FORMULATION DEVELOPMENT AND IN-VITRO CHARACTERIZATION OF BILAYER TABLETS OF AMOXICILLIN AND FAMOTIDINE

ISSN: 2395 1338 FORMULATION DEVELOPMENT AND IN-VITRO CHARACTERIZATION OF BILAYER TABLETS OF AMOXICILLIN AND FAMOTIDINE B. Venkateswara Reddy *, K. Navaneetha Department of Pharmaceutics, St.Paul s College of Pharmacy, Turkayamjal (V), Hayathnagar (M), R.R.Dist- 501510, India Corresponding Author B. Venkateswara Reddy E-mail Id: basu.pharmacist@gmail.com Abstract: The present study was aimed to develop a formulation which provides dual therapy for the treatment of peptic ulcer. Dual therapy goal was attained by preparing a bilayer tablet containing antimicrobial agent amoxicillin and anti- gastric acid secretory agent famotidine for the effective treatment of H. pylori associated gastric/duodenal ulcer, in an attempt to improve bioavailability and to get maximum therapeutic benefits and patient compliance. Bilayer tablets were prepared after the optimization of individual layer of tablets. In this study amoxicillin was incorporated into immediate release layer by using various disintegrants like crospovidone, croscarmellose sodium and sodium starch glycolate. The disintegration time of these formulations was less than 9mins and drug was released within 30mins. Famotidine was incorporated into 112

sustain release layer by employing HPMC, xanthan gum and guar gum as release retarding agent and the developed formulations were evaluated for various parameters. Of all the formulations developed one formulation from both the layers of tablets were optimized and utilized to prepare a bilayer tablet. This bilayer tablet was subjected to in-vitro drug release studies and found to retain its characteristics which were seen in individual tablets. Keywords: Dual therapy, Peptic ulcer, Bilayer tablet, Amoxicillin, Famotidine. Introduction: Bi-layer tablet is used for sequential release of two drugs in combination, separate two incompatible substances and also for sustained release tablet in which one layer is immediate release as initial dose and second layer is maintenance dose [1]. In which one layer is formulated to obtain immediate release of the drug, with the aim of reaching a high serum concentration in a short period of time. The second layer is a controlled release, which is designed to maintain an effective plasma level for a prolonged period of time. The pharmacokinetic advantage relies on the fact that drug release from fast releasing layer leads to a sudden rise in the blood concentration. However, the blood level is maintained at steady state as the drug is released from the sustaining layer [2, 3]. In the present research work bi-layered tablets containing one immediate release layer and one sustained release layer were prepared. Immediate release layer releases the initial dose of drug and the sustain release layer absorbs the gastric fluids and produces the bulk density of less than that of GI fluids and remain in stomach for an extended period of time [4]. Amoxicillin and famotidine are used for the treatment of H.pylori induced peptic ulcer to minimize the side effect, improve the prolongation of action and to reduce the frequency of drug administration [5, 6]. Amoxicillin is incorporated into immediate release layer and famotidine is incorporated into the sustain release layer which shows floating behavior due to the presence of gas generating agent. This layer of tablet remains floating in the gastric contents once the immediate release layer is completely dissolved. By this the bioavailability of the drug is increased and improves patient compliance. Materials and methods: Materials: Amoxicillin and Famotidine were obtained from Chandra labs, Hyderabad. Ethyl Cellulose, Guar gum, Sodium bicarbonate, microcrystalline cellulose, PVP, talc and magnesium stearate were purchased from SD Fine Chem. Pvt. Ltd, Mumbai. Crospovidone, sodium starch glycolate and croscarmellose sodium were purchased from Merk Specialities Pvt. Ltd, Mumbai, India. 113

Methods: Formulation of Bilayer tablet [7] : Formulation of sustain release floating Layer of famotidine The sustained release tablets containing 40mg famotidine were prepared with a total tablet weight of 300mg by direct compression method. Micro crystalline cellulose and different polymers were weighed according to the formulation table-1 and sifted through 40 mesh. To the above blend famotidine was added and sifted through 18 mesh and mixed for 10min. Magnesium Stearate and talc was weighed and sifted through 40 mesh. The lubricant blend is added to the above blend and compressed. Table-1: Composition for formulation of sustain release Floating layer (F1 to F5) Ingredients(mg) F1 F2 F3 F4 F5 Famotidine 40mg 40mg 40mg 40mg 40mg HPMC 90 105 -- -- -- Xanthan gum -- -- 30 -- 30 Guar gum -- -- 105 120 120 PVP K30 -- -- 30 30 30 Sodium bicarbonate 45 45 60 60 60 MCC 110 95 20 35 5 Talc 7.5 7.5 7.5 7.5 7.5 Magnesium stearate 7.5 7.5 7.5 7.5 7.5 Total weight(mg) 300mg 300mg 300mg 300mg 300mg Formulation of immediate release layer of Amoxicillin The immediate release tablets containing 250mg Amoxicillin were prepared with a total tablet weight of 500mg. Di calcium phosphate, super disintegrants like croscarmellose sodium and crospovidone were weighed according to the formulation table-2 and sifted through 40 mesh. To the above blend Amoxicillin was added and sifted through 18 mesh and mixed for 10min. Magnesium Stearate weighed and sifted through 40 mesh this mixture lubricated blend was added to the above blend and mixed properly then compressed. 114

