Cetirizine vs Diphenhydramine

## Cetirizine vs Diphenhydramine: Overview

This comparison examines the pharmacological differences between **Cetirizine** and **Diphenhydramine**.

## Mechanism of Action

**Cetirizine**: Second-generation H1 antihistamine.

**Diphenhydramine**: First-generation H1 antihistamine with anticholinergic properties.

## Pharmacokinetics

**Half-life**: Cetirizine — 6.5-10 hours; Diphenhydramine — 2-8 hours.

## Chemical Properties

**Molecular Formula**: Cetirizine — C21H25ClN2O3; Diphenhydramine — C17H21NO.

**Molecular Weight**: Cetirizine — 388.8900 g/mol; Diphenhydramine — 255.3550 g/mol.

**Type**: Cetirizine — Small molecule; Diphenhydramine — Small molecule.