A comparative bioavailability study of different aspirin formulations using on-line multidimensional chromatography

A multi-dimensional column chromatographic method employing UV spectrometri c detection was optimised and successfully used in a comparative bio-availa bility study of aspirin obtained from different commercially available oral dosage forms. Sample clean-up was achieved by on-line solid-phase extracti on. In this study, the bioavailability of aspirin was compared in plain asp irin tablets, chewed tablets, effervescent tablets and Enteric-coated aspir in tablets. Blood samples were taken at frequent intervals after single dos ing in ten healthy volunteers, the plasma samples were first treated with p hysostigmine sulphate to minimise enzymatic hydrolysis of aspirin to salicy late. The results showed the measured T-max, C-max and AUC was significantl y higher for soluble aspirin than for the other formulations and the t(1/2) was shorter. This indicates the rapid absorption of aspirin from a soluble formulation compared with that from the other formulations. These differen ces suggest that the soluble formulation could be the aspirin of choice to treat patients suspected to be at high risk of myocardial infarction. The m ethod performs, in a single step, an efficient extraction and clean-up of a spirin from human plasma. The calibration graph was linear over the calibra tion range 0.2-12 mu g ml(-1) plasma with a limit of detection of 0.1 mu g ml(-1). The intra- and inter-assay coefficients of variation were less than 6% and the recoveries ranged from 86 to 98%. The proposed method combines the advantages of being simple and selective in the presence of other poten tial interfering drugs and is suitable for routine analyses to obtain valua ble information about the clinical effects of the drug and its use in preve ntion treatments of acute myocardial infarction. The whole procedure takes similar to 7 min and is in agreement with other conventional methods. (C) 1 999 Elsevier Science B.V. All rights reserved.