The action of non-steroidal antiinflammatory agents on platelet aggregation and vessel tone in relation to inhibition of PGI2- and thromboxane-release. With particular reference to 5-benzoyl-alpha-methyl-2-thiophene acetic acid (tiaprofenic acid).

The actions of 5-benzoyl-alpha-methyl-2-thiophene acetic acid (tiaprofenic acid) on platelet aggregation, coronary vascular tone and myocardial oxygen consumption were studied in vitro and compared to those of diclofenac sodium, indometacin and meclofenamate. Tiaprofenic acid dose-dependently and reversibly inhibited collagen- and arachidonic acid-induced aggregation of rabbit platelet-rich plasma (IC50 2--5 micromol/l) and was as effective in this system as the reference compounds. Tiaprofenic acid did not alter the myocardial oxygen consumption up to 120 micromol/l but produced reversible and dose-dependent increases in the coronary vascular tone of both guinea pig hearts and isolated bovine coronary arteries at 0.1--10 micromol/l concentrations. This coronary vasomotor activity of tiaprofenic acid could be correlated to its ability to inhibit the vascular PGI2 production whereas the inhibition of platelet aggregation by all of the substances studied does not seem to be tightly correlated to their inhibitory effect on the thromboxane formation of blood platelets.