Morphine: continuous intravenous infusion versus intramuscular injections for postoperative pain relief.

Postoperative pain was controlled in 42 patients with either continuous intravenous (iv) or scheduled intramuscular morphine following surgery for gynecologic cancers. In this double-blind study, no statistical differences were found in pain control or rate of complications between the two methods of administration. Both routes were effective in controlling pain without producing major toxicity. Initial doses were based on the patient's weight and then adjusted every 4 hr. We conclude that both methods are safe and effective but that continuous iv infusion is the preferred route because of the ease of administration, elimination of multiple intramuscular injections, and possibly more even pain control.