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Oxymorphone
- indication:For the treatment of moderate-to-severe pain.
- pharmacologypharmacology:
- mechanism: Oxymorphone interacts predominantly with the opioid mu-receptor. These mu-binding sites are discretely distributed in the human brain, with high densities in the posterior amygdala, hypothalamus, thalamus, nucleus caudatus, putamen, and certain cortical areas. They are also found on the terminal axons of primary afferents within laminae I and II (substantia gelatinosa) of the spinal cord and in the spinal nucleus of the trigeminal nerve. Also, it has been shown that oxymorphone binds to and inhibits GABA inhibitory interneurons via mu-receptors. These interneurons normally inhibit the descending pain inhibition pathway. So, without the inhibitory signals, pain modulation can proceed downstream.
- toxicity: Oxymorphone overdosage is characterized by respiratory depression, extreme somnolence progressing to stupor or coma, skeletal muscle flaccidity, cold and clammy skin, and sometimes bradycardia and hypotension. In a severe case of overdose, apnea, circulatory collapse, cardiac arrest, and death may occur. Intravenous mouse LD<sub>50</sub> is 172 mg/kg.
- absorprion:
- halflife: 1.3 (+/-0.7) hours
- roouteelimination: Oxymorphone is highly metabolized, principally in the liver, and undergoes reduction or conjugation with glucuronic acid to form both active and inactive products. Because oxymorphone is extensively metabolized, <1% of the administered dose is excreted unchanged in the urine.
- volumedistribution:
- clearance: