Oral controlled-release morphine sulfate. Analgesic efficacy and side effects of a 100-mg tablet in cancer pain patients.

Fifty-one cancer pain patients with limited opioid exposure participated in a randomized, double-blind, repeated-dose, parallel-group comparison of two dosage strengths of the controlled-release morphine preparation, MS Contin tablets (The Purdue Frederick Company, Norwalk, CT). The patients were first stabilized on immediate-release oral morphine 30 mg every 4 hours, with 15 mg available every 2 hours as needed for breakthrough pain ("rescue" dose). Each patient then received either one 100 mg MS Contin tablet or three 30-mg MS Contin tablets every 12 hours, with rescue medication as needed, for 3 days. Analysis of study power revealed sufficient sensitivity to detect clinically relevant differences in pain intensity and use of rescue medication. The two tablet strengths yielded similar pain relief, use of rescue medication, and frequency of side effects. In addition, pain and use of rescue medication did not change from the beginning to the end of the 12-hour dosing intervals in either group. In the study population as a whole, pain intensity was lower and total morphine intake higher during the period on controlled-release morphine. These data establish comparable analgesic efficacy and side effect potential of these two dosage strengths and confirm a 12-hour duration of effect for both. The improved analgesia on the controlled-release morphine may be attributable to increased consumption of drug resulting from improved compliance.