International Journal of Biological Macromolecules 61 (2013) 333– 339
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International Journal of Biological Macromolecules
jo ur nal homep age: www.elsev ier .com/ locate / i jb iomac
valuation of Albizia procera gum as compression coating material forolonic delivery of budesonide
alduhsanga Pachuau1, Bhaskar Mazumder ∗
epartment of Pharmaceutical Sciences, Dibrugarh University, Assam, 786004, India
r t i c l e i n f o
rticle history:eceived 28 May 2013eceived in revised form 6 July 2013
a b s t r a c t
The purpose of this research was to develop and evaluate Albizia procera gum as compression-coatingpolymer for colonic delivery of budesonide. Tablets were prepared by direct compression method usingspray-dried lactose and microcrystalline cellulose as filler binders. The compatibility between the drug
and the polymer was studied through TGA and FTIR spectroscopy. In vitro drug release were studied indissolution media with or without 2% rat cecal contents while in vivo X-ray study was conducted onrabbits. The results indicate that procera gum and the drug were compatible with each other and tabletcoated with procera gum was suitable for colonic delivery of drugs.
Biomacromolecules such as naturally occurring polysaccharidesave been widely explored as drug delivery devices due to their
nherent biocompatibility and biodegradability [1]. These poly-ers are high molecular weight compounds found in abundance,
nexpensive, safe and available in a variety of structures whichan be easily modified chemically and biochemically. In recentears natural polysaccharides have received considerable inter-st as carrier for specific delivery of drugs to the colon. Manyolysaccharides such as amylase [2,3], pectin [4,5], guar gum [6],hitosan [7] and konjac glucomannan/xanthan gum [8] have been
nvestigated for peroral delivery of drugs to the colon. Due tohe distal location of the colon in the GI tract, a colon specificrug delivery system should prevent drug release in the stom-ch as well as the small intestine. Natural polysaccharides areeported to be capable of preventing this drug release in thepper GI tract while being susceptible to enzymatic degradationy colonic bacterial enzymes thereby releasing the drug for local
ction or improved absorption. Since the abrupt increase in bacte-ial population and its associated enzymatic activity in the colon arendependent of the pH and GI transit time, these colonic microfloractivated systems become most effective and preferable means
in terms of target specificity for colonic drug delivery systems[9].
Albizia trees are known to produce gums and have been reportedas substitute for arabic gum as natural emulsifier for foods andpharmaceuticals. Structural studies on Albizia gums reveal thepresence of �-(1-3) d-galactopyranose units with some �-(1-6)d-galactopyranose units and �-(1-3) l-arabinofuranose units [10].Albizia procera (Roxb.) Benth is a fast growing, medium sized treebelonging to Mimosaceae family and is known to exude gumsin small transparent tears and vermiform pieces. In our previ-ous studies we investigated the detail physicochemical propertiesof the gum [11] and have also reported the drug release mech-anism of controlled release matrix tablets based on this gum[12]. In the present paper, we develop a two stage/platform drugdelivery system based on a compression coated tablets contain-ing budesonide as the core and A. procera gum as the coat layer.The main reason for selecting A. procera gum, an arabinogalactanwas the biodegradation of arabinogalactans in the colon by thecolonic microflora as these microorganisms produce a wide rangeof enzymes such as �-glucuronidase, �-xylosidase, �- arabinosi-dase, �-galactosidase, nitroreductase, azoreductase, deaminase,urea hydroxylase etc. [13,14]. Budesonide, a novel gluccocorti-coid which is highly effective in the treatment of IBD due toits superior topical anti-inflammatory activity than many othergluccocorticoids has been selected as the model drug. Due to itsrapid, near complete first-pass hepatic conversion to its metabo-
lites, the systemic effects of budesonide are significantly lessthan other conventional corticosteroids making it an ideal can-didate for specific delivery to the colon for topical treatment ofIBDs.
Budesonide (Batch No. B110263) was received as gift sam-le from Cipla (Baddi, India). Microcrystalline cellulose (AvicelH 101), spray-dried lactose, magnesium stearate and talc weresed as supplied without further purification. A. procera gum exu-ates (Authenticated at the Department of Forestry, School of Earthciences, Mizoram University) were collected by hand picking inizoram (India) during the month of January–March and purified
11]. Geographically, Mizoram is located between East longitude2◦15′ to 93◦29′; North Latitude 21◦58′ to 24◦35′ with an averageltitude of 900 m. All other chemicals and reagents used were ofnalytical grade.
