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Oxycodone
- indication:For the treatment of diarrhoea, pulmonary oedema and for the relief of moderate to moderately severe pain.
- pharmacologypharmacology:
- mechanism: Oxycodone acts as a weak agonist at mu, kappa, and delta opioid receptors within the central nervous system (CNS). Oxycodone primarily affects mu-type opioid receptors, which are coupled with G-protein receptors and function as modulators, both positive and negative, of synaptic transmission via G-proteins that activate effector proteins. Binding of the opiate stimulates the exchange of GTP for GDP on the G-protein complex. As the effector system is adenylate cyclase and cAMP located at the inner surface of the plasma membrane, opioids decrease intracellular cAMP by inhibiting adenylate cyclase. Subsequently, the release of nociceptive neurotransmitters such as substance P, GABA, dopamine, acetylcholine, and noradrenaline is inhibited. Opioids such as oxycodone also inhibit the release of vasopressin, somatostatin, insulin, and glucagon. Opioids close N-type voltage-operated calcium channels (kappa-receptor agonist) and open calcium-dependent inwardly rectifying potassium channels (mu and delta receptor agonist). This results in hyperpolarization and reduced neuronal excitability.
- toxicity: Symptoms of overdose include respiratory depression, somnolence progressing to stupor or coma, skeletal muscle flaccidity, cold and clammy skin, constricted pupils, bradycardia, hypotension, and death.
- absorprion: Well absorbed with an oral bioavailability of 60% to 87%
- halflife: 4.5 hours
- roouteelimination: Oxycodone and its metabolites are excreted primarily via the kidney.
- volumedistribution: * 2.6 L/kg
- clearance: * 0.8 L/min [adults]