Pharmacology Notes

Oxycodone is one to two times as potent as morphine orally, because of its higher bioavailability (up to 90%). It is metabolised by CYP2D6 to oxymorphone, but the latter’s role in providing analgesia after a dose of oxycodone is thought to be limited. Efficacy of oxycodone is similar to that of morphine. An oral modified-release formulation is available that provides early onset of analgesia at one hour, and lasts 12 hours.

Oxycodone is also well, but slowly, absorbed through the rectal mucosa. Suppositories can provide analgesia for seven or more hours, with a lag time of approximately one hour after a single dose before becoming effective.