Opioid antagonist

An opioid antagonist is an receptor antagonist that acts on opioid receptors.

Naloxone and naltrexone are opioid antagonist drugs which are competitive antagonists that bind to the opioid receptors with higher affinity than agonists but do not activate the receptors. This effectively blocks the receptor, preventing our systems from making use of opiates and endorphins.

In Fiction

 * In the episode of House (TV series) - Skin Deep (House episode), opioid antagonist drugs were administered in order to completely remove the patient's heroin induced addiction/withdrawal symptoms (during an induced coma in order to relieve the extreme pain of their use), so that an accurate diagnosis of paraneoplastic syndrome caused by cancer was differentiated.