International Journal of Innovative Pharmaceutical Sciences and Research

Transcription

1 International Journal of Innovative Pharmaceutical Sciences and Research FORMULATION AND EVALUATION OF BILAYER TABLETS OF AMLODIPINE BESYLATE AND GLIMEPIRIDE 1 V.D.T. Basavaraju*, 2 Dr N. Srinivas Malla reddy institute of pharmaceutical sciences, Maisammaguda, Dhulapally, (Post Via Hakimpet, secunderabad , Telangana, INDIA Abstract The present work aims at formulation and evaluation of Bilayer matrixtablet that would release Amlodipine Besilate immediately and Glimepiride as extended release. The bilayer matrix tablets were prepared by direct compression method. Extended release layer (Glimepiride) pre compresses on compression machine manually and on the pre compressed layer immediate release layer (Amlodipine Besilate) was loaded and punched on compression machine automatically. Total seven batches were prepared and powder blends before compressions were subjected for evaluation of flow properties. All the parameters were within the limit showing good flow properties. Data from Preformulation compatability studies suggested that there is no interaction between the excipients and the drug and the same was confirmed from IR Spectroscopy. Weight variation test showed that the weights of all the formulations were within Pharmacopeial limits. Drug content in all the developed formulations was found to be uniform with sufficient hardness confirming a good mechanical strength to them. In vitro dissolution studies had shown a satisfactory drug release from all the formulation. Based on higher invitro release, F2A2 was selected as optimized formulation. The drug release from the optimized formulation was found to follow zero order kinetics for extended release layer and first order release for immediate release layer. The developed formulation was found to be stable during the stability studies of three months. Keywords: Amlodipine Besilate, Glimepiride, Direct compression method. Corresponding Author: V.D.T. Basavaraju Deparment of Pharmaceutics Malla reddy institute of pharmaceutical sciences Secunderabad , Telangana, INDIA 100basavaraju100@gmail.com Mobile: Available online: November Issue 2882

2 INTRODUCTION Bi-layer tablet is suitable 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.2 There is various application of the bi-layer tablet it consist of monolithic partially coated or multilayered matrices. In the case of bilayered tablets drug release can be rendered almost unidirectional if the drug can be incorporated in the upper non-adhesive layer its delivery occurs into the whole oral cavity. From various current methods for treating illness and diseases, chemotherapy (treatment with drugs) is the most frequently used technique. It has the broad range of applications over the greatest variety of disease states and is frequently the preferred treatment method [1]. For many decades, treatment of acute disease or chronic illness has been mostly accomplished by delivery of drugs to patients using various pharmaceutical dosage forms including tablets, capsules, pills, suppositories, creams, ointments, liquids, aerosols and injectables as drug carriers [2,3]. However, if it is a viable option, oral drug delivery will be chosen in all but the most exceptional circumstances. Moreover, if the oral route is not immediately viable, pharmaceutical companies will often invest resources in making it viable, rather than plumping for an alternative delivery system. Oral route of drug administration have wide acceptance up to 50-60% of total dosage forms and is the most convenient and preferred route for systemic effects due to its ease of dosing administration, pain avoidance, accurate dosage, patient compliance and flexibility in formulation [4,5,6,7] Conventional dosage form are accused of repetitive dosing and unpredictable absorption window that cause wide range of fluctuation in drug concentration in the blood stream and tissues with subsequent undesirable toxicity and poor therapeutic efficiency [8]. This dynamic such as repetitive dosing and irratic absorption led to the concept of controlled drug delivery systems. Formulation of layers from different polymers allows manipulation over more than one ratecontrolling polymer, thus enabling different types of drug delivery of one or more drugs, i.e. where the drug may be released with a bolus and then at a controlled rate or by targeted drug delivery in the GI tract using ph dependant polymers [9]. The aim in designing sustained or controlled delivery systems is to decrease the frequency of the dosing or to increase effectiveness of the drug by localization at the site of action, reducing the dose required or provide uniform drug delivery. The main objective of sustained release drug delivery is to make sure safety and to improve effectiveness of drugs as well as patient compliance. But often this controlles drug Available online: November Issue 2883

