Research Article FORMULATION DEVELOPMENT STUDIES OF BILAYER TABLET GLIPIZIDE: A NOVEL AND EVOLUTIONARY APPROACH IN THE TREATMENT OF DIABETES. GUPTA BIJANK 1 , DEBNATH RABINDRA 2 , GHOSH SOUMYADEEP 2 , CHAKRABORTY MANAS 2* , BISWAS AMITAVA 2 . 1 Former H.O.D, Department of Pharmaceutical Technology, Jadavpur University, Kol-32, West Bengal, India. 2 Department of Pharmaceutical Technology, Calcutta Institute of Pharmaceutical Technology and Allied Health Sciences, Division of Pharmaceutics, Howrah, West Bengal, India. Email: manas_borty12@yahoo.com Received: 27 August 2013, Revised and Accepted: 17 September 2013 ABSTRACT Objective:The aim of present study is to formulate glipizide sustained release (SR) and immediate release (IR) bilayer matrix tablet by different concentration of Hydroxypropyl methylcellulose (HPMC) and Ethyl Cellulose (EC) to control the release pattern. Method:The sustained release layer of glipizide was prepared by using different grades of HPMC like, HPMC K-100, HPMC K-50 and Ethyl Cellulose along with other excipients by wet granulation technique. The immediate release layer of glipizide was prepared by Lactose and Sodium starch glycolate by wet granulation Method. Result:The powders were evaluated for their flow properties and the finished tablets were evaluated for their physical parameters. The both immediate release and sustained release layers of glipizide were characterized by FT-IR and in vitro dissolution studies. The drug release study of glipizide was evaluated using USP-II paddle type dissolution apparatus. The release rate of glipizide in immediate release layer was studied for 1h in pH 7.4 phosphate buffer media and that of glipizide in sustained release layer was studied for 10 h in pH 7.4 phosphate buffer media. Conclusion:From the six batches F3 batch showed good release behaviour 91.92% of drug is released over 10 hours and r 2 value is 0.977 in zero- order kinetics. Glipizide is a poorly water soluble (BCS class 2) antidiabetic drug. Due to the poor water solubility of this drug, its bioavailability is dissolution rate-limited. Total four trial batches of each drug have been manufactured to optimize and develop a robust and stable formulation, the stability studies of the products also comply with ICH guideline Keywords: Bilayer tablets, Glipizide, HPMC, Sustained release, Wet granulation. INTRODUCTION Oral route is the most commonly employed route of drug administration. Although different route of administration are used for the delivery of drugs, oral route remain the preferred mode. The popularity of the oral route is attributed patient acceptance, ease of administration, accurate dosing, cost effective manufacturing method and generally improved shelf-life of the product. Even for sustained release systems the oral route of administration has been investigated the most, because of flexibility in dosage forms design that the oral route offers [1]. With many drugs, the basic goal of therapy is to achieve a steady-state blood level or tissue level that is therapeutically effective and non toxic for an extended period of time [2]. Bi-layer tablet concept has long been utilized to develop sustained released formulation. Such tablet has a fast releasing layer and may contain one (bi-layer), to sustain the drug release. The pharmacokinetic advantage relies on the criterion that, drug release from the fast releasing layer leads to a sudden rise in the blood concentration. However the blood level is maintained at steady state as the release from sustaining layer. Glipizide appears to lower blood glucose acutely by stimulating the release of insulin from the pancreas, an effect dependent upon functioning beta cells in the pancreatic islets [3]. Extrapancreatic effects also may play a part in the mechanism of action of oral sulfonylurea hypoglycaemic drugs. Glipizide is rapidly and completely absorbed following oral administration in an immediate release dosage form. The absolute bioavailability of glipizide was 100% after single oral doses in patients with type 2 diabetes. Beginning 2 to 3 hours after administration of glipizide extended- release tablets, plasma drug concentrations gradually rise reaching maximum concentrations within 6 to 12 hours after dosing. Glipizide is eliminated primarily by hepatic biotransformation: less than 10% of a dose is excreted as unchanged drug in urine and feces; approximately 90% of a dose is excreted as biotransformation products in urine (80%) and feces (10%). The mean terminal elimination half-life of glipizide ranged from 2 to 5 hours after single or multiple doses in patients with type 2 diabetes [4]. Materials and methods Glipizide and HPMC50were obtained as gift sample from StadmedPvt. Ltd, Kolkata. Sodium starch glycolate, Lactose monohydrate, Magnesium stearate and HPMCK100were obtained as gift sample from Merck specialties Private Limited. Ethyl cellulose was obtained as gift sample from Lobachem private limited, Mumbai. All other chemicals/reagents used were of analytical grade. Potency Calculation of Active Pharmaceutical Ingredients: Actual quantity of Active drug required per tablet, Potency = ((label claim X 100)/ Effective assay) X (100/ (100 – Water content)) Method Method of preparation of bi-layer tablets Preparation of drug loaded two different layers of tablet- Batch wise distribution of ingredients is shown in table 1.  Glipizide+HPMC sifted through sieve no 40.  The sifted materials were hand mixed in a polythene bag.  The mixed materials were granulated using granulating solution of starch pest, weighted the 10mg starch powder and dissolve in hot 100 ml distilled water and continuously stirring. The mixture was mixed thoroughly to get a damp mass, passed through sieve no8.  The above granules were air dried for 15 mins and finally dried in hot air oven at 45 0 C-50 0 C till load was<2%.  Then it is passed through sieve no20.  After that it is passed through sieve no30.  Then these were checked for their pre- compression properties. Compression stage Vol 6, Issue 4, 2013 ISSN - 0974-2441