556 Journal of Scientific & Industrial Research J SCI IND RES VOL 71 AUGUST 2012 Vol. 71, August 2012, pp. 556-561 Design of polypill for treatment of type -II diabetes mellitus associated with dyslipidemia Rohan D Deshpande 1 *, D.V. Gowda 1, Vasanti S 2, Nawaz Mahammed 1 1 JSS College of pharmacy, JSS University, S.S Nagar, Mysore 570 015, India 2 PES College of pharmacy, Hanumanthanagar, Bangalore 560 050, India Received 07 March 2012; revised 07 July 2012; accepted 11 July 2012 This study presents development of a bilayered tablet with sustained release (SR) of Metformin hydrochloride (MH) and immediate release of Atorvastatin calcium (AC), used as anti-hyperglycemic agent in patients with type 2 diabetes, by lowering both basal and postprandial plasma glucose and competitive inhibitor of HMG-CoA reductase. In SR layer, sodium carboxy methyl cellulose (Sodium CMC) and Hydroxy Propyl Methylcellulose K4M (HPMC K4M) were used as retarding material but Hydroxy Propyl Methylcellulose 15 Cps (HPMC 15 Cps) was used as channeling agent. Tablets were prepared by wet granulation method. FT-IR studies showed no interaction between drugs and polymers used in the study. Optimized formulation gave an initial burst effect and followed by SR for 8 h (92.53%), without any drug degradation during stability studies. Drug release from formulation was dose dependent and by diffusion mechanism. Keywords: Atorvastatin calcium (AC), HPMC 15Cps, HPMC K4M, Metformin hydrochloride (MH), Sodium CMC Introduction Bilayered tablet requires fewer materials than compression-coated tablets, weigh less and may be thinner 1. Bilayer tablet is suitable for sequential release of two drugs in combination, separate two incompatible substances, and also for sustained release (SR) tablet, in which one layer is immediate release (IR) as initial dose and second layer is maintenance dose 2. Higher rate of mortality in patients with diabetes mellitus patients is mainly due to cardiovascular diseases 3. Patients with type 2 diabetes have increased risk of atherosclerosis and it can be treated with statins 4,5. Blood glucose level impairs endothelial function and promotes atherogenesis in diabetic patients, and combined administration of metformin and atorvastatin prevent Endotheliumdependent dilation in patients compared with metformin alone 5,6. Mortality of diabetic patients after a cardiac event is significantly increased as compared to nondiabetics 7. Drugs should be stable in gastro-intestinal tract as SR systems release their contents over entire length of gastro-intestinal tract. Metformin hydrochloride (MH: biological half-life, 2-4 h) is an orally administered biguanide, which is widely used in management of *Author for correspondence E-mail: rohan11in@gmail.com type-2 diabetes. It is a hydrophilic drug and is slowly and incompletely absorbed from gastrointestinal tract and absolute bioavailability of a single 500 mg dose is reported to be 50-60% 1. SR formulation that maintains plasma levels of drug for 8-12 h might be sufficient for once daily dosing for MH. Atorvastatin calcium (AC) mimics activity of HMG-CoA reductase by blocking rate-limiting step of cholesterol biosynthesis. It reduces LDL cholesterol, apolipoprotein B and triglycerides and increases HDL in treatment of hyperlipidaemia. Atorvastatin is rapidly absorbed after oral administration; maximum plasma concentration occurs within 1-2 h and half-life in humans is 14 h 8. This study presents development of a bilayered tablet with SR of MH and IR of AC, used as anti-hyperglycemic agent in patients with type 2 diabetes, by lowering both basal and postprandial plasma glucose and competitive inhibitor of HMG-CoA reductase. Experimental Section MH (mol wt, 165.62; plasma elimination half-life, 2-4 h; apparent volume of distribution, 654±358 l) was a gift sample from Apotex India Ltd. It is soluble in water and methanol and practically insoluble in acetone and methylene chloride. AC (mol wt, 1155.36; plasma elimination half-life, 14 h; mean volume of distribution,
