Comparative Pharmacology
Head-to-head clinical analysis: COMPAZINE versus PROMETHAZINE W DEXTROMETHORPHAN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: COMPAZINE versus PROMETHAZINE W DEXTROMETHORPHAN.
COMPAZINE vs PROMETHAZINE W/ DEXTROMETHORPHAN
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Dopamine D2 receptor antagonist in the chemoreceptor trigger zone; also blocks alpha-1 adrenergic, histamine H1, and muscarinic M1 receptors.
Promethazine is a phenothiazine derivative that acts as a histamine H1 receptor antagonist and antiemetic; dextromethorphan is a non-opioid antitussive that acts as an NMDA receptor antagonist and sigma-1 receptor agonist.
5-10 mg IM/IV every 3-4 hours as needed; or 25 mg PO/PR twice daily for severe nausea/vomiting.
5 mL (containing promethazine 6.25 mg and dextromethorphan 15 mg) orally every 4-6 hours as needed, not to exceed 30 mL (promethazine 37.5 mg, dextromethorphan 90 mg) per 24 hours.
None Documented
None Documented
Terminal elimination half-life is approximately 23 hours (range 15-30 hours) after oral or intramuscular administration. Clinical context: requires multiple daily dosing for steady state.
Promethazine: 9-16 h; dextromethorphan: 3-5 h (extensive metabolizers), 30-50 h (poor metabolizers). Clinical context: dosing interval typically 4-6 h for dextromethorphan; promethazine accumulates with repeated dosing.
Renal (approximately 70% as metabolites, <1% unchanged), biliary/fecal (approximately 30%).
Renal: promethazine ~6% unchanged, dextromethorphan ~0.5% unchanged; metabolites primarily renal. Biliary/fecal: minor routes for both.
Category C
Category A/B
Antipsychotic (Phenothiazine) / Antiemetic
Antihistamine / Antiemetic