Pak. J. Pharm. Sci., Vol.31, No.1, January 2018, pp.069-073 69 Pharmaceutical equivalent dissertation of Metformin hydrochloride brands Safila Naveed 1 , Huma Dilshad 1 , Maheen Nafees 1 , Muhammad Ibrar Shinwari 3 , Khan Usmanghani 1,2 and Ghulam Sarwar 1 1 Faculty of Pharmacy, Jinnah University for Women, Karachi, Pakistan 2 Research and Development Department, Herbion Pakistan (Pvt.).Limited, Plot 30, Korangi industrial Area, Karachi, Pakistan 3 Department of Environmental Sciences, Faculty of Basic & Applied Sciences, International Islamic University, H-10, Islamabad, Pakistan Abstract: The aim of study is to establish pharmaceutical equivalence of different brands of Metformin tablets available in Karachi, Pakistan. The quality control parameters which are studied are weight variation test, hardness test, thickness, friability, disintegration and dissolution specified by BP/USP (British and United State Pharmacopoeia). Weight variation and hardness value requirement was complied by all brands. Disintegration time for all brands was within range i.e. 15 minutes and also complies with the BP/USP recommendation. All brands showed more than 90% drug release within forty five minutes. The present conclusion suggests that almost all the brands of Metformin that are available in Karachi meet the specification for quality control analysis. Assay performed by HPLC by keeping flow rate of 1.0 ml/min of the mobile phase and the quantitative evaluation at 225 nm was performed. The retention time of Metformin was found to be 2.5min. Method suitability for the quantitative determination of the drugs was proved by validation according to the International Conference on Harmonization (ICH) guidelines. Keywords: Metformin, analysis and HPLC. INTRODUCTION Metformin HCl belongs to drug category Oral Anti- Diabetics of class Biguanides. Its chemical name is N,N- Dimethyl-imido-dicarbonimidicdiamide with molecular formula of C 4 H 11 N 5. Its chemical structure is: Fig. 1: Structure of Metformin These tablets are being used as hypoglycemic agents to treat non-insulin dependent diabetes mellitus (type-2) which is also sometimes termed as maturity-onset diabetes as it develops in later life in which insulin secretion appears normal or excessive. Metformin tablets are the first line drug therapy to control high glucose levels in blood in type-2 diabetes mellitus patients (Jones et al., 2009). Metformin tablets work by lowering the amount of sugar in the blood by the following mechanisms (Akinleye et al., 2012): • It activates a liver enzyme called AMP-activated protein kinase (AMPK), thereby inhibits the production of glucose by liver cells i.e. hepatic gluconeogenesis and thus improves hyperglycemia. • It increases the removal of glucose from the blood by muscle and fat tissues. As a result of increased peripheral glucose uptake due to increased insulin sensitivity that results in improved binding of insulin to insulin receptors, it lowers the level of sugar in the blood. • Initially a dose of 500mg is given 12-hourly with meal to lessen the gastrointestinal side effects and a maximum dose of 3g daily is given in divided doses (Parvin et al., 2012). • Side effects with these tablets include: • Gastrointestinal side effects like nausea, anorexia, vomiting, diarrhea • Lactic acidosis in renal failure patients and • Hypoxia in cardiac failure patients (Danish 2012). The bioavailability is 50-60% under fasting conditions. The duration of action is 8-12 hours. The half-life of drug is 6.2 hours. It is not metabolized and excreted unchanged in urine by tubular secretion (Bristol-Myers Squibb 2008). MATERIALS ANDMETHODS The increasing level of use of Metformin HCl develops a need to monitor the quality for the assessment of its quality control parameters of the various brands of Metformin tablets that are available in the market. The objective of this study was to determine the physical and chemical properties of four different Metformin tablets brands marketed in Karachi. These tablets were evaluated by official and non-official standards like weight *Corresponding author: e-mail: safila117@yahoo.com