Diphenhydramine

sleep · nervous · immune-hematologic · Oral · IV · Intramuscular

Diphenhydramine, a sleep compound. First-generation H1 antihistamine; crosses the blood-brain barrier and produces sedation via H1 blockade.… Oral half-life 8 h.

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.

Pharmacokinetics

• Oral — t½ 8 h · F 72% · ka 1.8 h⁻¹ · Vd 315 L
• IV — t½ 8 h · F 100% · Vd 315 L

Sources: PMID:3760245, PMID:12065734, PMID:2369804