.2. Methods
.2.1. Instrumental analysis
.2.1.1. FTIR spectroscopy. FTIR spectroscopy was performed tossess the interaction of the drug with the polymer. Budesonidend procera gum were taken in 1:1 ratio and this sample is mixedniformly in a porcelain dish with 100 times its weight of KBr. About0 mg of the mixed sample was transferred into sample holder andressed lightly to make a smooth surface. The % transmittance wasecorded between 400 and 4000 cm−1 on FTIR spectrophotome-er (IR Prestige-21, Shimadzu). FTIR spectrum for budesonide, theried procera gum and budesonide-gum mixture was recorded andhe resultant spectra were carefully analyzed for possible signs ofnteraction between the gum and budesonide. Disappearance orignificant shifts in characteristic peaks were considered as a testi-ony to the interaction.
.2.1.2. Thermogravimetric analysis (TG analysis). TG analysis waslso performed on TGA (Pyris TGA, PerkinElmer) between 40 ◦C and55 ◦C to study the possible interaction between budesonide androcera gum and the thermal stability of the product. The heat-
ng rate and nitrogen purging were maintained at 10 ◦C/min and0 ml/min respectively. For each analysis, about 6 mg of the sam-le was taken into the aluminium sample pan and sealed. Emptyluminium pan was used as a reference and the thermogram washen recorded for budesonide, procera gum and budesonide-gum
ixture (1:1).
.2.2. Preparation of budesonide core tabletsBudesonide core tablets were prepared by direct compression
ethod. Each core tablet consists of 3 mg budesonide and spray-ried lactose was used as direct compression vehicle. Talc at 2%nd magnesium stearate at 1% was used as lubricant. Tabletsith total weight of 100 mg each containing 3 mg budesonideere compressed on a 12-station rotary tablet press (MiniPress
I MT, Karnavati Engg.) at 4000 kg using 6 mm, round and con-ave punches. Standard tablet quality control tests such as weightariation, crushing strength, content uniformity and friability wereerformed on the core tablets.
.2.3. Compression coating of tabletsBudesonide core tablets were compression coated with differ-
nt coat formulations as given in Table 1 using microcrystallineellulose (Avicel PH101) as a filler binder. Firstly, about 50% of the
oat formulation was placed in the die cavity (diameter of the dieas 10 mm) and budesonide core tablets were carefully positioned
n the centre of the die cavity. The remainder of the tablet coatormulation was then used to fill up the die and then the whole
Magnesium stearate 3 3 3 3Total 400 400 400 400
system was compressed at an applied force of 5000 kg using 10 mmconcave punches to make a tablet with total weight of 400 mg.
2.2.4. Characterization of compression-coated tabletsFor uniformity of weight, 20 tablets from each batch were
selected and weighed individually and their mean weights werecalculated. The crushing strength of the tablets was determinedusing Digital Tablet Hardness Tester (EH-01, Electrolab) taking 5tablets from each batch and the average was taken. Friability testwas performed on dual drum unit Friability Tester (EF-2, Elec-trolab). For each test, 20 tablets were taken and the drum wasmaintained at 25 rpm for 4 min and all the determinations weredone in triplicate.
2.2.5. In vitro release studyThe in vitro release of budesonide from the compression-coated
tablets was performed on USP Dissolution Tester using ApparatusI (Rotating basket, USP Dissolution Test Apparatus, ACMAS Tech-nocrat, India) at a rotation speed of 50 rpm and the dissolutionmedia was maintained at 37.0 ± 0.5 ◦C. The release study was per-formed in 250 ml 0.1 N HCl for the first 2 h, followed by 250 ml pH6.8 phosphate buffer for another 3 h and finally 250 ml pH 7.4 phos-phate buffer till 24 h to simulate the gastro-intestinal pH condition.2 ml of dissolution medium was withdrawn at predetermined timeintervals and analyzed for the drug using Waters HPLC systemwith UV/Visible detector (2489, Waters). Budesonide determina-tion was modified from the method developed by Naikwade andBajaj [15] and validated accordingly. Briefly, the analysis was car-ried out using Symmetry C18 Column (dimension = 150 × 4.6 mmand particle size 5 �m, Waters) at a wavelength of 244 nm. 20 �l ofthe suitably diluted and filtered sample was injected and the mobilephase used was methanol–water (80:20) maintaining a flow rateof 0.8 ml/min. Data acquisition and processing were performed byusing Empower 2 software (Waters).