3 delivery system fails to achieve the stated advantages due to lack of releasing the initial bolus dose. dose dumping and failure to achieve site specific drug delivery [10]. Immediate release drug delivery system is intended to disintegrate rapidly, and exhibit instant drug release. It is associated with fluctuations in drug plasma levels, which leads to reduction or loss in drug effectiveness or increase incidence of side effects. Administration of the DDS several times per day is therefore necessary to compensate the decrease in drug plasma concentration due to metabolism and excretion. A relatively constant plasma level of a drug is often preferred to maintain the drug concentration within the therapeutic window. However, it is difficult to achieve, especially for once-daily dosage forms, partly because the environment for drug diffusion and/or absorption varies along the gastrointestinal (GI) tract. On the basis of these considerations, we have proposed a bilayer tablet.[11,12]. MATERIALS Fig.1: Bilayer floating Tablet All Drug and chemicals used were analytical grade and procured either as gift samples or purchased. METHOD Preparation of bilayer tablets The bilayer tablets was prepared by direct compression method. Development of bilayer tablet of Amlodipine and Glimepiride was carried out in three stages. Two layers (Immediate release layer and controlled release layer) were formulated separately using different concentration of polymers in different ratios. After optimization of individual layers by in-vitro studies and statistical methods bilayer tablets was prepared using optimized formulae. Bilayer tablets were prepared on rotary tablet compression machine. First the extended release layer was precompressed on compression machine manually and the immediate release layer was loaded on the top of precompressed layer and punched with 6mm punch on compression machine automatically. Composition of immediate release and extended release are shown in below tables. Available online: November Issue 2884

4 Table 1: Composition of Immediate release layer Composition F1 F2 F3 Amlodipine besylate Croscarmellose sodium Sodium starch glycolate Microcrystalline cellulose Talc Magnesium stearate Total Tablet weight Table 2: Composition of Extended release layer Composition A1 A2 A3 A4 A5 Glimepiride Ethyl cellulose HPMC K4M Microcrystalline cellulose Talc Magnesium stearate Total Tablet weight RESULT & DISCUSSION Standard graph preparation Preparation of stock solution: Based on the information obtained from solubility studies of the drugs, methanol was selected as suitable solvent for analysis. Firstly, standard stock solution (1000µg/ml) of amlodipine Besilate was prepared by dissolving 10mg of the drug in 100ml methanol. The solution was kept for sonication for a period of 15 min to remove any air bubbles. Similarly, the stock solution of glimepiride (1000µg/ml) was prepared. The stock solution were individually diluted with HCL buffer of ph 2.0 containing 0.5%w/v SLS to get final concentration of 20µg/ml each and the diluted solutions were scanned in nm range to determine the maximum absorbance of corresponding solution, it was found that amlodipinebesilate and glimepiride show maximumabsorbance at 228nm and 239nm respectively. Preparation of standard solutions: From the above prepared stock solutions different aliquots of various concentrations (1, 2, 3, 4, 6, 8, 10, 12µg/ml) were prepared using HCL buffer ph 2.0 contain 0.5% w/v of SLS. The linearity Available online: November Issue 2885

