HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ASSAY FOR THE DETERMINATION OF 5-AMINOSALICYLIC ACID AND ACETYL-5-AMINOSALICYLIC ACID CONCENTRATIONS IN ENDOSCOPIC INTESTINAL BIOPSY IN HUMANS

A high-performance liquid chromatographic method for the simultaneous determination of 5-aminosalicylic acid (5-ASA) and N-acetyl-5-ASA (Ac-5-ASA) concentrations in endoscopic mucosal biopsy homogenates is presented. The mean recoveries of 5-ASA and Ac-5-ASA from spiked blank biopsy homogenates ranged from 95.9 to 120% and from 92.5 to 100%, respectively. The coefficients of variation for 5-ASA and Ac-5-ASA were 0.7-8.6% and 1.4-12.9%, respectively. This method is useful for direct determination of topical availability of 5-ASA and Ac-5-ASA and probably an accurate parameter of drug bioavailability.