OXYMORPHONE

Properties

Safety Information

Use

Oxymorphone is the 14 beta-hydroxyl version of hydromorphone,analogous to the hydrocodone, oxycodone pair discussedabove. Although the addition of the 14 beta-hydroxylgroup to hydrocodone (30 mg) yielded oxycodone (20 mg),a more potent drug, the opposite is true for the conversion ofhydromorphone (7.5 mg) to oxymorphone (10 mg). The reasonfor this is that the oral bioavailability of oxymorphone(10%) is lower than that of hydromorphone (35%) becauseof decreased absorption and increased first-pass metabolism.Presumably, the addition of the OH group does increaseits binding affinity at the receptor as the injectableform of oxymorphone (1 mg) is more potent than injectablehydromorphone (1.5 mg).Oxymorphone is available as a suppository (5 mg), an injection(1 mg/mL), an immediate-release tablet (5 mg, 10mg), and in 2003 the FDA approved a sustained release formulation(Opana ER 5 mg, 10 mg, 20 mg, and 40 mg). The12-hour coverage of the extended release tablet provides anotheroption for those patients suffering from chronic pain.The side effect profile of the extended release formulationsof morphine, oxycodone, and oxymorphone are similar, andthere appears to be no clear advantage of one over the other.