5 of the solutions was in the concentration range of 2-30µg/ml and 1-20µg/ml for amlodipine and glimepiride respectively. Simultaneous estimation: The simultaneous estimation of both amlodipine and glimepiride was done by simultaneous estimation method. Firstly, the absorptivity values of both the drugs were determined at lambda max of amlodipine 228nm andglimepiride 239nm. The absorptivity values of the drugs is the ratio of absorbance at selected wavelengths with the concentration of drugs in µg/ml. using the absorptivity values a set of two simultaneous equations were framed. The stock solution of the samples was further diluted with HCL buffer ph2.0 contain 0.5%w/v of SLS to get the standard solution of concentration 10µg/ml. Preparation of the standard calibration curve of Glimepiride in ph 6.8 Phosphate buffer: Glimepiride (50mg) was dissolved in 20ml of phosphate buffer ph6.8 and volume was made up to 100ml in volumetric flask using phosphate buffer ph6.8. from this stock solution 10ml was withdrawn and diluted to 50ml in volumetric flask which gives the concentrations of 100µg/ml. from this stock solution aliquots were withdrawn in volumetric flask to give concentrations of 0.2,5,10,15,20,50,and 75µg/ml. absorbance of each solution was measured at 239 nm using UV- Vis double beam spectrophotometer with phosphate buffer ph 6.8 as reference standard. Table 3: UV Absorbance of AmlodipineBesilate and Glimepiride in HCL buffer ph 2.0 Concentration (µg/ml) Amlodipine Besilate (228nm) Glimepiride (228nm) Absorbance Amlodipine Besilate (239nm) Glimepiride (239nm) ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±0.001 UV Absorbance values are expressed in mean±standard deviation (n=3) Available online: November Issue 2886

6 Fig.2: UV Absorbance of Amlodipine Besilate and Glimepiride in HCL buffer ph 2.0 Table 4: UV Absorbance of Glimepiride in phosphate buffer ph6.8 Concentration (µg/ml) Absorbance Trail 1 Trail 2 Trail 3 Mean SD Fig.3: Standard Calibration Curve for Glimepiride in Ph 6.8 Phosphate Buffer Available online: November Issue 2887

7 Drug-excipients interaction study Fourier Transform infra-red (FTIR) spectroscopy Table 5: Excipient Compatibility for Glimepiride Condition S.No. Drug+Excipients Ratio Initial 40 C/75%RH 7days 14days 30days Conclusion 1 Glimepiride+Dibasic calcium phosphate 1:1 Nochange Nochange Nochange compatible 2 Glimepiride+Microcrystalline cellulose(ph101) 1:1 Nochange Nochange Nochange Compatible 3 Glimepiride+Povidone 1:1 Nochange Nochange Nochange Compatible 4 Glimepiride+Microcrystalline 1:1 A white cellulose(ph102) oralmost Nochange Nochange Nochange Compatible 5 6 Glimepiride+MethocelK100M Glimepiride+Xanthangum 1:10 1:10 White Crystallin e powder Nochange Nochange Nochange Nochange Nochange Nochange Compatible Compatible 7 Glimepiride+polymerNF1 1:10 Nochange Nochange Nochange Compatible 8 Glimepiride+polymerNF2 1:10 Nochange Nochange Nochange Compatible 9 Glimepiride+Colloidal silicon Dioxide 1:0.25 Nochange Nochange Nochange Compatible 10 Glimepiride+StearicAcid 1:0.25 Nochange Nochange Nochange Compatible Fig.4: FTIR Spectrum of Glimepiride Fig.5: Combined Spectrum of Glimepiride & Excipients Available online: November Issue 2888

8 Fig.6: FTIR Spectrum of Amlodipine Fig. 7: Combined spectrum of Amlodipine & Excipients Compressibility index: The percentage compressibility of powder was determined using Carr s index. Compressibility index lies within the acceptable range of 8.84 to Indirectly it is showing that all the blends having good flow properties. Angle of repose: The values found to be in the range of to All the formulations showed angle of repose below 30 which indicated good flow properties of the blends. Formulation batch Code Table 6: Pre compression parameters of immediate release layer Angle of repose ±SD Bulk density (g/ml) Tapped density (g/ml) Carr's Index (%) Hausner's Ratio F ± F ± F ± Compressibility index: The percentage compressibility of powder was determined using Carr s index. Compressibility index lies within the acceptable range of 8.84 to Indirectly it is showing that all the blends having good flow properties. Angle of repose: The values found to be in the range of to All the formulations showed angle of repose below 30 which indicated good flow properties of the blends. Available online: November Issue 2889

