| Item |
Information |
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Drug Groups
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approved |
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Description
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A phenothiazine derivative with histamine H1-blocking, antimuscarinic, and sedative properties. It is used as an antiallergic, in pruritus, for motion sickness and sedation, and also in animals. [PubChem] |
| Indication |
For the treatment of allergic disorders, and nausea/vomiting. |
| Pharmacology |
Promethazine, a phenothiazine, is an H1-antagonist with anticholinergic, sedative, and antiemetic effects and some local anesthetic properties. Promethazine is used as an antiemetic or to prevent motion sickness. |
| Toxicity |
Symptoms of overdose include mild depression of the central nervous system and cardiovascular system to profound hypotension, respiratory depression, unconsciousness, and sudden death. Other reported reactions include hyperreflexia, hypertonia, ataxia, athetosis, and extensor-plantar reflexes (Babinski reflex). LD50=55mg/kg (I.V. in mice) |
| Affected Organisms |
| • |
Humans and other mammals |
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| Biotransformation |
Hepatic |
| Absorption |
On average, 88% of a promethazine dose is absorbed after oral administration; however, the absolute bioavailability is only 25% because of first-pass clearance. |
| Half Life |
16-19 hours |
| Protein Binding |
93% |
| Elimination |
Promethazine hydrochloride is metabolized in the liver, with the sulfoxides of promethazine and N-desmethylpromethazine being the predominant metabolites appearing in the urine. |
| References |
| • |
Peters RJ Jr, Kelder SH, Markham CM, Yacoubian GS Jr, Peters LA, Ellis A: Beliefs and social norms about codeine and promethazine hydrochloride cough syrup (CPHCS) onset and perceived addiction among urban Houstonian adolescents: an addiction trend in the city of lean. J Drug Educ. 2003;33(4):415-25.
[Pubmed]
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