2.2.6. In vitro release study in presence of rat cecal contentRat cecal content was prepared by the method reported by
Paharia et al. [16]. Dissolution medium containing 2% rat cecalcontent were prepared on pH 7.4 phosphate buffer which was pre-viously bubbled with N2 to make an anaerobic condition. Drugrelease behavior of the compression coated tablets in the physi-ological environment of colon was assessed by performing drugrelease studies in rat cecal content medium. Budesonide tablet wasplaced in 250 ml of dissolution medium which was maintained at37 ± 0.5 ◦C. Dissolution study was performed in 0.1 N HCl for thefirst two (2) hours followed by pH 6.8 phosphate buffer for thenext three (3) hours. Finally, pH 7.4 phosphate buffer containing2% rat cecal content was taken and the study was continued up to24 h. At different time intervals, 2 ml of the dissolution medium was
withdrawn, suitably diluted and filtered and analyzed using WatersHPLC system at 244 nm with UV/Visible detector (2489, Waters)following the validated method previously described.
L. Pachuau, B. Mazumder / International Journal of Biological Macromolecules 61 (2013) 333– 339 335
Table 2Characteristics of the compression-coated tablets.
.2.7. In-vivo X-ray studiesTwo adult male New Zealand white strain rabbits weighing
pproximately 2.0–2.5 kg were used for the study. The rabbits wereasted overnight before the start of the study. The animal study wasarried out according to the guidelines of CPCSEA, Ministry of Envi-onment & Forests, Government of India and the study protocolas approved by Institutional Animal Ethics Committee of Dibru-
arh University, India (Regd. No. 1576/GO/a/11/CPCSEA, India). Theore tablets were prepared by taking 100 mg of barium sulphate,5.5 mg spray-dried lactose and lubricated with 1% magnesiumtearate and 2% talc. The total weight of the core tablet was kept at50 mg. 100 mg of X-ray grade barium sulphate was taken in theore tablets as it permits clear visibility when X-ray photographsere taken on rabbits [17]. The prepared core tablet was then com-ression coated with coating formula containing 200 mg of proceraum 41 mg of microcrystalline cellulose and lubricated with 2% talcnd 1% magnesium stearate and the total weight of the compres-ion coated tablet was 400 mg. The tablet was administered orallyhrough plastic tubing followed by flushing of 20–30 ml of water.uring the entire study, the rabbits had free access to water only.-ray photographs were taken at 0, 2, 4 and 6 h.
.2.8. In vitro drug release kineticsTo determine the release mechanism from the microspheres,
n vitro drug release data were also fitted into Korsemeyer–Peppasquation [18] which is expressed as:
Qt
Q∞= kktn (1)
here kk is the kinetic constant, Q∞ is the amount release at time = ∞, thus Qt/Q∞ is the fraction of drug released at time t. Thealue ‘n’ is the diffusion exponent that can be used to character-ze the mechanism for both solvent penetration and drug release.he value of n = 0.5 indicates Fickian Diffusion, 0.5 < n < 1.0 indi-ates anomalous (non-Fickian) diffusion, n = 1.0 indicates case IIransport (zero-order release) and n > 1.0 indicates super case IIransport. Determining the correlation coefficient assessed fitnessf the data into various kinetic models. The rate constants, forespective models were also calculated from slope.
.2.9. Statistical analysisStatistical analysis was performed using computer software
igmaStat 2.03 (SPSS, USA). Analysis of variance/Tukey Test waserformed to compare the effects of different polymers concentra-ion on physical and drug release properties of the compressionoated tablets. The susceptibility of procera gum coating to thenzymatic action of colonic bacteria was assessed by continuinghe drug release studies in a medium with 2% rat cecal con-ent after completing 5 h in simulated gastric and small intestinal
edia.
