Morphine tablets have been formulated to produce an easily ingested effervescent
solution when placed in water. It was hypothesized that an aqueous
solution would result in fast gastrointestinal transit with a more rapid onset of action compared to immediate release
morphine sulfate (IRMS), which would be especially beneficial in treating
breakthrough pain (BTP). In an open-label safety and efficacy study, effervescent
morphine was given to 76 chronic
cancer pain patients for treatment of BTP evaluating time until
pain relief, global satisfaction and side effects. Results were compared to those obtained using an IRMS formulation in a preceding run-in period. For BTP, a mean dose of 28 mg of effervescent
morphine (range 10-80 mg) resulted in a highly significant reduction of
pain score (mean 7.8 to mean 3.2; P < 0.001). Efficacy was not different from that observed with IRMS. However, mean time until sufficient
pain relief was significantly shorter than with IRMS (13 +/- 5.6 vs. 27 +/- 4.4 minutes; P < 0.01). The incidence of side effects was similar with the new
morphine formulation and with IRMS. There was no relationship between the previous dose of the daily
opioid and the effective dose of effervescent
morphine. The dose for treatment of BTP was determined by individual titration and not predicted by the dose taken with the basic
pain medication. Compared to IRMS, overall satisfaction for effervescent
morphine was rated "superior" by 16.7%, and "better" by 63.2% of patients. Effervescent
morphine offers an alternative for management of breakthrough
cancer pain compared with the commonly used IRMS.