Comparative Pharmacology
Head-to-head clinical analysis: CYPROHEPTADINE HYDROCHLORIDE versus PROMETHAZINE W DEXTROMETHORPHAN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CYPROHEPTADINE HYDROCHLORIDE versus PROMETHAZINE W DEXTROMETHORPHAN.
CYPROHEPTADINE HYDROCHLORIDE vs PROMETHAZINE W/ DEXTROMETHORPHAN
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Cyproheptadine is a potent antihistamine (H1 receptor antagonist) and antiserotonergic agent (5-HT2 receptor antagonist). It also exhibits weak anticholinergic and sedative properties. It blocks histamine-mediated vasodilation, increased capillary permeability, and pruritus, as well as serotonin-mediated effects on appetite and mood.
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.
4 mg orally three times daily; range 4-20 mg/day, not to exceed 0.5 mg/kg/day
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.
None Documented
None Documented
Terminal half-life approximately 8–16 hours in adults; may be prolonged in elderly or hepatic impairment.
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.
Primarily renal (appreciable unchanged drug and metabolites); biliary/fecal elimination minor (<5%).
Renal: promethazine ~6% unchanged, dextromethorphan ~0.5% unchanged; metabolites primarily renal. Biliary/fecal: minor routes for both.
Category A/B
Category A/B
Antihistamine
Antihistamine / Antiemetic