The two trials, a spring study with a 10-week duration and the other conducted over 12 weeks in the fall allergy season, had a randomized, placebo-controlled, double-masked design with a combined enrollment of 500 patients.
Fall and spring studies
In the spring study, patients were asked to record the frequency of their nasal symptoms (itchy nose, stuffy nose, runny nose, postnasal drip, sneezing) while both frequency and severity of the same list of nasal symptoms were assessed in the fall study. Use of any other topical ocular medications or new systemic medications was not allowed. More than 90% of enrolled patients had a history of rhinoconjunctivitis.
In the spring study, frequency of sneezing and runny nose were significantly lower among patients using once-daily olopatadine 0.2% compared with controls, while in the fall study, the frequency of runny nose as well as the severity of sneezing, itchy nose, and runny nose all were significantly lower in the olopatidine-treated patients.
There was a marginally non-significant difference in the frequency of runny nose favoring the olopatadine group, according to Dr. Abelson, lead author of the published study results [Curr Med Res Opin. 2005;21:683-691].
"These two environmental studies of once-daily olopatadine 0.2% were designed primarily to investigate the safety and efficacy of olopatadine in treating ocular signs and symptoms in patients with allergic conjunctivitis or allergic rhinoconjunctivitis and not to assess its effects on nasal symptoms," said Dr. Abelson, associate clinical professor of ophthalmology, Harvard Medical School, and senior clinical scientist, Schepens Eye Research Institute, Boston.
"However, they were well-designed, rigorously conducted clinical trials representing a large population of patients primarily with rhinoconjunctivitis from across the nation and treated during two distinct allergy seasons," he said.
In addition, the results from both environmental studies were consistent and demonstrated that instillation of olopatadine in the eye also may have adjuvant effects for relieving runny nose, itchy nose, and sneezing, which are the primary symptoms of the early phase reaction in allergic rhinitis, according to Dr. Abelson.
Anti-allergy agents instilled into the eye for treating ocular disease would be expected to have a positive effect on concomitant nasal symptoms both from the direct action of medication reaching the nasal cavity through the nasolacrimal duct and from its ability to decrease draining of allergic reaction mediators from the ocular surface into the nose.
Results from previous duration of efficacy studies with olopatadine 0.2%, including animal models and human studies using the conjunctival allergen challenge (CAC) model, demonstrate its safety and efficacy in treating allergic conjunctivitis and support its use in a once-daily dosing regimen, said Dr. Abelson, who also is chairman and chief scientific officer, Ora Inc., Andover, MA.
Patients enrolled in the two environmental studies had to be at least 10 years old, have a history of allergic conjunctivitis or rhinoconjunctivitis, and demonstrate a positive reaction to both a skin prick test and a CAC using the relevant antigen (ragweed for the fall study, grass for the spring study). The patients had a mean age of about 37 years (range, 10 to 75) and were primarily Caucasian (81.4%).
Statistically significant differences in the activities of olopatadine and placebo in controlling allergic nasal symptoms were investigated using slope analysis that correlates the amount of environmental pollen to the degree of allergic reaction. Daily pollen counts for ragweed (fall study) or grass (spring study) were obtained from each investigative center participating in the trials for use in the analyses.