(Phenergan®) is an antihistamine. It relieves moderate to severe allergic reactions, reduces or prevents nausea and vomiting from illness or ... Promethazine, a phenothiazine derivative, is a drug with ... promethazine, the quantitative analysis for this drug is most ... Promethazine HCI (marketed as Phenergan) Information. studying a series of quarternary derivatives of promethazine, ... promethazine is low in comparison to that of promethazine. The droperidol, propofol and alizapride groups "had significantly lower incidences of pruritus compared with the control and promethazine groups, ... Alert - Promethazine and Fatal Respiratory