The ophthalmic combination product of 0.05%
naphazoline hydrochloride and 0.5%
antazoline phosphate (
Vasocon-A) was evaluated as an
antiallergic agent in 100 subjects with a known allergic history to cat dander, ragweed, or bluegrass pollen. Three independent study sites were used. The
allergen challenge model of acute
allergic conjunctivitis was selected to assess the agent as it provided a standardized and precise way to measure
drug effectiveness for this indication. In a double-masked randomized fashion, the subjects were assigned to one of three groups that received one drop of
Vasocon-A in one eye and one drop of either 0.05%
naphazoline (group 1), 0.5%
antazoline (group 2), or placebo (group 3) in the contralateral eye. After 10 minutes, the dose of
allergen shown to elicit a 2+ redness and
itching reaction was instilled bilaterally. Signs and symptoms of
allergic conjunctivitis were evaluated after 3, 5, and 10 minutes. Subjects were then rechallenged 2 hours after
drug administration to assess the duration of action of the agents.
Vasocon-A was found to significantly inhibit all five major signs and symptoms of
allergic conjunctivitis:
itching, redness, chemosis, lid swelling, and tearing, for more than 85% of the comparisons when compared over time with placebo,
naphazoline alone, or
antazoline alone. The results of this study indicate that the combination of
naphazoline and
antazoline was more effective in inhibiting redness than
naphazoline and more effective in inhibiting
itching than
antazoline. These findings support the use of such a combination for the treatment of
allergic conjunctivitis.