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Research ArticleDesign, Characterization, and Optimization of Controlled DrugDelivery System Containing Antibiotic Drug/s
Apurv Patel, Hitesh Dodiya, Pragna Shelate, Divyesh Shastri, and Divyang Dave
Department of Pharmaceutics and Pharmaceutical Technology, K.B. Institute of Pharmaceutical Education and Research Center,Gandhinagar 382023, India
Correspondence should be addressed to Apurv Patel; [email protected]
Received 15 March 2016; Accepted 3 July 2016
Academic Editor: Ali Nokhodchi
Copyright ยฉ 2016 Apurv Patel et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The objective of this work was design, characterization, and optimization of controlled drug delivery system containing antibioticdrug/s. Osmotic drug delivery system was chosen as controlled drug delivery system. The porous osmotic pump tablets weredesigned using Plackett-Burman and Box-Behnken factorial design to find out the best formulation. For screening of threecategories of polymers, six independent variables were chosen for Plackett-Burman design. Osmotic agent sodium chloride andmicrocrystalline cellulose, pore forming agent sodium lauryl sulphate and sucrose, and coating agent ethyl cellulose and celluloseacetate were chosen as independent variables. Optimization of osmotic tablets was done by Box-Behnken design by selecting threeindependent variables. Osmotic agent sodium chloride, pore forming agent sodium lauryl sulphate, and coating agent celluloseacetatewere chosen as independent variables.The result of Plackett-Burman andBox-Behnken design andANOVAstudies revealedthat osmotic agent and pore former had significant effect on the drug release up to 12 hr. The observed independent variables werefound to be very close to predicted values of most satisfactory formulation which demonstrates the feasibility of the optimizationprocedure in successful development of porous osmotic pump tablets containing antibiotic drug/s by using sodium chloride,sodium lauryl sulphate, and cellulose acetate as key excipients.
1. Introduction
Oral controlled drug delivery system can provide continuousdelivery of drugs at controlled rate and predictable kineticsthroughout the GI transit. Oral controlled drug deliverysystem targets drug delivery to a specific region for eitherlocal or systemic effect throughout the GI transit.This systemalso gives zero-order release profile [1].
Oral controlled release system can provide better effec-tiveness in treatment of chronic disease, reduce side effects,and improve patient compliance due to less frequent dosinginterval.
Drug release from oral controlled release dosage formsare affected by pH of GI fluid, GI motility, and presence offood in GI tract. Drug release from osmotic drug deliverysystem is independent of pH and other physiochemicalparameters and it is possible to modulate the release charac-teristic by optimizing the properties of drug and system [2, 3].
Osmotic pressure is used as driving force for osmotic drugdelivery systems to release the drug in controlled manner.Osmotic pressure created due to imbibition of fluid fromexternal environment into the dosage form regulates thedelivery of drug from osmotic device. Osmotic drug deliverytechnique is the most interesting and widely acceptableamong all other technologies used for the same purpose.Intensive research has been carried out on osmotic systemsand several patents are also published. These systems can beused for both routes of administration, that is, oral and par-enteral. Oral osmotic systems are known as gastrointestinaltherapeutic systems (GITS). Parenteral osmotic drug deliveryincludes implantable pumps [3].
Dicloxacillin sodium and amoxicillin trihydrate are ๐ฝ-Lactam antibiotics. Dicloxacillin sodium and amoxicillintrihydrate have short half-life and high protein binding. Thedrug that shows linear pharmacokinetics is suitable for oralcontrolled release tablets and it would be advantageous to
Hindawi Publishing CorporationJournal of Drug DeliveryVolume 2016, Article ID 9024173, 15 pageshttp://dx.doi.org/10.1155/2016/9024173
2 Journal of Drug Delivery
slow down its release in GI tract not only to prolong itstherapeutic action but also to minimize side effects of drugs.
2. Material and Methods
2.1.Materials. Dicloxacillin sodiumwas obtained as gift sam-ple from Suvik Hitek Pvt. Ltd. (Gandhinagar, India). Amox-icillin trihydrate was obtained as gift sample from AstralLife Care (Mumbai, India). Sodium chloride was purchasedfromMerck Pharmaceutical (Mumbai, India). Sodium laurylsulphate was purchased from Bombay Tablet (Gandhinagar,India). Cellulose acetate and PVP K30 were purchased fromChemdyes Corporation (Gujarat). Magnesium stearate andtalc were purchased fromSuvikHitek Pvt. Ltd. (Gandhinagar,India).
2.2. Differential Scanning Calorimetry (DSC). DSC studieswere carried out for the pure drug, physical mixtures of drugand excipients, and placebo of the porous osmotic pumptablets to study the compatibility.The analysis was performedunder nitrogen (nitrogen flow rate 50mL/min) in order toeliminate oxidative and pyrolytic effects at a standard heatingrate of 10โC/min over a temperature range of 50โCโ400โCusing Universal V4 5A TA instruments.
2.3. Preparation of Porous Osmotic Pump Tablet
2.3.1. Preparation of Core Tablets. Core tablets of dicloxacillinsodium were prepared by wet granulation method. All theingredients were sieved through # 40 sieve. Individual ingre-dients, sufficient for a batch of 25 tablets, were weighed ona digital weighing balance as per Table 1. All the ingredients(except PVP K30, magnesium stearate, and talc) were mixedin mortar and pestle using geometric dilution method. Thedry blend was granulated with sufficient quantity of PVP K30which was dissolved in isopropyl alcohol. The powder masswas dried at 60โC in hot air oven for 6 h and passed through# 20 sieve. Then dried granules were mixed with magnesiumstearate and talc for 3min. Tablets were prepared by 9mmconcave die punch set using rotary tablet punching machine[4, 5].
2.3.2. Method of Preparation of Tablet Coat Solution. Cellu-lose acetate and PEG 400 were added to 3/4th of the totalvolumeof acetone and stirred at 35 rpmusing propeller stirrerfor half an hour till the solutionwas clear.Magnesium stearateand coloring agentwere triturated thoroughly in amortar andadded to the above solution and stirring continued further.Finally, the volume was made up with acetone [4, 5] (seeTable 2).
2.4. Coating of the Core Tablets. Tablet coating was doneusing coating pan apparatus. Speed of coating pan was set at30 rpm, and inlet air temperature and flow rate were 50โC and3.2 kg/min, respectively. Spraying rate for coating solutionwas kept at 4-5mL/min. Number of tablets per batch wasfixed at 50 tablets. Ten tablets of test batch were mixed with40 dummy tablets. Empty coating pan was run at above setparameters for 5min. Tablets were loaded to the pan and
Table 1: Formulation of osmotic tablet.Ingredient Weight (mg)Dicloxacillin sodium 244Sodium chloride 100MCC 60Sodium lauryl sulfate 15Sucrose 60PVP K30 15Magnesium stearate 3Talc 3Total weight of one tablet = 500mg.Number of tablets per batch = 20.
