Comparative Pharmacology
Head-to-head clinical analysis: PROMETHAZINE DM versus VONTROL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETHAZINE DM versus VONTROL.
PROMETHAZINE DM vs VONTROL
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 via blockade of dopamine D2 receptors in the chemoreceptor trigger zone, and sedative via central anticholinergic effects. Dextromethorphan is an NMDA receptor antagonist and sigma-1 receptor agonist, suppressing cough by central action on the cough center.
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.
2 teaspoonfuls (10 mL) orally every 4-6 hours, not to exceed 8 teaspoonfuls (40 mL) per 24 hours.
10 mg orally twice daily; maximum 20 mg/day.
None Documented
None Documented
16-19 hours (terminal); note: effect may last longer due to active metabolites and tissue binding
12 hours; prolonged in renal impairment (up to 24 hours in ESRD)
Renal (70-80% as metabolites, <1% unchanged); biliary/fecal (20-30%)
Renal: 60% unchanged; fecal: 30% (biliary); hepatic metabolism: 10%
Category A/B
Category C
Antihistamine / Antiemetic
Antiemetic