparation and evaluationof lidocaine hydrochloride loaded TAT-conjugated polymericliposomes for transdermal deliveryrdquo International Journal ofPharmaceutics vol 441 no 1-2 pp 748ndash756 2013
[6] Y Zhang K Siebenaler K BrownDDohmeier andKHansenldquoAdjuvants to prolong the local anesthetic effects of coatedmicroneedle productsrdquo International Journal of Pharmaceuticsvol 439 no 1-2 pp 187ndash192 2012
[7] E Trovatti C Freire P C Pinto et al ldquoBacterial cellulosemembranes applied in topical and transdermal delivery of lido-caine hydrochloride and ibuprofen in vitro diffusion studiesrdquoInternational Journal of Pharmaceutics vol 435 no 1 pp 83ndash87 2012
[8] J S Yuan M Ansari M Samaan and E J Acosta ldquoLinker-based lecithin microemulsions for transdermal delivery oflidocainerdquo International Journal of Pharmaceutics vol 349 no1-2 pp 130ndash143 2008
[9] AK BangaTransdermal and IntradermalDelivery ofTherapeu-tic Agents Application of Physical Technologies pp 81ndash94 CRCPress Taylor amp Francis Group 2011
[10] S Hayashi S Ogami T Shibaji and M Umino ldquoLidocainetransport through a cellophane membrane by alternating cur-rent iontophoresis with a duty cyclerdquo Bioelectrochemistry vol74 no 2 pp 315ndash322 2009
[11] G Yan S K Li and W I Higuchi ldquoEvaluation of constantcurrent alternating current iontophoresis for transdermal drugdeliveryrdquo Journal of Controlled Release vol 110 no 1 pp 141ndash150 2005
[12] J P Howard T R Drake and D L Kellogg ldquoEffects ofalternating current iontophoresis on drug deliveryrdquo Archives ofPhysicalMedicine and Rehabilitation vol 76 no 5 pp 463ndash4661995
[13] J M DeCou R S Abrams J H Hammond L R Lowderand M W L Gauderer ldquoIontophoresis a needle-free electricalsystem of local anesthesia delivery for pediatric surgical officeproceduresrdquo Journal of Pediatric Surgery vol 34 no 6 pp 946ndash949 1999
[14] W T Zempsky and T M Parkinson ldquoLidocaine iontophoresisfor topical anesthesia before dermatologic procedures in chil-dren a randomized controlled trialrdquoPediatric Dermatology vol20 no 4 pp 364ndash368 2003
[15] M Ashburn M Gauthier G Love S Basta B Gaylord andK Kessler ldquoIontophoretic administration of 2 lidocaine HCLand 1100 000 epinephrine inmanrdquoTheClinical Journal of Painvol 13 no 1 pp 1322ndash1326 1997
[16] V Kumar and A K Banga ldquoModulated iontophoretic deliveryof small and large molecules through microchannelsrdquo Interna-tional Journal of Pharmaceutics vol 434 no 1-2 pp 106ndash1142012
[17] P D Sawant D Luu R Ye and R Buchta ldquoDrug releasefrom hydroethanolic gels Effect of drugrsquos lipophilicity (log P)polymer-drug interactions and solvent lipophilicityrdquo Interna-tional Journal of Pharmaceutics vol 396 no 1-2 pp 45ndash52 2010
[18] Y N Kalia A Naik J Garrison and R H Guy ldquoIontophoreticdrug deliveryrdquo Advanced Drug Delivery Reviews vol 56 no 5pp 619ndash658 2004
[19] V Sachdeva S Siddoju Y Yu H D Kim P M Friden andA K Banga ldquoTransdermal iontophoretic delivery of terbinafinehydrochloride quantitation of drug levels in stratum corneumand underlying skinrdquo International Journal of Pharmaceuticsvol 388 no 1-2 pp 24ndash31 2010
[20] M Kah and C D Brown ldquoLog D lipophilicity for ionisablecompoundsrdquo Chemosphere vol 72 no 10 pp 1401ndash1408 2008
[21] H Haga T Shibaji and M Umino ldquoLidocaine transportthrough living rat skin using alternating currentrdquo Medical andBiological Engineering and Computing vol 43 no 5 pp 622ndash629 2005
[22] A C Sintov and R B Sitton ldquoFacilitated skin penetrationof lidocaine combination of a short-term iontophoresis andmicroemulsion formulationrdquo International Journal of Pharma-ceutics vol 316 no 1-2 pp 58ndash67 2006
Submit your manuscripts athttpwwwhindawicom
PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Franz diffusion cells Receptor compartment was thoroughlywashed prior to the study and then filled with receptorbuffer (5mL 1X PBS pH 74) The temperature of the cellswas maintained at 37∘C during the study by using a watercirculation jacket built around receptor chamber Porcineskin was mounted on the receptor compartments (effectivearea of diffusion was 064 cm2) with the stratum corneumfacing the donor chamber Donor chambers were then placedon the mounted skin and secured into place using clampsLidocaine (1wv) solution in deionized water was used asthe donor (05mL) for the study Sodium chloride (23mM)was added to the donor solution to drive the electrochemistryof the silver-silver chloride electrodes Samples (05mL) werewithdrawn from the receptor compartment at predeterminedtime intervals over a period of 24 h and replenished withequal volume of fresh receptor buffer Samples obtained wereanalyzed using high performance liquid chromatography(HPLC) assay After the permeation studies tape strippingand skin extraction studies were performed to quantifydrug levels in the stratum corneum and the stripped skinrespectively
Lidocaine is a small molecule and is categorized phar-macologically as local anesthetic and antiarrhythmic drugIt is lipophilic in base form with a log 119875 of 26 whilethe hydrochloride salt of drug (used here) is hydrophilicin nature with log 119875 le 0 [17] The salt form of drug wasused for the study as active enhancement techniques likeiontophoresis require the drug to be hydrophilic and incharged form for the delivery also salt form of drug has theability to provide the chloride ions which is essential forthe completion of electrochemical reaction at anode whensilversilver chloride electrodes are used for iontophoresis[18]The electrochemistry at anode and cathode is as follows
Anode
Ag + Clminus 997888rarr AgCl + eminus (1)
Cathode
AgCl + eminus 997888rarr Ag + Clminus (2)
