Analgesic response to single and multiple doses of controlled-release morphine tablets and morphine oral solution in cancer patients.

Immediate-release oral morphine, given every four hours in individually titrated doses, is effective in the control of severe cancer pain. To evaluate the analgesic efficacy of a controlled-release morphine sulfate preparation, MS Contin tablets (MSC, Purdue Frederick, Toronto, Ontario, Canada), after a single dose and under steady-state conditions, the authors compared MSC administered every 12 hours with morphine oral solution (MOS) administered every 4 hours in 17 adult cancer patients with chronic severe pain. In the single-dose evaluation, in which the patients were randomly assigned to receive MSC or MOS, there were no significant differences in analgesic efficacy or requirement for supplemental morphine between the two treatments. With both preparations, pain severity ratings increased toward the end of the 12-hour, single-dose observation period and were higher than the pain scores reported after dose titration. In the steady-state evaluation, which was a randomized crossover comparison, both preparations provided effective pain control with minimal side effects. There was no significant difference between MSC and MOS in overall pain scores or in pain scores analyzed by time of day and day of therapy. In conclusion, that an individualized twice-daily regimen of MSC is as effective as 4-hourly MOS for the control of chronic severe cancer pain. The twice-daily regimen has several advantages: it allows an uninterrupted night's sleep, it is substantially more convenient, and it can be expected to reduce both medication errors and noncompliance.