What's in the Pipeline?

BY WILLIAM TOWNSEND, O.D.
MAR. 1997

The past year brought eyecare practitioners a number of new drugs, and the next few years hold great promise as more ophthalmic products continue to be developed and others enter the final phase of FDA approval.

ANTI-INFLAMMATORY DRUGS

We may soon have another topical NSAID to add to our therapeutic options. Akorn plans to market an ophthalmic version of piroxicam, which is presently marketed as the oral NSAID Feldene. The initial FDA approval for this drug will be as an agent to prevent postoperative miosis in cataract surgery. According to Akorn, topical piroxicam has the potential to be the strongest topical NSAID available, and unlike other NSAIDs, it doesn't sting.

For years, we've prescribed topical antihistamines and topical mast cell stabilizers for allergy patients. Although this combination works well, it requires the patient to purchase two separate medications and instill them independently. The effect of the antihistamine is often immediate, but it can take up to two weeks for topical mast cell stabilizers to reach maximum efficacy.

Olopatidine, a new product under development by Alcon, may change our treatment patterns for allergic eye disease because it contains both antihistamine and mast cell stabilizing properties. Early studies have demonstrated its efficacy in the short-term and long-term treatment of allergic conjunctivitis. Atopic conjunctivitis and vernal keratoconjunctivitis may also be added to the list of indications as the product nears release.

Alcon recently introduced rimexolone (Vexol), a potent steroid that is comparable to prednisolone (1%) in efficacy but is less likely to cause IOP elevation. "Soft steroids" such as rimexolone possess the same desirable anti-inflammatory qualities as conventional steroids, but they are are formulated to minimize undesirable side-effects.

Loteprednol, developed by Pharmos and marketed by Bausch & Lomb, may also be available soon. Like rimexolone, it is effective and is not likely to cause IOP elevation. With the advent of new, potent soft steroids, eyecare practitioners will have even more ways to treat inflammatory disorders such as chronic uveitis, stromal herpes simplex keratitis or vernal keratoconjunctivitis.

ANTIVIRALS

It has been several years since the last topical antiviral, trifluridine (Viroptic), was introduced by Burroughs Wellcome. Gilead Sciences, Foster City, Calif., developed cidofovir as an oral agent for the treatment of cytomegaloviral retinitis. Researchers found that a topical form of the same drug was active against herpes viruses as well as the adenoviruses that cause epidemic keratoconjunctivitis. Storz is presently evaluating this topical preparation, which will not only be a new agent for treatment of herpes viruses, but the first agent with proven activity against adenoviruses.

ANTI-GLAUCOMA

MEDICATIONS

The treatment of low tension glaucoma has been a problem for doctors and patients for many years. The etiology of the disease seems to be inadequate perfusion of the optic nerve head, so agents that simply lower intraocular tension are often only marginally effective. A more rational approach is to increase blood flow to the optic nerve head. To date, no really effective medication has been released.

Studies are underway for calcium channel blockers (CCBs) such as verapamil, which appear to reduce visual field loss and progressive optic nerve damage secondary to glaucoma. However, the efficacy of a CCB can differ depending upon how the drug is administered. Topical CCBs work best for primary open-angle glaucoma, while oral CCBs are effective only for low tension glaucoma. The ability of oral CCBs to reduce the progression of nerve damage from low tension glaucoma appears to be attributed to increased perfusion of the nerve head tissue. IOP reduction by topical CCBs is probably due to a localized reduction in arterial blood pressure with a corresponding reduction in aqueous production.

We've been blessed with a new crop of ophthalmic medications over the past few years. As this trend continues, and it appears that it will, we'll have a multitude of new agents with which to treat our patients. It's critical that eyecare practitioners continue to stay current as new technologies and medications become available. Stay tuned for more news from "the pipeline." CLS

Dr. Townsend is in private practice in Canyon, Texas, and is a consultant at the Amarillo VA Medical Center.