Comparative Pharmacology
Head-to-head clinical analysis: PROMETH PLAIN versus PROMETHAZINE HYDROCHLORIDE AND CODEINE PHOSPHATE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETH PLAIN versus PROMETHAZINE HYDROCHLORIDE AND CODEINE PHOSPHATE.
PROMETH PLAIN vs PROMETHAZINE HYDROCHLORIDE AND CODEINE PHOSPHATE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Antagonist at histamine H1 receptors; also exhibits anticholinergic, antiemetic, and sedative effects.
Promethazine is a phenothiazine derivative that antagonizes histamine H1 receptors, reducing allergic symptoms; it also has anticholinergic, antiemetic, and sedative effects. Codeine is an opioid agonist at mu-opioid receptors, producing analgesia and antitussive effects by central mechanisms.
12.5-25 mg intramuscularly or intravenously every 4-6 hours as needed; maximum 100 mg/day.
Adults: 5 mL (containing promethazine 6.25 mg and codeine 10 mg) orally every 4-6 hours as needed; maximum 30 mL per day.
None Documented
None Documented
Terminal elimination half-life is 10-14 hours in adults; may be prolonged in elderly or hepatic impairment.
Promethazine: 10-19 hours (range 5-30h); Codeine: 2.5-4 hours (rapidly metabolized); Clinical context: sustained antitussive effect from codeine despite short half-life. Half-life of promethazine extends with hepatic impairment.
Primarily renal (approximately 70%) as metabolites and unchanged drug; biliary/fecal excretion accounts for ~20%.
Renal: Codeine and metabolites ~90% (free and conjugated), Promethazine and metabolites primarily renal; minor biliary/fecal (<5% for codeine, ~6% for promethazine).
Category C
Category A/B
Antihistamine
Antihistamine / Antiemetic