Comparative Pharmacology
Head-to-head clinical analysis: BENADRYL versus PROMETHAZINE DM.
Peer-Reviewed Evidence
Head-to-head clinical analysis: BENADRYL versus PROMETHAZINE DM.
BENADRYL vs PROMETHAZINE DM
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Antihistamine; inverse agonist at histamine H1 receptors, blocking histamine-induced vasodilation, increased capillary permeability, and bronchoconstriction; also anticholinergic and sedative.
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.
25-50 mg orally every 4-6 hours as needed; maximum 300 mg per day. Alternatively, 10-50 mg intramuscularly or intravenously once, maximum 100 mg per dose (IV route preferred).
2 teaspoonfuls (10 mL) orally every 4-6 hours, not to exceed 8 teaspoonfuls (40 mL) per 24 hours.
None Documented
None Documented
Terminal elimination half-life 4-8 hours; prolonged in hepatic impairment (up to 20 hours).
16-19 hours (terminal); note: effect may last longer due to active metabolites and tissue binding
Renal (90% as metabolites, <5% unchanged); minimal biliary/fecal.
Renal (70-80% as metabolites, <1% unchanged); biliary/fecal (20-30%)
Category C
Category A/B
Antihistamine
Antihistamine / Antiemetic