Comparative Pharmacology
Head-to-head clinical analysis: PROMETH PLAIN versus PROMETHAZINE HYDROCHLORIDE AND DEXTROMETHORPHAN HYDROBROMIDE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETH PLAIN versus PROMETHAZINE HYDROCHLORIDE AND DEXTROMETHORPHAN HYDROBROMIDE.
PROMETH PLAIN vs PROMETHAZINE HYDROCHLORIDE AND DEXTROMETHORPHAN HYDROBROMIDE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Antagonist at histamine H1 receptors; also exhibits anticholinergic, antiemetic, and sedative effects.
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.
12.5-25 mg intramuscularly or intravenously every 4-6 hours as needed; maximum 100 mg/day.
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
Terminal elimination half-life is 10-14 hours in adults; may be prolonged in elderly or hepatic impairment.
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 renal (approximately 70%) as metabolites and unchanged drug; biliary/fecal excretion accounts for ~20%.
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
Antihistamine
Antihistamine / Antiemetic