Comparative Pharmacology
Head-to-head clinical analysis: DELSYM versus PHERAZINE DM.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DELSYM versus PHERAZINE DM.
DELSYM vs PHERAZINE DM
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Dextromethorphan is a non-competitive NMDA receptor antagonist and sigma-1 receptor agonist, which suppresses cough by elevating the threshold for coughing in the medullary cough center.
Phererazine DM is a combination of promethazine (a phenothiazine derivative with antihistaminic, sedative, antiemetic, and anticholinergic properties) and dextromethorphan (a non-opioid antitussive that acts on the sigma-1 receptor and NMDA receptor antagonist). Promethazine blocks H1 receptors and reduces histamine-mediated symptoms, while dextromethorphan suppresses cough by central action on the cough center.
60 mg orally every 12 hours (extended-release suspension).
Adults: 1 tablet (promethazine 25 mg / dextromethorphan 30 mg) orally every 6-8 hours as needed; maximum 4 tablets per day.
None Documented
None Documented
Terminal elimination half-life of dextromethorphan is approximately 11 hours (range 9-14 hours) in extensive metabolizers; in poor metabolizers (CYP2D6 deficiency), half-life can exceed 24 hours, leading to accumulation.
Terminal elimination half-life: 3-4 hours in children; 5-6 hours in adults; up to 8 hours in elderly. Clinical context: Dosing interval adjustment needed in renal impairment.
Renal excretion of unchanged drug and metabolites, primarily dextrorphan glucuronide; <5% excreted unchanged in urine. Biliary/fecal elimination is negligible.
Primarily renal: 60-70% as unchanged drug and glucuronide conjugate; 15-20% fecal via biliary excretion.
Category C
Category C
Antitussive
Antitussive/Antihistamine Combination