Rapid and Simple RPHPLC Method for the Estimation of Metformin in Rat Plasma.

A simple reverse phase high-performance liquid chromatographic method has been developed for determining the concentration of metformin in rat plasma. The method employs C(18) column (300 mm x 2.4 mm i.d.), ammonium acetate (0.15 M) and acetonitrile (90:10; pH-5.5; 1.0 ml/min) as mobile phase and ultraviolet detection at 236 nm. Acetonitrile was used to simultaneously deproteinize rat plasma and extract metformin. The assay was linear in the concentration range of 0.33 mug-16.6 mug/ml with co-efficient of correlation 0.994. The retention time was 4.7 min. The method was found to be precise (% CV < 15%), accurate and suitable for pharmacokinetic study of orally administered metformin in rats.