Characterization of the early pharmacodynamic profile of oral methadone for cancer-related breakthrough pain: a pilot study.

Methadone is effective for chronic cancer pain, but its early pharmacodynamic profile and effectiveness for breakthrough pain remain uncertain. This was an open-label, non-randomized, crossover study comparing the use of oral methadone for breakthrough pain with patients' usual opioid. Study variables included pain intensity (pretreatment and at 10-minute intervals post treatment), treatment-related side effects, and treatment satisfaction. In 37 discrete episodes of breakthrough pain, onset of analgesic effect of a titrated dose of oral methadone was rapid for all patients; 3 of 6 study patients experienced an onset of relief by 10 minutes post-ingestion. The adverse effect profile of oral methadone was not different from patients' usual 'rescue' opioid, and patients were moderately to completely satisfied with oral methadone as a breakthrough pain medication. These observations suggest that oral methadone can have a rapid onset of analgesic action and may have a legitimate role in the management of cancer-related breakthrough pain.