Comparative Pharmacology
Head-to-head clinical analysis: PROMETHAZINE W CODEINE versus VISTARIL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETHAZINE W CODEINE versus VISTARIL.
PROMETHAZINE W/ CODEINE vs VISTARIL
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Codeine is a prodrug converted to morphine, a mu-opioid receptor agonist, which inhibits nociceptive transmission; promethazine is a phenothiazine derivative with H1-receptor antagonism, anticholinergic, and antiemetic effects.
Hydroxyzine is a piperazine derivative antihistamine that acts as a competitive antagonist of histamine H1 receptors, thereby suppressing histamine activity in the subcortical area of the central nervous system. It also has anxiolytic, sedative, antiemetic, and antispasmodic effects.
10 mL (1 mg codeine, 6.25 mg promethazine per 5 mL) orally every 4-6 hours as needed for cough. Maximum: 60 mL per day. Do not exceed 5 days.
Oral: 50-100 mg 4 times daily; IM: 25-100 mg every 4-6 hours as needed.
None Documented
None Documented
Promethazine: 10-19 hours (terminal). Codeine: 2.5-3.5 hours (terminal); prolonged in renal impairment.
Terminal elimination half-life: 20-25 hours in adults; prolonged in hepatic impairment or elderly; steady-state achieved in ~4-5 days.
Promethazine: renal (70% as metabolites, <1% unchanged), fecal (20-30%). Codeine: renal (90%, of which 5-10% unchanged, rest as metabolites), fecal (minor).
Primarily hepatic metabolism; <1% excreted unchanged in urine; biliary/fecal elimination of metabolites accounts for approximately 50-60% of total clearance.
Category A/B
Category C
Antihistamine / Antiemetic
Antihistamine