For salt form of the drug log 119863 (logarithm of distributioncoefficient) is used which is the partition between organicand buffer phase and is determined by degree of ionization ofmolecule at a particular pHandpKa [19] log119863was calculatedby (3) as follows [20]
log119863 = log119875 minus log (1 + 10 and (pKa minus pH)) (3)
The log 119863 value of compound also determines its abilityto ionize at given pH condition so the effectiveness oftransport by iontophoresis through electrorepulsion can bedetermined Lidocaine hydrochloride has a log 119863 of 157(calculated from (3)) at pH 74 and the drug has pKa of79 hence at pH of 74 it will be positively charged andanodal iontophoresis will actively transport lidocaine byelectrorepulsion
225 Skin Extraction Skin extraction procedure was per-formed to determine the drug levels in skin Skin sampleswere removed from Franz diffusion cells at the end ofpermeation studies The skin surface was then thoroughlycleaned by dabbing it three times with Q-tips soaked inreceptor medium Skin was then tape stripped using 3MTranspore tapes to determine the amount of drug permeatedin stratum corneum The first five tape strips were extractedindividually and remaining tape strips were extracted in agroup of five Kim wipes were used to dry the skin surfaceAfter tape stripping skin samples were minced manuallyusing a pair of scissors and added to scintillation vials PBS(1X pH74) was used as an extraction solvent and was addedtominced skinThe extraction was carried out by shaking thevials overnight on the roller shaker (NewBrunswick ScientificCo Inc NJ USA) The samples were then centrifuged at13400 g for 2min at 200 rpm and the supernatant extract wasfiltered by using 045 120583mfilters (Milipore) and analyzed usingHPLC assay
226 Quantitative Analysis Lidocaine hydrochloride wasquantified using HPLC by using modified assay from litera-ture HPLC analysis was performed on Perkin Elmer System(Waltham MA) with a UV detector operating at 230 nmColumn used was RP-18 Phenomenex column (Luna 5120583C18 100A 250mm times 46mm Phenomenex Torrance CAUSA) Mobile phase consisted of methanol 01M sodiumdihydrogen phosphate (60 40 vv) Isocratic elution wasperformed at a flow rate of 06mLmin after injecting 10120583L ofsample the total run time was 10min and the retention timeof lidocaine hydrochloride was around 604min The Lowerlimit of detection (LOD) was 005120583g and the lower limit ofquantification (LOQ) was 01 120583g Standards were prepared inthe range of 01ndash100120583g The assay was sensitive for range ofinterest
227 Statistical Analysis Statistical significance was deter-mined using one-way analysis of variance (ANOVA) andDunnettrsquos test using GraphPad Prism software (version 50d)All results are reported as mean plusmn SD (119899 = 3) Values wereconsidered significantly different when 119875 le 05
3 Results and Discussion
31 Iontophoretic Drug Transport Mechanism Anodal ion-tophoresis was performed for one or two hours using alter-nating and direct current (Figure 1) to determine the effectof iontophoresis on the delivery of lidocaine hydrochlo-ride through porcine full thickness skin The present studyrevealed that both the DC and AC iontophoreses enhancedthe delivery of lidocaine hydrochloride through porcine skinStudies have demonstrated that the mechanisms responsiblefor the transport of drug substance after DC iontophore-sis are electrorepulsion electroosmosis and increased skinpermeability [21] It has been reported that electrorepulsionand electroosmosis are involved in transport of lidocaineafter the application of AC iontophoresis at low frequencyLidocaine used in the study is dissociated into positively
4 BioMed Research International
Current source+ minus
Figure 1 Iontophoretic setup that was used for iontophoreticstudies of lidocaine silver wire (represented in red) served asthe anode (active electrode) and silver wire coated with silverchloride (represented in black) serve as cathodeThe electrodes wereconnected to a current source to perform anodal iontophoresis
charged lidocaine and hydrogen ions along with negativelycharged chloride ions During electrorepulsion the chargedsubstances are repelled from the electrode of same polarity[22] Positively charge lidocaine ions would be similarlyrepelled during the positive phase of AC iontophoresisTransport mechanism of the substance after the applicationof electric field can be explained by following (4) [10]
119869L = 119869119901 + 119869er + 119869eo (4)
where 119869L is the mole flux of the substance L Jp is thepassive flux 119869er represents electrorepulsive contribution and119869eo depicts the electroosmotic flux Therefore both elec-trorepulsion and electroosmosis are the major mechanismsresponsible for the delivery of lidocaine hydrochloride afterAC and DC iontophoresis
32 Effect of Continuous Iontophoresis on Lidocaine Deliv-ery through Porcine Skin Continuous iontophoresis usingalternating and direct current iontophoresis enhanced thedelivery of lidocaine into porcine full thickness skin ascompared to passive diffusionThe amount of drug deliveredafter continuous DC iontophoresis for one hour was 68476plusmn2481 120583gsqsdotcm compared to 9127plusmn1871 120583gcm2 for passivedelivery (Figure 2) Continuous iontophoresis resulted in asteady rise of drug delivered when the current was appliedand the highest flux was 10659 plusmn 585 120583gcm2h at 2 h forDC iontophoresis after which the flux decreases gradually(Figure 3)
33 Effect of Modulated Iontophoresis on Lidocaine Deliverythrough Porcine Skin To determine the effect of modulatediontophoresis on the delivery of lidocaine modulated anodaliontophoresis (05mAcm2) using direct and alternatingcurrent iontophoresis was performed for two hours (from0-1 h and 4-5th h) on porcine full thickness skin and passivediffusion served as the control for the study
