Comparative Pharmacology
Head-to-head clinical analysis: PROMETHAZINE HYDROCHLORIDE PHENYLEPHRINE HYDROCHLORIDE W CODEINE PHOSPHATE versus ZADITOR.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETHAZINE HYDROCHLORIDE PHENYLEPHRINE HYDROCHLORIDE W CODEINE PHOSPHATE versus ZADITOR.
PROMETHAZINE HYDROCHLORIDE,PHENYLEPHRINE HYDROCHLORIDE W/CODEINE PHOSPHATE vs ZADITOR
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, sedative, and antiemetic via central dopamine D2 and muscarinic M1 receptor blockade. Phenylephrine is a sympathomimetic amine that acts as a selective α1-adrenergic receptor agonist, causing vasoconstriction. Codeine is an opioid agonist at mu-opioid receptors, producing analgesia and antitussive effects, partly after O-demethylation to morphine.
Selective histamine H1 receptor antagonist. Stabilizes mast cells, reducing release of histamine and other mediators of allergic response.
Each 5 mL of oral solution contains promethazine hydrochloride 6.25 mg, phenylephrine hydrochloride 5 mg, and codeine phosphate 10 mg. Adult dose: 5 mL every 4 to 6 hours as needed. Maximum 30 mL per day.
1 drop in each affected eye twice daily, approximately 6-8 hours apart.
None Documented
None Documented
Promethazine: 9-16 h (adults); prolonged in hepatic impairment. Phenylephrine: 2-3 h (oral); 5-10 min (IV due to rapid redistribution). Codeine: 2.5-3.5 h; active metabolites (morphine) 2-3 h.
Terminal elimination half-life is approximately 7 hours in adults, which supports twice-daily dosing for sustained ocular effects.
Promethazine: ~70% renal as metabolites, minor biliary/fecal. Phenylephrine: ~86-96% renal as metabolites (sulfate and glucuronide conjugates). Codeine: ~90% renal, primarily as morphine and norcodeine conjugates; 5-10% unchanged. Fecal excretion minimal.
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