Comparative Pharmacology
Head-to-head clinical analysis: BENADRYL PRESERVATIVE FREE versus DIPHENHYDRAMINE HYDROCHLORIDE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: BENADRYL PRESERVATIVE FREE versus DIPHENHYDRAMINE HYDROCHLORIDE.
BENADRYL PRESERVATIVE FREE vs DIPHENHYDRAMINE HYDROCHLORIDE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Diphenhydramine competitively antagonizes histamine at H1-receptors on effector cells, leading to relief of allergic symptoms. It also possesses anticholinergic, antiemetic, sedative, and local anesthetic effects.
Competitive antagonist of histamine H1 receptors, reducing allergic symptoms; also exerts anticholinergic, sedative, and antiemetic effects via central and peripheral receptor blockade.
25-50 mg IV/IM every 4-6 hours as needed; maximum single dose 100 mg, maximum daily dose 400 mg.
25-50 mg orally or intramuscularly every 4-6 hours as needed; maximum 300 mg per day.
None Documented
None Documented
Terminal elimination half-life: 4-8 hours (mean ~5 hours). Prolonged in hepatic impairment (up to 2-fold) and elderly (7-12 hours).
Terminal elimination half-life 4–10 hours (mean ~7 hours); prolonged in elderly, hepatic impairment, and with CYP2D6 poor metabolizers.
Primarily renal (90% as metabolites and unchanged drug); ~1% excreted in feces via bile. Unchanged diphenhydramine accounts for <5% of urinary recovery.
Renal elimination of metabolites accounts for ~60% of the dose; <5% excreted unchanged. Fecal excretion ~40% via bile.
Category C
Category A/B
Antihistamine
Antihistamine