0
200
400
600
800
1000
1200
1400
0 1 2 3 4 5 6 10 12 22 24
Aver
age c
umul
ativ
e am
ount
Time (hr)
Modulated iontophoretic delivery of lidocaine hydrochloride
of d
rug
(120583g
sqcm
plusmnSD
)
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
lowast
Figure 2 Cumulative amount of lidocaine delivered throughfull thickness porcine ear skin after continuous and modulatediontophoresis (lowast119875 lt 005 versus passive mean plusmn SD 119899 = 3)
0
50
100
150
200
250
300
350
400
0 1 2 3 4 5 6 10 12 22 24 Time (hr)
Transdermal flux of lidocaine hydrochloride
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
Flux
(120583g
sqcm
h)
lowast
Figure 3 Flux of lidocaine across full thickness pig ear skin aftercontinuous and modulated iontophoresis (lowast119875 lt 005 versus passivemean plusmn SD 119899 = 3)
Modulated iontophoresis enhanced the delivery of lido-caine significantly (119875 lt 005) from 9127 plusmn 1871 120583gcm2 forpassive delivery to 74481plusmn12541 120583gcm2 forAC iontophore-sis and 106987 plusmn 12001 120583gcm2 for DC iontophoresis Theamount of drug delivered by modulated alternating currentiontophoresis for duration of two hours at frequency of 1 kHzwas found to be comparable to the drug delivered by con-tinuous direct current iontophoresis for one hour as 74481 plusmn12541 120583gcm2 of lidocaine was delivered aftermodulated ACiontophoresis compared to 68476 plusmn 2481 120583gsqsdotcm2 afterone hour of continuous DC iontophoresis at the end of 24 h
BioMed Research International 5
study respectively (Figure 2) Plot of average flux versus time(Figure 3) shows that amount of lidocaine delivered at a par-ticular time point depends on the current appliedModulatediontophoresis (0-1 h + 4-5 h) resulted in increased flux ateach time period of current application during the durationof study that is 8968 plusmn 3578 120583gcm2h at 2 h and 6406 plusmn1661 120583gcm2h at 6 h for AC iontophoresis compared to16296 plusmn 4158 120583gcm2h at 2 h and 24887 plusmn 11695 120583gcm2hat 6 h for DC iontophoresis The study was continued till24 h to observe the postiontophoretic permeation and fluxdecreased gradually during the time period of the study Theamount of drug delivered by modulated alternating currentiontophoresis for total duration of two hours at frequencyof 1 kHz was found to be comparable to the drug deliveredby continuous direct current iontophoresis for one hourThis may be due to the periodic polarity alteration duringalternating current It has also been reported that the drivingforce of the alternating current is less compared to thatwith application of direct current due to periodic polarityalteration [10]
34 Drug Levels in Skin Layers following Iontophoresis StudiesTape stripping was done to quantify the amount of drugdelivered into the stratum corneum After tape stripping thestripped skin was minced and extracted with 1 times PBS pH 74to quantify the drug level in stripped skin The amount ofdrug delivered into the stratum corneum and stripped skinby anodal iontophoresis using alternating current and directcurrent iontophoresis was significantly (119875 lt 005) highercompared to the passive diffusion as demonstrated in Figures4 and 5 The average total amount of drug delivered intostripped skin following iontophoresis was also significantly(119875 lt 005) higher compared to the passive delivery The druglevels delivered into stripped skin following iontophoresiswere 3968 plusmn 111 120583g for AC iontophoresis and 4198 plusmn1309 120583g for DC iontophoresis for two hours which was5-fold higher than passive delivery (885 plusmn 269 120583g) Theseresults demonstrate the presence of rate limiting step whichrestricts the movement of drug into the stripped skin Thisrate-limiting step was however overcome by iontophoresisas the application of current was able to propel higher levelof drug into deeper skin layers as compared to passivediffusion Quantification of lidocaine in the skin establishedthat stratum corneum was the barrier to the delivery of thisdrug as a negligible amount was detected in the skin afterpassive delivery
4 Conclusions
Results of the iontophoretic studies demonstrated that anodaliontophoresis enhanced the delivery of lidocaine hydrochlo-ride into and across the porcine skin Direct current ion-tophoresis enhanced the permeation of lidocaine hydrochlo-ride by twelvefold compared to passive diffusion Direct cur-rent iontophoresis was also found to be more effective thanalternating current iontophoresis in enhancing the deliveryof lidocaine hydrochloride into and across the porcine skin
0
10
20
30
40
50
60
70
80
Aver
age a
mou
nt o
f dru
g
Drug in stratum corneum
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
in st
ratu
m co
rneu
m (120583
gplusmn
SD) lowast
Figure 4 Average amount of drug in stratum corneum followingiontophoresis and passive delivery (lowast119875 lt 005 versus passive meanplusmn SD 119899 = 3)
0
10
20
30
40
50
60
Aver
age a
mou
nt o
f dru
g in
Drug in stripped skin
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
strip
ped
skin
(120583gplusmn
SD)
lowast
Figure 5 Average amount of drug in stripped skin followingiontophoresis and passive delivery (lowast119875 lt 005 versus passive meanplusmn SD 119899 = 3)
Conflict of Interests
The authors declare that there is no conflict of interests
References
[1] D W Smith M R Peterson and S C DeBerard ldquoRegionalanesthesia nerve blocks of the extremities and facerdquo Postgrad-uate Medicine vol 106 no 4 pp 69ndash73 1999
[2] LHu SMC Silva B BDamaj RMartin andB BMichniak-Kohn ldquoTransdermal and transbuccal drug delivery systemsenhancement using iontophoretic and chemical approachesrdquoInternational Journal of Pharmaceutics vol 421 no 1 pp 53ndash62 2011
