Ocular itch relief with alcaftadine 0.25% versus olopatadine 0.2% in allergic conjunctivitis: pooled analysis of two multicenter randomized clinical trials

Abstract

Introduction: The efficacy and safety of the once-daily topical ophthalmic solutions, alcaftadine 0.25% and olopatadine 0.2%, in preventing ocular itching associated with allergic conjunctivitis were evaluated.

Methods: Pooled analysis was conducted of two double-masked, multicenter, active- and placebo-controlled studies using the conjunctival allergen challenge (CAC) model of allergic conjunctivitis. Subjects were randomized 1:1:1 to receive alcaftadine 0.25%, olopatadine 0.2%, or placebo. The primary efficacy measure was subject-evaluated mean ocular itching at 3 min post-CAC and 16 h after treatment instillation. Secondary measures included ocular itching at 5 and 7 min post-CAC. Ocular itch was determined over all time points measured (3, 5, and 7 min) post-CAC and the proportion of subjects with minimal itch (itch score<1) and zero itch (itch score=0) was also assessed.

Results: A total of 284 subjects were enrolled in the two studies. At 3 min post-CAC and 16 h after treatment instillation, alcaftadine 0.25% achieved a significantly lower mean itch score compared with olopatadine 0.2% (0.50 vs. 0.87, respectively; P=0.0006). Alcaftadine demonstrated a significantly lower mean itch score over all time points compared with olopatadine (0.68 vs. 0.92, respectively; P=0.0390); both alcaftadine- and olopatadine-treated subjects achieved significantly lower overall mean ocular itching scores compared with placebo (2.10; P<0.0001 for both actives). Minimal itch over all time points was reported by 76.1% of alcaftadine-treated subjects compared with 58.1% of olopatadine-treated subjects (P=0.0121). Treatment with alcaftadine 0.25% and olopatadine 0.2% was safe and well tolerated; no serious adverse events were reported.

Conclusion: Once-daily alcaftadine 0.25% ophthalmic solution demonstrated greater efficacy in prevention of ocular itching compared with olopatadine 0.2% at 3 min post-CAC (primary endpoint), and over all time points, 16 h post-treatment instillation. Alcaftadine and olopatadine both provided effective relief compared with placebo and were generally well tolerated.

Trial registration: ClinicalTrials.gov NCT01470118 NCT01732757.

Fig. 1

Subject disposition

Fig. 2

Comparison of mean itch scores at baseline and 16 h after treatment instillation at 3 min post-conjunctival allergen challenge (primary endpoint). Mean itch scores for alcaftadine 0.25%, olopatadine 0.2%, and placebo. *P < 0.0001 for alcaftadine and olopatadine versus placebo; **P = 0.0006 for alcaftadine versus olopatadine. P values calculated using the two-sample t test

Fig. 3

Comparison of overall mean itch scores at baseline and 16 h after treatment instillation over all time points (3, 5, and 7 min) post-conjunctival allergen challenge. Mean itch scores for alcaftadine 0.25%, olopatadine 0.2%, and placebo. *P < 0.0001 for alcaftadine and olopatadine versus placebo; **P = 0.0390 for alcaftadine versus olopatadine. P values calculated using the repeated measures analysis of covariance model accounting for treatment and time points

Fig. 4

Comparison of overall percentage of subjects with minimal itch and zero itch scores at 16 h after treatment instillation. Percentage of subjects with minimal itch (itch score <1) and zero itch for alcaftadine 0.25%, olopatadine 0.2%, and placebo at all time points post-conjunctival allergen challenge. Subjects had to meet the itch score criteria (<1 or 0) at 3, 5, and 7 min post-conjunctival allergen challenge. *P < 0.0001 for alcaftadine and olopatadine versus placebo; **P ≤ 0.0006 for alcaftadine and olopatadine versus placebo; ***P = 0.0121 for alcaftadine versus olopatadine. P values calculated using Fisher’s exact test

Fig. 5

Distribution of itch scores at baseline (a) and 16 h after treatment instillation (b). Itch scores of each eye at baseline (untreated) and 16 h after treatment with alcaftadine 0.25%, olopatadine 0.2%, and placebo at all time points measured (3, 5, and 7 min) post-conjunctival allergen challenge