Table-2: Composition for formulation of immediate release layer (F1 to F7) Ingredients(mg) F1 F2 F3 F4 F5 F6 F7 Amoxicillin 250mg 250mg 250mg 250mg 250mg 250mg 250mg SSG 37.5 -- -- 75 -- -- -- CCS -- 37.5 -- -- 75 -- -- CP -- -- 37.5 -- -- 75 50 MCC 200 200 200 162.5 162.5 162.5 187.5 Magnesium stearate 12.5 12.5 12.5 12.5 12.5 12.5 12.5 Total weight(mg) 500mg 500mg 500mg 500mg 500mg 500mg 500mg Bilayered tablet After the batch was optimized in both immediate release layer and floating layer. The optimized batch in both was compressed by using same ingredients to prepare a bilayer tablet. Evaluation parameters: Precompression studies: The powder blend of both the layer are subjected to evaluation for bulk density, tapped density, carr s index, hausner s ratio and angle of repose, to determine the flow properties and compressibility of the powder blend. Evaluation of compressed tablets: The quantitative evaluation and assessment of a tablets chemical, physical and bioavailability properties are important in the design of tablets and to monitor product quality. There are various standards that have been set in the various pharmacopoeias regarding the quality of pharmaceutical tablets. These include the diameter, size, shape, thickness, weight, hardness, Friability and invitro-dissolution characters. Hardness: Hardness of the tablet was determined by using the Monsanto hardness tester. The lower plunger was placed in contact with the tablet and a zero reading was taken. The plunger was then forced against a spring by turning a threaded bolt until the tablet fractured. As the spring was compressed a pointer rides along a gauge in the barrel to indicate the force. Thickness Control of physical dimensions of the tablets such as size and thickness is essential for consumer acceptance and tablet-to-tablet uniformity. The diameter size and punch size of tablets depends on the die and 115

- punches selected for making the tablets. The thickness of tablet is measured by Vernier Callipers scale. The thickness of the tablet related to the tablet hardness and can be used an initial control parameter. Tablet thickness should be controlled within a ±5%. In addition thickness must be controlled to facilitate packaging. Friability: 20 tablets are weighed and placed in the apparatus where they are exposed to rolling and repeated shocks as they fall 6 inches in each turn within the apparatus. After four minutes of this treatment or 100 revolutions, the tablets are weighed and the weight compared with the initial weight. The loss due to abrasion is a measure of the tablet friability. The value is expressed as a percentage. A maximum weight loss of not more than 1% of the weight of the tablets being tested during the friability test is considered generally acceptable and any broken or smashed tablets are not picked. The percentage friability was determined by the formula: % Friability = (W1-W2) / W1 X 100 W1 = Weight of tablets before test, W2 = Weight of tablets after test. In-vitro Buoyancy studies: The in-vitro buoyancy was determined by floating lag time, and total floating time. The tablets were placed in a 100ml beaker containing 0.1N HCl. The time required for the tablet to rise to the surface and float was determined as Floating Lag Time (FLT) and the duration of the time the tablet constantly floats on the dissolution medium was noted as the Total Floating Time respectively (TFT) [8]. In-vitro Dissolution Studies for floating layer of famotidine In-vitro drug release studies were carried out using USP dissolution apparatus type II, with 900ml of dissolution medium maintained at 37±1 C for 12 hr, at 50 rpm, 0.1 N HCl (ph 1.2) was used as a dissolution medium. 5ml of sample was withdrawn at predetermined time intervals replacing with an equal quantity of drug free dissolution fluid. The samples withdrawn were filtered through 0.45µ membrane filter, and drug release in each sample was analyzed after suitable dilution by UV/Vis Spectrophotometer at 266nm [9, 10]. In-vitro Dissolution Studies for immediate release layer of Amoxicillin In-vitro drug release studies were carried out using USP dissolution apparatus type II, with 900ml of dissolution medium maintained at 37±1 C for 1 hr, at 50 rpm, 0.1 N HCl was used as a dissolution medium.5ml of sample was withdrawn at predetermined time intervals replacing with an equal quantity of drug free dissolution fluid. The samples withdrawn were filtered through 0.45µ membrane filter and drug release in each sample was analyzed after suitable dilution by UV/Vis Spectrophotometer at 273 nm [11]. 116

