Diphenhydramine

Category: sleep

Aliases: Benadryl, ZzzQuil

Pharmacological Mechanism

First-generation H1 antihistamine; crosses the blood-brain barrier and produces sedation via H1 blockade. Strong anticholinergic — Beers-list problematic in elderly. OTC for allergy + sleep.

Half-Life (t½)

PO: 8h, IV: 8h

Dosing Guidelines

• PO: Typical 50mg (Range: 25 - 50 mg)

Target Organ Systems

• nervous
• immune-hematologic