Clinical Question: Do women and men react differently to different analgesics?

Setting: Emergency department

Study Design: Randomized controlled trial (double-blinded)

Synopsis: To investigate the difference in effectiveness between morphine and butorphanol, the authors enrolled 94 adults (48 percent were women) who had moderate to severe pain from an acute injury requiring intravenous medication for pain control. The patients were assigned randomly (allocation concealed) to receive 2.5 to 5 mg of morphine or 0.5 to 1 mg of butorphanol, both of which could be repeated, if necessary. Pain was measured on a 10-cm visual analog scale, with higher scores representing worse pain. At baseline, the average pain score was 7.6.

Overall, patient scores for both drugs were similar at 30, 60, and 120 minutes. At 60 minutes, scores in women were significantly lower for butorphanol (actual scores not reported; P = .046) with a trend toward better response to morphine in men than in women at 60 minutes (actual scores not reported; P = .06). No difference in response occurred in men between the two opioids. These P values were not adjusted for multiple comparisons, which means that these statistically significant differences could have occurred by chance instead of representing a real difference. Although more study is needed to confirm these results, they point to a preferential response to butorphanol in women.

Bottom Line: This preliminary study found that women seem to respond slightly better to butorphanol than to morphine. This difference may extend to other mixed-action opioids, such as pentazocine and nalbuphine. (Level of Evidence: 1b)