Effects of ketorolac tromethamine on hemostasis in volunteers.

Ketorolac tromethamine, an analgesic agent with prostaglandin synthetase--inhibiting activity, is more active than aspirin in vitro in inhibiting collagen- or arachidonic acid-induced platelet aggregation. In this randomized, double-blind study, 26 volunteers received ketorolac, 30 mg intramuscularly four times a day for 5 days, and placebo, two capsules orally four times a day for at the last 2 study days. The effects of this treatment were compared with those of intramuscular placebo and oral aspirin, two 325 mg capsules, given on the same schedule to eight volunteers. Aspirin at a mean serum concentration of 84 micrograms/ml did not affect prothrombin time, partial thromboplastin time, platelet count, or bleeding time. Ketorolac produced a modest prolongation of the bleeding time, from 4.9 +/- 1.1 minutes (mean +/- SD) to 7.8 +/- 4.0 minutes (p less than 0.005). Ketorolac did not affect the prothrombin time or partial thromboplastin time but was associated with clinically insignificant change in the platelet count from 303 +/- 57 X 10(3)/m3 to 277 +/- 56 X 10(3)/mm3.