Effect of diflunisal on platelet function and blood coagulation.

The effect of diflunisal on platelet function and blood coagulation in volunteers was studied. The drug was double-blind tested in 20 healthy males randomly assigned to diflunisal and placebo groups. The effect of high dosage was tested in an open design in six healthy males. Test systems were haemoglobin, mH, blood glucose, platelet counts, bleeding time, ADP- and collagen-induced platelet aggregation, PT, PTT, thrombin time, fibrinogen, antithrombin III, clot lysis, serum FDP and diflunisal blood levels. Paired and covariance tests were computed. The study design in both the double-blind and the open study was as follows: Acute single dose trial — diflunisal or placebo orally on day 1. Tests were monitored before and at regular intervals after administration on day 1 and further in the fasting state on days, 2, 4, 8, 10 and 12. Chronic multiple dose trial — diflunisal or placebo twice daily orally from day 15 to day 21. The same tests were monitored before and at regular intervals after administration on day 15, and in the fasting state on days 16, 18, 21, 25, 29, 31 and 33. Diflunisal at the dosages studied did not cause significant changes in any parameter measured at any time. Blood levels of diflunisal were comparable to those obtained during analgesic therapy. In the high dosage open study there were slight effects on platelet aggregation. Bleeding times were not influenced.