[3] H R Shah E Reichel and B G Busbee ldquoA novel lidocainehydrochloride ophthalmic gel for topical ocular anesthesiardquoLocal and Regional Anesthesia vol 3 no 1 pp 57ndash63 2010
[4] P J Lee N Ahmad R Langer S Mitragotri and V P ShastrildquoEvaluation of chemical enhancers in the transdermal deliveryof lidocainerdquo International Journal of Pharmaceutics vol 308no 1-2 pp 33ndash39 2006
6 BioMed Research International
[5] Y Wanga W Su Q Li et al ldquoPreparation and evaluationof lidocaine hydrochloride loaded TAT-conjugated polymericliposomes for transdermal deliveryrdquo International Journal ofPharmaceutics vol 441 no 1-2 pp 748ndash756 2013
[6] Y Zhang K Siebenaler K BrownDDohmeier andKHansenldquoAdjuvants to prolong the local anesthetic effects of coatedmicroneedle productsrdquo International Journal of Pharmaceuticsvol 439 no 1-2 pp 187ndash192 2012
[7] E Trovatti C Freire P C Pinto et al ldquoBacterial cellulosemembranes applied in topical and transdermal delivery of lido-caine hydrochloride and ibuprofen in vitro diffusion studiesrdquoInternational Journal of Pharmaceutics vol 435 no 1 pp 83ndash87 2012
[8] J S Yuan M Ansari M Samaan and E J Acosta ldquoLinker-based lecithin microemulsions for transdermal delivery oflidocainerdquo International Journal of Pharmaceutics vol 349 no1-2 pp 130ndash143 2008
[9] AK BangaTransdermal and IntradermalDelivery ofTherapeu-tic Agents Application of Physical Technologies pp 81ndash94 CRCPress Taylor amp Francis Group 2011
[10] S Hayashi S Ogami T Shibaji and M Umino ldquoLidocainetransport through a cellophane membrane by alternating cur-rent iontophoresis with a duty cyclerdquo Bioelectrochemistry vol74 no 2 pp 315ndash322 2009
[11] G Yan S K Li and W I Higuchi ldquoEvaluation of constantcurrent alternating current iontophoresis for transdermal drugdeliveryrdquo Journal of Controlled Release vol 110 no 1 pp 141ndash150 2005
[12] J P Howard T R Drake and D L Kellogg ldquoEffects ofalternating current iontophoresis on drug deliveryrdquo Archives ofPhysicalMedicine and Rehabilitation vol 76 no 5 pp 463ndash4661995
[13] J M DeCou R S Abrams J H Hammond L R Lowderand M W L Gauderer ldquoIontophoresis a needle-free electricalsystem of local anesthesia delivery for pediatric surgical officeproceduresrdquo Journal of Pediatric Surgery vol 34 no 6 pp 946ndash949 1999
[14] W T Zempsky and T M Parkinson ldquoLidocaine iontophoresisfor topical anesthesia before dermatologic procedures in chil-dren a randomized controlled trialrdquoPediatric Dermatology vol20 no 4 pp 364ndash368 2003
[15] M Ashburn M Gauthier G Love S Basta B Gaylord andK Kessler ldquoIontophoretic administration of 2 lidocaine HCLand 1100 000 epinephrine inmanrdquoTheClinical Journal of Painvol 13 no 1 pp 1322ndash1326 1997
[16] V Kumar and A K Banga ldquoModulated iontophoretic deliveryof small and large molecules through microchannelsrdquo Interna-tional Journal of Pharmaceutics vol 434 no 1-2 pp 106ndash1142012
[17] P D Sawant D Luu R Ye and R Buchta ldquoDrug releasefrom hydroethanolic gels Effect of drugrsquos lipophilicity (log P)polymer-drug interactions and solvent lipophilicityrdquo Interna-tional Journal of Pharmaceutics vol 396 no 1-2 pp 45ndash52 2010
[18] Y N Kalia A Naik J Garrison and R H Guy ldquoIontophoreticdrug deliveryrdquo Advanced Drug Delivery Reviews vol 56 no 5pp 619ndash658 2004
[19] V Sachdeva S Siddoju Y Yu H D Kim P M Friden andA K Banga ldquoTransdermal iontophoretic delivery of terbinafinehydrochloride quantitation of drug levels in stratum corneumand underlying skinrdquo International Journal of Pharmaceuticsvol 388 no 1-2 pp 24ndash31 2010
[20] M Kah and C D Brown ldquoLog D lipophilicity for ionisablecompoundsrdquo Chemosphere vol 72 no 10 pp 1401ndash1408 2008
[21] H Haga T Shibaji and M Umino ldquoLidocaine transportthrough living rat skin using alternating currentrdquo Medical andBiological Engineering and Computing vol 43 no 5 pp 622ndash629 2005
[22] A C Sintov and R B Sitton ldquoFacilitated skin penetrationof lidocaine combination of a short-term iontophoresis andmicroemulsion formulationrdquo International Journal of Pharma-ceutics vol 316 no 1-2 pp 58ndash67 2006
Submit your manuscripts athttpwwwhindawicom
PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Figure 1 Iontophoretic setup that was used for iontophoreticstudies of lidocaine silver wire (represented in red) served asthe anode (active electrode) and silver wire coated with silverchloride (represented in black) serve as cathodeThe electrodes wereconnected to a current source to perform anodal iontophoresis
charged lidocaine and hydrogen ions along with negativelycharged chloride ions During electrorepulsion the chargedsubstances are repelled from the electrode of same polarity[22] Positively charge lidocaine ions would be similarlyrepelled during the positive phase of AC iontophoresisTransport mechanism of the substance after the applicationof electric field can be explained by following (4) [10]
119869L = 119869119901 + 119869er + 119869eo (4)
where 119869L is the mole flux of the substance L Jp is thepassive flux 119869er represents electrorepulsive contribution and119869eo depicts the electroosmotic flux Therefore both elec-trorepulsion and electroosmosis are the major mechanismsresponsible for the delivery of lidocaine hydrochloride afterAC and DC iontophoresis
32 Effect of Continuous Iontophoresis on Lidocaine Deliv-ery through Porcine Skin Continuous iontophoresis usingalternating and direct current iontophoresis enhanced thedelivery of lidocaine into porcine full thickness skin ascompared to passive diffusionThe amount of drug deliveredafter continuous DC iontophoresis for one hour was 68476plusmn2481 120583gsqsdotcm compared to 9127plusmn1871 120583gcm2 for passivedelivery (Figure 2) Continuous iontophoresis resulted in asteady rise of drug delivered when the current was appliedand the highest flux was 10659 plusmn 585 120583gcm2h at 2 h forDC iontophoresis after which the flux decreases gradually(Figure 3)