9 Formulation batch Code Table 7: Precompression parameters of Extended release layer Angle of repose ±SD Bulk density (g/ml) Tapped density (g/ml) Carr's Index (%) A ± A ± A ± A ± A ± Bulk density and tapped density: Hausner's Ratio The blends of different formulations were evaluated for bulk density and tapped density. The results were shown in above table. The bulk density and tapped density for all the formulations of immediate release layer varied from to and to respectively. The values obtained were within the acceptable range and there was no large difference noticed. With this result we can calculate the % compressibility of the powder and Hausner ratio. Compressibility index: The percentage compressibility of powder was determined using Carr s index. Compressibility index lies within the acceptable range of 8.71 to Indirectly it is showing that all the blends having good flow properties. Angle of repose: The values found to be in the range of to All the formulations showed angle of repose below 30 which indicated good flow properties of the blends. Physical evaluation of tablets: Uniformity of weight: Twenty tablets were randomly selected from each formulation andevaluated. The average weight of each formulation was shown in the above table. The values are almost uniform and were within the USP specifications. The weights of the tablets ranged from 101±0.75mg to 101.9±0.64mg. Thus all the formulations passed the test for weight variation. Thickness test: The thickness of the tablets was determined using a calibrated dial caliper and results were shown in the above table. Tablet mean thickness is almost uniform in all the formulations and the values obtained are from 2.49±0.01 to 2.84±0.02 mm. the standard deviation values indicated that all the formulations werewithin the range with uniform thickness. Available online: November Issue 2890

10 Hardness: The values of hardness for tablets are ranged from 3.78±0.18 to 5.17±0.17. The lower values of standard deviation indicates that the hardness of all the formulations were almost uniform and possess good mechanical strength with sufficient hardness. Friability test: The friability of tablets were mentioned in above table. The values ranged from 0.40 to All the values are below 1% indicates that the tablets of all the formulations are having good withstanding property. Disintegration time: The disintegration test was performed for immediate releaselayer of all formulations. The DT recorded for F1, F2, F3 formulations was 36, 30 and 75 sec respectively. Drug content analysis: The content uniformity test was performed for all formulations and results were shown in above table. Three replicates from each test were recorded. The mean and SD of all the formulations are calculated. The drug content of amlodipine of tablets in HCl buffer ph. 2.0 was to be between 91.16±0.96 to 95.89±0.71. The drug content of glimepiride of tablets in HCl buffer ph. 2.0 was found between 92.13±0.98 to 96.48±0.86. The drug content of glimepiride layer of tablets in phosphate buffer ph. 6.8 was to be between 92.18±0.53 to 96.60±0.84. The cumulative % drug released by each formulation in vitro release studies was calculated on mean content of the drug present in the respective tablet in the respective dissolution medium. Formulation batch Code Table 8: Physico chemical characteristics of bilayer matrix tablets Average Weight (mg)±sd Hardness(Kg /cm2)±sd Thickness( mm)±sd Friability (%) Disintegration time for Amlodipine layer(sec) F1A ± ± ± ±1.53 F1A ± ± ± ±1.53 F1A ± ± ± ±1 F1A ± ± ± ±1.53 F1A ± ± ± ±1 F2A2 101± ± ± ±1 F3A ± ± ± ±1.53 Available online: November Issue 2891