DESHPANDE et al: DESIGN OF POLYPILL FOR TYPE -II DIABETES MELLITUS 557 Table 1 Ingredients (mg/tablet) for Metformin HCl sustained release layer Ingredients SR1 SR2 SR3 SR4 SR5 SR6 SR7 Metformin HCl 502.76 502.76 502.76 502.76 502.76 502.76 502.76 Sodium CMC 84.5 127 150 170 200 200 200 HPMC 15Cps - - - - 5 10 10 HPMC K4M - - - - - 85 60 DCP anhydrous 235.74 193.24 170.24 150.24 115.24 25.24 50.24 Povidone (K-30) 8 8 8 8 8 8 8 Purified water q.s q.s q.s q.s q.s q.s q.s Aerosil-200 3 3 3 3 3 3 3 Talc 5 5 5 5 5 5 5 Magnesium stearate 6 6 6 6 6 6 6 Total weight of layer- I 845 845 845 845 845 845 845 381 l), a gift sample from Maithri Laboratories Pvt Ltd, India, is soluble in dimethyl sulphoxide. Sodium carboxy methyl cellulose (Sodium CMC) was obtained from Pioma Chemicals, India. Hydroxy propyl methylcellulose K4M (HPMC K4M) and hydroxy propyl methylcellulose 15 Cps (HPMC 15 Cps) were procured from Enar chemicals, India.Lactose was obtained from DMV international, Netherlands. Croscarmellose sodium was obtained from hetero drugs as gift sample. All other chemicals used were of analytical grade. Drug-excipients Compatibility Studies MH and AC were taken in glass vials individually and along with various excipients (1:1). All mixtures of drug and excipients were kept at various accelerated condition (30ºC/65% RH and 40ºC/75% RH) in stability chamber for one month. At 2 weeks time interval and at the end of 4 th week, samples were withdrawn and checked out for any changes in physical character like color. Finally, combination of excipients with no colour change was selected for formulation. Preparation of Sustained Release Layer of Metformin Hydrochloride (MH) SR layer of Metformin, each containing MH (500 mg), were prepared by a conventional wet granulation technique (Table 1). All ingredients (MH, HPMC K4M, HPMC 15Cps, sodium CMC, dicalcium phosphate anhydrous) were passed through sieve no. 40. Povidone (K-30) was dissolved in purified water. Granules were prepared in rapid mixer granulator by adding binder solution to mixture of above ingredients and mixing at slow speed. MH granules were dried in fluidized bed dryer at 50ºC. Dried granules were passed through 20 mesh sieve. Shifted granules were transferred to double cone blender. Colloidal silicon dioxide was sifted through 40 mesh sieve, and magnesium stearate and talc were sifted through 60 mesh sieve and added to double cone blender and mixed for 2 min. Preparation of Immediate Release Layer of Atorvastatin Calcium (AC) IR layer of AC were prepared by wet granulation process (Table 2). Weighed AC, lactose monohydrate, microcrystalline cellulose, croscarmellose sodium and colloidal silicon dioxide were sifted through 40 mesh sieve and ponceu 4R supra was sifted through 100 mesh sieve. These ingredients were loaded into planetary mixture and mixed for 15 min at fast speed. Binder solution, prepared by dissolving polysorbate-80 in purified water, was added slowly to mixed contents in planetary mixer and mixed at slow speed for 5 min. Wet granules were loaded into fluidized bed dryer and dried at 50-60ºC. Produced granules were sized by sifting through 20 mesh sieve. In lubrication step, magnesium stearate, talc and sodium bicarbonate were sifted through 60 mesh sieves and croscarmellose sodium was sifted through 40 mesh sieve. Then, granules and lubricants were loaded into double cone blender and mixed for 3 min at slow speed. Prior to compression, granules were evaluated for characteristic parameters (bulk density, tapped density, compressibility index and hausner s ratio). Carr s compressibility index was calculated from bulk and tapped densities using a digital tap density apparatus (Electrolab Ltd. India). Preparation of Bilayer Formulation Final bilayer tablets (Fig. 1) were compressed as one layer only for MH (SR7) and second layer for AC (FR5) using 19.2 mm x 8.9 mm oblong shaped punch in
