New pharmaceutical products for glaucoma in the pipeline

The drug development pipeline is bursting with new pharmaceutical products that may one day be useful in glaucoma therapy. At least 50 novel treatments are under investigation or not yet available in all major markets, according to one presenter at Glaucoma Subspecialty Day.

The new agents can be classified as prostaglandins, combination products, neuroprotective agents, rho-kinase (ROCK) inhibitors, steroids, and drugs with a variety of other structures or mechanisms, according to Gary D. Novack, PhD, president of PharmaLogic Development Inc., San Rafael, CA.

Prostaglandins include AR-102 from Aerie Pharmaceuticals, which has 150-fold greater selectivity and 30-fold greater potency at the FP receptor than latanoprost (Xalatan, Pfizer), Dr. Novack said.

He provided an update on various treatments. Alcon Laboratories is developing a formulation of travoprost (Travatan-Z) that is preserved with sofzia, a combination of zinc, borate, propylene, glycol, and sorbitol, according to Dr. Novack. ISTA Pharmaceuticals has licensed two new product candidates from Senju Pharmaceuticals, a calcium-channel blocker and a new formulation of latanoprost, he said. In addition, Pfizer and NicOx are in phase II studies of a prostaglandin F2-alpha analog that also has nitric oxide-donating properties, and Santen is developing a drug called tafluprost, which was submitted for marketing approval in Europe in April, he added.

New combination products are also in the works. Three prostaglandin combinations have been approved in some major markets, while a brimonidine/timolol combination is approved in much of the world, except for the United States, Dr. Novack said. He also reported that a combination of brinzolamide and timolol is in development by Alcon.

In the neuroprotection class, memantine, a drug approved for treatment of Alzheimer's disease, is being investigated for preservation of visual function. Neurotech's core technology platform (Encapsulated Cell Technology) is an intravitreal implant for long-term, sustained drug delivery of therapeutic growth factors to the posterior pole. According to Dr. Novack, the company plans to evaluate this technology's applicability to glaucoma.

Several companies are investigating ROCK inhibitors that may play a role in cytsoskeletal regulation. Steroid products under development include anecortave acetate given by subtenon/anterior juxtascleral injection. Anecortave acetate is an angiostatic steroid. Also in phase II development is an eye-drop formulation of mifepristone (RU486) for corticosteroid-associated elevated IOP.