Comparative Pharmacology
Head-to-head clinical analysis: TUZISTRA XR versus VICKS FORMULA 44.
Peer-Reviewed Evidence
Head-to-head clinical analysis: TUZISTRA XR versus VICKS FORMULA 44.
TUZISTRA XR vs VICKS FORMULA 44
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Tuzistra XR is a combination of codeine (an opioid agonist) and promethazine (a phenothiazine derivative with antihistaminic, sedative, and anticholinergic effects). Codeine binds to mu-opioid receptors in the CNS, inhibiting cough reflex. Promethazine acts as a histamine H1 receptor antagonist and may have additional central anticholinergic and sedative effects.
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).
Initial: 25 mg orally twice daily; may increase to 50 mg twice daily after 1 week based on tolerability; maximum 50 mg twice daily.
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 is 7 hours for the parent drug; clinically, this supports twice-daily dosing for sustained symptom relief.
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 hepatic metabolism via glucuronidation; approximately 20% of the dose is excreted unchanged in urine, and 80% is eliminated as metabolites in feces 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/decongestant combination
Antitussive