558 J SCI IND RES VOL 71 AUGUST 2012 Table 2 Ingredients (mg/tablet) for Atorvastatin Calcium immediate release layer Ingredients FR1 FR2 FR3 FR4 FR5 Atorvastatin Calcium 11.345 11.345 11.345 11.345 11.345 Calcium carbonate 76.5 76.5 76.5 76.5 76.5 Lactose monohydrate 78.565 77.565 76.278 75.665 75.002 Micro crystalline cellulose 58.49 58.49 58.49 58.49 58.49 Colloidal silicon dioxide 5 5 5 5 5 Croscarmellose sodium 7.650 7.650 7.650 7.650 7.650 Ponceu 4R Supra 0.500 0.500 0.500 0.500 0.500 Purified water q.s q.s q.s q.s q.s Polysorbate-80 - - 0.637 1.25 1.913 Talc - 1 1.650 1.650 1.650 Magnesium stearate 1.650 1.650 1.650 1.650 1.650 Croscarmellose sodium 7.650 7.650 7.650 7.650 7.650 Sodium bicarbonate 7.650 7.650 7.650 7.650 7.650 Total weight of layer- II 255 255 255 255 255 Total weight of bilayer tablet 1100 1100 1100 1100 1100 a) b) Fig. 1 Bilayer tablets of Metformin HCl (MH) and Atorvastatin Calcium (AC): a) heap of tablets; and b) sides of tablets 27 station tablet compression machine (Cadmach, India). MH granules were introduced first into die cavity and slightly pre compressed. After that, AC granules were added and a final compression was made. Film Coating of Bilayer Tablets of MH and AC Coating Solution Preparation Over head stirrer was operated containing sufficient quantity of isopropyl alcohol and methylene chloride to form a mixture. To this, Transparent Coat IC-U-6638 was added in vortex without formation of lumps and continuously stirred for 45 min for homogenization. Coating solution was filtered through 200 mesh nylon cloth and used for coating of bilayer core tablets. Film Coating of Tablets Compressed tablets were loaded into Neocota coating machine containing pan and tablets were film coated to get the build of 2.0% with following parameters: pan speed, 5 rpm; gun type, spray gun; inlet temp., 40-45 C; outlet temp., 30 Cl; and spray rate, 3 ml/min. Physical Tests for Bilayer Tablets Standard physical test for bilayer tablets were performed and average values were calculated. Weight variation was determined by weighing 20 tablets individually, average mass was calculated and variation% of each tablet was calculated. Hardness was determined by taking 6 tablets from each formulation using a Monsanto hardness tester (Tab machine Ltd., India) and average pressure (kg/cm 2 ) applied for crushing tablet was determined. Friability was determined by weighing 20 tablets after dusting and placing them in a roche friabilator (Electro lab ET-2, India), which was rotated for 100 revolutions. After dusting, total remaining mass of tablets was recorded and friability% was calculated.
DESHPANDE et al: DESIGN OF POLYPILL FOR TYPE -II DIABETES MELLITUS 559 Table 3 Result of evaluation of Metformin Hydrochloride Atorvastatin Calcium bulk powder Material Bulk Tapped Carr s Hausner Angle of density density index ratio repose g/ml g/ml % Metformin hydrochloride 0.415 0.591 29.78 1.42 33.63 0 Atorvastatincalcium 0.455 0.626 27.23 1.38 35.91 0 Table 4 Evaluation of Metformin HCl granules and Atorvastatin calcium granules S. No Formulation Bulkdensity Tappeddensity Carr sindex Hausner Angle of Code * g/ml g/ml % ratio repose Evaluation of Metformin HCl granules 1 SR1 0.52 0.62 16.12 1.19 28.2 0 2 SR2 0.50 0.58 13.79 1.16 25.3 0 3 SR3 0.51 0.64 20.31 1.25 24.5 0 4 SR4 0.47 0.57 17.54 1.12 27.9 0 5 SR5 0.52 0.62 22.58 1.19 26.8 0 6 SR6 0.53 0.62 14.51 1.16 24.1 0 7 SR7 0.50 0.57 12.28 1.14 25.9 0 Evaluation of Atorvastatin calcium granules 8 FR1 0.44 0.54 18.51 1.23 26.5 0 9 FR2 0.42 0.55 23.63 1.30 31.3 0 10 FR3 0.47 0.58 23.03 1.23 34.8 0 11 FR4 0.44 0.53 16.98 1.20 32.0 