Comparative Pharmacology
Head-to-head clinical analysis: PROMETHAZINE VC W CODEINE versus TIGAN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETHAZINE VC W CODEINE versus TIGAN.
PROMETHAZINE VC W/ CODEINE vs TIGAN
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Codeine is a prodrug converted to morphine, which acts as a mu-opioid receptor agonist inhibiting ascending pain pathways and altering pain perception. Promethazine is a phenothiazine derivative that antagonizes histamine H1 receptors, suppresses cough reflex via central action, and has anticholinergic, sedative, and antiemetic effects. Phenylephrine is a selective alpha-1 adrenergic receptor agonist causing vasoconstriction of nasal blood vessels, reducing congestion.
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.
1-2 tablets orally every 4-6 hours as needed for cough and congestion. Maximum 12 tablets in 24 hours.
Adults: 200 mg IM or 100 mg PO or 200 mg PR every 6–8 hours as needed.
None Documented
None Documented
Promethazine: 9-16 hours (range 7-20 hours) in adults; codeine: 2.5-3.5 hours (terminal) with clinical considerations for prolonged effects in hepatic impairment and CYP2D6 poor metabolizers.
12-15 hours; may be prolonged in hepatic impairment.
Renal: 70-80% as unchanged promethazine and metabolites (including codeine and its glucuronides); biliary/fecal: 10-20%.
Renal (30-50% as unchanged drug and metabolites), biliary/fecal (minor).
Category A/B
Category C
Antihistamine / Antiemetic
Antiemetic