Determination of mefenamic acid in a topical emulgel by a validated HPLC method

Abstract

Objective: The present study is aimed to develop and validate a simple, precise and accurate high-performance liquid chromatography (HPLC) method, according to ASEAN guideline for the validation of the analytical procedure, for the determination of mefenamic acid in a topical emulgel preparation. Methods: An emulgel of 1 % mefenamic acid was prepared using carbopol 940 as a gelling agent and cremophor EL as an emulsifying agent. It was diluted with ethanol to make a sample concentration of 200 µg/ml. The method used a C18 column (5 µm; 250 x 4.6 mm) with the mobile phase, consisting of acetonitrile, acetic acid, and water in a ratio of 75:1:24. The column was maintained at 25 °C. The flow rate was 1 ml/min and the injection volume was 10 µl. The peak response was monitored by UV at 282 nm. It was validated for specificity, range, linearity, precision, accuracy, limit of detection (LOD) and limit of quantification (LOQ). In addition, forced degradation (hydrolysis, oxidation and dry heat) was performed to determine the capability of the proposed method to analyze the chemical stability of the drug samples during storage. Results: The method was specific to the drug while other excipients did not interfere with the quantitation of mefenamic acid. It was linear in the concentration range of 1.29 to 806 µg/ml. LOD and LOQ were 4.88 and 14.78 µg/ml, respectively. Accuracy of the method was demonstrated by recovery experiments on the synthetic mixture method and the mean percent recovery was 101.10±1.56. Repeatability and intermediate precision were rugged with %RSD values of 1.30 and 1.07, respectively. The method could separate mefenamic acid from other degradation products of forced degradation. Conclusion: The HPLC method presented herein is simple, accurate, sensitive and reproducible for the determination of mefenamic acid in an emulgel. It is served as a stability-indicating method and can be used for the analysis of the drug during product development and stability studies.