Comparative Pharmacology
Head-to-head clinical analysis: PROMETHAZINE W CODEINE versus ZADITOR.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETHAZINE W CODEINE versus ZADITOR.
PROMETHAZINE W/ CODEINE vs ZADITOR
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Codeine is a prodrug converted to morphine, a mu-opioid receptor agonist, which inhibits nociceptive transmission; promethazine is a phenothiazine derivative with H1-receptor antagonism, anticholinergic, and antiemetic effects.
Selective histamine H1 receptor antagonist. Stabilizes mast cells, reducing release of histamine and other mediators of allergic response.
10 mL (1 mg codeine, 6.25 mg promethazine per 5 mL) orally every 4-6 hours as needed for cough. Maximum: 60 mL per day. Do not exceed 5 days.
1 drop in each affected eye twice daily, approximately 6-8 hours apart.
None Documented
None Documented
Promethazine: 10-19 hours (terminal). Codeine: 2.5-3.5 hours (terminal); prolonged in renal impairment.
Terminal elimination half-life is approximately 7 hours in adults, which supports twice-daily dosing for sustained ocular effects.
Promethazine: renal (70% as metabolites, <1% unchanged), fecal (20-30%). Codeine: renal (90%, of which 5-10% unchanged, rest as metabolites), fecal (minor).
Primarily renal excretion as unchanged drug (approximately 30-40% of dose) and biliary/fecal elimination of metabolites (60-70%).
Category A/B
Category C
Antihistamine / Antiemetic
Antihistamine