Cetirizine, an antihistamine, is a histamine-1 (H1) receptor antagonist. Its effects are mediated via selective inhibition of H1 histamine receptors. The antihistaminic activity of cetirizine has been documented in a variety of animal and human models. In vivo and ex vivo animal models have shown negligible anticholinergic and antiserotonergic activity. In vitro receptor binding studies have shown no measurable affinity for other than H1 receptors.

In healthy subjects, bilateral topical ocular dosing of one drop of cetirizine ophthalmic solution 0.24% resulted in a mean cetirizine plasma Cmax of 1.7 ng/mL following a single dose and 3.1 ng/mL after twice-daily dosing for one week. The observed mean terminal half-life of cetirizine was 8.6 hours following a single dose and 8.2 hours after twice-daily dosing of Cetirizine for one week.

Cetirizine 0.24% ophthalmic solution is indicated for the treatment of ocular itching associated with allergic conjunctivitis.

Adults and children (age 2 years and above): The recommended dosage is to instill one drop in the affected eye(s) twice daily (approximately 8 hours apart).

The most common adverse reactions are ocular hyperemia, instillation site pain and visual acuity reduction.

Care should be taken not to touch the eyelids or surrounding areas with the dropper tip of the bottle to prevent contaminating the tip and solution. Keep the bottle closed when not in use. Patients should be advised not to wear a contact lens if their eye is red. Remove contact lenses prior to instillation of the drug. Lenses may be reinserted after 10 minutes following the drug administration.

Use in Special Populations

Pediatric use: The safety and effectiveness have been established in pediatric patients two years of age and older.

Geriatric use: No overall differences in safety or effectiveness have been observed between elderly and younger patients.

Pregnancy & Lactation

Pregnancy: There is no adequate or well-controlled study with Cetirizine 0.24% ophthalmic solution in pregnant women. It should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus.

Lactation: It is not known whether the systemic absorption resulting from topical ocular administration of Cetirizine could produce detectable quantities in human breast milk. There is no adequate information regarding the effects of Cetirizine on breastfed infants, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for this drug and any potential adverse effects on the breastfed child from Cetirizine.