Naloxone is a synthetic morphinane alkaloid that is morphinone in which the enone double bond has been reduced to a single bond, the hydrogen at position 14 has been replaced by a hydroxy group, and the methyl group attached to the nitrogen has been replaced by an allyl group. A specific opioid antagonist, it is used (commonly as its hydrochloride salt) to reverse the effects of opioids, both following their use of opioids during surgery and in cases of known or suspected opioid overdose. It has a role as a mu-opioid receptor antagonist, a central nervous system depressant and an antidote to opioid poisoning. It is an organic heteropentacyclic compound, a morphinane alkaloid and a tertiary alcohol. It is a conjugate base of a naloxone(1+). It derives from a hydride of a morphinan.