. Results and discussion
Procera gum based compression coated tablets intended forolonic drug delivery was successfully prepared following directompression method. The mean drug content of the budesonide
.75 0.033 ± 0.02 1.185 0.991 1.529
.22 0.135 ± 0.042 2.492 0.929 3.311
.78 0.464 ± 0.045 2.243 0.932 3.079
core tablets was found to be 2.91 ± 0.04 mg and the averagecrushing strength and percent friability were 95 ± 3.4 N and0.32 ± 0.05% respectively. The percent drug content of the coretablets therefore, was within 100 ± 5% and friability weight losswas less than 1% which is within the pharmacopoeial limit [19].Drug delivery system targeted to the colon should ideally remainintact in the upper GI tract and release the drug load once it reachesthe colon [20]. Four different levels of coating formulations contain-ing varying amount of procera gum were prepared for compressioncoating of the core budesonide tablets to evaluate the potentials ofthe developed system to serve as specific drug carriers to the colon.
3.1. Physical properties of compression coated tablets
Table 2 presents the results of analysis on weight, drug con-tent uniformity, friability and crushing strength of the compressioncoated tablets. All the formulations are within the pharmacopoeiallimit as shown in the results of the analysis [19]. Mechanical proper-ties of pharmaceutical tablets are quantifiable by crushing strengthand friability of the tablets. Crushing strength provides a measure oftablet strength while friability is a measure of tablet weakness [21].The crushing strength of the compression coated tablets varies from118.51 N in F1 to 51.50 N in F4 which indicate that the tablets havegood crushing strength. Determination of the crushing strengthshowed dependence on the quantity of the polysaccharide usedin the tablet. There was statistically significant decrease in crus-hing strength (P < 0.001) when the amount of procera gum wasincreased in the formulations. The friability was also increased sig-nificantly (P < 0.001) with increase in the amount of procera gumin the formulations. The mechanical strength of tablets dependson the extent of plastic deformation particles underwent duringcompression. The trend for mechanical properties observed in thecompression coated tablets may be due to the lower amount of totalplastic deformation exhibited by the procera gum during compres-sion.
3.2. FTIR analysis
FTIR spectroscopy was performed to assess the interactionof budesonide with the natural polysaccharide-procera gum.Fig. 1 shows the FTIR spectra of budesonide, procera gumand budesonide-procera gum physical mixture. A typical FTIRspectrum of budesonide showed characteristic O H stretch-ing peak at 3378 cm−1, C H stretching peak at 2935 cm−1,and C O stretching peaks at 1720 and 1659 cm−1 [22]. Thesetypical peaks were observed for the budesonide sample (A)at 3483.44 cm−1(O H stretch), 2935.66 cm−1 (C H stretch),1716.65 cm−1 and 1658.78 cm−1 (C O stretch). The recordedspectrum for procera gum shows a characteristic peaks forpolysaccharides. The peak present at 3280.92 cm−1 is attributedto hydroxyl groups, while the peaks at 1610.56 cm−1 and1415.75 cm−1 are due to carboxyl groups. Specifically, peaks at
898.96 cm−1 and 845.61 cm−1 are taken as an evidence for �- and�-linkages in the molecule respectively [23].
The characteristic peaks of both the drug and the polymerare observed in the FTIR spectrum of their solid admixture
336 L. Pachuau, B. Mazumder / International Journal of Biological Macromolecules 61 (2013) 333– 339
gum,
(oo(sd
3
paiFwT
Fig. 1. FTIR spectrum of – (A) budesonide, (B) procera
C) and the spectrum could be regarded as a superimpositionf the drug and the polymer. The typical peaks for budes-nide appeared at 3321.42 cm−1 (O H stretch), 2935.66 cm−1
C H stretch), 1716.65 cm−1 and 1658.78 cm−1 (C O stretch) withlightly reduced intensities as a result of interaction between therug and the polymer.
.3. Thermogravimetric analysis
TG analysis was performed to investigate the thermal decom-osition characteristics of the tablet components and their soliddmixture. Thermograms for budesonide, procera gum and a phys-
cal mixture of budesonide and procera gum were depicted inig. 2. The TG curve for budesonide (A) showed a single thermaleight loss event starting at 235.81 ◦C that continued to 486.59 ◦C.
here was a significant weight loss of 82.54% during this event.
Fig. 2. TGA of – (A) budesonide, (B) procera gum, (C) so
(C) solid admixture of budesonide with procera gum.
