Comparative Pharmacology
Head-to-head clinical analysis: PROMETHAZINE W DEXTROMETHORPHAN versus TAVIST.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETHAZINE W DEXTROMETHORPHAN versus TAVIST.
PROMETHAZINE W/ DEXTROMETHORPHAN vs TAVIST
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
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.
Antihistamine; selective inverse agonist at histamine H1 receptors, blocking histamine-mediated allergic and inflammatory responses.
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.
1.34 mg orally twice daily; maximum 8.04 mg/day.
None Documented
None Documented
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.
Terminal elimination half-life is 12-15 hours in healthy adults; prolonged in renal/hepatic impairment.
Renal: promethazine ~6% unchanged, dextromethorphan ~0.5% unchanged; metabolites primarily renal. Biliary/fecal: minor routes for both.
Renal excretion of metabolites (approx. 60%) and unchanged drug (<5%); biliary/fecal elimination accounts for about 40%.
Category A/B
Category C
Antihistamine / Antiemetic
Antihistamine