Chemical Structure:
C19H21NO3 · HCl
Mechanism of Action:
Mixed Opioid Agonist-Antagonist: Nalorphine is a mixed agonist-antagonist at opioid receptors. It acts as an antagonist primarily at the mu-opioid receptor and as a partial agonist at kappa-opioid receptors.
Counteracting Opioid Effects: By antagonizing mu-opioid receptors, it can counteract the effects of opioids, particularly respiratory depression and CNS depression caused by opioid overdose.
Uses:
Opioid Overdose: Used to reverse opioid-induced respiratory depression.
Diagnostic Tool: Sometimes used in diagnosing opioid addiction and physical dependence.
Side Effects:
Opioid Withdrawal Symptoms: In patients dependent on opioids, nalorphine can precipitate withdrawal symptoms.
Psychotomimetic Effects: Hallucinations and other dysphoric effects, likely due to kappa-opioid receptor agonism.
Respiratory and Cardiovascular Effects: Rarely, may cause respiratory depression or hypertension in sensitive individuals.