Table 2: Composition of coating solvent.
Ingredient CompositionCellulose acetate 2% w/vPEG 400 2% v/vTiO2
0.2% w/vColoring agent 0.2% w/vAcetone Up to 100mL
allowed to gain equilibrium. Coating solution was sprayedat 5mL/min rate for 2-3 seconds. Coating solution on thetablets was allowed to dry for 5min and again sprayed.Approximately 100mL coating solution was used for a batchof 50 tablets.
2.5. Characterization of Osmotic Tablet
2.5.1. Hardness. The fracture strength, which is defined as theforce, was required to break a tablet by radial compressionand was measured with a Monsanto tablet hardness tester inpresent study.Themean hardness is calculated and expressedas kg/cm2.
2.5.2. Friability. The friability of the tablets was measuredin a Roche friabilator. Tablets of a known weight (๐ค
0) or a
sample of 10 tablets are dedusted in a drum for a fixed time(100 revolutions) andweighed (๐ค) again. Percentage friabilitywas calculated from the loss in weight as given in equation asbelow.The weight loss should not be more than 1%. Consider
% Friability =๐ค0โ ๐ค
๐ค0
ร 100. (1)
2.5.3. Weight Variation Test. To study weight variation, 20tablets of each formulation were weighed using an electronicbalance individually, calculating the average weight, andcomparing the individual tablet weights to the average. Thetablets meet the IP test if no more than 2 tablets are outsidethe percentage limit and if no tablet differs by more than 2times the percentage limit.
2.5.4. Thickness. The thickness of the tablets was determinedusing a Vernier caliper. 20 tablets were used and mean wascalculated. Tablet thickness should not deviate by ยฑ5%.
Journal of Drug Delivery 3
2.6. Determination of Drug Content. Ten tablets were accu-rately weighed and powdered. A quantity of the powderequivalent to 100mg of dicloxacillin sodium was weighedaccurately and extracted in 100mL water by shaking for20min. After filtration through Whatman filter paper num-ber 1 and sufficient dilutionwithwater, sampleswere analyzedspectrophotometrically at 273 nm. Amount of drug presentwas determined from the calibration curve of dicloxacillinsodium [5].
2.7. In Vitro Drug Release Study. The release rate ofdicloxacillin sodium from developed tablets was determinedusing USP dissolution testing apparatus I (Basket type). Thedissolution test was performed using 900mL 0.1M HCl (pH1.2) for 2 hr and then in pH 6.8 phosphate buffer for 10 hr,at 37 ยฑ 0.5โC and 100 rpm. A sample (1mL) of the solutionwas withdrawn from the dissolution apparatus hourly for12 h, and the samples were replaced with fresh dissolutionmedium. The samples were passed through Whatman filterpaper after dilution and the absorption of these solutions wasmeasured at 273 nm.The cumulative percentage drug releasewas calculated.
2.8. Curve Fitting Analysis. For the determination of the drugrelease kinetics from the porous osmotic pump tablet, thein vitro release data were analyzed by zero-order, first-order,Higuchi, and Korsmeyer and Peppas equations [6].
2.9. Zero-Order Release Kinetics. To study the zero-orderrelease kinetics the release data was fitted into the followingequation:
๐๐
๐๐ก= ๐พ0, (2)
where โ๐โ is the amount of drug release, โ๐พ0โ is the zero-
order release rate constant, and โ๐กโ is the release time. Thegraph is plotted percentage cumulative drug release (% CDR)versus time.
2.10. First-Order Release Kinetics. To study the first-orderrelease kinetics the release rate data are fitted into thefollowing equation:
๐๐
๐๐ก= ๐พ1๐, (3)
where โ๐โ is the fraction of drug release, โ๐พ1โ is the first-
order release rate constant, and โ๐กโ is the release time.
2.11. Higuchi Release Model. To study the Higuchi releasemodel the release rate data are fitted into the followingequation:
๐ = ๐พ๐ป๐ก1/2, (4)
where โ๐โ is the fraction of drug release, โ๐พ๐ปโ is the release
rate constant, and โ๐กโ is the release time. The graph is plottedas % CDR versus square root of time.
Table 3: Formulation of osmotic tablet (F1โF6).
Ingredient Batch numberF1 F2 F3 F4 F5 F6
Dicloxacillin sodium (mg) 244 244 244 244 244 244NaCl (mg) 150 150 150 150 150 50MCC (mg) 30 30 90 30 90 30SLS (mg) 20 10 10 20 10 10Sucrose (mg) 90 30 30 90 90 30PVP K30 (mg) 15 15 15 15 15 15EC (%) 4 4 2 2 4 2CA (%) 2 2 4 4 4 2PEG 400 (%) 2 2 2 2 2 2Magnesium stearate (mg) 3 3 3 3 3 3Talc (mg) 3 3 3 3 3 3Coloring agent q.s q.s q.s q.s q.s q.s
Table 4: Formulation of osmotic tablet (F7โF12).
Ingredient Batch numberF7 F8 F9 F10 F11 F12
Dicloxacillin sodium (mg) 244 244 244 244 244 244NaCl (mg) 50 50 50 150 50 50MCC (mg) 30 90 90 90 30 90SLS (mg) 20 20 10 20 10 20Sucrose (mg) 50 90 90 30 90 30PVP K30 (mg) 15 15 15 15 15 15EC (%) 4 2 4 2 2 4CA (%) 4 2 2 2 4 2PEG 400 (%) 2 2 2 2 2 2Magnesium stearate (mg) 3 3 3 3 3 3Talc (mg) 3 3 3 3 3 3Coloring agent q.s q.s q.s q.s q.s q.s
2.12. Korsmeyer and Peppas Kinetics. To study the Korsmeyerand Peppas release kinetics the release rate data are fitted intothe following equation:
๐๐ก
๐โ
= ๐พKP๐ก๐, (5)
where ๐๐ก/๐โ
is the fraction of drug release, โ๐พKPโ is therelease rate constant, โ๐กโ is the release time, and โ๐โ is thediffusion exponent related to mechanism of drug release.Thegraph is plotted as log% CDR versus log time [6].
2.13. Selection of Polymers by Plackett-Burman FactorialDesign. A Plackett-Burman design was adopted to selectionof polymers of different category. In this design six factorswere evaluated. Hence by applying Plackett-Burman factorialdesign, influence of six independent variables, osmotic agents(NaCl, MCC), pore forming agents (SLS, sucrose), andcoating agents (cellulose acetate, ethyl cellulose), was studiedover three dependent variables' drug release at 2 hr, 6 hr, and12 hr and was checked [6, 7]. Formulation of osmotic tabletsof factorial batches is shown in Tables 3 and 4.
4 Journal of Drug Delivery
Table 5: Formulation of osmotic tablet (F13โF20).
Ingredient Batch numberF13 F14 F15 F16 F17 F18 F19 F20
Dicloxacillin sodium (mg) 244 244 244 244 244 244 244 244NaCl (mg) 100 100 50 100 150 50 50 100SLS (mg) 10 10 20 20 20 15 15 20PVP K30 (mg) 15 15 15 15 15 15 15 15CA (%) 4 2 3 4 3 4 2 2PEG 400 (%) 2 2 2 2 2 2 2 2Magnesium stearate (mg) 3 3 3 3 3 3 3 3Talc (mg) 3 3 3 3 3 3 3 3Coloring agent q.s q.s q.s q.s q.s q.s q.s q.s
Table 6: Formulation of osmotic tablet (F21โF27).
Ingredient Batch numberF21 F22 F23 F24 F25 F26 F27
Dicloxacillin sodium (mg) 244 244 244 244 244 244 244NaCl (mg) 100 150 150 50 150 100 100SLS (mg) 20 15 10 10 15 15 15PVP K30 (mg) 15 15 15 15 15 15 15CA (%) 2 2 3 3 4 3 3PEG 400 (%) 2 2 2 2 2 2 2Magnesium stearate (mg) 3 3 3 3 3 3 3Talc (mg) 3 3 3 3 3 3 3Coloring agent q.s q.s q.s q.s q.s q.s q.s
2.14. Optimization of Osmotic Tablet by Box-Behnken Facto-rial Design. In this optimization technique, the desirabilityapproach was used to generate the optimum settings forthe formulation. From the trial batches, three independentvariables were found to affect drug release significantly.Concentration of coating agent (NaCl) and pore formingagent (SLS) and concentration of coating agent (celluloseacetate) were taken as independent variables [8, 9]. For theoptimized formulation, the drug release at 2 hr, 6 hr, and 12 hrand release exponent (๐) were kept in target. Formulation ofosmotic tablets of factorial batches is shown in Tables 5 and6.
2.15. Effect of pH onDrug Release. Theoptimized formulationof porous osmotic pump tablets was tested for the effect ofpH on drug release.The best formulations were undergone indissolution studies in 0.1 N HCl, 6.8 pH phosphate buffer, 7.5pH phosphate buffer, and distilled water in rotation speed of100 rpm and 37 ยฑ 0.5โC using USP dissolution test apparatustype 1.
2.16. Effect of Agitation Intensity Drug Release. Theoptimizedformulation of matrix and porous osmotic pump tablets aretested for the effect of agitation intensity on drug release.The best formulations are undergone in dissolution studies bymaintaining different rotation speed of 50, 100, and 150 rpm
DSC
(mW
)
0.00
โ2.00
โ4.00
โ6.00
โ8.00
100.00 200.00 300.00
PeakOnsetEndsetHeat
169.28โC
144.20โC
180.41โC
โ674.87 mJโ168.72 J/g
Temperature (โC)
Figure 1: DSC spectra of pure drug (dicloxacillin sodium).
and at 37 ยฑ 0.5โC in 7.5 pH phosphate buffer for 8 h using USPdissolution test apparatus type 1.
2.17. Stability Studies. The stability studies were carried out asper the ICH and WHO guidelines of stability testing. Opti-mized formulations were kept inside the stability chambermaintained at 45โC and 75% RH for the period of 30 days. Atthe end of the stability study period, samples were analyzedfor parameters like physical characteristics, drug content, andin vitro drug release.
3. Result and Discussion
3.1. Drug Polymer Compatibility Studies Using DSC. DSCthermograms of pure drug (dicloxacillin sodium) and phys-ical mixtures of drug and excipients (NaCl, SLS, and CA)were studied for their interactions. It was observed thatthere was no significant drug polymer interaction observedamong drug, NaCl, SLS, and CA even at higher temperature.From DSC study, we can see that there is no change indrugโsmelting peak (169.28โCโ172.77โC) after the preparationof mixture. There is the no interaction between drug andexcipient shown in this study. So, we can conclude that drug iscompatible with all polymers. DSC thermogramswere shownin Figures 1 and 2.
Journal of Drug Delivery 5
Table 7: Physiochemical parameters of factorial batches.
Batch code Diameter (mm) Thickness (mm) Hardness (kg/cm2) % friability Uniformity of weight (mg) % drug content (% w/w)F1 10.0 ยฑ 0.05 5.2 ยฑ 0.5 6.3 ยฑ 0.2 0.54 540 ยฑ 2.7 103.2 ยฑ 2.1F2 10.1 ยฑ 0.05 4.9 ยฑ 0.5 6.8 ยฑ 0.4 0.39 470 ยฑ 4.8 99.3 ยฑ 3.6F3 10.1 ยฑ 0.05 5.1 ยฑ 0.2 6.5 ยฑ 0.5 0.72 530 ยฑ 2.9 98.2 ยฑ 4.3F4 10.1 ยฑ 0.05 5.2 ยฑ 0.5 6.3 ยฑ 0.7 0.43 540 ยฑ 3.1 97.3 ยฑ 4.7F5 10.0 ยฑ 0.05 4.6 ยฑ 0.4 6.8 ยฑ 0.3 0.11 385 ยฑ 3.4 100.3 ยฑ 2.2F6 10.0 ยฑ 0.05 5.4 ยฑ 0.3 6.9 ยฑ 0.2 0.47 590 ยฑ 1.8 99.5 ยฑ 1.4F7 10.1 ยฑ 0.05 4.7 ยฑ 0.5 6.8 ยฑ 0.2 0.52 380 ยฑ 4.4 101.4 ยฑ 1.2F8 10.0 ยฑ 0.05 4.9 ยฑ 0.5 6.8 ยฑ 0.5 0.65 500 ยฑ 2.5 96.3 ยฑ 3.3F9 10.0 ยฑ 0.05 4.8 ยฑ 0.4 6.5 ยฑ 0.2 0.83 430 ยฑ 3.7 98.4 ยฑ 1.4F10 10.0 ยฑ 0.05 5.2 ยฑ 0.2 6.8 ยฑ 0.4 0.49 540 ยฑ 1.2 99.2 ยฑ 3.8F11 10.1 ยฑ 0.05 4.8 ยฑ 0.5 6.8 ยฑ 0.5 0.57 430 ยฑ 5.1 97.7 ยฑ 2.6F12 10.0 ยฑ 0.05 4.8 ยฑ 0.5 6.5 ยฑ 0.3 0.34 440 ยฑ 2.9 97.2 ยฑ 1.3All values are mean of three readings.
DSC
(mW
)
0.00
โ2.00
โ4.00
โ6.00
100.00 200.00 300.00
PeakOnsetEndsetHeat
PeakOnsetEndsetHeat
PeakOnsetEndsetHeat
103.91โC
96.79โC
109.56โCโ13.71 mJโ3.43 J/g
172.77โC
158.24โC
180.75โC
โ135.34 mJโ33.83 J/g
239.19โC
233.76โC
257.02โC
โ115.33 mJโ28.83 J/g
Temperature (โC)
Figure 2: DSC spectra of drug and polymers.
3.2. Screening of Polymers by Plackett-BurmanFactorial Design
3.2.1. Physicochemical Properties. Twelve batches were pre-pared for screening of polymers. The mean values of hard-ness, friability, thickness, weight, and drug content of pre-pared porous osmotic pump tablets are shown in Table 7.
3.2.2. In Vitro Dissolution Study. To study all the possiblecombinations of all factors at all levels, a six-factor, two-level Plackett-Burman factorial design was constructed andconducted in a fully randomized order. Six factors, NaCl(๐1),MCC(๐2), SLS(๐3), sucrose(๐4), EC(๐5), and CA(๐6),were selected as independent variables. Twelve batches wereprepared to study Plackett-Burman factorial design forosmotic tablets. Two checkpoint batches were also evaluatedto validate the design. The dependent variables (responses)studied were % drug release after 1 hr, 6 hr, and 12 hr ofdissolution. Results of the drug release profile obtained forosmotic tablets are shown in Figures 3(a), 3(b), 3(c), and 3(d).
Effect of formulation variable on drug release at 1 hr, 6 hr,and 12 hr was carried out using Design-Expert Software(Version 7.1.6, Stat-Ease Inc., Minneapolis, MN).
Effect of Formulation Variable on Drug Release at 1 hr (Y1).From the equation, factor value of ๐1 was +2.08 and ๐2was โ1.41 indicating that ๐1 had more effect on drug releasethan ๐2. Factor value of ๐3 was +5.75 and ๐4 was +0.41indicating that ๐3 had more effect on drug release than ๐4.Factor value of ๐5 was +0.08 and ๐6 was +0.53 indicatingthat๐6 hadmore effect on drug release than๐5. Positive signof ๐1, ๐3 , and ๐6 indicates positive effect on drug release.Figures 4(a)โ4(d) show contour plot and 3D surface plot for๐1 suggesting effect of variables as described above. Consider
๐1 = 2.08๐1 โ 1.41๐2 + 5.75๐3 + 0.41๐4 + 0.08๐5
+ 0.53๐6.(6)
The relationship between formulation variables (๐1 and๐2)and ๐1 was further elucidated using 3D surface plot. FromFigure 4(b) it can be concluded that factor NaCl(๐1) hadmore osmotic effect on drug release while MCC(๐2) had nosignificant effect on drug release.
The relationship between formulation variables (๐3 and๐4) and ๐1 was further elucidated using 3D surface plot.From Figure 4(d) it can be concluded that factor SLS(๐3) hadmore pore forming effect on drug release while sucrose(๐4)had no significant effect on drug release.Effect of Formulation Variable on Drug Release at 6 hr (๐2).From the equation, factor value of ๐1 was +6.66 and ๐2was โ3.66 indicating that๐1 had more effect on drug releasethan ๐2. Factor value of ๐3 was +12.66 and ๐4 was +0.66indicating that ๐3 had more effect on drug release than ๐4.Factor value of๐5wasโ0.16 and๐6was +3.83 indicating that๐6 had more effect on drug release than ๐5. Positive signof ๐1, ๐3, and ๐6 indicates positive effect on drug release.Figures 5(a)โ5(d) show contour plot and 3D surface plot for๐2 suggesting effect of variables as described above. Consider
๐2 = 6.66๐1 โ 3.66๐2 + 12.66๐3 + 0.66๐4
โ 0.16๐5 + 3.83๐6.(7)
The relationship between formulation variables (๐1 and๐2)and ๐2 was further elucidated using 3D surface plot. From
6 Journal of Drug Delivery
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14
% d
rug
rele
ase
Time (hr)
F1F2
F3
(a)
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14
% d
rug
rele
ase
Time (hr)
F4F5
F6
(b)
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14
% d
rug
rele
ase
Time (hr)
F7F8
F9
(c)
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10 12 14
% d
rug
rele
ase
Time (hr)
F10F11
F12
(d)
Figure 3: (a) Drug release profile for batches F1 to F3. (b) Drug release profile for batches F4 to F6. (c) Drug release profile for batches F7 toF9. (d) Drug release profile for batches F10 to F12.
Figure 5(b) it can be concluded that factor NaCl(๐1) hadmore osmotic effect on drug release while MCC(๐2) had nosignificant effect on drug release.
The relationship between formulation variables (๐3 and๐4) and ๐2 was further elucidated using 3D surface plot.From Figure 5(d) it can be concluded that factor SLS(๐3) hadmore pore forming effect on drug release while sucrose(๐4)had no significant effect on drug release.
Effect of Formulation Variable on Drug Release at 12 hr (๐3).From the equation, factor value of ๐1 was +5.08 and ๐2was โ5.19 indicating that๐1 had more effect on drug releasethan ๐2. Factor value of ๐3 was +19.75 and ๐4 was โ1.08indicating that ๐3 had more effect on drug release than ๐4.Factor value of๐5was +2.41 and๐6was +7.25 indicating that๐6 had more effect on drug release than ๐5. Positive signof ๐1, ๐3, and ๐6 indicates positive effect on drug release.
Figures 6(a)โ6(d) show contour plot and 3D surface plot for๐3 suggesting effect of variables as described above. Consider
๐3 = 5.08๐1 โ 5.19๐2 + 19.75๐3 โ 1.083๐4
+ 2.41๐5 + 7.25๐6.(8)
The relationship between formulation variables (๐1 and๐2)and ๐3 was further elucidated using 3D surface plot. FromFigure 6(b) it can be concluded that factor NaCl(๐1) hadmore osmotic effect on drug release while MCC(๐2) had nosignificant effect on drug release.
The relationship between formulation variables (๐3 and๐4) and ๐3 was further elucidated using 3D surface plot.From Figure 6(d) it can be concluded that factor SLS(๐3) hadmore pore forming effect on drug release while sucrose(๐4)had no significant effect on drug release.
Journal of Drug Delivery 7
1.00
1.00
0.50
0.50
0.00
0.00
โ0.50
โ0.50
โ1.00
โ1.00
B: M
CC
A: NaCl
Actual factorsSLS = โ1.00
sucrose = โ1.00
CA = โ1.00
EC = โ1.00
4.41667
5.58333
6.75
7.91667
9.08333
% DR at 1hr
% DR at 1hr
error 1 = 0.00
error 2 = 0.00
error 3 = 0.00
error 4 = 0.00
error 5 = 0.00
24
3
C:D:E:F:G:H:J:K:L:
X1 = A: NaClX2 = B: MCC
Design-Expert Software
(a)
1.00
10.3
8.525
6.75
4.975
3.2
1.00
0.50 0.50
0.00 0.00
โ0.50 โ0.50
โ1.00 โ1.00
% D
R at
1hr
% DR at 1hr24
3
Actual factorsSLS = โ1.00
sucrose = โ1.00
CA = โ1.00
EC = โ1.00
error 1 = 0.00
error 2 = 0.00
error 3 = 0.00
error 4 = 0.00
error 5 = 0.00
C:D:E:F:G:H:J:K:L:
X1 = A: NaClX2 = B: MCC
B: MCC A: NaCl
Design-Expert Software
(b)
% DR at 1hr
1.00
1.00
0.50
0.50
0.00
0.00
โ0.50
โ0.50
โ1.00
โ1.00
D: s
ucro
se
C: SLS
NaCl = 0.00
MCC = 0.00
9.47222 11.5278 13.583315.6389 17.6944
% DR at 1hr24
3
Actual factors
CA = 0.00
EC = 0.00
error 1 = 0.00
error 2 = 0.00
error 3 = 0.00
error 4 = 0.00
error 5 = 0.00
A:B:E:F:G:H:J:K:L:
X1 = C: SLSX2 = D:sucrose
Design-Expert Software
(c)
1.001.00
0.50 0.50
0.00 0.00
โ0.50 โ0.50
โ1.00โ1.00
20
16.75
13.5
10.25
7
% D
R at
1hr
% DR at 1hr24
3
MCC = 0.00
Actual factors
CA = 0.00
EC = 0.00
error 1 = 0.00
error 2 = 0.00
error 3 = 0.00
error 4 = 0.00
error 5 = 0.00
A:B:E:F:G:H:J:K:L:
X1 = C: SLSX2 = D:sucrose
NaCl = 0.00
D: sucrose C: SLS
Design-Expert Software
(d)
Figure 4: (a) Contour plot for response ๐1 (drug release at 1 hr) (for ๐1 and ๐2). (b) 3D surface plot of response ๐1 (drug release at 1 hr)(for๐1 and ๐2). (c) Contour plot for response ๐1 (drug release at 1 hr) (for๐3 and ๐4). (d) 3D surface plot of response ๐1 (drug release at1 hr) (for๐3 and ๐4).
8 Journal of Drug Delivery
% DR at 6hr
% DR at 6hr1.00
1.00
0.50
0.50
0.00
0.00
โ0.50
โ0.50
โ1.00
โ1.00
35.1111
38.5556
4245.4444
48.8889
70
19
CA = 0.00
EC = 0.00
SLS = 0.00
sucrose = 0.00
Actual factors
error 1 = 0.00
error 2 = 0.00
error 3 = 0.00
error 4 = 0.00
error 5 = 0.00
X1 = A: NaClX2 = B: MCC
C:D:E:F:G:H:J:K:L:
B: M
CC
A: NaCl
Design-Expert Software
(a)
% D
R at
6hr
1.00 1.00
0.50 0.50
0.00 0.00
โ0.50 โ0.50
โ1.00 โ1.00
53
47.5
42
36.5
31
% DR at 6hr70
19
CA = 0.00
EC = 0.00
SLS = 0.00
sucrose = 0.00
Actual factors
error 1 = 0.00
error 2 = 0.00
error 3 = 0.00
error 4 = 0.00
error 5 = 0.00
C:D:E:F:G:H:J:K:L:
X1 = A: NaClX2 = B: MCC
B: MCC A: NaCl
Design-Expert Software
(b)
% DR at 6hr
1.00
1.00
0.50
0.50
0.00
0.00
โ0.50
โ0.50
โ1.00
โ1.00
33.1111 37.5556 42 46.4444 50.8889
% DR at 6hr70
19
Actual factors
X1 = C: SLSX2 = D:sucrose
NaCl = 0.00
MCC = 0.00
CA = 0.00
EC = 0.00
error 1 = 0.00
error 2 = 0.00
error 3 = 0.00
error 4 = 0.00
error 5 = 0.00
A:B:E:F:G:H:J:K:L:
C: SLS
D: s
ucro
se
Design-Expert Software
(c)
% D
R at
6hr
1.00 1.00
0.50 0.50
0.00 0.00
โ0.50 โ0.50
โ1.00 โ1.00
56
49
42
35
28
% DR at 6hr70
19
Actual factors
X1 = C: SLSX2 = D:sucrose
NaCl = 0.00
MCC = 0.00
CA = 0.00
EC = 0.00
error 1 = 0.00
error 2 = 0.00
error 3 = 0.00
error 4 = 0.00
error 5 = 0.00
A:B:E:F:G:H:J:K:L:
C: SLSD: sucrose
Design-Expert Software
(d)
Figure 5: (a) Contour plot for response ๐2 (drug release at 6 hr) (for ๐1 and ๐2). (b) 3D surface plot of response ๐2 (drug release at 6 hr)(for๐1 and ๐2). (c) Contour plot for response ๐2 (drug release at 6 hr) (for๐3 and ๐4). (d) 3D surface plot of response ๐2 (drug release at6 hr) (for๐3 and ๐4).