33 Effect of Modulated Iontophoresis on Lidocaine Deliverythrough Porcine Skin To determine the effect of modulatediontophoresis on the delivery of lidocaine modulated anodaliontophoresis (05mAcm2) using direct and alternatingcurrent iontophoresis was performed for two hours (from0-1 h and 4-5th h) on porcine full thickness skin and passivediffusion served as the control for the study
0
200
400
600
800
1000
1200
1400
0 1 2 3 4 5 6 10 12 22 24
Aver
age c
umul
ativ
e am
ount
Time (hr)
Modulated iontophoretic delivery of lidocaine hydrochloride
of d
rug
(120583g
sqcm
plusmnSD
)
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
lowast
Figure 2 Cumulative amount of lidocaine delivered throughfull thickness porcine ear skin after continuous and modulatediontophoresis (lowast119875 lt 005 versus passive mean plusmn SD 119899 = 3)
0
50
100
150
200
250
300
350
400
0 1 2 3 4 5 6 10 12 22 24 Time (hr)
Transdermal flux of lidocaine hydrochloride
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
Flux
(120583g
sqcm
h)
lowast
Figure 3 Flux of lidocaine across full thickness pig ear skin aftercontinuous and modulated iontophoresis (lowast119875 lt 005 versus passivemean plusmn SD 119899 = 3)
Modulated iontophoresis enhanced the delivery of lido-caine significantly (119875 lt 005) from 9127 plusmn 1871 120583gcm2 forpassive delivery to 74481plusmn12541 120583gcm2 forAC iontophore-sis and 106987 plusmn 12001 120583gcm2 for DC iontophoresis Theamount of drug delivered by modulated alternating currentiontophoresis for duration of two hours at frequency of 1 kHzwas found to be comparable to the drug delivered by con-tinuous direct current iontophoresis for one hour as 74481 plusmn12541 120583gcm2 of lidocaine was delivered aftermodulated ACiontophoresis compared to 68476 plusmn 2481 120583gsqsdotcm2 afterone hour of continuous DC iontophoresis at the end of 24 h
BioMed Research International 5
study respectively (Figure 2) Plot of average flux versus time(Figure 3) shows that amount of lidocaine delivered at a par-ticular time point depends on the current appliedModulatediontophoresis (0-1 h + 4-5 h) resulted in increased flux ateach time period of current application during the durationof study that is 8968 plusmn 3578 120583gcm2h at 2 h and 6406 plusmn1661 120583gcm2h at 6 h for AC iontophoresis compared to16296 plusmn 4158 120583gcm2h at 2 h and 24887 plusmn 11695 120583gcm2hat 6 h for DC iontophoresis The study was continued till24 h to observe the postiontophoretic permeation and fluxdecreased gradually during the time period of the study Theamount of drug delivered by modulated alternating currentiontophoresis for total duration of two hours at frequencyof 1 kHz was found to be comparable to the drug deliveredby continuous direct current iontophoresis for one hourThis may be due to the periodic polarity alteration duringalternating current It has also been reported that the drivingforce of the alternating current is less compared to thatwith application of direct current due to periodic polarityalteration [10]
34 Drug Levels in Skin Layers following Iontophoresis StudiesTape stripping was done to quantify the amount of drugdelivered into the stratum corneum After tape stripping thestripped skin was minced and extracted with 1 times PBS pH 74to quantify the drug level in stripped skin The amount ofdrug delivered into the stratum corneum and stripped skinby anodal iontophoresis using alternating current and directcurrent iontophoresis was significantly (119875 lt 005) highercompared to the passive diffusion as demonstrated in Figures4 and 5 The average total amount of drug delivered intostripped skin following iontophoresis was also significantly(119875 lt 005) higher compared to the passive delivery The druglevels delivered into stripped skin following iontophoresiswere 3968 plusmn 111 120583g for AC iontophoresis and 4198 plusmn1309 120583g for DC iontophoresis for two hours which was5-fold higher than passive delivery (885 plusmn 269 120583g) Theseresults demonstrate the presence of rate limiting step whichrestricts the movement of drug into the stripped skin Thisrate-limiting step was however overcome by iontophoresisas the application of current was able to propel higher levelof drug into deeper skin layers as compared to passivediffusion Quantification of lidocaine in the skin establishedthat stratum corneum was the barrier to the delivery of thisdrug as a negligible amount was detected in the skin afterpassive delivery
4 Conclusions
Results of the iontophoretic studies demonstrated that anodaliontophoresis enhanced the delivery of lidocaine hydrochlo-ride into and across the porcine skin Direct current ion-tophoresis enhanced the permeation of lidocaine hydrochlo-ride by twelvefold compared to passive diffusion Direct cur-rent iontophoresis was also found to be more effective thanalternating current iontophoresis in enhancing the deliveryof lidocaine hydrochloride into and across the porcine skin
0
10
20
30
40
50
60
70
80
Aver
age a
mou
nt o
f dru
g
Drug in stratum corneum
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
in st
ratu
m co
rneu
m (120583
gplusmn
SD) lowast
Figure 4 Average amount of drug in stratum corneum followingiontophoresis and passive delivery (lowast119875 lt 005 versus passive meanplusmn SD 119899 = 3)
0
10
20
30
40
50
60
Aver
age a
mou
nt o
f dru
g in
Drug in stripped skin
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
strip
ped
