| Indication |
For the treatment of diarrhoea, pulmonary oedema and for the relief of moderate to moderately severe pain. |
| Pharmacodynamics |
Oxycodone, a semisynthetic opiate agonist derived from the
opioid alkaloid, thebaine, is similar to other phenanthrene derivatives
such as hydrocodone and morphine. Oxycodone is available in combination
with aspirin or acetaminophen to control pain and restless leg and
Tourette syndromes. |
| Mechanism of action |
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. |
| Absorption |
Well absorbed with an oral bioavailability of 60% to 87% |
| Volume of distribution |
|
| Protein binding |
45% |
| Metabolism |
Hepatic |
| Route of elimination |
Oxycodone and its metabolites are excreted primarily via the kidney. |
| Half life |
4.5 hours |
| Clearance |
|
| 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. |
