While higher CYP2D6 activity increases the effects of oxycodone (owing to increased conversion into oxymorphone), higher CYP3A4 activity has the opposite effect and decreases the effects of oxycodone (owing to increased metabolism into noroxycodone and noroxymorphone). The dose of oxycodone must be reduced in patients with reduced liver function. Elimination
The clearance of oxycodone is 0.8 L/min. Oxycodone and its metabolites are mainly excreted in urine. Therefore, oxycodone accumulates in patients with kidney impairment. Oxycodone is eliminated in the urine 10% as unchanged oxycodone, 45% ± 21% as N-demethylated metabolites (noroxycodone, noroxymorphone, noroxycodols), 11 ± 6% as O-demethylated metabolites (oxymorphone, oxymorphols), and 8% ± 6% as 6-keto-reduced metabolites (oxycodols). Duration of action
Oxycodone has a half-life of 4.5 hours. It is available as a generic medication. The manufacturer of OxyContin, a controlled-release preparation of oxycodone, Purdue Pharma, claimed in their 1992 patent application that the duration of action of OxyContin is 12 hours in "90% of patients". It has never performed any clinical studies in which OxyContin was given at more frequent intervals. In a separate filing, Purdue claims that controlled-release oxycodone "provides pain relief in said patient for at least 12 hours after administration". However, in 2016 an investigation by the Los Angeles Times found that "the drug weans off hours early in many people", inducing symptoms of opiate withdrawal and intense cravings for OxyContin. One doctor, Lawrence Robbins, told journalists that over 70% of his patients would report that OxyContin would only provide 4–7 hours of relief.
Los Angeles Times journalists argue using interviews from opioid addiction experts that such high doses of OxyContin spaced 12 hours apart create a combination of agony during opiate withdrawal (lower lows) and a schedule of reinforcement that relieves this agony, fostering addiction. Chemistry
Oxycodones chemical name is derived from codeine. The chemical structures are very similar, differing only in that

Oxycodone has a hydroxy group at carbon-14 (codeine has just a hydrogen in its place)
Oxycodone has a 7,8-dihydro feature. Codeine has a double bond between those two carbons; and
Oxycodone has a carbonyl group (as in ketones) in place of the hydroxyl group of codeine.It is also similar to hydrocodone, differing only in that it has a hydroxyl group at carbon-14. Biosynthesis
In terms of biosynthesis, oxycodone has been found naturally in nectar extracts from the orchid family Epipactis helleborine; together along with another opioid: 3-{2-{3-{3-benzyloxypropyl}-3-indol, 7,8-didehydro- 4,5-epoxy-3,6-d-morphinan.Thodey et al., 2014 introduces a microbial compound manufacturing system for compounds including oxycodone. The Thodey platform produces both natural and semisynthetic opioids including this one. This system uses Saccharomyces cerevisiae with transgenes from Papaver somniferum (the opium poppy) and Pseudomonas putida to turn a thebaine input into other opiates and opioids. Detection in biological fluids
Oxycodone and/or its major metabolites may be measured in blood or urine to monitor for clearance, non-medical use, confirm a diagnosis of poisoning, or assist in a medicolegal death investigation. Many commercial opiate screening tests cross-react appreciably with oxycodone and its metabolites, but chromatographic techniques can easily distinguish oxycodone from other opiates.