skin
(120583gplusmn
SD)
lowast
Figure 5 Average amount of drug in stripped skin followingiontophoresis and passive delivery (lowast119875 lt 005 versus passive meanplusmn SD 119899 = 3)
Conflict of Interests
The authors declare that there is no conflict of interests
References
[1] D W Smith M R Peterson and S C DeBerard ldquoRegionalanesthesia nerve blocks of the extremities and facerdquo Postgrad-uate Medicine vol 106 no 4 pp 69ndash73 1999
[2] LHu SMC Silva B BDamaj RMartin andB BMichniak-Kohn ldquoTransdermal and transbuccal drug delivery systemsenhancement using iontophoretic and chemical approachesrdquoInternational Journal of Pharmaceutics vol 421 no 1 pp 53ndash62 2011
[3] H R Shah E Reichel and B G Busbee ldquoA novel lidocainehydrochloride ophthalmic gel for topical ocular anesthesiardquoLocal and Regional Anesthesia vol 3 no 1 pp 57ndash63 2010
[4] P J Lee N Ahmad R Langer S Mitragotri and V P ShastrildquoEvaluation of chemical enhancers in the transdermal deliveryof lidocainerdquo International Journal of Pharmaceutics vol 308no 1-2 pp 33ndash39 2006
6 BioMed Research International
[5] Y Wanga W Su Q Li et al ldquoPreparation and evaluationof lidocaine hydrochloride loaded TAT-conjugated polymericliposomes for transdermal deliveryrdquo International Journal ofPharmaceutics vol 441 no 1-2 pp 748ndash756 2013
[6] Y Zhang K Siebenaler K BrownDDohmeier andKHansenldquoAdjuvants to prolong the local anesthetic effects of coatedmicroneedle productsrdquo International Journal of Pharmaceuticsvol 439 no 1-2 pp 187ndash192 2012
[7] E Trovatti C Freire P C Pinto et al ldquoBacterial cellulosemembranes applied in topical and transdermal delivery of lido-caine hydrochloride and ibuprofen in vitro diffusion studiesrdquoInternational Journal of Pharmaceutics vol 435 no 1 pp 83ndash87 2012
[8] J S Yuan M Ansari M Samaan and E J Acosta ldquoLinker-based lecithin microemulsions for transdermal delivery oflidocainerdquo International Journal of Pharmaceutics vol 349 no1-2 pp 130ndash143 2008
[9] AK BangaTransdermal and IntradermalDelivery ofTherapeu-tic Agents Application of Physical Technologies pp 81ndash94 CRCPress Taylor amp Francis Group 2011
[10] S Hayashi S Ogami T Shibaji and M Umino ldquoLidocainetransport through a cellophane membrane by alternating cur-rent iontophoresis with a duty cyclerdquo Bioelectrochemistry vol74 no 2 pp 315ndash322 2009
[11] G Yan S K Li and W I Higuchi ldquoEvaluation of constantcurrent alternating current iontophoresis for transdermal drugdeliveryrdquo Journal of Controlled Release vol 110 no 1 pp 141ndash150 2005
[12] J P Howard T R Drake and D L Kellogg ldquoEffects ofalternating current iontophoresis on drug deliveryrdquo Archives ofPhysicalMedicine and Rehabilitation vol 76 no 5 pp 463ndash4661995
[13] J M DeCou R S Abrams J H Hammond L R Lowderand M W L Gauderer ldquoIontophoresis a needle-free electricalsystem of local anesthesia delivery for pediatric surgical officeproceduresrdquo Journal of Pediatric Surgery vol 34 no 6 pp 946ndash949 1999
[14] W T Zempsky and T M Parkinson ldquoLidocaine iontophoresisfor topical anesthesia before dermatologic procedures in chil-dren a randomized controlled trialrdquoPediatric Dermatology vol20 no 4 pp 364ndash368 2003
[15] M Ashburn M Gauthier G Love S Basta B Gaylord andK Kessler ldquoIontophoretic administration of 2 lidocaine HCLand 1100 000 epinephrine inmanrdquoTheClinical Journal of Painvol 13 no 1 pp 1322ndash1326 1997
[16] V Kumar and A K Banga ldquoModulated iontophoretic deliveryof small and large molecules through microchannelsrdquo Interna-tional Journal of Pharmaceutics vol 434 no 1-2 pp 106ndash1142012
[17] P D Sawant D Luu R Ye and R Buchta ldquoDrug releasefrom hydroethanolic gels Effect of drugrsquos lipophilicity (log P)polymer-drug interactions and solvent lipophilicityrdquo Interna-tional Journal of Pharmaceutics vol 396 no 1-2 pp 45ndash52 2010
[18] Y N Kalia A Naik J Garrison and R H Guy ldquoIontophoreticdrug deliveryrdquo Advanced Drug Delivery Reviews vol 56 no 5pp 619ndash658 2004
[19] V Sachdeva S Siddoju Y Yu H D Kim P M Friden andA K Banga ldquoTransdermal iontophoretic delivery of terbinafinehydrochloride quantitation of drug levels in stratum corneumand underlying skinrdquo International Journal of Pharmaceuticsvol 388 no 1-2 pp 24ndash31 2010
[20] M Kah and C D Brown ldquoLog D lipophilicity for ionisablecompoundsrdquo Chemosphere vol 72 no 10 pp 1401ndash1408 2008
[21] H Haga T Shibaji and M Umino ldquoLidocaine transportthrough living rat skin using alternating currentrdquo Medical andBiological Engineering and Computing vol 43 no 5 pp 622ndash629 2005
[22] A C Sintov and R B Sitton ldquoFacilitated skin penetrationof lidocaine combination of a short-term iontophoresis andmicroemulsion formulationrdquo International Journal of Pharma-ceutics vol 316 no 1-2 pp 58ndash67 2006
Submit your manuscripts athttpwwwhindawicom
PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
study respectively (Figure 2) Plot of average flux versus time(Figure 3) shows that amount of lidocaine delivered at a par-ticular time point depends on the current appliedModulatediontophoresis (0-1 h + 4-5 h) resulted in increased flux ateach time period of current application during the durationof study that is 8968 plusmn 3578 120583gcm2h at 2 h and 6406 plusmn1661 120583gcm2h at 6 h for AC iontophoresis compared to16296 plusmn 4158 120583gcm2h at 2 h and 24887 plusmn 11695 120583gcm2hat 6 h for DC iontophoresis The study was continued till24 h to observe the postiontophoretic permeation and fluxdecreased gradually during the time period of the study Theamount of drug delivered by modulated alternating currentiontophoresis for total duration of two hours at frequencyof 1 kHz was found to be comparable to the drug deliveredby continuous direct current iontophoresis for one hourThis may be due to the periodic polarity alteration duringalternating current It has also been reported that the drivingforce of the alternating current is less compared to thatwith application of direct current due to periodic polarityalteration [10]