Journal of Drug Delivery 9
1.00
1.00
0.50
0.50
0.00
0.00
โ0.50
โ0.50
โ1.00
โ1.00
% DR at 12hr
% DR at 12hr
64.75
68.4167
72.0833
75.75
79.4167
106
33
EC = 0.00
CA = 0.00
SLS = 0.00
sucrose = 0.00
Actual factors
error 1 = 0.00
error 2 = 0.00
error 3 = 0.00
error 4 = 0.00
error 5 = 0.00
X1 = A: NaClX2 = B: MCC
B: M
CC
A: NaCl
C:D:E:F:G:H:J:K:L:
Design-Expert Software
(a)
% D
R at
12
hr
1.00 1.00
0.50 0.50
0.00 0.00
โ0.50 โ0.50
โ1.00 โ1.00
84
78.25
72.5
66.75
61
% DR at 12hr106
33
EC = 0.00
CA = 0.00
SLS = 0.00
sucrose = 0.00
Actual factors
error 1 = 0.00
error 2 = 0.00
error 3 = 0.00
error 4 = 0.00
error 5 = 0.00
X1 = A: NaClX2 = B: MCC
B: MCC A: NaCl
C:D:E:F:G:H:J:K:L:
Design-Expert Software
(b)
1.00
1.00
0.50
0.50
0.00
0.00
โ0.50
โ0.50
โ1.00
โ1.00
58.194465.1389
72.0833 79.0278 85.9722
% DR at 12hr
% DR at 12hr106
33
Actual factors
X1 = C: SLSX2 = D:sucrose
C: SLS
D: s
ucro
se
NaCl = 0.00
MCC = 0.00
EC = 0.00
CA = 0.00
error 1 = 0.00
error 2 = 0.00
error 3 = 0.00
error 4 = 0.00
error 5 = 0.00
A:B:E:F:G:H:J:K:L:
Design-Expert Software
(c)
% D
R at
12
hr
1.00 1.00
0.50 0.50
0.00 0.00
โ0.50 โ0.50
โ1.00 โ1.00
93
82.5
72
61.5
51
% DR at 12hr106
33
Actual factors
X1 = C: SLSX2 = D:sucrose
C: SLSD: sucrose
NaCl = 0.00
MCC = 0.00
EC = 0.00
CA = 0.00
error 1 = 0.00
error 2 = 0.00
error 3 = 0.00
error 4 = 0.00
error 5 = 0.00
A:B:E:F:G:H:J:K:L:
Design-Expert Software
(d)
Figure 6: (a) Contour plot for response ๐3 (drug release at 12 hr) (for๐1 and ๐2). (b) 3D surface plot of response ๐3 (drug release at 12 hr)(for๐1 and ๐2). (c) Contour plot for response ๐3 (drug release at 12 hr) (for๐3 and ๐4). (d) 3D surface plot of response ๐3 (drug releaseat 12 hr) (for๐3 and ๐4).
10 Journal of Drug Delivery
0
10
20
30
40
50
60
70
80
90
0 2 4 6 8 10 12 14
% d
rug
rele
ase
Time (hr)
F13F14
F15F16
(a)
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14
% d
rug
rele
ase
Time (hr)
F17F18
F19F20
(b)
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14
% d
rug
rele
ase
Time (hr)
F21F22
F23F24(c)
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10 12 14
% d
rug
rele
ase
Time (hr)
F25F26
F27
(d)
Figure 7: (a) Drug release profile for batches (F13โF16). (b) Drug release profile for batches (F17โF20). (c) Drug release profile for batches(F21โF24). (d) Drug release profile for batches (F25โF27).
3.3. Optimization of Osmotic Tablet by Box-BehnkenFactorial Design
3.3.1. Physiochemical Parameter. 15 batches were prepared foroptimization of osmotic tablets. Tablets were evaluated foruniformity of weight, uniformity of contents, tablet thicknessand diameter, and hardness and friability. Results of thephysiochemical tests obtained are shown in Table 8.
3.3.2. In Vitro Dissolution Study. To study all the possi-ble combinations of all factors at all levels, a three-factor,three-level Box-Behnken factorial design was constructedand conducted in a fully randomized order. Three factors,NaCl(๐1), SLS(๐2), and CA(๐3), were selected as inde-pendent variables. 15 batches were prepared to study Box-Behnken factorial design for osmotic tablets. Two checkpoint
batches were also evaluated to validate the design. Thedependent variables (responses) studied were % drug releaseafter 1 hr, 6 hr, and 12 hr of dissolution. Results of the drugrelease profile obtained for osmotic tablets are shown inFigures 7(a), 7(b), 7(c), and 7(d).
Figure 7(a) contains dissolution profile for batches F13โF16. Figure 7(b) contains dissolution profile for batches F17โF20. Figure 7(c) contains dissolution profile for batches F21โF124. Figure 7(d) contains dissolution profile for batches F25โF127.
Effect of Formulation Variable on Drug Release at 1 hr (Y1).Equation shows that coefficients ๐
1and ๐2bear a positive sign
and ๐3bears a negative sign and coefficient value for ๐1 is
7.50, ๐2 is 0.25, and ๐3 is โ0.50. So it indicates that ๐1 hasmore effect on drug release than๐2 and๐3. Figures 8(a) and
Journal of Drug Delivery 11%
DR
at1
hr
1.00 1.00
0.50 0.50
0.00 0.00
โ0.50 โ0.50
โ1.00 โ1.00
Actual factorC:
31
26
21
16
11
CA = 0.00
% DR at 1hr31
11
B: SLS A: NaCl
X1 = A: NaClX2 = B: SLS
Design-Expert Software
(a)
% D
R at
1hr
1.00 1.00
0.50 0.50
0.00 0.00
โ0.50 โ0.50
โ1.00 โ1.00
Actual factorB:
29
24.5
20
15.5
11
SLS = 0.00
% DR at 1hr31
11
X1 = A: NaClX2 = C: CA
C: CA A: NaCl
Design-Expert Software
(b)
Figure 8: (a) 3D surface plot of response ๐1 (drug release at 1 hr) (for ๐1 and ๐2). (b) 3D surface plot of response ๐1 (drug release at 1 hr)(for๐1 and ๐3).
Table 8: Physiochemical parameters of factorial batches.
Batch code Diameter Thickness Hardness % friability Weight variation % drug contentF13 10.1 ยฑ 0.05 4.6 ยฑ 0.5 6.8 ยฑ 0.3 0.54 375 ยฑ 2.6 101.2 ยฑ 2.3F14 10.1 ยฑ 0.05 4.6 ยฑ 0.3 6.4 ยฑ 0.3 0.39 375 ยฑ 4.8 98.3 ยฑ 3.6F15 10.0 ยฑ 0.05 4.2 ยฑ 0.2 6.5 ยฑ 0.3 0.72 335 ยฑ 2.9 99.2 ยฑ 4.1F16 10.0 ยฑ 0.05 4.7 ยฑ 0.5 6.3 ยฑ 0.5 0.43 384 ยฑ 3.1 95.3 ยฑ 4.4F17 10.1 ยฑ 0.05 5.1 ยฑ 0.4 6.8 ยฑ 0.2 0.11 435 ยฑ 3.4 103.3 ยฑ 2.5F18 10.0 ยฑ 0.05 4.2 ยฑ 0.3 6.9 ยฑ 0.3 0.47 330 ยฑ 1.8 97.5 ยฑ 1.7F19 10.0 ยฑ 0.05 4.3 ยฑ 0.5 6.8 ยฑ 0.5 0.52 330 ยฑ 4.4 101.4 ยฑ 1.2F20 10.1 ยฑ 0.05 4.7 ยฑ 0.5 6.8 ยฑ 0.4 0.65 380 ยฑ 2.5 98.3 ยฑ 3.5F21 10.1 ยฑ 0.05 4.8 ยฑ 0.4 6.5 ยฑ 0.2 0.83 385 ยฑ 3.7 99.4 ยฑ 1.4F22 10.0 ยฑ 0.05 5.0 ยฑ 0.2 6.8 ยฑ 0.2 0.49 430 ยฑ 1.2 97.2 ยฑ 3.8F23 10.1 ยฑ 0.05 4.9 ยฑ 0.5 6.9 ยฑ 0.3 0.57 426 ยฑ 5.1 98.7 ยฑ 2.6F24 10.0 ยฑ 0.05 5.2 ยฑ 0.5 6.5 ยฑ 0.2 0.34 440 ยฑ 2.9 98.2 ยฑ 1.3F25 10.1 ยฑ 0.05 4.2 ยฑ 0.4 6.6 ยฑ 0.5 0.43 325 ยฑ 1.3 99.4 ยฑ 5.4F26 10.1 ยฑ 0.05 4.7 ยฑ 0.1 6.9 ยฑ 0.2 0.61 380 ยฑ 3.4 98.5 ยฑ 1.7F27 10.0 ยฑ 0.05 4.7 ยฑ 0.5 6.8 ยฑ 0.1 0.53 380 ยฑ 2.7 99.9 ยฑ 2.3All values are mean of three readings.
