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The present study was envisaged to reduce the dosing frequency and improve patient compliance by designing and evaluating sustained release microspheres of acarbose for effective control of type-II diabetes mellitus. Microspheres were prepared by emulsification solvent evaporation method using sodium alginate and HPMC K15M as sustained release agents. The prepared microspheres were evaluated for particle size, drug content, surface morphology, drug entrapment efficiency, flow properties, in vitro drug release and stability studies. The drug excipients compatibility was determined by FTIR studies. The surface morphology of prepared microspheres was measured by SEM and the particle size distribution was determined using an optical microscope. The particles were found to be discrete and spherical with the average particle size in the range of 91±1.24 to 207±1.49μm. The formed acarbose microspheres showed high drug entrapment efficiency of 74.01 to 88.9%. The effect of factors like concentration of polymer, emulsifying agent, stirring speed, alginate: HPMC ratio on drug entrapment efficiency, morphology and drug release was studied. In vitro results showed that the formulation F3 containing 1:1 ratio of sodium alginate and HPMC K15 M released maximum amount of drug i.e. 36.17% (pH 1.2) and 95.83% (pH 7.4) due to the proper cross linking between sodium alginate and HPMC K15 M. *Corresponding author, Mailing address: Amanpreet Kaur Assistant Professor, Department of Pharmaceutics, Rayat and Bahra Institute of Pharmacy, Sahauran, Distt. Mohali, Punjab, India Email: aman.rai14@gmail.com Article History:-----------------------Date of Submission: 06-12-2012 Date of Acceptance: 20-12-2012 Conflict of Interest: NIL Source of Support: NONE F u ll L e n g t h R e s e a r c h M a n u s c r ip t Int. J. Drug Dev. & Res., January-March 2013, 5 (1): 70-82 Covered in Scopus & Embase, Elsevier 70 widely accepted to achieve oral controlled drug delivery. Microspheres are solid spherical particles ranging in size from 1-1000μm. Microspheres offer advantages like limiting fluctuation within therapeutic range, reducing side effects due to decrease in dosing frequency and improved patient compliance2. Diabetes mellitus is a chronic disease that is characterized by impaired carbohydrate, protein and lipid metabolism. Its central disturbance appears to involve an abnormality either in the secretion of or effects produced by insulin although other factors may also be involved3. Acarbose is an oral αglucosidase inhibitor and used in the management of type II diabetes mellitus. Acarbose inhibits enzymes glycoside hydrolases needed to digest carbohydrates, specifically, α-glucosidase enzyme in the brush border of the small intestines and pancreatic αamylase. Pancreatic α-amylase hydrolyzes complex starch to oligosaccharides in the lumen of the small intestine, whereas the membrane-bound intestinal αglucosidases hydrolyze oligosaccharides, trisaccharides and disaccharides to glucose and other monosaccharides in the small intestine. Inhibition of these enzymes systems reduces the rate of digestion of complex carbohydrates4. Because of its higher water solubility and shorter half life (2 h), drug requires frequent dosing by oral route. A sustained release formulation reduces the frequent drug administration and thus improves patient compliance. Sustained release formulation prolongs the action of the drug for a long period of time5. One of the very common and suitable method to prepare these polymeric microspheres is emulsification solvent evaporation method because it facilitates sustain release of a drug which has many clinical advantages as well as it provides compatibility to use more than one novel polymers like hydroxypropylmethylcellulose (HPMC K15 M) and sodium alginate as encapsulation matrix6. The main objective of this work was to investigate the possibility of obtaining sustained release microspheres of acarbose by using sodium alginate and HPMC K15 M as sustained release polymers in various ratios. The various physicochemical characteristics and the in vitro release rates from these microspheres were thus examined. MATERIALS AND METHODS Materials Acarbose was obtained as gift sample from Windlass biotech Ltd. Dehradun, Uttranchal. Hydroxypropyl methyl cellulose (HPMC K 15M) procured from Central Drug House (P) Ltd., New Delhi. Sodium alginate was purchased from Thomas Baker Pvt. Ltd., Mumbai. Other materials used were of analytical grade, and procured from commercial sources. Methods Preparation of sustained release microspheres of acarbose The sustained release microspheres of acarbose were prepared by emulsifications solvent evaporation method employing two different polymers, viz. sodium alginate and HPMC K15 M7, 8,9,10. For this, aqueous solution of drug and polymer is prepared. Then drug and polymer solution was added drop wise to the liquid paraffin containing 0.5 % span 20 as an emulsifying agent with constant stirring. The constant stirring was carried out using magnetic stirrer. The beaker and its content were heated at 80οC with constant stirring for 2 h until the aqueous phase was completely removed by evaporation. The liquid paraffin was decanted and collected microspheres were washed 5 times with n-hexane, filtered through Whatmann filter paper and dried in hot air oven at 50°C for 2 h. Seven batches of microspheres were prepared as per Table 1. Various variables like the polymer concentration, stirring speed, amount of emulsifying agent and sodium alginate-HPMC ratio were considered in the optimization of the formulation. Amanpreet Kaur et al: Design and Characterization of sustained release Microspheres of Acarbose Int. J. Drug Dev. & Res., January-March 2013, 5 (1): 70-82 Covered in Scopus & Embase, Elsevier 71 F u ll L e n g t h R e s e a r c h M a n u s c r ip t Table 1: Composition of drug loaded microspheres formulations Sl. No. Formulation Code Amount of Drug (mg) Polymer Ratio (w/w) Amount of Polymer (mg) Sodium Alginate HPMC K15M 1 F1 150 -1000 --