Butorphanol and morphine: a double-blind comparison of their parenteral analgesic activity.

The analgesic effects of butorphanol tartrate and morphine sulfate were compared in 127 patients judged to have moderate to severe pain following major operations. The study was double-blind, and the drugs were given IM at several dosage levels. Scores for pain intensity and relief, as well as pain-intensity difference, were determined at 30, 60 and 120 minutes after medication, then were analyzed by a parallel-line assay method in a modified computer program. The analysis indicated butorphanol tartrate to be 7 times as potent as morphine sulfate. Peak analgesic effects were obtained at 60 minutes with both drugs. Side effects were minimal in degree and incidence. Neither butorphanol nor morphine induced any changes in blood pressure, pulse rate, or respiratory rate. These data, along with those from studies elsewhere, suggest that butorphanol is a safe, potent, and effective analgesic agents, with probably a low potential for inducing drug dependence.