Comparison of spectrophotometric and high performance liquid chromatographic methods in the bioavailability studies of aspirin and salicylic acid in healthy human volunteers

Abstract

The aim of the work was to develop a simple, rapid and accurate multiple component spectrophotometric method for the determination of aspirin and its major metabolite, salicylic acid, in plasma and the results obtained compared with the results of the same analysis using HPLC method. With HPLC, the drugs aspirin, salicylic acid and paracetamol (as internal standard) were eluted with 10μm reversed phase C_18-support column at ambient temperature with a mobile phase consisting of methanol: 5% acetic acid (25:75) adjusted to pH 3.45 with glacial acetic acid, at a flow rate of 1.5ml/min with U.V detection at 280nm. Each analysis required no longer than 10min. Quantitation was achieved by measurement of the peak-height ratio and the relative and absolute recoveries varied from 90 to 98%. For U.V. spectrophotometric analysis, Beer's law plots were prepared using standard solutions of each of the salicylates (aspirin and salicylic acid) in 0.1M HCl and plasma. Extraction recoveries in plasma and 0.1M HCl (as control) were developed and the relative and absolute recoveries varied from 90 to 98%. The methods were applied for the determination of the pharmacokinetic parameters of aspirin and its major metabolite salicylic acid. Comparing the bioavailability of the drug under the two analytical methods employed in the study, it was observed that higher concentrations were observed with HPLC than U.V. Spectrophotometric method. However, the results obtained from these two analytical methods correlate with each other with the degree of probability (0.05

Key words: Comparison of Analytical Methods, Bioavailability of Aspirin, Human.

Nig. J. Pharm. Res. 3(1) 2004: 96-101