Normal-release and controlled-release oxycodone: pharmacokinetics, pharmacodynamics, and controversy.

Oxycodone has become one of the most popular opioids in the United States. It is superior to morphine in oral absorption and bioavailability, and similar in terms of protein binding and lipophilicity. Gender more than age influences oxycodone elimination. Unlike morphine, oxycodone is metabolized by the cytochrome isoenzyme CYP2D6, which is severely impaired by liver dysfunction. Controlled-release (CR) oxycodone has become one of the most frequently utilized sustained-release opioids in the United States. Both its analgesic benefits and its side effects are similar to those of CR morphine. CR oxycodone is similar to morphine and other opioids in its abuse potential. Deaths attributable to oxycodone are usually associated with polysubstance abuse in which oxycodone is combined with psychostimulants, other opioids, benzodiazepines or alcohol. Oxycodone's kappa receptor binding has little role in abuse or addiction. The cost of CR oxycodone is prohibitive for most American hospices.