Comparative Pharmacology
Head-to-head clinical analysis: PROMETHAZINE DM versus TRANSDERM SCOP.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETHAZINE DM versus TRANSDERM SCOP.
PROMETHAZINE DM vs TRANSDERM SCOP
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.
Competitive antagonist at muscarinic acetylcholine receptors (M1, M2, M3 subtypes) in the vestibular system, gastrointestinal tract, and central nervous system, inhibiting vagal nerve activity and preventing motion-induced nausea and vomiting.
2 teaspoonfuls (10 mL) orally every 4-6 hours, not to exceed 8 teaspoonfuls (40 mL) per 24 hours.
One transdermal patch (1 mg/72 hours) applied to the hairless area behind the ear at least 4 hours before anticipated exposure; replace every 72 hours as needed.
None Documented
None Documented
16-19 hours (terminal); note: effect may last longer due to active metabolites and tissue binding
The terminal elimination half-life of scopolamine is approximately 9.5 hours (range 6-12 hours) following transdermal administration. In elderly patients, half-life may be prolonged to up to 20 hours.
Renal (70-80% as metabolites, <1% unchanged); biliary/fecal (20-30%)
Scopolamine is extensively metabolized; about 50% of a dose is excreted renally as metabolites and unchanged drug, with less than 10% excreted unchanged in urine. Biliary/fecal excretion accounts for approximately 30-40% of the dose.
Category A/B
Category C
Antihistamine / Antiemetic
Antiemetic