Promethazine (PMZ)

Promethazine is a neuroleptic medication and first-generation antihistamine of the phenothiazine family. The drug has strong sedative and weak antipsychotic effects. It also reduces motion sickness and has antiemetic and anticholinergic properties. In some countries it is prescribed for insomnia when benzodiazepines are contraindicated. Promethazine, a phenothiazine derivative, is structurally different from the neuroleptic phenothiazines, with similar but different effects. It acts primarily as a strong antagonist of the H1 receptor (antihistamine) and a moderate mACh receptor antagonist (anticholinergic), and also has weak to moderate affinity for the 5-HT2A, 5-HT2C, D2, and α1-adrenergic receptors, where it acts as an antagonist at all sites, as well. Solid promethazine hydrochloride is a white to faint-yellow, practically odorless, crystalline powder. Slow oxidation may occur upon prolonged exposure to air, usually causing blue discoloration.