8(b) show cube and 3D surface plot for ๐1 suggesting effectof variables as described above. Consider๐1 = 7.50๐1 + 0.25๐2 โ 0.50๐3 + 1.50๐1๐2
+ 0.00๐1๐3 + 0.50๐2๐3 โ 1.92๐12 + 1.58๐22
+ 0.58๐32.
(9)
The relationship between formulation variables (๐1, ๐2,and ๐3) and ๐1 was further elucidated using cube and 3D
surface plot. From Figure 8(a) it can be concluded that factorNacl(๐1) hasmore effect on drug release than SLS(๐2). FromFigure 8(b) it can be concluded that factor๐3 (Coating agent)has negative effect on drug release. As we increase the level of๐3, it decreases drug release.Effect of Formulation Variable on Drug Release at 6 hr (Y2).Equation shows that coefficients ๐
1and ๐2bear a positive sign
and ๐3bears a negative sign and coefficient value for ๐1 is
11.62, ๐2 is 0.38, and ๐3 is โ0.75. So it indicates that ๐1 has
12 Journal of Drug Delivery
1.00 1.00
0.50 0.50
0.00 0.00
โ0.50 โ0.50
โ1.00 โ1.00
% D
R at
6hr
65
57
49
41
33
% DR at 6hr64
31
Actual factorC: CA = 0.00
X1 = A: NaClX2 = B: SLS
B: SLS A: NaCl
Design-Expert Software
(a)
1.00
0.50
0.00
โ0.50
โ1.00
1.00
0.50
0.00
โ0.50
โ1.00
% D
R at
6hr
61
53.5
46
38.5
31
% DR at 6hr64
31
Actual factorB: SLS = 0.00
X1 = A: NaClX2 = C: CA
C: CAA: NaCl
Design-Expert Software
(b)
Figure 9: (a) 3D surface plot of response ๐2 (drug release at 6 hr) (for๐1 and ๐2). (b) 3D surface plot of response ๐2 (drug release at 6 hr)(for๐1 and ๐3).
more effect on drug release than๐2 and๐3. Figures 9(a) and9(b) show cube and 3D surface plot for ๐2 suggesting effectof variables as described above. Consider๐1 = 11.62๐1 + 0.38๐2 โ 0.75๐3 + 3.25๐1๐2
+ 0.50๐1๐3 + 0.00๐2๐3 โ 3.54๐12
+ 3.96๐22 โ 0.96๐32.
(10)
The relationship between formulation variables (๐1, ๐2,and ๐3) and ๐2 was further elucidated using cube and 3Dsurface plot. From Figure 9(a) it can be concluded that factorNaCl(๐1) has more effect on drug release than SLS(๐2).From Figure 9(b) it can be concluded that factor๐3 (Coatingagent) has negative effect on drug release. As we increase thelevel of๐3, it decreases drug release.Effect of Formulation Variable on Drug Release at 12 hr (Y3).Equation shows that coefficients ๐
1and ๐2bear a positive sign
and ๐3bears a negative sign and coefficient value for ๐1 is
17.50, ๐2 is 0.88, and ๐3 is โ0.80. So it indicates that ๐1 hasmore effect on drug release than๐2 and๐3. Figures 10(a) and10(b) show cube and 3D surface plot for ๐2 suggesting effectof variables as described above. Consider๐3 = 17.50๐1 + 0.88๐2 โ 0.80๐3 + 5.00๐1๐2
โ 1.00๐1๐3 + 2.25๐2๐3 โ 1.29๐12
+ 5.96๐22 โ 1.04๐32.
(11)
The relationship between formulation variables (๐1, ๐2,and ๐3) and ๐3 was further elucidated using cube and 3D
Table 9: Desirable values selected for dependent variables.
Dependent variables Desirable valuesLower limit Upper limit
๐1 (% drug release at 1 hr) 20 30๐2 (% drug release at 6 hr) 50 60๐3 (% drug release at 12 hr) 90 100
surface plot. From Figure 10(a) it can be concluded that factorNaCl(๐1) has more effect on drug release than SLS(๐2).From Figure 10(b) it can be concluded that factor๐3 (coatingagent) has negative effect on drug release. As we increase thelevel of๐3, it decreases drug release.
3.4. Selection of Optimized Batch. Selection of best batchwas carried out using Design-Expert Software (Version 7.1.6,Stat-Ease Inc., Minneapolis, MN). After statistical analysis thedesirability function was applied to select the best batch.The desirable values selected for dependent variables ๐1, ๐2,and ๐3 are given in Table 9.
Desirable value range selected that was 5% varies fromoptimum value.
Batch F22 came closest to satisfying all the selectioncriteria. The results were further reinstated using the overlayplot in Figure 11. The yellow region of the plot indicatesthe area where all the selection criteria are satisfied. BatchF22 falls in this yellow area, indicating the formulationhaving amount of osmotic agent (150mg), pore forming agent(15mg), and coating agent (2%) that possessed the desirablecharacteristics.
Journal of Drug Delivery 13
1.00 1.00
0.50 0.50
0.00 0.00
โ0.50 โ0.50
โ1.00 โ1.00
% D
R at
12
hr
104
92
80
68
56
% DR at 12hr104
52
Actual factorC: CA = 0.00
X1 = A: NaClX2 = B: SLS
B: SLS A: NaCl
Design-Expert Software
(a)
1.00
0.50
0.00
โ0.50
โ1.00
1.00
0.50
0.00
โ0.50
โ1.00
% D
R at
12
hr
98
86.5
75
63.5
52
% DR at 12hr104
52
Actual factorB: SLS = 0.00
X1 = A: NaClX2 = C: CA
C: CAA: NaCl
Design-Expert Software
(b)
Figure 10: (a) 3D surface plot of response ๐3 (drug release at 12 hr) (for ๐1 and ๐2). (b) 3D surface plot of response ๐3 (drug release at12 hr) (for๐1 and ๐3).
