chemical engineering research and design x x x ( 2 0 1 4 ) xxx–xxx
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Chemical Engineering Research and Design
j ourna l h omepage: www.elsev ier .com/ locate /cherd
evelopment of topical gel containingceclofenac-crospovidone solid dispersion byQuality by Design (QbD)” approach
ougata Janaa, Syed Ansar Alib, Amit Kumar Nayakc,∗,alyan Kumar Sena, Sanat Kumar Basud
Department of Pharmaceutics, Gupta College of Technological Sciences, Ashram More, Asansol 713301, W.B., IndiaDepartment of Pharmaceutics, Karnataka College of Pharmacy, 33/2 Thirumenahalli, Bangalore 560064, IndiaDepartment of Pharmaceutics, Seemanta Institute of Pharmaceutical Sciences, Jharpokharia, Mayurbhanj 757086,disha, IndiaDivision of Pharmaceutics, Department of Pharmaceutical Technology, Jadavpur University, Kolkata 700032,.B., India
a b s t r a c t
This article describes the development, optimization, and evaluation of Carbopol 940 topical gel containing
aceclofenac-crospovidone (1:4) solid dispersion using “Quality by Design (QbD)” approach based on 23 factorial design.
The effect of crospovidone, tri-ethanolamine, and ethyl alcohol amount on the drug permeation profile of the topical
gel containing aceclofenac-crospovidone solid dispersion was optimized by 23 factorial design. The optimized gel
showed improved permeation profile with cumulative drug permeation of 26.262 ± 2.157%, and permeation flux of
0.059 ± 0.011 �g/cm2/h. These gels were characterized by pH, viscosity, gel strength and FTIR study. The in vivo anti-
inflammatory activity of the optimized gel was evaluated in rats using carrageenan-induced rat-paw oedema model
and found excellent anti-inflammatory comparable with a marketed gel without producing any skin irritation.
metabolism, and maintains the plasma drug level for a longer
. Introduction
n general, gels are formed from a liquid phase that has beenhickened with other components. Among them, Carbopolels offer good alternatives to oil based topical formula-ions. Carbopols are polymers of acrylic acid cross-linked witholyalkenyl ethers or divinyl glycol. They are readily hydratedo swell. Because of the hydrophilic nature, the cross-linkedtructures of Carbopols make them potential candidates forse as gel type formulation for topical use (Carnali and Naser,992; Garcia-Gonzalez et al., 1994). Topical use of these gelss advantageous, as they possess good rheological propertiesesulting in long residue times at the site of administration.ue to their extremely high molecular weight, they cannotenetrate the skin and offer good alternatives to oil based
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Aceclofenac, chemically [2-(2′,6′-dichlorophenyl)amino]phenylacetoxyacetic acid, is used as a non-steroidal anti-inflammatory drug (NSAID) indicated for the symptomatictreatment of pain and inflammation (Chakraborty et al., 2010).It is also used in the treatment of arthritis, osteoarthritis,rheumatoid arthritis and ankylosing spondylitis (Yadav et al.,2010). However, like other NSAIDs, oral administration of ace-clofenac is also associated with gastrointestinal side effectslike gastric ulceration, gastrointestinal bleeding and liver andkidney trouble (Insel, 1992). In view of adverse drug reactionassociated with oral formulations, aceclofenac is increas-ingly administered by topical route (Heyneman et al., 2000).Furthermore, the topical route of administration eliminatesside effects, increases patient compliance, avoids first-pass
el containing aceclofenac-crospovidone solid dispersion by “Quality0.1016/j.cherd.2014.01.025
period. Aceclofenac has a poor aqueous solubility (Nagariya
neers. Published by Elsevier B.V. All rights reserved.
2 chemical engineering research and design x x x ( 2 0 1 4 ) xxx–xxx
et al., 2010) that may cause a problem of migrating throughhydrophilic base.
Crospovidone is a synthetic polymer derived from themonomer of vinyl pyrrolidone by popcorn polymerization(Haaf et al., 1985). It is mainly used as disintegrant in tabletsand capsules. Crospovidone has been used as a carrier of soliddispersion for various drugs to improve their aqueous sol-ubility (Loganathan et al., 2000; Makiko et al., 2005). In thepresent study, an attempt was made to develop Carbopol 940gel for topical application containing solid dispersion of ace-clofenac using crospovidone as carrier to improve the skinpermeation profile of aceclofenac using “Quality by Design(QbD)” approach.
