The effect of acetylsalicylic acid in 3 different formulations on in vitro and in vivo platelet function tests. An experimental study on healthy male volunteers.

The template bleeding time (TBT), ADP-induced platelet aggregation, and serum production of TXB2 were measured in healthy young male subjects immediately before, and on days 1, 4 and 6 after the ingestion of 1 single dose of 500 mg acetylsalicylic acid (ASA) in 3 different formulations: Aspirin (Bayer), and the 2 enteric-coated formulations Reumyl (Hässle) and Premaspin (Lääke). The ingestion of Aspirin resulted in a significant prolongation of the TBT over a period of 6 d. However, after the ingestion of the same amount of ASA in the 2 enteric coated formulations, the TBT as measured on day 6 had become normalized. After the ingestion of Aspirin, there was no reappearance of the second wave of ADP-induced platelet aggregation during the study period; however, after the ingestion of the 2 enteric-coated formulations, secondary platelet aggregation occasionally returned on day 6. In response to the intake of each of the 3 ASA formulations, the serum TXB2 production as measured 24 h later was almost completely inhibited. In each of the 3 study groups, the TXB2 formation as measured on day 6 was still significantly impaired.