QUALITY ASSESSMENT AND COMPARATIVE STUDY OF DIFFERENT MARKETED BRANDS OF SIMVASTATIN IN MALAYSIA

Introduction: Simvastatin is one of the cholesterol-reducing agents, in the class of statins which is an HMG-CoA reductase inhibitors, used in the treatment of hyperlipidemia. It was categorized in biopharmaceutics classification system (BCS) class II drug, which has low solubility in aqueous media. It is a white-to-off white crystalline and non-hygroscopic powder, insoluble in water, but soluble in methanol, chloroform, and ethanol. Characterization test as FTIR spectroscopy was important to identify the identity of tablets. Tablets properties were evaluated by various physicochemical parameters including dissolution test to examine the equivalence and quality of different marketed brands of Simvastatin. They should comply with the specified pharmacopoeia limit for each test. Objectives: Objective of this study was to analyze the identity and evaluate the quality control parameters of different brands of Simvastatin with the specified pharmacopoeia limit. Method: Different brands of Simvastatin 20 mg tablets were collected by purchasing from local pharmacies in Malaysia. Physicochemical parameters such as weight variation, thickness and diameter measurement were performed. Besides, characterization test using FTIR spectrophotometer, dissolution test as well as disintegration test of each brand of Simvastatin tablets were also performed. Results: There were no abnormalities in the physical appearance of all tablets from different brands. All the brands complied with the official specifications for weight uniformity where no tablet showed deviation more than ±7.5%. Thickness, diameter measurement and disintegration test of each brand of Simvastatin tablets also passed the specified limit. Characterization test using FTIR spectrophotometer confirmed the identity of Simvastatin with peak of aromatic hydroxyl group around 3700-3100 cm-1, methyl group around 3000 -2800 cm-1 and aromatic carbonyl group around 1800 -1600 cm-1, except the standard Simvastatin showed strong and sharp peak for aromatic carbonyl group whereas other brands showed weak peak. A Characterization test using MS also confirmed the identity of Simvastatin with base peak of 419.3 m/z for protonated molecular ion [Simvastatin + H] + and major product ions at 199 m/z and 285 m/z were also observed compared to standard Simvastatin. Regarding dissolution test, Brand B achieved a bioavailability rate of 80.35%, AUC0-2 44.47 mg.hr/l and Brand E achieved a bioavailability rate of 70.11%, AUC0-2 29.8 mg.hr/l which was the highest among the brands tested, indicate immediate drug release pattern. Other brands might exhibit more sustained release profiles over a longer period of time. Conclusion: Results of all the parameters such as weight variation, thickness, diameter, and disintegration test obtained from the study comply with the USP and BP Pharmacopoeia limits. Brand C was identified having the most immediate drug release based on AUC despite the initial low percentage of release rate. Brands A and D showed prolonged drug release whereas Brand B and E showed potential immediate drug release.