Ista Pharmaceuticals Inc announced that the U.S. Food & Drug Administration (FDA) has issued an approvable letter for Istalol, a once-a-day liquid formulation of timolol which has been developed for the treatment of glaucoma.

Under an agreement between Ista and Senju Pharmaceutical Co. Ltd., Ista holds exclusive marketing rights to Istalol in the United States. In the letter, the FDA cited issues related to manufacturing methods and controls. No additional clinical studies were requested.

Vicente Anido, Jr., President and Chief Executive Officer of Ista stated, "We're very pleased with the progress of the NDA submission for Istalol. We believe that the issues cited by FDA in the approvable letter are readily addressable. In addition, we are seeking to qualify an alternate manufacturing site. Based on this, we believe that the product remains on track for approval and launch in early 2004. We anticipate that the introduction of Istalol in the U.S. market, assuming FDA approval, would provide a significant improvement in patient care for the treatment of glaucoma."

Istalol was developed by Senju to be applied topically, once per day. Clinical trials of this new formulation have shown comparable efficacy and safety to timolol maleate ophthalmic solution, the leading beta-blocker, which is commonly applied twice a day. Istalol will compete in the glaucoma market, which according to published reports is valued at $1.1 billion per year in the United States.

Istalol is a branded, patent-protected product. ISTA believes that Istalol is eligible to receive certain FDA statutory exclusivity upon approval and therefore, if granted, Istalol will not be immediately substitutable by any of the generic timolol products currently on the market.