Cetirizine

Cetirizine Non Drowsy Antihistamine

Marketed under several trade names, including Zyrtec and Allacan. A generic trade name is Equate Allergy Relief. It is also available in combination with pseudoephedrine, where the brand names often include a "-D" suffix, such as Zyrtec-D, Zyrtec-D 12 Hour, All Day Allergy-D, and Allergy Relief D.

Cetirizine is classified as a non-drowsy (second-generation) antihistamine, meaning it is less likely to cause sleepiness compared to first-generation antihistamines like diphenhydramine or chlorphenamine. It works by blocking histamine, a chemical released during allergic reactions that causes symptoms such as sneezing, runny nose, itchy eyes, and skin rashes. Cetirizine typically starts working within an hour and provides 24 hours of relief from allergy symptoms.

Cetirizine is not a petroleum-based medication. The active ingredient, cetirizine hydrochloride, is chemically synthesized and not derived from petroleum products. While some inactive ingredients in cetirizine formulations may include substances like polyethylene glycol or polydextrose, which can have petroleum-derived sources, the drug itself is not classified as a petroleum-based medication.

The molecular formula of cetirizine is C₂₁H₂₅ClN₂O₃. This formula represents the core structure of the compound, which is a racemic mixture of enantiomers. The dihydrochloride salt form, commonly used in pharmaceutical preparations, has the molecular formula C₂₁H₂₇Cl₃N₂O₃. This salt form results from the addition of two hydrochloride molecules to the parent cetirizine molecule.