Comparative Pharmacology
Head-to-head clinical analysis: BENADRYL PRESERVATIVE FREE versus EPINASTINE HYDROCHLORIDE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: BENADRYL PRESERVATIVE FREE versus EPINASTINE HYDROCHLORIDE.
BENADRYL PRESERVATIVE FREE vs EPINASTINE 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.
Selective histamine H1-receptor antagonist. Inhibits histamine release from mast cells and basophils, and reduces chemotaxis and activation of eosinophils. Also suppresses cytokine production from T lymphocytes.
25-50 mg IV/IM every 4-6 hours as needed; maximum single dose 100 mg, maximum daily dose 400 mg.
For allergic rhinitis and urticaria: 10 mg twice daily orally (20 mg/day). For ophthalmic use: 1 drop in affected eye(s) twice daily of 0.05% solution.
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).
The terminal elimination half-life is approximately 5.7 to 9.2 hours in healthy adults. In elderly patients, the half-life may be prolonged due to reduced renal function. The half-life supports twice-daily dosing for most indications.
Primarily renal (90% as metabolites and unchanged drug); ~1% excreted in feces via bile. Unchanged diphenhydramine accounts for <5% of urinary recovery.
Renal excretion accounts for approximately 39% of the administered dose, with about 28% as unchanged drug and 11% as metabolites. Fecal excretion is minimal at approximately 10%. Biliary excretion is not a significant route. Overall, renal clearance is the primary elimination pathway.
Category C
Category A/B
Antihistamine
Antihistamine