Clinical Pharmacology of Oxymorphone

Oxymorphone (14-hydroxydihydromorphinone) is primarily a potent μ-opioid receptor agonist with oral immediate-release (IR) and extended-release (ER) formulations approved in the United States in 2006. The oral oxymorphone formulations are roughly three times more potent than oral morphine. It is more lipophilic than morphine and, thus, may more easily cross the blood-brain barrier because it differs from morphine having a ketone-group substituent at the C-6 position. Oxymorphone IR is indicated for the relief of moderate—to severe pain, while oxymorphone ER is indicated for persistent pain. Initial doses (opioid-naïve) are 10–20 mg every 4–6 hours (IR) and 5 mg every 12 hours (ER). Oxymorphone was found not to have any clinically significant cytochrome (CYP)3A4, CPY2C9, or CYP2D6 interactions, thus limiting its potential for causing some of the more common drug–drug interactions via the CYP450 system. The common adverse effects of oxymorphone are consistent with those commonly seen with other opioid, including nausea/vomiting, constipation, pruritis, pyrexia, somnolence, and sedation.