A systematic review of oxymorphone in the management of chronic pain.

Opioids are recommended for control of moderate-to-severe, chronic, malignant, and nonmalignant pain. A controlled-release formulation of the opioid oxymorphone has recently been launched. The aim of this review was to assess the effectiveness of oxymorphone as an analgesic in chronic pain. A systematic search for published studies of oral oxymorphone in the management of chronic pain was conducted. The studies were evaluated for their internal validity according to standard criteria. They were also evaluated for their external validity and research ethic aspects. A meta-analysis was performed to examine the effect of oxymorphone compared with placebo. Nine studies were evaluated; three were excluded because of low quality. Six controlled studies (duration 2-12 weeks) included a total of 1489 subjects suffering from chronic low back pain, chronic pain from osteoarthritis, and chronic cancer pain. Three of the studies were of high quality and three of medium quality. External validity was assessed to be high, medium, and low (in one, three, and two studies, respectively). The meta-analysis suggests that daily doses of 40-100mg are superior to placebo; however, the estimate (reduction of pain intensity compared with placebo) of the treatment effect is imprecise (95% confidence interval -17.08, -8.69). Limited evidence suggests that oxymorphone is effective for pain control in patients with cancer. No significant differences between oxymorphone and oxycodone at equipotent doses were found. In conclusion, oxymorphone is superior to placebo. There is no evidence that the efficacy of oxymorphone differs from other opioids.