CAPILLARY ELECTROPHORESIS WITH ELECTROKINETIC INJECTION SIMPLIFIES THE DISSOLUTION TESTING OF AMOXICILLIN CAPSULES

Abstract

The purpose of this work was to assess the ability of capillary electrophoresis (CE) to simplify sample preparation in dissolution testing of an acid labile drug (amoxicillin). The use of electrokinetic injection technique in (CE) was shown to enable direct injection of dissolution samples, without the need for filtration. Together with its ability to achieve sufficient selectivity, CE was shown to be a suitable technique for studying the dissolution of amoxicillin. A simple and reasonably rapid analytical CE method was developed to assess the dissolution of amoxicillin in neutral and acidic media. The electrophoretic conditions of the proposed method were: 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid (HEPES) buffer (pH 7.1; 200 mM) containing 30% acetonitrile and 10% β-cyclodextrin. Samples were injected using electrokinetic injection (5KV, for 100 s). Electrophoresis was performed at positive polarity mode of 25KV and a temperature of 30°C. Amoxicillin was separated from its acid-degradation products using cyclodextrin as a buffer additive. The method was validated and shown to have sufficient linearity, precision, accuracy, selectivity, and sensitivity. The method was applied to commercial amoxicillin capsules and was favorably compared with an official HPLC method.