Description
Mechanism of Action
Diphenhydramine blocks histamine H1-receptors on effector cells of the GI tract, blood vessels and respiratory tract. It also causes sedation and has some anticholinergic action.
Absorption: Absorbed well from the GI tract (oral); peak plasma concentrations after 1-4 hr.
Distribution: Widely distributed, CNS; crosses the placenta and enters breast milk. Protein-binding:Highly bound.
Metabolism: Extensive first-pass metabolism.
Excretion: Via urine (as metabolites, small amounts as unchanged drug); 1-4 hr (elimination half-life).
MIMS Class
Antihistamines & Antiallergics
ATC Classification
D04AA32 – diphenhydramine; Belongs to the class of topical antihistamines used in the treatment of pruritus.;
R06AA02 – diphenhydramine; Belongs to the class of aminoalkyl ethers used as systemic antihistamines
