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OXYCODONE UNDER THE MAGNIFYING GLASS
H.G. Kress
Department of Anaesthesiology and Intensive Care (B) / Medical University - AKH
Wien, Vienna, Austria
Oxycodone is a semisynthetic derivative from thebaine and is in clinical use for over 80
years. It is a WHO-step III opioid with 1.5 to 2-fold higher oral analgesic potency and
higher oral bioavailability compared to morphine. Controlled (CR) and immediate-
release (IR) tablets are available and were shown to be effective in postoperative pain,
low back pain, osteoarthritis, post-herpetic neuralgia, diabetic neuropathy and cancer
pain. At equianalgetic doses, oxycodone is pharmacodynamically comparable to
morphine – with the exception of its κ-binding activity. Oxycodone shows typical
opioid side effects, but hallucinations occur more rarely. Because of biphasic
absorption, oral CR oxycodone has a fast onset of pain relief. Oxycodone is extensively
metabolized in the liver, only 10 % of dose is excreted unchanged in urine. O-
demethylation (CYP2D6) and N-demethylation (CYP3A4, CYP3A5) produce active
metabolites (noroxycodone, oxymorphone, noroxymorphone) that differentially
contribute to analgesic activity. Poor and ultrarapid metabolizers are found in the
caucasian population. Children and patients with liver/renal failure need dose
adjustment and should be carefully monitored. The addictive potential is equivalent to
that of morphine, but because of liberal prescription policy, the abuse of oxycodone has
escalated in rural areas of eastern U.S. (”Hillbilly or poor man’s heroin”). In Europe,
illicit use is not that problem. CR oxycodone is a WHO-step III opioid with proven
potency in neuropathic pain, showing faster onset but a safety profile comparable to CR
morphine. When oxycodone is given, the same precaution should be taken as with
morphine or other strong opioid drugs.