11 Table 9: Drug content analysis of Bilayer Matrix Tablet Drug content in Ph6.8 Formulation batch Drug content in ph2.0 HCl buffer ± SD phosphate buffer ± SD Code AmlodipineBesilate Glimepiride Glimepiride F1A ± ± ±0.79 F1A ± ± ±0.84 F1A ± ± ±0.73 F1A ± ± ±0.81 F1A ± ± ±0.53 F2A ± ± ±0.68 F3A ± ± ±0.81 In vitro drug release study: The in vitro study was carried out using USP dissolution apparatus II (paddle type) and results were shown in below table. From the dissolution profile of all the extended release formulations (A1-A5), it was found that the formulations A2, A3, A5 showed drug release up to 12hrs. In these three formulations A2 showed best release profile when compared to the other two formulations. The formulation A1 and A4 showed their release profile up to 11hrs only. It is because of the presence of more amount of hydrophilic matrix in A1 formulation. Faster release of drug from the hydrophilic matrix was probably due to gel effect, erosion effect. A4 formulation released drug up to 11h higher release rate because of higher fraction of ethyl cellulose is in comparison to HPMC. Due to the insufficient amount of HPMC, the gaps formed in the matrix system were not filled properly and diffuse out through the pores. Formulation A2 contain ethyl cellulose (2%) and HPMC (4%) Showed Maximum Delayed Release. Possibly swelled gel of HPMC might have packed sufficiently the aforementioned cracks. The drug release of A2 formulation in 2 and 12 hrs was 19.36% and 84.26% respectively. From the dissolution profile of all immediate release formulations (F1-F3), it was found that F2 formulation showed faster release. It has 1%croscarmellose sodium and 4% sodium starch glycolate used in the allowable range. The drug released was 89.52% within 60min. F1 formulation showed 85.31% drug release within 60min because of presence of less % of croscarmellose sodium. F3 formulation showed 81.91% drug release with in 60min because of excess Superdisintegrants. Comparative in vitro drug release pattern of immediate release layers of amlodipine was shown in below figure. The extended release formulations A3 and immediate Available online: November Issue 2892

12 release formulation F2 showed best release. Hence we chooses F2A2 as the optimized formulation for further studies. Table 10: In vitro drug Release profile of Immediate Release Layer (%CDR) In vitro drug Release profile of Immediate Release Layer (%CDR) Time (Min) F1 F2 F Table 11: In vitro drug Release profile of Extended Release Layer (%CDR) In vitro drug Release profile of Extended Release Layer (%CDR) Time (Hrs) A1 A2 A3 A4 A Release kinetics: The release profile of extended release layer of glimepiride of all formulations were compared with zero order, first order, higuchi model and korsemeyer Peppas model in the below table. The data were processed for regression analysis. The data was evaluated for zero order, first order, higuchi model and korsemeyer Peppas model, the R2 values obtained were shown below table. The data suggested that release kinetics of glimepiride from A1 to A5 follow zero order drug release, because the values of regression coefficient obtained for zero order release profiles are higher as compared to first order and higuchi plot. The mechanism involved in the release of drug from polymer matrix traced by Available online: November Issue 2893

13 comparing the n values of formulations which obtained from kosermeyer-peppas model. The n values were in between the range of 0.5 to 1.0. The release profiles of immediate release layer of amlodipine Besilate of all formulations were compared to zero order and first order. The data was evaluated for first order and zero order. The R2 values obtained were as shown in below figure. The data suggested that release kinetics of amlodipine from F1 to F3 seem to follow first order drug release because the values of regression coefficient obtained for first order release profiles are higher as compared to zero order. Table 12: Release kinetics of immediate release layer Release kinetics of Immediate release layer Formulation Zero order Plot First order Plot Best fit Model R2 R2 F First order F First order F First order Table 13: Release kinetics of extended release layer Release kinetics of Extended release layer Formulation Zero order Plot First order Plot Higuchi Matrix Korsmeyer Peppas Best fit Model R 2 R 2 R 2 n R 2 A Zero Order A Zero Order A Zero Order A Zero Order A Zero Order Stability studies: The accelerated stability studies were carried out according to ICH guidelines. Optimized formulation F2A2 was packed in strips of aluminum foil laminated with PVC by strip packing and this packed formulation was stored in ICH certified stability chambers maintained at 40 C and 75% rh?(zone III) for 3months. The tablets were evaluated before and after one month of stabilization for the drug content, friability, hardness, DT and in-vitro release. After a period of 3 months, the samples were observed for any change in appearance of tablet and no change in the appearance of tablet was noted. The drug content of amlodipine andglimepiride in the formulation was found to be 94.18±0.93, 95.32±0.64 and 94.76±0.75 which showed slight decrease in drug Available online: November Issue 2894

