A comparison of the clinical efficacy of pheniramine maleate/naphazoline hydrochloride ophthalmic solution and olopatadine hydrochloride ophthalmic solution in the conjunctival allergen challenge model

Abstract

The signs and symptoms of allergic conjunctivitis include ocular redness and itching. Two treatment options currently indicated for acute ocular allergic reaction are pheniramine maleate 0.3%/naphazoline hydrochloride 0.025% ophthalmic solution, an over-the-counter antihistamine/vasoconstrictor combination; and olopatadine hydrochloride 0.1% ophthalmic solution, a prescription antihistamine/mast cell stabilizer. This study was designed to compare, at onset of action, the relative effectiveness of pheniramine/naphazoline and olopatadine, when administered before conjunctival allergen challenge (CAC), using the ocular allergy index (OAI) as the primary end point. This was a prospective, randomized, double-masked, contralateral, active- and placebo-controlled, single-center study of the CAC model. The first 2 study visits established and confirmed the subjects' ocular allergic reaction (no medication administered). At visit 3, the subjects were randomly assigned to 1 of 3 contralateral (right eye vs left eye) treatment combinations: pheniramine/naphazoline + olopatadine, pheniramine/naphazoline + placebo, or olopatadine + placebo. Medication was given 10 minutes before CAC. The subjects' erythema in the ciliary, conjunctival, and episcleral vessel beds; eyelid swelling; chemosis; and itching were evaluated at 7, 12, and 20 minutes after CAC. The OAI was calculated as a composite score of 6 signs and symptoms of allergic conjunctivitis to assess global severity. Between-treatment differences in OAI scores were used to evaluate efficacy. Subjects were asked their eye drop preference at the conclusion of visit 3. Subjects (n = 83) ranged in age from 20 to 70 years (mean, 42.5 years), 61.4% (n = 51) were female, and 94.0% (n = 78) were white. Both pheniramine/naphazoline and olopatadine were associated with significantly lower OAI scores than placebo at all 3 time points (all, P < 0.001). OAI scores were significantly lower with pheniramine/naphazoline than with olopatadine at 12 and 20 minutes (P = 0.005 and P = 0.001, respectively). In this patient sample, studied in a CAC model of onset of action, prophylactic pheniramine/naphazoline was more effective than olopatadine and placebo in alleviating the signs and symptoms of the acute ocular allergic reaction, as measured by the OAI.