A comparison of regularly administered sustained release oral morphine with intramuscular morphine for control of postoperative pain

We studied the efficacy and side effect profile of regularly administered, oral sustained-release morphine sulfate tablets (MST) and IM morphine in pa tients undergoing total hip arthroplasty under lumbar spinal anesthesia. Pa tients in Group I received MST 20 mg 12 hourly and a placebo IM injection 6 hourly regularly. Group II patients received an oral placebo 12 hourly and morphine sulfate 10 mg IM 6 hourly regularly. Rescue analgesia was provide d with regular diclofenac suppositories and patient-controlled analgesia. P ain scores assessed by using visual analog scale and verbal pain scoring at rest and with movement were low in both groups, with no statistical differ ence between groups. Mean patient-controlled analgesia morphine consumption during the 48-h study was 16.7 mg in the IM group and 25.9 mg in the MST g roup. The difference between the groups was significant at 36 h postoperati vely (0.03). Side effects of sedation and respiratory depression were not p roblematic in either group, with a maximal sedation score of 2 occurring on ce in a patient in Group II. Nausea and vomiting occurred more often in Gro up II, but this was not statistically significant, with a mean nausea/vomit ing score for Group II of 1.7. We conclude that oral, sustained-release mor phine is an attractive alternative to LM opiates in patients undergoing bod y surface surgery under regional anesthesia. Implications: Each postoperati ve analgesic has its own limitations for route of administration, dosage, a nd potential side effects. Using the oral route for drug administration see ms more attractive than other methods but may not be suitable in all postop erative patients. We studied the efficacy and side effect profile of sustai ned-release, oral morphine compared with standard IM morphine for the treat ment of pain after hip replacement surgery. We concluded that use of the or al preparation is a suitable alternative to the IM route in this population undergoing surgery under spinal anesthesia.