Comparison of oral controlled release morphine and epidural morphine in the management of postoperative pain

Abstract

Oral controlled release morphine (CRM) was compared in a double-blind study with epidural morphine (EM) for postoperative pain relief in 20 patients undergoing knee arthrotomy under epidural anesthesia. Ten patients received 30 mg CRM orally and saline epidurally (CRM group), and ten patients received placebo tablets orally and 4 mg morphine epidurally (EM group), both at the time of skin incision and then every 8 hr for 48 hr during which patients evaluated pain intensity using a visual analog scale. Nine of the ten patients in the EM group had good relief of pain throughout the study period. Seven of the ten patients in the CRM group needed rescue analgesics within 6 hr of the initiation of the study (P less than 0.01). We conclude that CRM is not suitable for the control of early postoperative pain, whereas epidural morphine is excellent.