Validated Chromatographic Methods for the Simultaneous Estimation of Etamsylate and Mefenamic Acid in the Presence of Their Main Impurities

Background: Etamsylate (ETS), a haemostatic drug, is formulated with mefenamic acid (MFA) for pain relief. Objective: The aim of this work was to develop chromatographic methods for the estimation of ETS and MFA in the presence of their main impurities. These methods could be used in the routine analysis in quality control laboratories. Methods: The first method was RP-HPLC method, the separation was carried out on an Inertsil® ODS- 3V C18 column using a mobile phase composed of acetonitrile: potassium dihydrogen phosphate buffer adjusted to pH 7 with 0.1 N NaOH (55: 45, v/v) at a flow rate of 1 ml/ min. The detection was carried out at 220 nm. The second method was a TLC-densitometric method where the studied components were separated using a developing system composed of dichloromethane: ethyl acetate: methanol: triethylamine (6: 2: 2: 0.5, v/v/v/v) on TLC silica gel 60 F254 plates, followed by densitometric scanning at 300 nm. Results: In RP-HPLC method, the peaks were sharp and well separated, good retention times were obtained. Linearity was obtained over the concentration range 20-90 μg/ml, for both ETS and MFA. In the TLC-densitometric method, well separation of drug spots and linear relationship were achieved over the concentration range of 0.4-2.8 μg/spot, for both ETS and MFA. Method validation was conducted according to ICH guidelines. Conclusion: The developed methods were applied for the determination of the cited drugs in laboratory prepared mixtures and in tablets containing the two drugs. The methods are simple and precise and can be used for routine analysis of the drugs in combined dosage forms in quality control laboratories.