Effects of topically applied PGF2 alpha and its isopropylester on normal and glaucomatous human eyes

A lipid-soluble PG ester such as PGF2 alpha-IE reduces IOP in the human eye when given in considerably lower doses than are needed for the tromethamine salt of this PG to do so. However, with the pharmaceutical composition now used, the concomitant and dose-related side effects, both objective and subjective, are clearly clinically unacceptable at doses corresponding to the upper part of the dose-response curve for IOP reductions. Moderate side effects were observed after twice-daily treatment with the 0.5 microgram dose for up to two weeks. The pressure reduction obtained in healthy eyes with this dose of PGF2 alpha-IE was less than one would expect with conventional glaucoma drugs. However, the pressure reduction in response to this dose of PGF2 alpha-IE among glaucoma patients who had moderately increased IOP was adequate for clinical use. A useful approach to the development of PGs as potential drugs for the treatment of glaucoma would clearly be the identification of an alternative PG or PG formulation that will permit the use of doses at the upper portion of the IOP dose-response curve without unacceptable side effects. Long-term studies on glaucoma patients, using an appropriate PG formulation, remain to be done before we can evaluate the true clinical usefulness of this new class of ocular hypotensive drugs.