"By Matt McMillen
WebMD Health News
Reviewed by Brunilda Nazario, MD
April 9, 2015 -- Spring is finally here, and with it comes tree pollen. For people with allergies, that could spell misery. But despite the hars"...
(Generic versions may still be available.)
Promethazine is a phenothiazine derivative which differs structurally from the antipsychotic phenothiazines by the presence of a branched side chain and no ring substitution. It is thought that this configuration is responsible for its relative lack (1/10 that of chlorpromazine) of dopamine antagonist properties.
Promethazine is an H1 receptor blocking agent. In addition to its antihistaminic action, it provides clinically useful sedative and antiemetic effects.
Promethazine is well absorbed from the gastrointestinal tract. Clinical effects are apparent within 20 minutes after oral administration and generally last four to six hours, although they may persist as long as 12 hours. Promethazine is metabolized by the liver to a variety of compounds; the sulfoxides of promethazine and N-demethylpromethazine are the predominant metabolites appearing in the urine.
Last reviewed on RxList: 6/21/2007
This monograph has been modified to include the generic and brand name in many instances.
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