Diphenhydramine

Benadryl, ZzzQuil, Sominex

Antihistamine • First-generation H1 antihistamine

CNS Depressant

Half-life

2.4-9.3 hours

Protein Binding

80-85%

Metabolized By

CYP2D6

External

Non-selective H1 antagonist with significant anticholinergic and CNS effects

Drug Class

Antihistamine

Subclass

First-generation H1 antihistamine

BenadrylZzzQuilSominex

Half-life

2.4-9.3 hours

Time for plasma concentration to decrease by 50%

Protein Binding

80-85%

Fraction bound to plasma proteins

Therapeutic Index

Wide

Margin between therapeutic and toxic doses