Comparative Pharmacology
Head-to-head clinical analysis: PROMETHAZINE WITH CODEINE versus VONTROL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETHAZINE WITH CODEINE versus VONTROL.
PROMETHAZINE WITH CODEINE vs VONTROL
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Promethazine is a phenothiazine derivative that antagonizes histamine at H1 receptors, acting as a sedative and antiemetic. Codeine is an opioid agonist at mu-opioid receptors, producing analgesia and antitussive effects via central nervous system depression.
VONTROL (trimethobenzamide) acts centrally to inhibit the chemoreceptor trigger zone (CTZ) in the medulla oblongata, thereby suppressing nausea and vomiting. Its exact mechanism is not fully understood but may involve antagonism of dopamine D2 receptors and serotonin 5-HT3 receptors.
10-20 mg promethazine and 10-20 mg codeine (based on phosphate) orally every 4-6 hours as needed for cough; maximum daily codeine dose 120 mg.
10 mg orally twice daily; maximum 20 mg/day.
None Documented
None Documented
Promethazine: 9-16 hours (mean 12 hours), clinically significant for sedation duration. Codeine: 2.5-4 hours (mean 3 hours), with active metabolite morphine 2-3 hours.
12 hours; prolonged in renal impairment (up to 24 hours in ESRD)
Promethazine: renal 70% as metabolites and unchanged drug, biliary/fecal 20-30%. Codeine: renal 90% (5-15% unchanged, rest as morphine and conjugates), fecal <10%.
Renal: 60% unchanged; fecal: 30% (biliary); hepatic metabolism: 10%
Category A/B
Category C
Antihistamine / Antiemetic
Antiemetic