Intravenous Ketorolac: Are Lower Doses Just as Effective?

Authors: Motov S et al., Ann Emerg Med 2016 Dec 16;

Limiting the assessment of pain relief with ketorolac to 30–120 minutes after administration limits the conclusions we can draw from this study.

To determine the optimal dose of ketorolac, investigators at a single U.S. emergency department conducted a randomized double-blind trial in 240 patients with moderate-to-severe pain at various body sites. Patients received 10, 15, or 30 mg intravenous ketorolac. The primary outcome was pain reduction at 30 minutes, and outcomes were assessed for up to 120 minutes.

Baseline pain scores on a 10-point numeric rating scale were similar among the three groups. The mean improvements in pain ratings at 30 minutes were 2.5, 2.4, and 3.0 in the 10-, 15-, and 30-mg groups, respectively, but the between-group differences were not statistically significant, implying equivalence of the three doses. Differences in pain ratings remained similar at all time points.

Comment

This study provides robust evidence that ketorolac 10 mg intravenously is just as effective as 30 mg intravenously during the first 2 hours after administration. However, the authors correctly note that the study “did not assess whether higher doses may have resulted in prolonged pain relief beyond the 120-minute mark.” It’s a shame that they went to so much trouble to do this study and did not collect data at later time points. Basic pharmacology would lead us to assume that patients receiving the higher dose would get relief for longer, as ketorolac’s half-life is 4 to 6 hours. Therefore, I don’t think this study should change practice. While ketorolac is a platelet inhibitor that should be used sparingly or not at all in patients who may require major surgery, those with renal failure, and the elderly, all other patients are likely to benefit from the prolonged action of the higher 30-mg intravenous or 60-mg intramuscular doses.