34 Drug Levels in Skin Layers following Iontophoresis StudiesTape stripping was done to quantify the amount of drugdelivered into the stratum corneum After tape stripping thestripped skin was minced and extracted with 1 times PBS pH 74to quantify the drug level in stripped skin The amount ofdrug delivered into the stratum corneum and stripped skinby anodal iontophoresis using alternating current and directcurrent iontophoresis was significantly (119875 lt 005) highercompared to the passive diffusion as demonstrated in Figures4 and 5 The average total amount of drug delivered intostripped skin following iontophoresis was also significantly(119875 lt 005) higher compared to the passive delivery The druglevels delivered into stripped skin following iontophoresiswere 3968 plusmn 111 120583g for AC iontophoresis and 4198 plusmn1309 120583g for DC iontophoresis for two hours which was5-fold higher than passive delivery (885 plusmn 269 120583g) Theseresults demonstrate the presence of rate limiting step whichrestricts the movement of drug into the stripped skin Thisrate-limiting step was however overcome by iontophoresisas the application of current was able to propel higher levelof drug into deeper skin layers as compared to passivediffusion Quantification of lidocaine in the skin establishedthat stratum corneum was the barrier to the delivery of thisdrug as a negligible amount was detected in the skin afterpassive delivery
4 Conclusions
Results of the iontophoretic studies demonstrated that anodaliontophoresis enhanced the delivery of lidocaine hydrochlo-ride into and across the porcine skin Direct current ion-tophoresis enhanced the permeation of lidocaine hydrochlo-ride by twelvefold compared to passive diffusion Direct cur-rent iontophoresis was also found to be more effective thanalternating current iontophoresis in enhancing the deliveryof lidocaine hydrochloride into and across the porcine skin
0
10
20
30
40
50
60
70
80
Aver
age a
mou
nt o
f dru
g
Drug in stratum corneum
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
in st
ratu
m co
rneu
m (120583
gplusmn
SD) lowast
Figure 4 Average amount of drug in stratum corneum followingiontophoresis and passive delivery (lowast119875 lt 005 versus passive meanplusmn SD 119899 = 3)
0
10
20
30
40
50
60
Aver
age a
mou
nt o
f dru
g in
Drug in stripped skin
PassiveDC ITP 1h
AC ITP (1 + 1h)DC ITP (1 + 1h)
strip
ped
skin
(120583gplusmn
SD)
lowast
Figure 5 Average amount of drug in stripped skin followingiontophoresis and passive delivery (lowast119875 lt 005 versus passive meanplusmn SD 119899 = 3)
Conflict of Interests
The authors declare that there is no conflict of interests
References
[1] D W Smith M R Peterson and S C DeBerard ldquoRegionalanesthesia nerve blocks of the extremities and facerdquo Postgrad-uate Medicine vol 106 no 4 pp 69ndash73 1999
[2] LHu SMC Silva B BDamaj RMartin andB BMichniak-Kohn ldquoTransdermal and transbuccal drug delivery systemsenhancement using iontophoretic and chemical approachesrdquoInternational Journal of Pharmaceutics vol 421 no 1 pp 53ndash62 2011
[3] H R Shah E Reichel and B G Busbee ldquoA novel lidocainehydrochloride ophthalmic gel for topical ocular anesthesiardquoLocal and Regional Anesthesia vol 3 no 1 pp 57ndash63 2010
[4] P J Lee N Ahmad R Langer S Mitragotri and V P ShastrildquoEvaluation of chemical enhancers in the transdermal deliveryof lidocainerdquo International Journal of Pharmaceutics vol 308no 1-2 pp 33ndash39 2006
6 BioMed Research International
[5] Y Wanga W Su Q Li et al ldquoPreparation and evaluationof lidocaine hydrochloride loaded TAT-conjugated polymericliposomes for transdermal deliveryrdquo International Journal ofPharmaceutics vol 441 no 1-2 pp 748ndash756 2013
[6] Y Zhang K Siebenaler K BrownDDohmeier andKHansenldquoAdjuvants to prolong the local anesthetic effects of coatedmicroneedle productsrdquo International Journal of Pharmaceuticsvol 439 no 1-2 pp 187ndash192 2012
[7] E Trovatti C Freire P C Pinto et al ldquoBacterial cellulosemembranes applied in topical and transdermal delivery of lido-caine hydrochloride and ibuprofen in vitro diffusion studiesrdquoInternational Journal of Pharmaceutics vol 435 no 1 pp 83ndash87 2012
[8] J S Yuan M Ansari M Samaan and E J Acosta ldquoLinker-based lecithin microemulsions for transdermal delivery oflidocainerdquo International Journal of Pharmaceutics vol 349 no1-2 pp 130ndash143 2008
[9] AK BangaTransdermal and IntradermalDelivery ofTherapeu-tic Agents Application of Physical Technologies pp 81ndash94 CRCPress Taylor amp Francis Group 2011
[10] S Hayashi S Ogami T Shibaji and M Umino ldquoLidocainetransport through a cellophane membrane by alternating cur-rent iontophoresis with a duty cyclerdquo Bioelectrochemistry vol74 no 2 pp 315ndash322 2009
[11] G Yan S K Li and W I Higuchi ldquoEvaluation of constantcurrent alternating current iontophoresis for transdermal drugdeliveryrdquo Journal of Controlled Release vol 110 no 1 pp 141ndash150 2005
[12] J P Howard T R Drake and D L Kellogg ldquoEffects ofalternating current iontophoresis on drug deliveryrdquo Archives ofPhysicalMedicine and Rehabilitation vol 76 no 5 pp 463ndash4661995
[13] J M DeCou R S Abrams J H Hammond L R Lowderand M W L Gauderer ldquoIontophoresis a needle-free electricalsystem of local anesthesia delivery for pediatric surgical officeproceduresrdquo Journal of Pediatric Surgery vol 34 no 6 pp 946ndash949 1999