The melting point of budesonide is around 220–235 ◦C which cor-relates well with the TG curve. Thermogram for procera gum (B)showed two weight loss events with increase in temperature. Thefirst event occurred at 49.15 ◦C which continued to 145.73 ◦C with7.08% weight loss which may be attributed to evaporation of wateror loss of moisture. The second event which occurred between224.04 ◦C and 406.77 ◦C with total weight loss of 56.08% showeda typical decomposition patterns for polysaccharides. The TG curveof budesonide and procera gum mixture (C) also showed two stagesof thermal weight loss. The first weight loss took place at 45.47 ◦Cwhich continued to 110.55 ◦C during which there was 9.72% weightloss. The second event was observed in between 219.01 ◦C and
405.57 ◦C which may be attributed to a composite of the eventsobserved for budesonide and procera gum demonstrating the slightdecrease in thermal stability of the drug when mix with the proceragum.
lid admixture of budesonide with procera gum.
L. Pachuau, B. Mazumder / International Journal of B
Fig. 3. Percent drug release vs. time graph of different formulations under disso-lc
3
atwsccFtptadaccoeb
idgfvipfrsbsotsoc(fMt
ferent time intervals, it is evident that after 2 h, the tablet remained
ution medium with rat cecal contents (RCF1, RCF2, RCF3 & RCF4) and without ratecal contents (F1, F2, F3 & F4).
.4. In-vitro drug release
The in vitro drug release profiles of the different formulationslong with error bars are depicted in Fig. 3. Drug release fromhe tablets was studied on simulated GI tract conditions with orithout rat cecal contents in the dissolution media. Hydration and
welling of the polymers take place when the tablets come inontact with the dissolution media. This swelling and hydrationorrelated well with the level of procera gum in the formulations.or any polysaccharide-based colon-specific drug delivery devices,he rate-limiting step for activation of the system is the ability ofolysaccharides to hydrate and swell [24]. Theoretically, this resul-ant swelling creates a diffusion barrier at the surface of the systemllowing the penetration of colonic enzymes/bacteria leading toegradation of the polysaccharide barriers and the release of drugt the target site. Albizia gums are susceptible to degradation in theolon [25] due to the presence of a wide range of enzymes expe-ially �-arabinosidase and �-galactosidase. Hydration and swellingf the tablets investigated would create a chance for the colonicnzymes to penetrate through it and degrade the polysaccharidearrier.
A colon specific drug delivery should prevent drug releasen the stomach as well as in the small intestine. The medium ofissolution study was designed to mimic the GI tract condition byradually increasing the pH of the medium. Release of budesoniderom different formulations under acidic medium after two hoursaries between 12.19% in F1 which contain 50% of procera gumn the coating formulation and 0.02% in F4 which contain 97% ofrocera gum in the coating formulation. After 5 h, drug release wasound to be 38.85%, 25.47%, 13.50% and 9.14% in F1, F2, F3 and F4espectively. The amount of drug released in F3 and F4 after 5 hhows the capability of procera gum in preventing the drug fromeing completely released in the physiological environment of thetomach and small intestine [26]. The decrease in dissolution timef the drug with increase in the amount of procera gum from F1o F4 after 24 h dissolution study was also found to be statisticallyignificant (P < 0.001). The decrease in the release rate of the drugn increasing the amount of procera gum can be traced back to theoating formulations which also contain microcrystalline celluloseMCC) as filler binder. Decrease in the amount of procera gum in the
ormulations is compensated by an increase in the proportion of
CC. MCC is known to produce very hard, yet rapidly disintegratingablets due to swelling of its particles in water. This characteristic
iological Macromolecules 61 (2013) 333– 339 337
was also evident in the mechanical properties of the tablet whereincrease in procera gum in the formulations (with correspondingdecrease in MCC) resulted in decreased crushing strength. Whenthese tablets were tested for dissolution, formulations containingless amount of procera gum undergo faster disintegration anderosion resulting in increased drug release. Tablets with higheramount of procera gum in the coating showed reduced disinte-gration and erosion which slows down the release of the drugcandidate.
