High performance liquid chromatographic determination of epirizole and tiaramide in pharmaceutical preparations

Rapid, accurate and reliable high performance liquid chromatographic methods for the determination of non-steroidal anti-inflammatory drugs epirizole and tiaramide in pharmaceutical preparations were developed using triethylamine, a modifying agent to the mobile phase. Extraction was carried out with methanol-water (1:1,v/v) after grounding tablet and granule preparations. The methods utilized reversed phase C18 column, UV monitoring at 250 nm, ethyl p-hydroxybenzoate as an internal standard for epirizole, and at 295 nm, methyl p-aminobenzoate as an internal standard for tiaramide. Regression analyses of three standard plots in concentration ranges of 0.05-0.4 mg/mL for epirizole and 0.18-1.44 mg/mL for tiaramide gave respective correlation coefficients > 0.99998 and > 0.99997. Relative standard deviations of the slopes were 0.180% and 0.888%, respectively. Percentage recoveries of these compounds for four commercially available drugs ranged between 99.06 and 103.14 and between 99.15 and 99.71 of the labeled amounts of epirizole and tiaramide, respectively. The methods were successfully applied to determine contents of epirizole and tiaramide in marketed drugs.