Failure of ketamine to interact with opiate receptors

Ketamine, an anesthetic agent endowed with several morphine-like effects, failed to displace 3H-dihydromorphine or 3H-methionine-enkephalin from opiate receptors in the rat brain synaptosomal-mitochondrial membrane preparations. Furthermore, ketamine-induced analgesia in rats was not antagonized by naloxone, suggesting that this effect is not mediated by opiate receptors.