Comparative Pharmacology
Head-to-head clinical analysis: PROMETHAZINE HYDROCHLORIDE CODEINE PHOSPHATE versus TAVIST 1.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETHAZINE HYDROCHLORIDE CODEINE PHOSPHATE versus TAVIST 1.
PROMETHAZINE HYDROCHLORIDE; CODEINE PHOSPHATE vs TAVIST-1
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, antiemetic, and sedative via blockade of central and peripheral H1 receptors and antagonism of dopamine D2 receptors. Codeine is an opioid agonist that binds to mu-opioid receptors in the CNS, producing analgesia and cough suppression; it also has antitussive effects via central action.
TAVIST-1 (clemastine fumarate) is a first-generation antihistamine that acts as a competitive antagonist at histamine H1 receptors, thereby preventing histamine-mediated effects such as vasodilation, increased capillary permeability, and bronchoconstriction. It also exhibits anticholinergic and sedative properties.
Promethazine hydrochloride 6.25-25 mg / codeine phosphate 10-20 mg (based on codeine component) orally every 4-6 hours as needed. Maximum codeine dose: 60 mg per dose, 120 mg per day.
1.34 mg orally twice daily; maximum 8.04 mg/day.
None Documented
None Documented
Promethazine: 10-19 hours (terminal); Codeine: 2.4-4 hours (terminal), prolonged in hepatic impairment. Clinical context: Dosing interval typically 4-6 hours for codeine; promethazine accumulates with repeated dosing.
Terminal half-life 12–15 hours; clinical dosing interval every 12 hours.
Promethazine: Renal (70-80% as metabolites, <1% unchanged); Codeine: Renal (70-90% as metabolites, 5-15% unchanged). Biliary/feces: Minor (<10% total).
Primarily renal: ~60% unchanged; biliary/fecal: ~30% as metabolites; minor via feces.
Category A/B
Category C
Antihistamine / Antiemetic
Antihistamine