Oxycodone is a semisynthetic opioid used for the management of acute and chronic pain severe enough to require an opioid analgesic and for which alternative treatments are inadequate. Oxycodone is a highly selective full agonist of the μ-opioid receptor (MOR), with low affinity for the δ-opioid receptor (DOR) and κ-opioid receptor (KOR). After oxycodone binds to the MOR, a G protein-complex is released, which inhibits the release of neurotransmitters by the cell by reducing the amount of cAMP produced, closing calcium channels, and opening potassium channels. After a dose of conventional (instant-release) oral oxycodone, the onset of action is 10–30 minutes, and peak plasma levels of the drug are attained within roughly 30–60 minutes in contrast, after a dose of OxyContin (an oral controlled-release formulation), peak plasma levels of oxycodone occur in about three hours. The duration of instant-release oxycodone is 3 to 6 hours, although this can be variable depending on the individual. Oxycodone in the blood is distributed to skeletal muscle, liver, intestinal tract, lungs, spleen, and brain. Serious side effects of oxycodone include reduced sensitivity to pain (beyond the pain the drug is taken to reduce), euphoria, anxiolysis, feelings of relaxation, and respiratory depression. Common side effects of oxycodone include constipation (23%), nausea (23%), vomiting (12%), somnolence (23%), dizziness (13%), itching (13%), dry mouth (6%), and sweating (5%).