Comparative Pharmacology
Head-to-head clinical analysis: PROMETHAZINE versus TRANSDERM SCOP.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PROMETHAZINE versus TRANSDERM SCOP.
PROMETHAZINE 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 potent histamine H1 receptor antagonist, thereby blocking the effects of histamine. It also has central anticholinergic, antiemetic, and sedative properties, likely mediated through antagonism at muscarinic, dopamine D2, and serotonin receptors in the brain.
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.
12.5-25 mg IM or IV every 4-6 hours; also 25 mg PO or PR every 6-8 hours. Maximum 100 mg/day.
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
Clinical Note
moderatePromethazine + Risedronic acid
"Promethazine can cause an increase in the absorption of Risedronic acid resulting in an increased serum concentration and potentially a worsening of adverse effects."
Clinical Note
moderatePromethazine + Methylphenidate
"Promethazine can cause an increase in the absorption of Methylphenidate resulting in an increased serum concentration and potentially a worsening of adverse effects."
Clinical Note
moderatePromethazine + Artesunate
"The serum concentration of Artesunate can be increased when it is combined with Promethazine."
Clinical Note
moderateTerminal elimination half-life 9-16 hours; may be prolonged in hepatic impairment.
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 minor.
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
Promethazine + Clotrimazole
"The metabolism of Clotrimazole can be decreased when combined with Promethazine."