QbD approach encompasses designing and developingformulations, in which manufacturing processes ensure pre-defined product specifications (Nayak et al., 2011). Theimportant part of this approach is to understand how pro-cess and formulation parameters affect the product qualityand subsequent optimization parameters with respect tofinal specifications (Maltesen et al., 2008). QbD refers to theachievement of certain predictable quality with desired andpredetermined specifications. Therefore, a very useful com-ponent of the QbD is the understanding of various factors(variables) and their interactions by a desired set of exper-iments using a statistical tool (Menini et al., 2012). In thepresent investigation, the planned aceclofenac-loaded Car-bopol 940 topical gel containing aceclofenac-crospovidonesolid dispersion was optimized in terms of cumulative drugpermeation through the excised mouse skin after 10 h (%)and permeation flux (�g/cm2/h) by three-factor and two-level(23) factorial design. The considered factors were amountof crospovidone (mg), amount of tri-ethanolamine (ml) andamount of ethanol (ml). The selected QbD strategy allowedan efficient selection of the best formulation composition andof the most suitable experimental conditions in the shortesttime and with the minimum number of experiments. The bestformulation was studied for in-vivo pharmacodynamic perfor-mance in carrageen-induced rat paw oedema model and wascompared with marketed gel formulation.
2. Materials and methods
2.1. Materials
Aceclofenac was obtained as the gift sample from SuyashLab, India. Carbopol 940 and crospovidone were obtained asgift sample from C.I. Laboratories, India. Tri-ethanolamineand ethanol were commercially purchased from Merck, Indiaand Bengal Chemical & Pharmaceuticals Ltd., India. Allother reagents were of analytical grade and commerciallyavailable.
2.2. Preparation of aceclofenac-crospovidone soliddispersion
Aceclofenac-crospovidone (1:4) solid dispersion was preparedby solvent evaporation technique. Aceclofenac was dissolvedin ethanol to get clear solution. Then, crospovidone was dis-
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persed as fine particles and the solvent was removed byevaporation on a water bath at 60 ◦C. The dried mass wasstored in desiccator until constant mass was obtained, pul-verized and passed through sieve no. 22.
2.3. Characterization of aceclofenac-crospovidone soliddispersion
2.3.1. Saturation solubility measurementThe known excess samples (solid dispersions, physicalmixture and aceclofenac) of 10 mg equivalent weight of ace-clofenac was added to 10 ml of phosphate buffer saline, pH7.4 and these samples were rotated at 20 rpm in a water bath(37 ± 0.5 ◦C) for 48 h. The samples were then filtered, suitablydiluted, and analyzed by UV–vis spectrophotometer (ThermoSpectronic UV-1, USA) at 274 nm wavelength using appropriateblank solution.
2.3.2. Differential scanning calorimetric (DSC) analysisDSC analyses of the pure aceclofenac, and aceclofenac-crospovidone (1:4) solid dispersion were performed. Thesamples were heated to remove the moisture. Then thesamples (7 mg) were placed into a platinum crucible 40-�l aluminium pan in hermetically sealed condition, where∝-alumina powder was used as a reference. Thermogramswere recorded from 30 ◦C to 415 ◦C at the heating rate of10 ◦C/min under a constant flow of an inert nitrogen gas atmo-sphere with the flow rate of 20 ml/min. These analyses weredone using a differential scanning calorimeter (Perkin Elmer®
Instrument, Pyris diamond, Osaka, Japan).
2.4. Preparation of Carbopol 940 gel containingaceclofenac-crospovidone solid dispersion
Carbopol 940 gels containing aceclofenac-crospovidone soliddispersion were prepared according to the literature withlittle modification (Dua et al., 2010). In brief for each for-mulation, required amount of aceclofenac-crospovidone soliddispersion equivalent to 150 mg aceclofenac was dissolved inethanol and deionised water, respectively. Both the solutionsare mixed together thoroughly. Then 100 mg of Carbopol 940,previously soaked in 6.50 ml of deionised water overnight,was added to the above mixture with stirring at 500 rpm bymagnetic stirrer (Remi Motors, India) for 1 h. Finally, weighedquantity of tri-ethanolamine was added to obtain a clear gel.