14 content but statistically insignificant. The results were tabulated below. The formulation F2A2 was found to be stable in terms of drug content and slight decrease in hardness and increase in friability were observed, while the in vitro release profile is shown in below tables. The invitro release profile of F2A2 formulation initially and after 3 months was almost comparable and there was no much difference observed. Thus the developed formulation was found to be stable at given storage conditions. Table 14: Physico chemical characteristics of optimised formulation stored at 40 C/75%RH Physico chemical characteristics of optimised formulation stored at 40 C/75%RH F2A2 0 Days 90 Days Friability Hardness 4.33± ±0.683 Disintegration time 30±1 33±1.52 Table 15: Drug content analysis stored at 40 C/75%RH%RH Drug content analysis stored at 40 C/75%RH Drug content Pioglitazone in HCL Buffer Glimepiride in HCl Buffer Glimepiride in Phosphate Buffer 0 Days 95.89± ± ± Days 94.18± ± ±0.753 Table 16: In-vitro drug release profile of Formulation of F2 Layer stored at 40 C/75%RH In-vitro drug release profile of Formulation of F2 Layer stored at 40 C/75%RH Time (Min) 0 Days 30 Days 60 Days 90 Days Fig. 8: Comparative invitro drug release profiles of formulation of F2 layer stored at 40 C/75%RH Available online: November Issue 2895

15 Table 17: In-vitro drug release profile of Formulation of A2 Layer stored at 40 C/75%RH In-vitro drug release profile of Formulation of A2 Layer stored at 40 C/75%RH Time (Hrs ) 0 Days 30 Days 60 Days 90 Days Fig 9: Comparative invitro drug release profiles of formulation of A2 layer stored at 40 C/75%RH REFERENCES 1. Banker G S, Drug products: Their role in the treatment of disease, their quality, and their status and future as drug-delivery systems, In: Banker GS, Rhodes CT, editors. Modern Pharmaceutics, 2nd edition, Marcel Dekker, New York: Madison Avenue, 1990, Chein YW, Novel Drug Delivery Systems, 2nd edition, Marcel Dekker, New York: Madison Avenue, 1992, Herber.A.Lieberman, Leon Lachman, Joseph B.Schwetz, Pharmaceutical dosage forms, vol: 1, 2nd edition, Available online: November Issue 2896

16 4. Guncel W.C, Compression-Coated and layer tablet In: Lieberman A.H., Pharmaceutical dosage forms: tablets, Newyork: Decker, 1989, Dahiya A, Rohilla A, Rohilla S and Khan MU, Gastroretentive dosage forms: Review on floating drug delivery systems, Int Res J Pharm, 2011, 2(5), Sharma A, Jain A, Purohit A, Jatav R and Sheorey RV, Formulation and evaluation of aceclofenac fast dissolving tablets, Int J Pharm & Life Sci, 2011, 2 (4), Sampath Kumar K P, Bhowmik D, Chiranjib, Chadira M and Tripathi K K, Innovations in sustained release drug delivery system and its market opportunities, J Chem Pharm Res, 2010, 2(1), Divya.A, K. Kavitha, M. Rupesh Kumar, Dakshayani S, Jagadeesh Singh SD, Bilayer tablet technology: An overview, Journal of Applied Pharmaceutical Science, 01 (08), 2011, Micheal AE, Modified release per oral dosage forms, Pharmaceutics The Science of Dosage form Design, Churchill Livingston, New York, Shiyani B, Gattani S, Surana S, Formulation and evaluation of bi-layer tablet of Metoclopramide hydrochloride and Ibuprofen, AAPS Pharm Sci Tech, 2008, 9(3), Preeti Karwa, P.V.Kasture, Formulation and invitro evaluation of Bilayer tablets of zolpidem tartrate for Biphasic drug release, International Journal of Pharmatech Research, 2011, 3(4), Patel G M and Patel D H, Formulation and evaluation of once a day region selective dual component tablet of atorvastatin calcium and metoprolol succinate, Int J PharmTech Res, 2010, 2 (3), Available online: November Issue 2897