0 12 FR5 0.48 0.60 19.35 1.25 27.6 0 Thickness (mm) was determined by digital vernier caliper (Mitutoyo corp., Japan). In vitro Dissolution Studies Release of MH was determined using a dissolution apparatus type I of USP (Basket) at 100 rpm. Dissolution was studied at 37 ± 0.5ºC using 900 ml of phosphate buffer (ph 6.8). Samples (5 ml) were withdrawn at different intervals (1, 4 and 8 h) and filtered through 0.45 micro membrane filter. Filtrate was collected after discarding first few ml of filtrate. Sample solutions were analyzed by high performance liquid chromatography (HPLC) using following chromatographic conditions: column, C18 (250 X 4.6m), 5 µ; flow rate, 1.0 ml/min; UV detector, 225 nm; mobile phase, filtered and degassed mixture of buffer and acetonitrile (700: 300); and buffer, dissolved sodium dihydrogen phosphate (3.9 g) in 1000 ml purified water. ph6 was adjusted with dilute sodium hydroxide. Release of AC was determined using a dissolution apparatus type II of USP (Paddle) at 50 rpm. Dissolution was studied at 37 ± 0.5ºC using 0.1% sodium lauryl sulphate solution (1000 ml). Samples (5 ml) were withdrawn at 15 th, 30 th & 45 th min and filtered through 0.45 µ membrane filter. Filtrate was collected after discarding first few ml of filtrate. Sample solutions were analyzed by HPLC using UV detector under following chromatographic conditions: column, C8 (250 mm x 4.6 mm) 5µ SS column; wavelength, 254 nm; flow rate, 1.0 ml/min; mobile phase, filtered and degassed mixture of buffer and acetonitrile (400: 600) and adjusted ph 2.5 with Trifluoro acetic acid solution; and buffer, dissolved sodium dihydrogen phosphate (13.8 g) in 1000 ml water. Release data obtained were treated according to zero-order (cumulative amount of drug release vs time), first-order (log cumulative% drug remaining vs time), Higuchi (cumulative% release vs time) and Korsmeyer- Peppas (log cumulative% drug release vs log time) equation models. Stability Studies Promising formulation was tested for 3 months at 25ºC and 40ºC with 60% RH and 75% RH. At the interval of 15 days, tablets were withdrawn and evaluated for thickness, hardness, friability, weight variation, content uniformity, in vitro drug release and assay.
560 J SCI IND RES VOL 71 AUGUST 2012 a) b) Fig. 2 Drug release (%) profile of: a) Metformin Hydrochloride (MH) tablet matrices; and b) Atorvastatin Calcium (AC) tablet matrices Log % drug remaning Amount of drug release Drug release, % Drug release, % logmt/m Cumulative % drug release Fig. 3 First order kinetics, Higuchi model, Zero order kinetics and Peppas model of formulation F-7 Results and Discussion MH and AC were used as a model drugs for treatment of type-2 diabetes mellitus with associated dyslipidemia. Preformulation studies of MH and AC were evaluated for various physical properties individually (Table 3) and flow was found poor in the case of both drugs. In drug excipients compatibility studies, there was no incompatibility in drugs alone or with excipients. Bulk densities for granules of optimized formulation (Table 4) indicated good packing character. Compressibility index
DESHPANDE et al: DESIGN OF POLYPILL FOR TYPE -II DIABETES MELLITUS 561 (CI) for optimized formulation was found to be below 13%, indicating good flow properties. Flow properties of granules were further analyzed by determining angle of repose for all granules and it was below 30º for optimized formulation. Hausner s ratio for all granules formulated was less than 2%. By in vitro release study, SR7 and FD5 were considered to be optimized one (Fig. 2). Drug release rate in SR decreases as the concentration of sodium CMC, HPMC K4M and HPMC 15 Cps polymer increases. Thus concentration of polymers was predominant controlling factor. Good dissolution profile of SR7 might be due to HPMC 15 Cps as it is used as channeling agent, were