Peak Effect Time of Ketorolac
The peak analgesic effect of ketorolac occurs within 2 to 3 hours after oral administration, regardless of the dose within the recommended range. 1
Route-Specific Peak Times
The peak effect timing varies significantly by route of administration:
- Oral ketorolac: Peak analgesic effect at 2-3 hours 1
- Intramuscular ketorolac: Peak effect at approximately 1-2 hours 2
- Intravenous ketorolac: Peak effect at approximately 15 minutes (similar to other IV analgesics) 3
Maximum plasma concentrations (Cmax) occur at 20-60 minutes after administration, but this does not correspond to peak analgesic effect. 4
Clinical Implications for Timing
When prescribing oral ketorolac for procedural pain (such as IUD placement), administer 1-2 hours before the procedure to ensure peak analgesic effect coincides with the painful stimulus. 3 The American College of Obstetricians and Gynecologists recommends oral ketorolac 20 mg taken 40-60 minutes before IUD placement for optimal pain control during and 10 minutes after the procedure. 3
For intramuscular ketorolac 30 mg, administration 30 minutes prior to a procedure may not reduce pain during the procedure itself, but effectively reduces pain at 5 and 15 minutes after the procedure. 3
Important Pharmacokinetic Considerations
Food delays absorption: High-fat meals decrease peak concentrations and delay time-to-peak by approximately 1 hour, though total absorption remains unchanged. 1
Duration exceeds opioids: While the peak effect may be slightly delayed compared to opioids, the analgesic effect of ketorolac often persists longer than morphine or meperidine. 5
Dose does not affect peak timing: The greatest difference between large and small doses is in the duration of analgesia, not the timing or magnitude of peak effect. 1
Practical Dosing Strategy
For breakthrough pain management, wait the full 2-3 hours after oral administration before concluding the dose is inadequate and considering additional analgesia. 1 Premature redosing risks adverse effects without additional benefit, as the drug has not yet reached peak effect.