Mixing Fentanyl and Ketorolac in a Syringe for Intramuscular Injection
Fentanyl and ketorolac should not be mixed in the same syringe for intramuscular injection as this combination is contraindicated according to the FDA drug labeling for ketorolac. 1
Compatibility Issues
- The FDA drug labeling for ketorolac specifically states that "ketorolac tromethamine injection should not be mixed in a small volume (e.g., in a syringe) with morphine sulfate, meperidine hydrochloride, promethazine hydrochloride or hydroxyzine hydrochloride; this will result in precipitation of ketorolac from solution." 1
- While fentanyl is not specifically mentioned in this list, the general principle of avoiding mixing medications in the same syringe applies, especially with opioids and NSAIDs that have different chemical properties. 2
- Medication safety guidelines emphasize that each medication should be prepared and administered separately to prevent physical and chemical incompatibilities. 2
Administration Recommendations
- Administer ketorolac intramuscularly as a single agent, injecting it "slowly and deeply into the muscle" as directed by the FDA labeling. 1
- For adults under 65 years, the recommended IM dose of ketorolac is 60 mg as a single dose or 30 mg every 6 hours for multiple dosing. 1
- For adults 65 years and older, renally impaired, or under 50 kg, the recommended IM dose is 30 mg as a single dose or 15 mg every 6 hours for multiple dosing. 1
- Administer fentanyl as a separate intramuscular injection if both medications are required. 2
- For adults requiring IM fentanyl, dosing typically ranges from 50-100 μg depending on patient factors. 3
Safety Considerations
- Mixing medications increases the risk of precipitation, altered drug efficacy, and potential adverse effects. 2
- Standardized medication preparation protocols recommend against mixing different drug classes in the same syringe to prevent medication errors. 2
- When administering multiple medications, each should have its own properly labeled syringe with clear identification of the drug, concentration, and route of administration. 2
Alternative Approaches
- If both medications are clinically indicated, administer them as separate injections at different sites. 1
- Consider sequential administration rather than simultaneous administration if concerned about patient comfort. 4
- Studies have shown that the combination of fentanyl and ketorolac (administered separately) provides superior pain control compared to either agent alone in certain clinical scenarios. 4, 5
Clinical Evidence
- A study on pediatric bilateral myringotomy showed that combination therapy with intramuscular fentanyl and ketorolac (administered separately) was associated with superior pain control compared to either agent alone. 4
- Another study demonstrated that the combination of transdermal fentanyl and IM ketorolac was more effective for postoperative pain than ketorolac alone. 6
Remember that medication safety is paramount, and following proper administration guidelines helps prevent adverse events and ensures optimal therapeutic outcomes.