Promethazine

Nervous system

Neuroleptic malignant syndrome has been associated with promethazine [ ].

• A 42-year-old man took promethazine 50 mg every 4–6 hours for 2 days and developed hyperthermia (42.4 °C). He died 3 days later despite intensive care and treatment with bromocriptine.

Promethazine intoxication from topical application has been observed in children [ ] and adults [ ]. Symptoms include disorientation, hallucinations, hyperactivity, convulsions, and coma.

Psychological

The effects of cetirizine, loratadine, and promethazine on cognitive function and psychomotor performance have been assessed in healthy volunteers [ ]. The test battery consisted of critical flicker fusion, choice reaction time, compensatory tracking task, and assessment of subjective sedation. All measures, with the exception of the compensatory tracking task, were significantly altered by promethazine. Cetirizine and loratadine at all doses tested were not significantly different from placebo in any of the tests.

Skin

A fixed drug eruption has been attributed to promethazine [ ].

• A 52-year-old woman with no history of allergy or skin disease took the recommended dose of an over-the-counter cold remedy that contained promethazine methylene disalicylate and developed an itchy macular erythematous rash on her right forearm, back, and buttocks within 24 hours. The authors performed an oral provocation test with the cold remedy. After 8 hours new lesions appeared at the previous locations. Further provocation tests were performed with each of the four components of the remedy; promethazine methylene disalicylate alone gave a positive reaction. Patch tests and oral provocation tests were then carried out to determine which component was responsible for the fixed drug eruption. In both tests, promethazine hydrochloride gave a positive result only at the previously involved sites. By contrast, the salicylic acid derivatives salicylamide and acetylsalicylic acid gave negative results, indicating that the causative agent was the promethazine hydrochloride rather than the methylene disalicylate. However, further challenges gave similar positive results for promethazine, pethidine, and omeprazole, which do not share common chemical structures or common metabolites.