2.5. Experimental design
For the optimization of Carbopol 940 gels containingaceclofenac-crospovidone solid dispersion, a 23 factorialdesign was employed. Amount of crospovidone (X1, mg),amount of tri-ethanolamine (X2, ml) and amount of ethanol(X3, ml) were selected as independent variables (factors),which were varied at two levels (low and high). The cumu-lative drug permeation through the excised mouse skin after10 h (CDP10, %) and permeation flux (PF, �g/cm2/h) wereused as dependent variables (responses). Design-Expert 8.0.6.1software (Stat-Ease Inc., USA) was used for generation andevaluation of the statistical experimental design. The matrixof the design including investigated factors and responses areshown in Table 2. For optimization, effects of various inde-pendent variables upon measured responses were modelledusing following mathematical model equation involving inde-pendent variables and their interactions for various measuredresponses generated by 23 factorial design is as follows:
chemical engineering research and design x x x ( 2 0 1 4 ) xxx–xxx 3
aaer
2a
2p(cf
2Fpstsw
2T4utu
S
wsHo
2Ta(2(
2a
Fomgp1wPbwo
2
T9sm
re undependable variables; X1X2, X2X3, and X1X3 are inter-ctions between variables. One-way ANOVA was applied tostimate the significance of the model (p < 0.05) and individualesponse parameters.
.6. Characterization of Carbopol 940 gel containingceclofenac-crospovidone solid dispersion
.6.1. pH determinationH of the prepared gel was measured using a digital pH meter
Systronics Instruments, India) by placing the glass electrodeompletely into the gel system and compared with marketedormulation.
.6.2. Determination of drug contentor each batch, 500 mg of gel was dissolved in 500 ml of phos-hate buffer saline, pH 7.4 with stirring at 500 rpm by magnetictirrer (Remi Motors, India) for 1 h. After suitable dilution,he absorbance of the above solution was analyzed by UV–vispectrophotometer (Thermo Spectronic UV-1, USA) at 274 nmavelength using appropriate blank solution.
.6.3. Measurement of gel strengthhe gel strength of formulated gels were determined after8 h of preparation by measuring the weight required to movepper plate by 3 cm, when 1 g of each gel was placed betweenwo 20 cm × 20 cm plates. The gel strength was calculated bysing the formula:
= M × L
T
here S is the gel strength, M is the weight tied to the upperlide, L is the length glass slide travelled and T is time taken.omogeneity of various gel formulations were tested by visualbservations (Covert, 1986).
.6.4. Viscosity measurementhe viscosity of the formulations were determined by using
Brookfield DV III ultra V6.0 RV cone and plate viscometerBrookfield Engineering Laboratories, Middleborough, MA) at5 ± 0.3 ◦C; the software used for calculation was Rheocalc V2.6Chawla and Saraf, 2012).
TIR spectroscopy of pure aceclofenac, physical mixturef aceclofenac-crospovidone (1:4) solid dispersion and opti-ized aceclofenac gel were performed. Each sample were
round thoroughly with KBr (1:19) and then pellets were pre-ared using a hydraulic press under a hydraulic pressure of00 kg/cm2 for 10 min. These KBr pellets containing samplesere analyzed by using a FTIR spectroscope (Spectrum BX,
erkin-Elmer® Instruments, USA). The pellets were placed oney one in the sample holder. Spectral scanning was taken inavelength region between 4000 and 400 cm−1 at a resolutionf 4 cm−1 with 2 mm/s scan speed.
.8. Ex vivo permeation study
he ex vivo permeation of aceclofenac from Carbopol40 gels containing aceclofenac-crospovidone solid disper-
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ion were performed using excised skin of Swiss albinoice (weight 162–188 g). The experiment was approved by
Institutional Animal Ethical Committee, under registrationnumber 955/A/06/CPCSEA. The animals were sacrificed usinganaesthetic ether. The hair of abdominal skin was removed byusing an animal hair clipper. A full thickness of skin was takenout and the fat adhering to the dermis side was removed byusing surgical scalpel. Finally, the skin was rinsed using phos-phate buffer, pH 7.4 and packed in aluminium foil. The skinsample was stored at −20 ◦C and was used within 24 h.
