BIOINEQUIVALENCE OF 4 100MG ORAL ASPIRIN FORMULATIONS IN HEALTHY-VOLUNTEERS

The single dose pharmacokinetics of 4 commercially available 100mg oral aspirin formulations were studied in 6 healthy men and 6 healthy women. Two of the formulations were rapid release ('Cardiprin' 100, 'Platelin') and the other 2 were enteric coated formulations ('Astrix' 100, 'Cartia'). There were marked differences in the plasma concentration-time profiles between the rapid release and the enteric coated formulations. There were no significant differences (p > 0.05) in the mean time to achieve maximum aspirin concentrations between 'Cardiprin' 100 (0.48h) and 'Platelin' (0.35h), but this was significantly prolonged (p < 0.001) for 'Astrix' 100 (3.73h) and even more prolonged for 'Cartia' (6.84h). Similar between-formulation differences were seen in the areas under the plasma concentration-time curves, for which the rank order was 'Cardiprin' 100 (1.60 mg/L . h) = 'Platelin' (1.54 mg/L . h) > 'Astrix' 100 (0.73 mg/L . h) > 'Cartia' (0.56 mg/L . h). For 'Cardiprin' 100, 'Platelin' and 'Astrix' 100 plasma aspirin concentrations were below 5-mu-g/L by 7h after ingestion, whereas for 'Cartia' aspirin was detectable for up to 16h, giving the appearance of sustained release. The enteric coated formulations produced the greatest variability in the plasma aspirin concentration vs time profiles. The urinary recovery of salicylate was greater than 80% of the administered dose for all 4 formulations. The clinical significance of the marked pharmacokinetic differences observed with these 4 low-dose aspirin formulations is not known.