[14] W T Zempsky and T M Parkinson ldquoLidocaine iontophoresisfor topical anesthesia before dermatologic procedures in chil-dren a randomized controlled trialrdquoPediatric Dermatology vol20 no 4 pp 364ndash368 2003
[15] M Ashburn M Gauthier G Love S Basta B Gaylord andK Kessler ldquoIontophoretic administration of 2 lidocaine HCLand 1100 000 epinephrine inmanrdquoTheClinical Journal of Painvol 13 no 1 pp 1322ndash1326 1997
[16] V Kumar and A K Banga ldquoModulated iontophoretic deliveryof small and large molecules through microchannelsrdquo Interna-tional Journal of Pharmaceutics vol 434 no 1-2 pp 106ndash1142012
[17] P D Sawant D Luu R Ye and R Buchta ldquoDrug releasefrom hydroethanolic gels Effect of drugrsquos lipophilicity (log P)polymer-drug interactions and solvent lipophilicityrdquo Interna-tional Journal of Pharmaceutics vol 396 no 1-2 pp 45ndash52 2010
[18] Y N Kalia A Naik J Garrison and R H Guy ldquoIontophoreticdrug deliveryrdquo Advanced Drug Delivery Reviews vol 56 no 5pp 619ndash658 2004
[19] V Sachdeva S Siddoju Y Yu H D Kim P M Friden andA K Banga ldquoTransdermal iontophoretic delivery of terbinafinehydrochloride quantitation of drug levels in stratum corneumand underlying skinrdquo International Journal of Pharmaceuticsvol 388 no 1-2 pp 24ndash31 2010
[20] M Kah and C D Brown ldquoLog D lipophilicity for ionisablecompoundsrdquo Chemosphere vol 72 no 10 pp 1401ndash1408 2008
[21] H Haga T Shibaji and M Umino ldquoLidocaine transportthrough living rat skin using alternating currentrdquo Medical andBiological Engineering and Computing vol 43 no 5 pp 622ndash629 2005
[22] A C Sintov and R B Sitton ldquoFacilitated skin penetrationof lidocaine combination of a short-term iontophoresis andmicroemulsion formulationrdquo International Journal of Pharma-ceutics vol 316 no 1-2 pp 58ndash67 2006
Submit your manuscripts athttpwwwhindawicom
PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
[5] Y Wanga W Su Q Li et al ldquoPreparation and evaluationof lidocaine hydrochloride loaded TAT-conjugated polymericliposomes for transdermal deliveryrdquo International Journal ofPharmaceutics vol 441 no 1-2 pp 748ndash756 2013
[6] Y Zhang K Siebenaler K BrownDDohmeier andKHansenldquoAdjuvants to prolong the local anesthetic effects of coatedmicroneedle productsrdquo International Journal of Pharmaceuticsvol 439 no 1-2 pp 187ndash192 2012
[7] E Trovatti C Freire P C Pinto et al ldquoBacterial cellulosemembranes applied in topical and transdermal delivery of lido-caine hydrochloride and ibuprofen in vitro diffusion studiesrdquoInternational Journal of Pharmaceutics vol 435 no 1 pp 83ndash87 2012
[8] J S Yuan M Ansari M Samaan and E J Acosta ldquoLinker-based lecithin microemulsions for transdermal delivery oflidocainerdquo International Journal of Pharmaceutics vol 349 no1-2 pp 130ndash143 2008
[9] AK BangaTransdermal and IntradermalDelivery ofTherapeu-tic Agents Application of Physical Technologies pp 81ndash94 CRCPress Taylor amp Francis Group 2011
[10] S Hayashi S Ogami T Shibaji and M Umino ldquoLidocainetransport through a cellophane membrane by alternating cur-rent iontophoresis with a duty cyclerdquo Bioelectrochemistry vol74 no 2 pp 315ndash322 2009
[11] G Yan S K Li and W I Higuchi ldquoEvaluation of constantcurrent alternating current iontophoresis for transdermal drugdeliveryrdquo Journal of Controlled Release vol 110 no 1 pp 141ndash150 2005
[12] J P Howard T R Drake and D L Kellogg ldquoEffects ofalternating current iontophoresis on drug deliveryrdquo Archives ofPhysicalMedicine and Rehabilitation vol 76 no 5 pp 463ndash4661995
[13] J M DeCou R S Abrams J H Hammond L R Lowderand M W L Gauderer ldquoIontophoresis a needle-free electricalsystem of local anesthesia delivery for pediatric surgical officeproceduresrdquo Journal of Pediatric Surgery vol 34 no 6 pp 946ndash949 1999
[14] W T Zempsky and T M Parkinson ldquoLidocaine iontophoresisfor topical anesthesia before dermatologic procedures in chil-dren a randomized controlled trialrdquoPediatric Dermatology vol20 no 4 pp 364ndash368 2003
[15] M Ashburn M Gauthier G Love S Basta B Gaylord andK Kessler ldquoIontophoretic administration of 2 lidocaine HCLand 1100 000 epinephrine inmanrdquoTheClinical Journal of Painvol 13 no 1 pp 1322ndash1326 1997
[16] V Kumar and A K Banga ldquoModulated iontophoretic deliveryof small and large molecules through microchannelsrdquo Interna-tional Journal of Pharmaceutics vol 434 no 1-2 pp 106ndash1142012
[17] P D Sawant D Luu R Ye and R Buchta ldquoDrug releasefrom hydroethanolic gels Effect of drugrsquos lipophilicity (log P)polymer-drug interactions and solvent lipophilicityrdquo Interna-tional Journal of Pharmaceutics vol 396 no 1-2 pp 45ndash52 2010
[18] Y N Kalia A Naik J Garrison and R H Guy ldquoIontophoreticdrug deliveryrdquo Advanced Drug Delivery Reviews vol 56 no 5pp 619ndash658 2004
[19] V Sachdeva S Siddoju Y Yu H D Kim P M Friden andA K Banga ldquoTransdermal iontophoretic delivery of terbinafinehydrochloride quantitation of drug levels in stratum corneumand underlying skinrdquo International Journal of Pharmaceuticsvol 388 no 1-2 pp 24ndash31 2010
[20] M Kah and C D Brown ldquoLog D lipophilicity for ionisablecompoundsrdquo Chemosphere vol 72 no 10 pp 1401ndash1408 2008
[21] H Haga T Shibaji and M Umino ldquoLidocaine transportthrough living rat skin using alternating currentrdquo Medical andBiological Engineering and Computing vol 43 no 5 pp 622ndash629 2005
[22] A C Sintov and R B Sitton ldquoFacilitated skin penetrationof lidocaine combination of a short-term iontophoresis andmicroemulsion formulationrdquo International Journal of Pharma-ceutics vol 316 no 1-2 pp 58ndash67 2006
Submit your manuscripts athttpwwwhindawicom
PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
