Intraocular Pressure Reduction with PhXA34, a New Prostaglandin Analogue, in Patients with Ocular Hypertension

In a randomized, double-masked, parallel study, one drop of 0.003% (1 μg; n=9) or 0.01% (3 μg; n=10) PhXA34, a new phenyl-substituted prostaglandin F_2α analogue (13,14-dihydro-15[R,S]-17-phenyl18,19,20-trinor-prostaglandin F_2α-1-isopropyl ester), or its vehicle (n=10) was applied topically twice daily for 6 days to one eye in each of 29 patients with ocular hypertension. Compared with either baseline, contralateral, or vehicle control values, PhXA34 caused a significant (P<.001) dose-dependent reduction of intraocular pressure. The reduction lasted at least 12 hours after each drop and 24 to 48 hours after the last drop, with a significant (P<.0001) mean±SEM reduction of as much as 10±1 mm Hg (40%). Conjunctival hyperemia was not produced by 0.003% PhXA34, but was noted in some eyes treated with 0.01% PhXA34, and after repeated tonometry with either concentration. The prostaglandin analogue did not produce clinically obvious miosis, anterior chamber flare or cellular response, or any subjective adverse effects. PhXA34 is a potent, effective, and welltolerated ocular hypotensive agent based on our results in this small, short-term study. Its potential as a new drug for glaucoma therapy warrants further investigation in long-term, larger studies.