The ex vivo permeation through excised mouse skin wasperformed by Franz diffusion cells. The cells consist of twochambers, the donor and the receptor compartment withan available diffusion area of 0.949 cm2. The donor compart-ment was open at the top and was exposed to atmosphere.The excised mouse skin was mounted between the com-partments of the diffusion cell with stratum corneum facingthe donor compartment and clamped into position. Magneticstirrer bars were added to the receptor chambers and filledwith the receptor phase. Phosphate buffer saline, pH 7.4 wasused as the receptor medium. The small concentration ofsodium azide (0.0025%, w/v) was added to prevent any micro-bial growth (Pillai and Panchagnula, 2004). The entire setupwas placed over magnetic stirrer, and the temperature wasmaintained at 37 ± 0.5 ◦C. The skin sections were initially leftin the Franz cells for 2 h in order to facilitate hydration of theskin samples. 1 g of each gel formulation was applied onto theexcised mouse skin fitted on the Franz diffusion cell. 1 ml ofmedium was collected from the receptor compartment at pre-determined intervals over study period and replaced with thesame amount of fresh buffer. The amount of permeated drugwas analyzed by UV–vis spectrophotometer (Thermo Spec-tronic UV-1, USA) at 274 nm wavelength using appropriateblank solution.
2.9. Permeation data analysis
The amount of aceclofenac permeated from various gelsthrough excised mouse skin was plotted against the functionof time. The slope and intercept of the linear portion of plotswere derived by regression. The permeation fluxes for each gelwere calculated as the slope divided by the skin surface area(Malakar et al., 2011; Nayak et al., 2010):
Jss = (dQ/dt)ss × 1A
,
where Jss is the steady-state permeation flux (�g/cm2/h), Ais the area of skin tissue (cm2) through which drug perme-ation takes place, and (dQ/dt)ss is the amount of drug passingthrough the skin per unit time at a steady state (�g/h).
2.10. In vivo evaluation
The experiment was approved by Institutional Animal EthicalCommittee, under registration number 955/A/06/CPCSEA. Thecarrageenan-induced rat-paw oedema model (Winter et al.,1962) was performed to assess anti-inflammatory activityevaluation of the optimized gel. Male Sprague Dawley ratsweighing 200–250 g were used for the experiment. The accli-matized rats were kept fasting for 24 h with water ad libitum.The anti-inflammatory effect of the optimized aceclofenac gelwas evaluated by applying 1 g of optimized formulated gelon the skin (1 cm2) back of the rats. The control group wastreated with the normal saline. After 3 h interval, 0.1 ml of a
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1% carrageenan solution in physiological saline as the con-trol was injected intradermally in the right hind paw of the
rat. The oedema volumes are measured using plethysmome-ter (Ugo Bacile, model 7150) after 3 h of carrageenan injection.The extent of swelling (%) were calculated from the differ-ence in the volume between immediately and 3 h after thecarrageenan injection (6 rats in each group) using the followingformula (Shin et al., 2000):
Swelling (%) = V − V1
V1× 100
where V is the volume 3 h after the carrageenan injection inthe sole of the foot and V1 is the volume immediately after theinjection.
2.11. Skin irritation test
The skin irritation was performed on healthy New Zealandrabbits (2.07–2.56 kg). The experiment was approved byInstitutional Animal Ethical Committee, under registrationnumber 955/A/06/CPCSEA. For each gel, five rabbits wereselected and after cleaning, the dorsal skin 1 g of optimized gelwas applied on an area of 2 in.2 to the back. The animals werekept under standard laboratory conditions at 25 ± 1 ◦C and rel-ative humidity of 55 ± 5%. The animals were housed with freeaccess to a standard laboratory diet and water ad libitum. Therabbits were then observed for lesions or irritation in presenceand absence of sunlight exposure of 30 min (Van-Abbe et al.,1975).
2.12. Statistical analysis
Statistical optimization was performed using Design-Expert8.0.6.1 software (Stat-Ease Inc., USA). The in vivo data weretested for significant differences (p < 0.05) by paired samples t-test. All other data were analyzed by average mean ± standarddeviation. The simple statistical analysis and paired samplest-test were conducted using MedCalc software version 11.6.1.0.
