Comparative Pharmacology
Head-to-head clinical analysis: PHERAZINE DM versus VICKS FORMULA 44.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PHERAZINE DM versus VICKS FORMULA 44.
PHERAZINE DM vs VICKS FORMULA 44
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
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.
VICKS FORMULA 44 contains dextromethorphan (NMDA receptor antagonist and sigma-1 receptor agonist; suppresses cough by acting on the medullary cough center) and doxylamine (first-generation antihistamine; H1-receptor antagonist; anticholinergic and sedative effects).
Adults: 1 tablet (promethazine 25 mg / dextromethorphan 30 mg) orally every 6-8 hours as needed; maximum 4 tablets per day.
VICKS FORMULA 44 is a combination product containing dextromethorphan (cough suppressant) and doxylamine (antihistamine). The typical adult dose is 30 mg dextromethorphan/6.25 mg doxylamine (15 mL) orally every 6 hours as needed for cough and cold symptoms, not to exceed 4 doses per 24 hours.
None Documented
None Documented
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.
Dextromethorphan: 3-6 hours (extensive metabolizers), up to 24 hours (poor metabolizers); doxylamine: 10-12 hours. Clinically, half-life may be prolonged in elderly, hepatic impairment, or CYP2D6 poor metabolizers.
Primarily renal: 60-70% as unchanged drug and glucuronide conjugate; 15-20% fecal via biliary excretion.
Renal excretion of unchanged drug and metabolites (dextromethorphan and doxylamine): dextromethorphan is extensively metabolized; <10% excreted unchanged. Doxylamine: ~60% excreted renally as unchanged and metabolites.
Category C
Category C
Antitussive/Antihistamine Combination
Antitussive