Drug release kinetics: To study the release kinetics, data obtained from in-vitro drug release study was fitted into Zero order equation, first order equation, higuchi square root law and korsmeyer peppas equation. Zero order equation assumes that the cumulative amount of drug release is directly related to time. The release behavior of first order equation is expressed as log cumulative percentage of drug remaining vs time. The Higuchi release model describes the cumulative percentage of drug release vs square root of time. Korsmeyer et al developed a simple, semi-empirical model relating exponentially the drug release to the elapsed time. The diffusion exponent (n) depends on the release mechanism. If n 0.5, the release mechanism follows a Fickian diffusion, and if 0.5<n<1, the release follows non-fickian diffusion or anomalous transport. The drug release follows zero order and case II transport if n=1. But when n>1, then the release mechanism is super case II transport. This model is used in the polymeric dosage form when the release mechanism is unknown or more than one release phenomenon is present in the preparation [12]. Results and discussion: Pre-compression studies: From the pre-compression parameters results given in table-3 and 4 it is found that powder blend has good flow properties, so direct compression method was preferable. Table-3: Results of pre-compression parameters of famotidine sustain release layer Formulations Angle of Repose (θ) Bulk Density (g/cc) Tapped Density (g/cc) Carr s index (%) Hausner s ratio F1 22.6 0.45 0.52 13.4 1.15 F2 24.9 0.44 0.52 15.3 1.18 F3 21.6 0.43 0.50 14.0 1.16 F4 22.5 0.44 0.50 12.0 1.13 F5 22.4 0.45 0.51 11.7 1.13 Table-4: Results of pre-compression parameters of Amoxicillin immediate release layer Formulations Angle of Repose (θ) Bulk Density (g/cc) Tapped Density (g/cc) Carr s index (%) Hausner s ratio F1 25.6 0.4 0.46 13.04 1.15 F2 26.8 0.43 0.49 12.24 1.14 F3 28.4 0.41 0.48 14.58 1.17 117

F4 25.2 0.39 0.45 13.33 1.15 F5 26.5 0.45 0.52 13.46 1.16 F6 29.6 0.42 0.49 14.29 1.17 F7 27.5 0.46 0.56 17.86 1.22 Evaluation of compressed tablets: Post compression evaluation results for sustained release layer The results of post compression studies are given in the table-5. All the evaluated parameters were within the specified limits. Weight variation of the formulations was in the range of 298.94±0.27 to 301.12±0.21 mg, hardness was maintained in the range of 6-7 kg/cm 2, thickness of the formulations was in the range of 3.06 ± 0.20 to 3.55 ± 0.22mm, friability was less than 1% in all the formulations. The buoyancy lag time was less than 12mins in the formulations and remained floating for more than 7 hours in the simulated gastric fluid of ph1.2. Table-5: Post compression parameters for sustained release layer F.CODE Weight Hardness Thickness Friability Buoyancy Lag Total floating variation (mg) (kg/cm 2 ) (mm) (%) time (min) time(hrs) F1 301.12±0.21 6.3 ± 0.54 3.44 ± 0.17 0.46 12 7 F2 299.47±0.47 6.6 ± 0.11 3.55 ± 0.22 0.49 10 9 F3 299.64±0.52 7.0 ± 0.55 3.18 ± 0.21 0.31 8 13 F4 300.87±0.84 7.3 ± 0.75 3.06 ± 0.20 0.32 5 12 F5 298.94±0.27 7.0 ± 0.55 3.18± 0.21 0.31 6 10 Post compression evaluation results for immediate release layer The results of the uniformity of weight, hardness, thickness, friability of the tablets are given in Table-6. All the tablets of different batches complied with the official requirements of uniformity of weight as their weights varied between 497±0.31 to 501±0.10. The hardness of the tablets ranged from 3.2±0.21 to 4.6±0.37kg/cm 2 and the friability values were less than 0.5% indicating that the matrix tablets were compact and hard. The thickness of the tablets ranged from to 2.22±0.27 to 2.68±0.54mm. Disintegration time of the formulations ranged from 4 to 9mins. Thus all the physical attributes of the prepared tablets were found be practically within control. 118