3.5. So F22 Batch Was Selected as Optimized Batch
3.5.1. Effect of pH on Drug Release. When formulation F22was subjected to in vitro release studies in buffers withdifferent pH and distilled water, no significant differences inthe release profiles were seen compared to that in phosphatebuffer pH 6.8. Thus the fluid in different parts of the GI tractwill scarcely affect drug release from the osmotic system.
3.5.2. Effect of Agitation Intensity on Drug Release. Therelease profile of dicloxacillin sodium from the optimizedformulation F22 was independent of the agitational intensityof the release media.
4. Osmotic Tablet of Amoxicillin Trihydrate
Optimized batch of amoxicillin trihydratewas prepared usingF22 batch composition of Box-Behnken design batches. Fromthe drug release data and also release pattern shown inFigure 12 it can be concluded that there is no significantdifference between two drug release profiles.
5. Release Kinetics and Release Mechanism
Six kinetic models were used for controlled release curvefitting to select the most appropriate model. The dissolutiondata for optimized batch was fitted to the zero-order, first-order, Higuchi, Hixson-Crowell, Korsmeyer-Peppas, andWeibull models. Best fitting model was selected on thebasis of highest correlation coefficient and lowest ๐น value.
Table 10: Comparison of drug release profiles of dicloxacillinsodium and amoxicillin trihydrate.
Time (hr) Dicloxacillin sodium Amoxicillin trihydrate0 0 01 28.56 30.072 34.38 35.983 38.72 38.724 45.72 43.725 57.23 57.236 61.81 60.377 67.04 69.848 74.53 72.539 79.45 77.7510 84.02 82.0911 89.39 90.3912 95.72 93.88
Comparative statistical parameters for all the models wereobtained as shown in Table 11. Drug release mechanism wasexplored on the basis of release exponent (๐) value.
Model fitting results revealed that the Korsmeyer-Peppasmodel was best fitted to the release kinetics (๐2 = 0.9960,highest; ๐น = 6.8629, lowest). Higuchi model was also close tothe Korsmeyer-Peppas model. Hence ๐น test was performedfor both models. It revealed significant difference betweenthe two models. Hence Korsmeyer-Peppas model was finallyselected as best fitted model. Release exponent ๐ was found
14 Journal of Drug Delivery
Table 11: Kinetic modeling of drug release.
Parameter Kinetic modelZero-order First-order Higuchi Hixson-Crowell Korsmeyer-Peppas Weibull
Sum of residuals 1314.416 346.8983 205.599 336.2533 75.4920 258.9369Correlation coefficient (๐) 0.9781 0.9821 0.9905 0.9877 0.9960 0.9860๐ square (๐2) 0.8595 0.9629 0.9780 0.9635 0.9918 0.9719๐น 109.534 28.9081 17.1332 28.0211 6.8629 25.8936Model fitting results revealed that the Korsmeyer-Peppas model was best fitted to the release kinetics (๐2 = 0.9960, highest,๐น = 6.8629, lowest). Higuchi modelwas also close to the Korsmeyer-Peppas model. Hence ๐น test was performed for both models. It revealed significant difference between two models. HenceKorsmeyer-Peppas model was finally selected as best fitted model. Release exponent ๐ was found to be 0.580, indicating that the drug was released from theformulation by anomalous (non-Fickian) mechanism.
1.00
0.50
0.00
โ0.50
โ1.00
% DR at 1hr: 20
% DR at 6hr: 50
% DR at 6hr: 60
% DR at 6hr: 60
% DR at 12hr: 903
Overlay plot% DR at 1hr% DR at 6hr% DR at 12hr
Actual factor
1.000.500.00โ0.50โ1.00
Design points
Overlay plot
B: S
LS
A: NaCl
C: CA = 0.00
X1 = A: NaClX2 = B: SLS
Design-Expert Software
Figure 11: Overlay plot of ๐1, ๐2, and ๐3.
Table 12: Results of stability study of optimized batch (F22).
Evaluation parameters Initially After 30 daysWeight variation (๐ = 10) 430 ยฑ 1.2 429 ยฑ 3.3Diameter (mm) 10.0 ยฑ 0.05 10.0 ยฑ 0.05Thickness (mm) 5.0 ยฑ 0.2 5.0 ยฑ 0.1Hardness (kg/cm2) 6.8 ยฑ 0.2 6.7 ยฑ 0.5Friability (%) 0.49 0.52% drug content 97.2 ยฑ 3.8 97.0 ยฑ 1.3๐1 (% drug release at 1 hr) 28.56% 30.07%๐2 (% drug release at 6 hr) 61.81% 60.37%๐3 (% drug release at 12 hr) 95.72% 93.88%
to be 0.580, indicating that the drug was released from theformulation by anomalous (non-Fickian) mechanism.
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14
% d
rug
rele
ase
Time (hr)
Dicloxacillin sodiumAmoxicillin trihydrate
Figure 12: Drug release data of dicloxacillin sodium and amoxicillintrihydrate.
6. Stability Study
After the 1-month storage of formulation F22, values ofall parameters like hardness, diameter, thickness, % drugcontent, and friability were checked periodically and foundto be almost similar to the initial values.The drug profile wassimilar to the initial profile shown in Figure 13.There was notany significant change in any value and also no changes inthe physical appearance. So it can be said that formulation isstable (see Table 12).
7. Conclusion
The observed independent variables were found to be veryclose to predicted values of optimized formulation whichdemonstrates the feasibility of the optimization procedurein successful development of porous osmotic pump tabletscontaining dicloxacillin sodium and amoxicillin trihydrate asmodel drug by using sodium chloride (150mg) as osmotic
Journal of Drug Delivery 15
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14
% d
rug
rele
ase
Time (hr)
InitiallyAfter 30 days
Figure 13: Drug release data for stability study of osmotic tablet(F22).
agent, sodium lauryl sulphate (15mg) as pore former, cellu-lose acetate (2%) as coating agent, and control membranepermeability. Batch F22 was selected as optimized batch.Stability studies also revealed that optimized formulation isstable.
From the comparison of dissolution profile of optimizedbatch for both drugs (dicloxacillin sodium and amoxicillintrihydrate) it can be concluded that there was no signifi-cance difference in drug release observed, so it concludesthat porous osmotic pump tablets of antibiotic drugs weresuccessfully developed (see Table 10).
Competing Interests
The authors declare that they have no competing interests.
References
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