1. Home>
2. Specialties>
3. Emergency Medicine>
4. Summary and Comment

Morphine Dosing in Acute Pain: How Much Is Enough?

Morphine at 0.15 mg/kg adds little analgesia to 0.10 mg/kg.

Underdosing of opioid analgesia is a significant problem in emergency medicine. Although many dosing regimens for intravenous morphine have been studied, 0.10 mg/kg generally is recommended as an acceptable starting dose for treating patients with acute pain. Unfortunately, many physicians start much lower. In a prospective, randomized, placebo-controlled, double-blind study, researchers compared the effects of morphine at doses of 0.10 mg/kg and 0.15 mg/kg in 280 adult patients (age range, 21–65) who presented with pain of less than 7 days’ duration and who were deemed to require opioid analgesia by an attending emergency physician.

All patients received an initial dose of 0.10 mg/kg of morphine. After 30 minutes, those randomized to the higher dose received 0.05 mg/kg of morphine, while the lower-dose group received placebo. Pain scores were assessed at baseline, 30 minutes, and 60 minutes using a standardized numeric pain scale (0 = no pain, 10 = worst pain possible).

At 30 minutes, reductions in pain were similar in the two groups. Both groups had further pain reduction at 60 minutes, but the higher-dose group had a small, statistically significant but clinically insignificant greater reduction in pain than the lower-dose group (between-group difference, 0.4; 95% confidence interval, 0.0–0.9). Adverse events were similar in the two groups.

Comment: This study did not show a clinically significant benefit of administering a standard incremental dose of morphine and thus supports previous studies demonstrating that opioid dosing needs to be individualized to patient response. The bottom line is that EPs tend to routinely underdose opioid analgesia, even though virtually every study has demonstrated that an initial dose higher than is typically used — followed by individualized incremental dosing at intervals as frequent as 10 minutes or less — is required for effective analgesia and is not associated with adverse events.

— Richard D. Zane, MD, FAAEM

Published in Journal Watch Emergency Medicine May 4, 2007

Citation(s):

Birnbaum A et al. Randomized double-blind placebo-controlled trial of two intravenous morphine dosages (0.10 mg/kg and 0.15 mg/kg) in emergency department patients with moderate to severe acute pain. Ann Emerg Med 2007 Apr; 49:445-53.

• Medline abstract (Free)