The effect of IM ketorolac tromethamine on bleeding time: a prospective, interventional, controlled study

Opiates, although effective analgesics, have significant adverse side effects. Ketorolac, the only parental nonsteroidal antiinflammatory drug available for use in the United States does not cause significant respiratory depression or hypotension, but it is a reversible inhibitor of platelet aggregation with a theoretical increased bleeding risk, which limits its use. The objective of this study was to determine the effect of a single intramuscular dose of 60 mg ketorolac on 4-hour bleeding times in healthy volunteers. This was a prospective, paired, unblinded, before-and-after interventional study performed in a suburban university-based EM residency training program. Subjects were 20 healthy volunteer EM residents. Standard Ivy bleeding times were measured before and 4 hours after intramuscular administration of 60 mg ketorolac. Before-and-after bleeding times were compared using a paired t-test. The study had 90% power to detect an effect size of 0.5. The subjects' mean age was 31.6 and 7 (35%) were females. Bleeding time was increased from a mean baseline time of 3 minutes 34 seconds (+/- 1 min 20 sec) to a mean 4-hour postinjection time of 5 minutes 20 seconds (+/- 3 min 8 sec). The mean prolongation of bleeding time was 1 minute 46 seconds (50% increase with 95% confidence interval, 25%-75%). There were no adverse events. A standard intramuscular dose of 60 mg ketorolac resulted in prolongation of the bleeding time in healthy volunteers. The clinical significance of this prolongation in patients is unclear.