Comparative Pharmacology
Head-to-head clinical analysis: EMEND versus PROMETHAZINE HYDROCHLORIDE AND DEXTROMETHORPHAN HYDROBROMIDE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: EMEND versus PROMETHAZINE HYDROCHLORIDE AND DEXTROMETHORPHAN HYDROBROMIDE.
EMEND vs PROMETHAZINE HYDROCHLORIDE AND DEXTROMETHORPHAN HYDROBROMIDE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Selective substance P/neurokinin 1 (NK1) receptor antagonist, which inhibits the binding of substance P in the emetic pathway.
Promethazine is a phenothiazine derivative that acts as a histamine H1 receptor antagonist, antiemetic, and sedative. Dextromethorphan is a cough suppressant that acts as an NMDA receptor antagonist and sigma-1 receptor agonist.
125 mg orally once 1 hour before chemotherapy; then 80 mg orally once daily on Days 2 and 3.
For cough and upper respiratory symptoms: 5 mL (containing promethazine hydrochloride 6.25 mg and dextromethorphan hydrobromide 15 mg) orally every 4 to 6 hours, not to exceed 30 mL in 24 hours.
None Documented
None Documented
9–13 hours (terminal) in healthy adults; clinically, this supports once-daily dosing. In patients with severe renal impairment (CrCl <30 mL/min), half-life is prolonged to ~16 hours.
Promethazine: 10-19 hours (mean 12 hours). Dextromethorphan: extensive metabolizers (CYP2D6) 3-5 hours; poor metabolizers 20-30 hours. Clinical context: accumulation with repeated dosing, especially in poor metabolizers.
Primarily metabolized; ~5% unchanged in urine, ~57% in feces as metabolites, ~32% in urine as metabolites. Renal elimination of parent drug is minimal.
Promethazine: primarily hepatic metabolism, renal excretion of metabolites (~70%, <1% unchanged); fecal excretion (20-30%). Dextromethorphan: hepatic metabolism, renal excretion of metabolites and <1% unchanged drug.
Category C
Category A/B
Antiemetic
Antihistamine / Antiemetic