Biomedical Frontiers: Fall 1996, Vol.4, No.1
Drug Development Success Story

Twenty years ago, reports on the effects of prostaglandins in the eyes caught the interest of Dr. Laszlo Z. Bito, professor of ocular physiology. That interest eventually led to an innovative new drug for glaucoma, to the successful licensing of the drug to Pharmacia & Upjohn, and, this past summer, to FDA approval of the drug, latanoprost (Xalatan).

When Dr. Bito first began his research, most experts believed that prostaglandins (PGs) were harmful to the eye. But because the eye naturally produces PGs, Dr. Bito believed that the harmful effects were due to the high doses and method of delivery (intraocular injection) used in the 1970s. In preclinical research, Dr. Bito found that low daily doses of PGs given topically to eyes of cats and primates maintained reduced intraocular pressure--a finding that went against conventional wisdom of the time. Nevertheless, Dr. Bito persisted in his research, eventually applying for and receiving three patents related to his work.

After the first patent was awarded, the Office of Science and Technology Development (now Columbia Innovation Enterprise) licensed the rights to Dr. Bito's work to Pharmacia (now Pharmacia & Upjohn). With this year's FDA approval of the drug, latanoprost becomes the first drug to treat glaucoma via a unique method: Most glaucoma treatments reduce intraocular pressure by reducing the production of aqueous humor. Latanoprost instead decreases pressure by aiding the drainage of fluid from the eye into the orbital space.

One interesting side effect of the drug is that it can increase the melanin content of the iris in some patients, inducing a gradual change in eye color. According to Dr. Bito, this side effect may indicate other potential therapeutic uses of latanoprost and other PGs: Melanin may protect the eye against light-induced damage and may prevent the accumulation of toxic products including reactive oxygen species. Generally latanoprost increases the melanin content only in eyes with an irregularly colored iris with a darker area around the pupil, a pattern that may represent an age-related loss of pigmentation from the periphery of the iris.