Metformin : A Review of it s Chemistry , Pharmacology , Impurity Profiling

Metformin is a widely used in the oral antidiabetic drug belonging to the biguanide class and is primarily used in the management of type 2 diabetes mellitus. This review summarizes the chemistry and physicochemical properties of metformin, its mechanism of action, pharmacokinetic characteristics, and the importance of impurity profiling. Metformin has the molecular formula C₄H₁₁N₅ and a molecular weight of 129.16 g/mol. It is hydrophilic and freely soluble in water. Its glucose-lowering action is mainly associated with reduced hepatic glucose production and improved insulin sensitivity. Pharmacokinetically, metformin has limited plasma-protein binding, undergoes minimal hepatic metabolism, and is eliminated predominantly by the kidneys in unchanged form. Therefore, renal function is an important consideration during treatment. Impurity profiling is an essential part of pharmaceutical quality assessment because it supports the detection, identification, structural characterization, and quantification of impurities in an active pharmaceutical ingredient. Impurities may be classified as organic impurities, inorganic impurities, and residual solvents. Understanding these categories and applying appropriate analytical evaluation and relevant ICH guidance are important for assessing the quality and safety of metformin. Overall, this review brings together key information on metformin's chemistry, pharmacological action, pharmacokinetics, and impurity profiling.