The purpose of polysaccharide based colon targeted drug deliv-ery system is not only to prevent drug release in the stomach andsmall intestine but also to release the drug in the colon after enzy-matic degradation of the carrier by colonic bacteria [26]. Thereforethe susceptibility of procera gum coating to the enzymatic action ofcolonic bacteria was assessed by continuing dissolution study in 2%rat cecal content medium after 5 h drug release study under sim-ulated gastric and intestinal conditions. The dissolution mediumwas changed at the 6th hour to simulate the colon arrival timeunder normal conditions. At this point, simulated small intesti-nal media was replaced by colonic fluid with 2% rat cecal content.The presence of 2% rat cecal content in simulated colonic fluidshowed evidence of improved drug release at different time periodswhen compared with release study without rat cecal content. Thepercent drug release from the different formulations after 24 h dis-solution study under a medium with 2% rat cecal contents were99%, 90%, 68% and 60% in F1, F2, F3 and F4 respectively. Biodegra-dation of arabinogalactans such as natural gums from A. proceratook place in the colon as the colonic microflora produced a widerange of enzymes such as �-glucuronidase, �- arabinosidase, �-galactosidase, etc. [13,14]. However, when the difference in theamount of drug release at different time periods were comparedbetween the media with or without 2% rat cecal contents, theimprovement in drug release under 2% rat cecal content was notstatistically significant as the P values were found to be more than0.05 (P = 0.975 for F1, P = 0.863 for F2, P = 0.897 and P = 0.810 for F4).This could be attributed to the fact that the colonic bacterial actionof the rat cecal medium might not be sufficient to degrade a gelbarrier developed at the surface of the compression-coated tablets.However, the human cecal contents would be far better than whatwas used in the present study [27].
3.5. In vitro drug release kinetics
The mechanism of drug release was also determined throughKorsemeyer–Peppas model and given in Table 2. The release expo-nent ‘n’ calculated from the equation shows that in all the batchesthe ‘n’ values were between 1.185 and 2.492. In all the formulations,the ‘n’ value was higher than 1.0 indicating a super case II transportand there is more than one mechanism involved in the release ofdrug from the tablets.
3.6. In vivo X-ray
It is important to correlate the in vitro performance of a con-trolled drug release system with suitable in vivo studies to ascertaincharacteristic and site of drug release. In vivo X-ray imaging methodwas successfully applied in evaluation of mucoadhesive multipar-ticulate system in rabbits [17] and colon target drug release systemin human [28,29]. In the present study, the core tablets containing100 mg of barium sulphate was compression-coated with a coatingformula containing 200 mg of procera gum. The details of the resultsare shown in Fig. 4. From the abdominal radiographs taken at dif-
unchanged in the stomach. X-ray photographs which were takenafter 4 h after tablet administration showed the arrival of the tabletat the cecum, tablet being more or less intact. After 6 h the presence
338 L. Pachuau, B. Mazumder / International Journal of Biological Macromolecules 61 (2013) 333– 339
t time
ostiws
4
dpdtFfuiwr
Fig. 4. X-ray images of rabbit at differen
f the tablet was observed at the proximal colonic region showingigns of tablet disintegration. This is evident through the size of theablet and intensity of image shown in the X-ray photograph. Then vivo X-ray studies on rabbit clearly showed that tablets coated
ith procera gum remained intact until it reaches the colon andupported well the in vitro studies.
. Conclusion
Compression coated tablets for based on A. procera for colonicelivery of budesonide was successfully prepared by direct com-ression method. The compatibility of procera gum with the modelrug was confirmed through FTIR and TGA studies. Results fromhe in vitro drug release study suggest that formulations F3 and4 containing 83% and 97% procera gum respectively in the coatormulations were able to provide minimal drug release in the
pper GI tract condition. The presence of 2% rat cecal content
n the media resulted in improved drug release which howeveras not significant statistically from dissolution media without
at cecal content. In vivo X-ray studies on rabbit also showed that
intervals after administration of tablet.
compression-coated tablets reach the colon intact and showedsigns of disintegrate once in the colon. Therefore, procera gumwas suitable to be used as compression coating polymer for colonicdelivery of drugs.
Acknowledgement
Authors are thankful to the Director, RIPANS for providing nec-essary facilities and the HOD and Staff, Department of RICIT, RIPANSfor providing materials and facilities required for conducting X-raystudies. They are also grateful to Cipla, Baddi for providing gratissample of budesonide.
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