Comparative Pharmacology
Head-to-head clinical analysis: PROMETHAZINE HYDROCHLORIDE AND DEXTROMETHORPHAN HYDROBROMIDE versus TIGAN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETHAZINE HYDROCHLORIDE AND DEXTROMETHORPHAN HYDROBROMIDE versus TIGAN.
PROMETHAZINE HYDROCHLORIDE AND DEXTROMETHORPHAN HYDROBROMIDE vs TIGAN
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.
TIGAN (trimethobenzamide) acts on the chemoreceptor trigger zone (CTZ) to inhibit emetic stimuli, primarily through antagonism of dopamine D2 receptors, though its exact mechanism is not fully elucidated.
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.
Adults: 200 mg IM or 100 mg PO or 200 mg PR every 6–8 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.
12-15 hours; may be prolonged in hepatic impairment.
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.
Renal (30-50% as unchanged drug and metabolites), biliary/fecal (minor).
Category A/B
Category C
Antihistamine / Antiemetic
Antiemetic