Onset of Action for Toradol (Ketorolac)
The peak analgesic effect of Toradol (ketorolac) occurs within 2 to 3 hours after administration, regardless of route (IV, IM, or oral). 1, 2, 3
Pharmacokinetic Timeline by Route
Intravenous Administration
- Time to peak plasma concentration (Tmax): 1.1 ± 0.7 minutes for 15 mg dose and 2.9 ± 1.8 minutes for 30 mg dose 1, 2
- Peak analgesic effect: 2-3 hours 1, 2
- Clinical onset: While IV ketorolac reaches peak plasma levels within minutes, the analgesic onset is delayed 30-60 minutes, with significant limitations as more than 25% of patients exhibit little or no response 4
Intramuscular Administration
- Time to peak plasma concentration (Tmax): 33 ± 21 minutes for 60 mg dose and 44 ± 29 minutes for 30 mg dose 1, 2
- Peak analgesic effect: 2-3 hours (approximately 1-2 hours in some studies) 1, 5
- Clinical onset: 30-60 minutes, though this prolonged onset limits utility when rapid pain relief is necessary 4
Oral Administration
- Time to peak plasma concentration (Tmax): 44 ± 34 minutes for 10 mg dose and 33 ± 21 minutes for 15 mg dose 3
- Peak analgesic effect: 2-3 hours 3
- Bioavailability: 100% absorption after oral administration, though high-fat meals delay time-to-peak by about 1 hour 3
Important Clinical Considerations
Duration of Effect
- The greatest difference between large and small doses of ketorolac is in the duration of analgesia rather than peak effect 1, 2, 3
- Duration of effect is not statistically significantly different over the recommended dosage range 1, 2
Key Pharmacologic Properties
- No sedative or anxiolytic properties 1, 2, 3
- Mechanism of action likely related to prostaglandin synthetase inhibition, with the S-enantiomer providing the analgesic activity 1, 2, 3
- Highly protein bound (99%) with linear pharmacokinetics in the recommended dosage ranges 1, 2, 3
Clinical Efficacy Limitations
- Despite achieving peak plasma levels quickly with IV/IM routes, the prolonged onset to analgesic action (30-60 minutes) limits utility in emergency settings requiring rapid pain relief 4
- A significant percentage of patients (>25% in most studies) fail to obtain adequate relief with ketorolac monotherapy 4
- Most useful when supplementing parenteral opiates rather than as monotherapy for moderate-to-severe acute pain 4