Table-6: Post compression parameters for immediate release layer F.CODE Weight variation Hardness Thickness Friability Disintegration time (mg) (kg/cm 2 ) (mm) (%) (min) F1 497±0.31 4.6±0.37 2.22±0.27 0.30 9mins37sec F2 498±0.2 4.2±0.54 2.34±0.83 0.42 7mins24sec F3 498±0.56 4.0±0.11 2.45±0.32 0.40 6mins15sec F4 499±0.52 4.4±0.98 2.49±0.23 0.38 7mins21sec F5 498±0.17 3.8±0.44 2.52±0.20 0.39 5mins46sec F6 501±0.06 3.2±0.21 2.68±0.54 0.41 4mins 24sec F7 501±0.10 3.8±0.11 2.52±0.54 0.42 5mins51sec Results of in-vitro dissolution studies The results of dissolution testing of sustain release tablets of famotidine are represented in the table-7. Formulations F1 and F2 containing HPMC were not able to sustain the drug release and have shown maximum drug release within 6-8 hours. But the formulations containing xanthan gum and guar gum were sustaining the drug release for a prolonged period of time. Formulation F4 with combination of both the gum has shown the desired drug release upto 12hours with a maximum drug release of 97.80% and this formulation have show a low buoyancy lag time of 5mins, thus based on these results formulation F 4 was considered as the optimized one. Table-7: Cumulative percentage drug release of the sustained release formulations Time(hrs) Cumulative percentage drug release F1 F2 F3 F4 F5 1 25.09 10.97 8.06 19.16 9.40 2 32.57 25.90 14.81 28.16 18.45 3 40.60 37.57 21.80 36.38 24.85 4 62.31 42.09 33.1 48.47 30.63 5 85.70 66.70 46.9 56.80 42.19 6 92.60 79.20 52.6 68.09 50.64 8 -- 96.41 61.4 76.40 59.24 10 -- -- 72.8 84.18 65.68 12 -- -- 83.51 97.80 79.09 119

The results of in-vitro dissolution studies of immediate release layer are represented in the table-8. From the results we can find that formulations with low concentration of disintegrants were slowing drug release upto 60 mins, the formulation F6 containing crospovidone have shown the drug release within 30mins and is best among all the formulations developed. Table-8: Cumulative percentage drug release of the immediate release formulations Time(mins) Cumulative percentage drug release F1 F2 F3 F4 F5 F6 F7 5 15.2 10.3 25.7 17.3 12.3 34.8 29.3 10 34.7 27.4 44.1 35.9 26.8 49.6 35.1 15 45.1 36.9 55.9 47.2 45.3 72.8 68.3 20 52.4 45.2 65.1 56.1 52.1 84.2 76.2 30 65.7 55.4 72.5 74.6 67 98.5 80.34 45 73.1 70.1 81.7 88.3 84.2-96.2 60 88.1 83.5 95.3 - - - - The optimized formulations of both the layers were taken and formulated into a bilayer tablets and dissolution studies were carried out and the results are mentioned in the table-9. Table-9: Dissolution data for the bilayered tablet Time Cumulative percentage drug release of Bilayered tablet (IR + SR) 0.1N Hcl as dissolution medium for immediate release tablets (dose 250mg) 30min 99.19 0.1N Hcl as dissolution medium for floating tablets (dose 40mg) 1hr 14.20 2hr 25.70 3hr 38.25 4hr 48.43 5hr 54.30 6hr 66.70 8hr 75.03 10hr 81.06 12 hr 98.91 120

Release kinetics: In-vitro drug release data of optimized formulation(f4) of sustain release layer was subjected to kinetic study by linear regression analysis according to zero order and first order kinetic equations, Higuchi and Korsmeyer-Peppas models and the mechanism of drug release was found to be independent of concentration i.e. Zero order kinetics, and follows non-fickian diffusion mechanism. Table-10: Release kinetics for the optimized formulation of sustain release tablets Zero Order First Order Higuchi Peppas Q Vs T Log % Remain Vs T Q Vs T Log C Vs Log T Slope 7.6954-0.0162 32.6171 0.6761 Intercept 12.2973 2.4076-16.2501 1.2685 R 2 0.9547 0.8617 0.9904 0.9914 Conclusion: The Bilayered tablets containing Amoxicillin and Famotidine were successfully prepared by direct compression method. Immediate release layer containing amoxicillin were prepared by employing CP, SSG and CCS as superdisintegrants and formulation F6 containing CP was optimized based on the disintegration time and in-vitro dissolution studies. Sustain release layer containing famotidine was formulated using HPMC, xanthan gum and guar gum were prepared and formulation F4 containing xanthan and guar gum was optimized based on the buoyancy lag time and in-vitro dissolution studies. Both the layers were optimized separately and then bilayer tablet was prepared by using the composition of the optimized layers and evaluated for the drug release. The percentage drug release from the bilayer tablet was found to be 99.19% after 30mins indicating release of amoxicillin completely and then release of Famotidine was 98.91% at the end of 12 hour and fulfilled the requirements of the study. The mechanism of drug release form the optimized formulation of sustain release layer was found to be by zero order kinetics and non-fickian diffusion. References: 1. Sowmya, Suryaprakash C, Reddy, Tabasum SG, Varma V. An overview Bilayer Tablets. Int. J. Pharm. Tech. 2012; 4(2): 2143-2156. 2. Abebe A, Akseli I, Sprockel O. Review of bilayer tablet technology. Int. J. Pharm. 2014; 461(1 2): 549 558. 121

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