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

A multi-dimensional column chromatographic method employing UV spectrometric detection was optimised and successfully used in a comparative bio-availability study of aspirin obtained from different commercially available oral dosage forms. Sample clean-up was achieved by on-line solid-phase extraction. In this study, the bioavailability of aspirin was compared in plain aspirin tablets, chewed tablets, effervescent tablets and Enteric-coated aspirin tablets. Blood samples were taken at frequent intervals after single dosing in ten healthy volunteers, the plasma samples were first treated with physostigmine sulphate to minimise enzymatic hydrolysis of aspirin to salicylate. The results showed the measured Tmax, Cmax, and AUC was significantly higher for soluble aspirin than for the other formulations and the t1/2 was shorter. This indicates the rapid absorption of aspirin from a soluble formulation compared with that from the other formulations. These differences suggest that the soluble formulation could be the aspirin of choice to treat patients suspected to be at high risk of myocardial infarction. The method performs, in a single step, an efficient extraction and clean-up of aspirin from human plasma. The calibration graph was linear over the calibration range 0.2-12 microg ml(-1) plasma with a limit of detection of 0.1 microg 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 potential interfering drugs and is suitable for routine analyses to obtain valuable information about the clinical effects of the drug and its use in prevention treatments of acute myocardial infarction. The whole procedure takes 7 min and is in agreement with other conventional methods.