3. Results and discussions
3.1. Characterization of aceclofenac-crospovidone soliddispersion
3.1.1. Saturation solubilityAceclofenac-crospovidone (1:4) solid dispersion was preparedby solvent evaporation technique to improve the solubil-ity of aceclofenac. The concentration of saturated aqueoussolution of prepared aceclofenac-crospovidone (1:4) solid dis-persion was measured and compared with the correspondingphysical mixture, and pure aceclofenac (Table 1). The pre-
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pared solid dispersion showed improved aqueous solubility ofaceclofenac (0.248 ± 0.020 mg/ml) than that of corresponding
Table 1 – Saturation solubility of pure aceclofenac andprepared aceclofenac-crospovidone (1:4) soliddispersion.
Samples Saturation solubility(mg/ml)a
Pure aceclofenac 0.091 ± 0.009Physical mixture of
aceclofenac-crospovidone (1:4)0.146 ± 0.012
Aceclofenac-crospovidone (1:4)solid dispersion
0.248 ± 0.020
a Mean ± S.D., n = 3.
physical mixture (0.126 ± 0.012 mg/ml) and pure aceclofenac(0.091 ± 0.009 mg/ml). This might be attributed to an improvedwetting of drug particles and localized solubilization by thehydrophilic polymeric carrier, crospovidone.
3.1.2. DSC analysisDSC thermograms of pure drug aceclofenac and preparedaceclofenac-crospovidone (1:4) solid dispersion are presentedin Fig. 1. Thermogram of pure aceclofenac (a) showed sharppeaks at 152 ◦C and 275.60 ◦C, indicating the melting point andpolymorphic nature of aceclofenac, respectively. However, thethermogram of prepared aceclofenac-crospovidone (1:4) soliddispersion depicted that there was a noticeable reduction inendothermic peak heights and heat of fusion compared topure aceclofenac, suggesting the change of crystalline state inpure aceclofenac to amorphous form in aceclofenac solid dis-persion. It has been understood that transforming the physicalstate of the drug to amorphous or partially amorphous stateleads to a high-energy state, resulting in enhanced aqueoussolubility and faster dissolution of drug candidates.
3.2. Optimization of Carbopol 940 gel containingaceclofenac-crospovidone solid dispersion
23 (three-factors, two-levels) factorial design was employed forthe optimization of Carbopol 940 gels containing aceclofenac-crospovidone (1:4) solid dispersion. A total 8 trial formulationswere proposed by the 23 factorial design for three indepen-dent variables (factors) namely, amount of crospovidone (X1,mg), amount of tri-ethanolamine (X2, ml) and amount ofethanol (X3, ml) were selected as independent variables (fac-tors), which were varied at two levels (low and high). Theeffects of these independent variables on the CDP10 (%) andPF (�g/cm2/h) were investigated as responses and optimized.According to experimental design, 8 trial formulations wereformulated and evaluated for their responses investigated.The matrix of the design including investigated factors andresponses are shown in Table 2.
Design-Expert 8.0.6.1 software (Stat-Ease Inc., USA) wasused for generation and evaluation of the statistical exper-imental design. The values of responses for each trialformulations were fitted in the design to get model equationsfor each response.
The model equation relating CDP10 (%) as responsebecame: CDP10 (%) = 4.359 + 0.031X1 − 10.508X2 + 1.783X3 +0.183X X + 4.811 × 10−3X X − 7.271X X [R2 = 0.9996; F-value
el containing aceclofenac-crospovidone solid dispersion by “Quality0.1016/j.cherd.2014.01.025
chemical engineering research and design x x x ( 2 0 1 4 ) xxx–xxx 5
Table 2 – 23 full factorial design (coded values in bracket) with observed response values for different Carbopol 940 gelscontaining aceclofenac-crospovidone (1:4) solid dispersion.
Code Normalized levels of independent variables (factors) employed
The results of ANOVA, as shown in Table 3, indicatedhat all models were significant (p < 0.05) for all responsearameters investigated. Model simplification was car-ied out by eliminating non-significant terms (p > 0.05)n model equations (Nayak et al., 2011), giving: CDP10
Each response coefficient was studied for its statisticalignificance by Pareto charts as shown in Fig. 2 and Fig. 3.hese charts depicted the statistical significance of eachesponse coefficient. Coefficients with t values of effects abovehe Bonferroni line are designated as significant coefficient;oefficients with t values of effects between Bonferroni linend t limit line are termed as coefficients likely to be sig-
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ificant, while coefficients with t values of effects below the limit line is statistically insignificant coefficient (Shah and
Table 3 – Summary of ANOVA for the response parameters.
