1475 ISSN 0326-2383 KEY WORDS: Gliclazide, Glyceryl monostearate, Matrix tablets, Stearic acid, Sustained-release. * Author to whom correspondence should be addressed. E-mail: mna19bwp@yahoo.com Latin American Journal of Pharmacy (formerly Acta Farmacéutica Bonaerense) Lat. Am. J. Pharm. 30 (8): 1475-80 (2011) Regular Article Received: April 26, 2011 Revised version: June 3, 2011 Accepted: June 8, 2011 Development of Gliclazide Matrix Tablets from Pure and Blended Mixture of Glyceryl Monostearate and Stearic Acid Talib HUSSAIN 1 , Tariq SAEED 1 , Ahmed M. MUMTAZ 1 , Muhammad JAMSHAID 2 , Muhammad N. AAMIR 3 *, Khizar ABBAS 1 , Zeshan JAVAID 4 & Azeema AWAIS 5 1 University College of Pharmacy, University of the Punjab, Lahore, Pakistan 2 Faculty of Pharmacy, Hajvery University, Lahore, Pakistan 3 Institute of Pharmaceutical Sciences, University of Veterinary and Animal Sciences, Lahore, Pakistan 4 Department of Pharmacy, The Islamia University of Bahawalpur, Bahawalpur, Pakistan 5 Bahauddin Zakariya University, Multan, Pakistan SUMMARY. The present study was undertaken to evaluate the effect of glyceryl monostearate (GMS) and stearic acid (SA) on the release profile of gliclazide from the matrix. Matrix tablets for the controlled de- livery of gliclazide were prepared by hot melt method using pure and blended mixture of glyceryl monos- tearate and stearic acid in different drug to polymer and polymer to polymer ratios. In vitro release char- acteristics of gliclazide from these hydrophobic matrices were studied over 8 h in phosphate buffer media of pH 7.4. The release kinetics of drug was evaluated for zero order, first order, Higuchi and Peppas kinet- ic models. It was observed that the release of drug from the matrix was greatly retarded by GMS and re- tarding effect increased with increasing polymer to drug ratios. On the other hand SA appeared to chan- nel the drug from the wax matrix and release was greatly increased with increasing polymer to drug ra- tios. The kinetic evaluation of release profile indicated that the Higuchi model was the most appropriate model for describing the release profile of gliclazide. The application of Peppas biexponential equation in- dicated that non-Fickian release was the predominant mechanism of drug release. The FTIR results showed no interaction between the drug and the polymers and DSC results indicated that both the drug and polymers are in amorphous state and no significant complexes were formed. The results indicated that proper selection of drug to polymer and polymer to polymer ratios were important in order to achieve the desired dissolution profile in these matrix tablets. INTRODUCTION It is of great advantage to both the patient and the physician that medication be formulated so that it may be administered in a minimum number of daily doses from which the drug is uniformLy released over a desired extended pe- riod of time. This effect is accomplished using sustained-release compositions 1 . Developing oral controlled release tablets for highly water- soluble drugs with constant release rate have al- ways been a challenge to the pharmaceutical technologist. Most of these highly water-soluble drugs, if not formulated properly, may readily release the drug at a faster rate, and are likely to produce toxic concentration of the drug on oral administration. The sustained-release dosage forms are now gaining popularity due to their programmable de- livery rates and especially for drugs used for chronic treatment or with narrow therapeutic in- dices. Though various formulation approaches are used to control the release of water soluble drugs, matrix tablets are proving to be potential 2 . In matrix system, the drug is uniformLy dis- tributed throughout a solid polymer. Drug diffu- sion through the polymer is the rate-limiting step. Most of the oral matrix sustained release products utilize either hydrophilic or hydropho- bic matrix system in which the drug is homoge- neously distributed or dissolved in the polymer- ic matrix. Gliclazide 1-(1-azabicyclo- [3,3,0]-oct-3-yl)-3- (p-tolylsulfonyl) urea is a second generation oral hypoglycemic agent. Its major indication for use is in the treatment of noninsulin-dependent dia-