Comparative Pharmacology
Head-to-head clinical analysis: PROMETHAZINE W DEXTROMETHORPHAN versus X TROZINE L A.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETHAZINE W DEXTROMETHORPHAN versus X TROZINE L A.
PROMETHAZINE W/ DEXTROMETHORPHAN vs X-TROZINE L.A.
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 and antiemetic; dextromethorphan is a non-opioid antitussive that acts as an NMDA receptor antagonist and sigma-1 receptor agonist.
X-TROZINE L.A. is a piperazine derivative that acts as a centrally acting alpha-2 adrenergic agonist, reducing sympathetic outflow from the brainstem, leading to decreased peripheral vascular resistance and lowered blood pressure.
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.
250 mg orally once daily. May be increased to 500 mg once daily if needed.
None Documented
None Documented
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.
12-15 hours; prolonged in renal impairment (up to 30 hours in CrCl <30 mL/min).
Renal: promethazine ~6% unchanged, dextromethorphan ~0.5% unchanged; metabolites primarily renal. Biliary/fecal: minor routes for both.
Primarily renal (70-80% as unchanged drug), with 20-30% fecal via biliary excretion.
Category A/B
Category C
Antihistamine / Antiemetic
Antihistamine