The relative potency between high dose oral oxycodone and intravenous morphine: a case illustration

Oxycodone is an effective opioid analgesic for cancer pain. In the United States, it is available exclusively as an oral formulation, predominantly in fixed dose combination with acetaminophen or aspirin. The latter limits its use in cancer pain due to the potential toxicity of the nonopioid component. Oxycodone is now available as a single agent, controlled release formulation. The following case report of an opioid tolerant cancer patient taking repeated high doses of oral oxycodone supports the use of a 1:1 milligram conversion ratio for oral morphine and oral oxycodone. This patient's clinical course indicates that oral oxycodone can be used safely and to good effect at high dose, that the milligram relative potency ratio for oral oxycodone to parenteral morphine during repeated dosing is 3:1, and suggests that availability of multiple formulations of oxycodone may benefit cancer patients.