Spectrophotometric method of quantitative estimation of metformin hydrochloride in tablets

Abstract

In Ukraine, more than one million people suffer from diabetes, and this number increases every year. Metformin is one of the most widely used and most effective hypoglycemic agents for oral administration, available in tablet form with various dosages from multiple manufacturers. In this regard, an important task of modern pharmaceutical analysis is the development of highly accurate, reproducible, accessible, and rapid methods for the quantitative determination of this medicinal product. The aim of the work is to develop a spectrophotometric technique for the quantitative determination of metformin hydrochloride based on the reaction with bromothymol blue in compliance with the SPhU. Material and methods. As reagent and solvent, bromothymol blue «Honeywell Fluka», acetone of AR grade and purified water were used. Analytical equipment: Specord 200 spectrophotometer, ABT-120-5DM and Radwag XA 210.4Y electronic scales, Elmasonic E 60H ultrasonic bath, measuring glassware of A class. Results. A novel, sensitive and simple spectrophotometric method for the quantitative determination of metformin hydrochloride (MFH) in tablets was developed and validated. The proposed method is based on the reaction of the analyte with a sulfophthalein dye, in particular with bromothymol blue, using a mixture of distilled water with acetone (1 : 50) as a solvent. The final yellow product has a maximum optical density at 404 nm. Regression analysis of the method demonstrated a strong correlation (not less than 0.998) within the concentration range of 5.20–7.80 μg/mL. Intra-laboratory precision confirmed the absence of interference from excipients and proved the reproducibility of the method within the selected concentration range. The purposed method is accurate, precise and sensitive, so that it is valuable for routine quality control of MFH in solid dosage forms.