liquid penetration into the matrix is the rate-limiting step. All batches of tablets were manufactured under similar conditions to avoid processing variables. Different parameters of bilayer tablets were: mass, 1120 ± 3.09 mg; hardness, 9 ± 0.89 kg/cm 2 ; thickness, 6.92 ± 0.6 mm; and friability of all formulations, 0.14 ± 0.2%. Hardness and friability of prepared bilayer tablets indicated good handling properties. Drug content uniformity in bilayer matrix tablets was 98.9 ± 0.39% for AC. Drug Release Study In vitro release study data (Fig. 3) indicated that the best fit model in all the cases was First order release for optimized formulation SR7 (0.9987; K value, 0.1389). Thus release of drug from dosage form was found to be dose dependent. First order release was found to be. Stability Studies No significant changes were observed in physical appearance, color, hardness, IR spectroscopy of bilayer tablet and dissolution studies of SR layer. Drug content% at different temperature after 2 weeks and 4 weeks was found to be within limits. From the data obtained (not shown), formulation was found to be stable under the conditions mentioned. Conclusions Bilayer tablets of MH and AC using hydrophilic swellable polymers HPMC and Sodium CMC as sustaining layer and croscarmellose sodium and polysorbate-80 for IR layer by wet granulation method were found to be good without chipping, capping and sticking. Granules of MH SR layer were prepared by using different viscosity of HPMC (15 Cps and 4000 Cps) and Sodium CMC as retarding agent. Granules of AC IR layer were prepared by using super disintegrants, croscarmellose sodium and polysorbate-80 as surfactant. Drug polymer ratios were found to influence the release of drug from SR layer of formulation. As the amount of polymer increases, drug release was found to decrease. In case of IR layer, as the concentration of surfactant was increased, drug release was also found to be increased. Drug release from optimized formulation SR7 was found to follow First order release kinetics. Thus release of drug from dosage form was found to be dose dependent. Formulation SR7 containing Sodium CMC (23.66% w/w), HPMC 15 Cps (1.18% w/w) and HPMC K4M (7.1% w/w) in following ratios releases the drug at desired rate. One month short term stability studies performed for optimized formulation at 25ºC and 40ºC with 60% RH and 75% RH indicated no appreciable changes in drug content% and in-vitro drug release studies. References 1 Ohmura C, Tanaka Y, Mitsuhashi N et al, Efficacy of low-dose metformin in japanese patients with type 2 diabetes mellitus, Curr Therap Res, 59 (1998) 889-895. 2 Streubel A, Siepmann J, Peppas N. A & Bodmeier R. Bimodal drug release achieved with multi-layer matrix tablets: transport mechanisms and device design, J Control Release, 69 (2000) 455-468. 3 Yoshino G, Hirano T & Kazumi T, Dyslipidemia in diabetes mellitus, Diabetes Res Clin Prac, 33 (1996) 1-14. 4 Erkelens D W, Insulin resistance syndrome and type 2 diabetes mellitus, Am J Cardiol, 88 (2001) 38J-42J. 5 Tousoulis D, Koniari K, Antoniades C et al, Impact of 6 weeks of treatment with low-dose Metformin and Atorvastatin on glucose-induced changes of endothelial function in adults with newly diagnosed type 2 diabetes mellitus: a single-blind study, Clin Ther, 32 (2010) 1720-1728. 6 Tousoulis D, Koniari K, Antoniades C et al, Combined effects of atorvastatin and metformin on glucose-induced variations of inflammatory process in patients with diabetes mellitus, Int J Cardiol, 149 (2011) 46-69. 7 Raza J F & Movahed A, Current concepts of cardiovascular diseases in diabetes mellitus, Int J Cardiol, 89 (2003) 123-124. 8 Kadu P J, Kushare S S, Thacker D D & Gattani S G. Enhancement of oral bioavailability of atorvastatin calcium by self-emulsifying drug delivery systems (SEDDS), Pharm Dev Technol, 16 (2011) 65-74.