Comparative Pharmacology
Head-to-head clinical analysis: DIPHENHYDRAMINE versus PROMETHAZINE HYDROCHLORIDE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DIPHENHYDRAMINE versus PROMETHAZINE HYDROCHLORIDE.
Diphenhydramine vs PROMETHAZINE HYDROCHLORIDE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Inverse agonist at histamine H1 receptors, blocking histamine-mediated effects in blood vessels, respiratory smooth muscle, and GI tract; also anticholinergic by blocking muscarinic receptors and sedative via central H1 receptor antagonism.
Promethazine is a phenothiazine derivative that acts as a histamine H1 receptor antagonist, blocking the effects of histamine at H1 receptors. It also has anticholinergic, antiemetic, sedative, and antidopaminergic properties.
25-50 mg orally or intramuscularly every 4-6 hours; maximum 300 mg/day. Intravenous administration: 10-50 mg slow IV push (max 25 mg/min).
25-50 mg intramuscular or intravenous injection every 4-6 hours as needed; also 12.5-25 mg orally every 4-6 hours.
None Documented
None Documented
Clinical Note
moderateDiphenhydramine + Deferasirox
"The serum concentration of Deferasirox can be increased when it is combined with Diphenhydramine."
Clinical Note
moderateDiphenhydramine + Fluticasone propionate
"The risk or severity of adverse effects can be increased when Diphenhydramine is combined with Fluticasone propionate."
Clinical Note
moderateDiphenhydramine + Tenofovir disoproxil
"The metabolism of Tenofovir disoproxil can be decreased when combined with Diphenhydramine."
Clinical Note
moderateTerminal elimination half-life 4-8 hours in adults; prolonged in hepatic impairment (up to 20 hours) and elderly.
Terminal elimination half-life is 10-19 hours in adults; prolonged in hepatic impairment (up to 30+ hours) and in elderly.
Primarily renal (90-95% as metabolites, <5% unchanged). Minor biliary/fecal elimination (<5%).
Primarily hepatic metabolism; renal excretion of metabolites accounts for <1% of unchanged drug; biliary/fecal excretion of metabolites ~70-80%.
Category C
Category A/B
Antihistamine
Antihistamine / Antiemetic
Diphenhydramine + Sulfisoxazole
"The metabolism of Sulfisoxazole can be decreased when combined with Diphenhydramine."