Source Sum of squares d.f.a
(a) For CDP10 (%)b
Model 154.88 6
X1 91.76 1
X2 2.04 1
X3 56.24 1
X1X2 1.68 1
X1X3 1.63 1
X2X3 1.52 1
(b) For PF (�g/cm2/h)c
Model 6.828 × 10−4 6
X1 3.781 × 10−4 1
X2 3.127 × 10−6 1
X3 2.761 × 10−4 1
X1X2 3.125 × 10−6 1
X1X3 2.112 × 10−5 1
X2X3 1.125 × 10−6 1
X1, X2 and X3 represent amount of crospovidone (mg), tri-ethanolamine (minteraction effects. S and NS indicate significant and not significant, respea Degree of freedom.b Cumulative drug permeation after 10 h (%).c Permeation flux.
Pathak, 2010). Therefore, these Pareto charts supported alsothe ANOVA results for the model simplification by eliminatingnon-significant terms (p > 0.05) in both the model equations.In addition, Design-Expert 8.0.6.1 software generated three-dimensional response surface plots (Fig. 4 and Fig. 5) andcorresponding contour plots (Fig. 6 and Fig. 7) to estimatethe effects of the independent variables (factors) on eachresponse investigated (CDP10, % and PF, �g/cm2/h). The three-dimensional response surface plot is very useful in learningabout the main and interaction effects of the independentvariables (Nayak and Pal, 2011; Malakar et al., 2012). Thethree-dimensional response surface plots relating CDP10 (%)(Fig. 4a–c) depict the increase in CDP10 with the increasing ofboth the amount of crospovidone (X1), and ethyl alcohol (X3),whereas slight decreasing of CDP10 was found with the incre-ment of the amount of tri-ethanolamine (X2). On the otherhand, the three-dimensional response surface plots relat-ing PF (�g/cm2/h) (Fig. 5a–c) also indicate the increase in PFwith the increasing of both the amount of crospovidone (X1),
el containing aceclofenac-crospovidone solid dispersion by “Quality0.1016/j.cherd.2014.01.025
and ethyl alcohol (X3), whereas slight decreasing of PF wasfound with the increment of the amount of tri-ethanolamine
6 chemical engineering research and design x x x ( 2 0 1 4 ) xxx–xxx
art re
Fig. 2 – Pareto ch
(X2). The two-dimensional contour plots (Fig. 6 and Fig. 7)were presented significant nonlinear relationships betweenthe amount of crospovidone (X1) and tri-ethanolamine (X2)and amount of crospovidone (X1) and ethyl alcohol (X3) in caseof CDP10 (%); whereas in case of PF (�g/cm2/h), the contourplots presented significant nonlinear relationship betweenamount of crospovidone (X1) and ethyl alcohol (X3) only.
A numerical optimization technique using the desirabil-ity approach was employed to develop new formulationswith desired response (desired quality). A constraint to max-imizing the aceclofenac permeation was to set the goal tolocate the optimum settings of independent variables forthe optimized formula by QbD approach using the DesignExpert 8.0.3 software based on the criterion of desirability.QbD approach stresses the need to understand the criticalprocess parameters with the aim of achieving successful prod-uct development in predefined quality attributes thoroughly(Lionberger et al., 2008). Critical quality attributes are theproperties that need to be controlled as they affect either
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patient safety or efficacy (Verma et al., 2009). To get thedesired optimum responses, independent variables (factors)
Fig. 3 – Pareto chart rela
lating CDP10 (%).
were restricted to X1 = 260.00 mg, X2 = 0.01 ml, and X2 = 4.20 ml.In order to evaluate optimization capability of models gener-ated according to the results of 23 factorial design, optimizedCarbopol 940 gel containing aceclofenac-crospovidone (1:4)solid dispersion was prepared using the optimal process vari-able settings. The gel (F-O) was evaluated for various measuredresponses, i.e., CDP10 (%) and PF (�g/cm2/h). Table 4 liststhe results of experiments with predicted responses by themathematical model and those actually observed. The opti-mized gel (F-O) showed CDP10 of 26.262 ± 2.157%, and PF of0.059 ± 0.011 �g/cm2/h with small error-values (−4.139 and−3.279, respectively). This reveals that mathematical modelsobtained from the 23 factorial design were well fitted.
