Comparative Pharmacology
Head-to-head clinical analysis: PROMETHAZINE HYDROCHLORIDE AND DEXTROMETHORPHAN HYDROBROMIDE versus VISTARIL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETHAZINE HYDROCHLORIDE AND DEXTROMETHORPHAN HYDROBROMIDE versus VISTARIL.
PROMETHAZINE HYDROCHLORIDE AND DEXTROMETHORPHAN HYDROBROMIDE vs VISTARIL
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, antiemetic, and sedative. Dextromethorphan is a cough suppressant that acts as an NMDA receptor antagonist and sigma-1 receptor agonist.
Hydroxyzine is a piperazine derivative antihistamine that acts as a competitive antagonist of histamine H1 receptors, thereby suppressing histamine activity in the subcortical area of the central nervous system. It also has anxiolytic, sedative, antiemetic, and antispasmodic effects.
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.
Oral: 50-100 mg 4 times daily; IM: 25-100 mg every 4-6 hours as needed.
None Documented
None Documented
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.
Terminal elimination half-life: 20-25 hours in adults; prolonged in hepatic impairment or elderly; steady-state achieved in ~4-5 days.
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.
Primarily hepatic metabolism; <1% excreted unchanged in urine; biliary/fecal elimination of metabolites accounts for approximately 50-60% of total clearance.
Category A/B
Category C
Antihistamine / Antiemetic
Antihistamine