Purpose: To establish the dose-response relationship for the effect on intraocular pressure (IOP) and side effects during long-term treatment of patients with ocular hypertension with the prostaglandin F2 alpha (PGF2 alpha) analog PhXA41.
Methods: A three-center, randomized, double-masked study where IOP, conjunctival hyperemia, and ocular irritation were followed during a 1-month twice-daily treatment with placebo or 35, 60, or 115 micrograms/ml PhXA41 in 60 patients with ocular hypertension, primary open-angle glaucoma, or capsular glaucoma.
Results: The three concentrations of PhXA41 reduced the average IOP between 31% and 38% during the second day of treatment, with only a weak dose-response relationship. The initial effect declined somewhat during the first 2 weeks of treatment but then remained at the same level for the rest of the study, with a pressure reduction of approximately 20% for all three concentrations. On the second day of treatment, mild conjunctival hyperemia could be observed in most treated patients. Nineteen of 45 PhXA41-treated patients, compared with 2 of 15 placebo-treated patients, reported to have mild to moderate ocular irritation. These side effects became less pronounced during the study, and at the end there was little difference in the degree of conjunctival hyperemia between placebo- and drug-treated eyes, and no drug-related ocular irritation was reported with the two lowest concentrations of PhXA41.
Conclusions: It is confirmed that the PGF2 alpha analog PhXA41 is a major improvement with respect to the effect-side effect relationship and that it may become a valuable new agent for the treatment of glaucoma.