Comparative Pharmacology
Head-to-head clinical analysis: PROMETHAZINE HYDROCHLORIDE AND CODEINE PHOSPHATE versus TIGAN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETHAZINE HYDROCHLORIDE AND CODEINE PHOSPHATE versus TIGAN.
PROMETHAZINE HYDROCHLORIDE AND CODEINE PHOSPHATE vs TIGAN
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
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.
TIGAN (trimethobenzamide) acts on the chemoreceptor trigger zone (CTZ) to inhibit emetic stimuli, primarily through antagonism of dopamine D2 receptors, though its exact mechanism is not fully elucidated.
Adults: 5 mL (containing promethazine 6.25 mg and codeine 10 mg) orally every 4-6 hours as needed; maximum 30 mL per day.
Adults: 200 mg IM or 100 mg PO or 200 mg PR every 6–8 hours as needed.
None Documented
None Documented
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.
12-15 hours; may be prolonged in hepatic impairment.
Renal: Codeine and metabolites ~90% (free and conjugated), Promethazine and metabolites primarily renal; minor biliary/fecal (<5% for codeine, ~6% for promethazine).
Renal (30-50% as unchanged drug and metabolites), biliary/fecal (minor).
Category A/B
Category C
Antihistamine / Antiemetic
Antiemetic