RELATIVE BIOAVAILABILITY OF RAPIDLY DISPERSING, PLAIN, AND MICROENCAPSULED ACETYLSALICYLIC-ACID TABLETS AFTER SINGLE-DOSE ADMINISTRATION

Extent and rate of absorption of acetylsalicylic acid (ASA) from rapid ly dispersing (Acesal Extra) and plain tablets (Acesal) relative to re ference 1 (plain tablets, Aspirin) and from microcapsuled tablets (Mic ristin) relative to comparable listed tablets (reference 2, Colfarit) were assessed in 2 single-dose (0.5 g ASA), open, randomized, crossove r studies with intervals of 14 days between 2 periods. Both studies we re performed in 24 male and female healthy volunteers each (age 18 - 3 2 years, body weight 48 - 90 kg, body height 161 - 190 cm). ASA and it s metabolite salicylic acid (SA) were measured with an HPLC method val idated for ASA between 0.2 and 20 mu g/ml and for SA between 0.4 and 4 0 mu g/ml. The test tablets were considered bioequivalent with referen ce in extent of absorption if the 90% confidence limits of the AUC(0-i nfinity) ratio were within the range of 0.80 - 1.25, and in rate of ab sorption if the confidence limits of the C-max/AUC(0-infinity) ratios were within 0.70 - 1.43. Results: Geometric means and 90% confidence l imits for the test/reference ratios of the comparisons Acesal vs refer ence 1, Acesal Extra vs reference 1 and Micristin vs reference 2 were 1.05 (0.97 - 1.13), 1.13 (1.05 - 1.22), 1.02 (0.92 - 1.14) for ASA AUC (0-infinity) and 1.02 (0.96 - 1.07), 1.05 (0.99 - 1.11), 0.98 (0.91 - 1.04) for SA AUC(0-infinity), respectively. The results for C-max/AUC of ASA were 1.16 (1.00 - 1.34), 1.72 (1.49 - 1.99), 0.83 (0.73 - 0.94) and of SA 1.02 (0.98 - 1.07), 1.07 (1.02 - 1.12), 0.93 (0.88 - 0.97). Conclusion: Acesal and Micristin were bioequivalent with the respecti ve references in both extent and rate of absorption. Acesal Extra and reference 1 were bioequivalent with regard to extent only. Acesal Extr a was absorbed faster.