3.3. Characterization of Carbopol 940 gel containingaceclofenac-crospovidone solid dispersion
3.3.1. pHThe pH of all formulated Carbopol 940 gels containing
el containing aceclofenac-crospovidone solid dispersion by “Quality0.1016/j.cherd.2014.01.025
aceclofenac-crospovidone (1:4) solid dispersion were mea-sured and found within the range of 6.52–7.24 (Table 5), which
chemical engineering research and design x x x ( 2 0 1 4 ) xxx–xxx 7
Fig. 4 – Effect of crospovidone (mg), tri-ethanolamine (ml)and ethyl alcohol (ml) on CDP10 (%) presented by responsesurface plot (a–c).
latfo
3Tbsi
Fig. 5 – Effect of crospovidone (mg), tri-ethanolamine (ml)and ethyl alcohol (ml) on PF (�g/cm2/h) presented byresponse surface plot (a–c).
ies in the normal pH range of the skin. In the development ofny topical formulation, the pH of the formulation is impor-ant. Because, the more acidic or more basic pH of the topicalormulation can change the environment of the skin, whichccasionally produce skin irritation upon application.
.3.2. Viscosity and gel strengthhe viscosities of these formulated gels were determinedy using a Brookfield DV-III ultra V6.0 RV at 25 ± 0.3 ◦C; the
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oftware used for calculation was Rheocalc V2.6. The viscos-ty of these gels were within the range of 0.173 ± 0.017 to
0.407 ± 0.036 Pa-s. Among all formulations, the optimized gelexhibited maximum viscosity of 0.407 ± 0.036 Pa-s. From theviscosity result, it was clear that the viscosity of gels wereincreased with the increasing of crospovidone in their formuladue to crospovidone hydrophilic nature.
The gel strengths of these formulated gels were within therange between 0.116 ± 0.078 and 0.248 ± 0.065 g/cm/s. The gelstrengths were found to be increased with increased viscosityvalue measured. The high gel strength might be related to thehigher degree of polymer network in the gel.
3.3.3. FTIR analysisThe FTIR spectra of aceclofenac, aceclofenac-crospovidone
el containing aceclofenac-crospovidone solid dispersion by “Quality0.1016/j.cherd.2014.01.025
(1:4) solid dispersion, and optimized gel containingaceclofenac-crospovidone (1:4) solid dispersion are shown
8 chemical engineering research and design x x x ( 2 0 1 4 ) xxx–xxx
Fig. 6 – Effect of crospovidone (mg), tri-ethanolamine (ml)and ethyl alcohol (ml) on CDP10 (%) presented by contourplot (a–c).
Fig. 7 – Effect of crospovidone (mg), tri-ethanolamine (ml)and ethyl alcohol (ml) on PF (�g/cm2/h) presented bycontour plot (a–c).
in Fig. 8. The FTIR spectra of aceclofenac showed principal
peaks at 3027.73 and 2936.75 cm−1 (due to both aromaticand aliphatic C H stretching vibrations, respectively), aband at 1717 cm−1 (due to C O stretching), a sharp band at1771.97 cm−1 (due to C O stretching of carboxylic acid), a bandat 3319.64 cm−1 (due to secondary N H rocking vibrations),and two sharp peaks at 716.11 cm−1 (due to 1,2-di-substitutedC Cl stretching) (Mutalik et al., 2007a,b). The solid dispersion
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of aceclofenac-crospovidone (1:4) showed a sharp peak at1256.86 cm−1 (due to C N stretching), which is a characteristic
peak of crospovidone moiety, while the other bands presentwere similar due to the presence of pure drug. In case ofoptimized gel containing aceclofenac-crospovidone (1:4) soliddispersion, similar bands were observed as compared thanthat of previous one. Therefore, the FTIR analyses indicatedabsence of any significant interaction between the drug,
el containing aceclofenac-crospovidone solid dispersion by “Quality0.1016/j.cherd.2014.01.025
a Cumulative drug permeation after 10 h (%).b Permeation flux.c Mean ± S.D., n = 3.d Percentage of error (%) = (actual value − predicted value)/predicted value × 100.
