Validation of a simple and rapid HPLC method for determination of metronidazole in dermatological formulations

A rapid and simple method using an isocratic high-pressure liquid chromatography (HPLC) and UV detection for the determination of metronidazole in dermatological formulations is presented. Metronidazole samples were extracted with a solution composed of 60% methanol and 40% mobile phase by a procedure that can be completed in less than 10 min. Subsequent separation and quantification was accomplished in less than 20 min using reversed-phase HPLC with isocratic elution with 0.01% trifluoroacetic acid/acetonitrile (85:15%, vol/vol). Validation experiments confirmed the precision and accuracy of the method. When applied to a commercial metronidazole cream and gel formulation, recoveries of 100.4% for cream formulations and 102.3% for gel formulations were obtained. The method should facilitate studies of the formulation compatibility of metronidazole topical formulations with agents that may improve its clinical tolerability for treatment of rosacea.