Phenergan
Clinical Notes
Phenergan is a medication used in clinical practice.
| Indication | Nausea/vomiting, allergic conditions, motion sickness, sedation, adjunct to anesthesia |
| Mechanism of Action | Phenothiazine antihistamine; blocks H1 receptors, muscarinic receptors, and dopamine receptors |
| Pharmacokinetics | Oral bioavailability 25%; hepatic metabolism; half-life 10-19 hours |
| Dosing | Nausea: 12.5-25 mg every 4-6 hours; Allergy: 25 mg at bedtime or 6.25-12.5 mg TID; IV: dilute, slow push |
| Contraindications | Children <2 years, comatose states, respiratory depression, lower respiratory tract symptoms |
| Adverse Effects | Sedation, dry mouth, blurred vision, constipation, extrapyramidal symptoms, severe tissue injury with extravasation/arterial injection |
| Drug Interactions | CNS depressants, anticholinergics, MAO inhibitors |
| Monitoring | Sedation level, respiratory status, injection site (IV), blood pressure |
| Other Considerations | Brand name for promethazine; black box warning: severe tissue necrosis with extravasation/arterial injection, respiratory depression in children <2; prefer alternative antiemetics |
| Reference | Lexicomp, UpToDate 2024 |
Quick-reference tip: Phenergan – Nausea/vomiting, allergic conditions, motion sickness, sedation, adjunct to anes.
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