3
Teatpgscattiipm0hogo
3
Tmr
Table 5 – Results of physical characterization of differentCarbopol 940 gels containing aceclofenac-crospovidone(1:4) solid dispersion.
hese gels were studied for ex vivo skin permeation throughxcised mouse skin. All these formulated gels containingceclofenac-crospovidone (1:4) solid dispersion were sus-ained over 10 h, which was evidenced in ex vivo skinermeation study results (Fig. 9). In the optimization of theseels, it was found that drug permeation through mousekin was found to be increased with increasing amount ofrospovidone and ethyl alcohol. This phenomenon can bettributed by the aceclofenac solubility improvement withhe increasing amount of crospovidone in the gels con-aining aceclofenac-crospovidone (1:4) solid dispersion andncreased skin permeation enhancement capacity of increas-ng amount of ethanol, present in the gel formulations. Theermeation fluxes for all these gels through the excisedouse skin were within the range between 0.014 ± 0.002 and
.059 ± 0.011 �g/cm2/h. Among all the formulated gels, theighest permeation profile (with the highest permeation fluxf 0.059 ± 0.011 �g/cm2/h) was observed in case of optimizedel (F-O), which contained 260.00 mg of crospovidone, 0.01 mlf tri-ethanolamine and 4.20 ml of ethyl alcohol.
.5. In vivo evaluation
he in vivo anti-inflammatory activity evaluation of the opti-
Please cite this article in press as: Jana, S., et al., Development of topical gby Design (QbD)” approach. Chem. Eng. Res. Des. (2014), http://dx.doi.org/1
ized topical gel was performed in male Sprague Dawleyats using carrageenan-induced rat-paw oedema model. The
percent swelling (%) of rat paw oedema for control group,optimized gel and one marketed gel containing aceclofenacafter 3 h were calculated and are presented in Fig. 10. How-ever, a slightly lower percent of swelling (%) compared withcontrol group was shown by the optimized gel and mar-keted gel. This could be well explained again by the fact thatcrospovidone network in Carbopol 940 topical gel containingaceclofenac-crospovidone (1:4) solid dispersion increased therate of permeation of the drug, aceclofenac. This higher quan-
el containing aceclofenac-crospovidone solid dispersion by “Quality0.1016/j.cherd.2014.01.025
tity of drug permeation resulted in increase in the intensity ofresponse.
4) solid dispersion, and optimized Carbopol 940 gel
10 chemical engineering research and design x x x ( 2 0 1 4 ) xxx–xxx
Fig. 9 – Ex vivo permeation of aceclofenac from various Carbopol 940 topical gels containing aceclofenac-crospovidone (1:4)solid dispersion through excised mouse skin.
Fig. 10 – A comparison of percent swelling incarrageenean-induced rats: control (a), optimized Carbopol940 topical gels containing aceclofenac-crospovidone (1:4)solid dispersion (b) and a marketed aceclofenac gel (c).
3.6. Skin irritation test
The development of erythema was monitored for 6 days andno significant development of any erythema or lesions on thesurface of rabbit skin was found, which indicated the safetyand acceptability of the optimized Carbopol 940 gel contain-ing aceclofenac-crospovidone (1:4) solid dispersion for topicaladministration.
4. Conclusion
Carbopol 940 topical gel containing aceclofenac-crospovidonesolid dispersion was successfully developed by QbD approachbased on 23 factorial design. These formulated gels showedsustained permeation of aceclofenac over 10 h in ex vivoskin permeation study using excised mouse skin. These gelswere characterized by pH, viscosity, and gel strength. FTIRstudy clearly indicated absence of any significant interactionbetween the drug, aceclofenac and other excipients presentin the formulation. The in vivo anti-inflammatory activity inmale Sprague Dawley rats using carrageenan-induced rat-paw oedema model demonstrated that the optimized gel wascomparable with a marketed gel without producing any skinirritation. Overall, these results indicated the promise of Car-
Please cite this article in press as: Jana, S., et al., Development of topical gby Design (QbD)” approach. Chem. Eng. Res. Des. (2014), http://dx.doi.org/1
bopol 940 topical gel containing aceclofenac-crospovidone(1:4) solid dispersion for transdermal delivery of aceclofenac
with improved permeation profile and thus, improved patientcompliance.
Conflict of interest
The authors report no declarations of interest.
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