Oxymorphone & Concomitant Use with Cytochrome P450 (CYP) Enzyme Inhibitors

Drug-drug interactions are an important clinical concern. In a March 2017 Advisory Committee, briefing documents raised the possibility that oxymorphone may be used for a particular niche - patients taking multiple medications - because its metabolism did not involve the hepatic cytochrome P450 system. FDA conducted an analysis to assess whether oxymorphone’s metabolism influenced prescriber practices. Results revealed that similar proportions of patients were dispensed oxymorphone combined with other CYP modifiers relative to reference products, suggesting that drug metabolism differences did not influence prescribing behavior. These results contributed to regulatory discussions about the use of oxymorphone drugs, including reformulated Opana ER (oxymorphone hydrochloride) that was withdrawn from the market for public health safety reasons.