The FDA approved 3 new glaucoma agents
FDA clears several ophthalmic drops for glaucoma in a row
In short order, the Food & Drug Administration has approved three new drugs for glaucoma patients. For at least two million people in the United States affected by glaucoma, these agents will provide alternatives in treating the elevated intraocular pressure (IOP) associated with glaucoma.
The three new drugs are travoprost ophthalmic solution 0.004% (Travatan, Alcon), bimatoprost ophthalmic solution 0.03% (Lumigan, Allergan), and brimonidine ophthalmic solution 0.15% (Alphagan P, Allergan).
Travoprost and bimatoprost are approved for reducing elevated IOP for patients with open-angle glaucoma or ocular hypertension who are intolerant of, or inadequately controlled when using, other IOP-lowering medications.
According to the FDA, travoprost and bimatoprost exhibited similar effects in lowering ocular pressure in separate clinical trials. Both medications showed greater efficacy in lowering IOP in comparison with the current gold standard for glaucoma, timolol (Timoptic, Merck) and to the prostaglandin inhibitor, latanoprost (Xalatan, Pharmacia).
Side effects of the two agents include gradual darkening of the eye color; darkening of eyelid skin; and increased thickness, number, and darkness of eyelashes. These side effects precluded the two drugs from being indicated as first-line treatment. The implications of these effects are unknown and are currently being evaluated for long-term safety. Other adverse reactions reported were conjunctival hyperemia (with 3% discontinuing therapy) and ocular pruritus. Bimatoprost and travoprost are both dosed once daily in the evening.
"While Travatan is a great choice for all patient groups, it is particularly exciting for the African-American population," declared Stuart Raetzman, global marketing director for glaucoma and retina for Alcon. He noted that patients of African descent are four times more likely to suffer from glaucoma and are at higher risk to go blind from this disease than are individuals of other races. When Alcon examined trial results and looked at the effectiveness in black patients, they found that travoprost provides an additional 1.8 mmHg of IOP-lowering beyond that seen in non-African-American patients. Alcon has ongoing studies to further investigate this finding.
Travoprost, a synthetic prostaglandin analog, is believed to reduce IOP by increasing uveoscleral outflow. "Travatan is a full agonist. When it binds to the receptor, it turns the cell on 100%. When compared with Xalatan, which also binds to the receptor but not as completely, Travatan showed better IOP control earlier on," Raetzman said.
Bimatoprost is the first synthetic prostamide analog (prostamides are naturally occurring substances in the eye). "Even though it is structurally similar to Xalatan, it doesn't have any of the prostaglandin analog qualities. So the hope is that it won't have some of the side effects associated with Xalatan, such as the iris color change," said Steven Simmons, M.D., codirector of Glaucoma Consultants, Albany, N.Y., and associate clinical professor of ophthalmology at Albany Medical College.
From the initial pivotal trial, the incidence of these adverse events was much less with bimatoprost than seen in the first year with latanoprost, Simmons said. Another unique feature of bimatoprost, he said, is its dual mechanism of action. The drug is believed to lower the IOP by increasing the outflow of aqueous humor through both the trabecular meshwork and uveoscleral routes.
The third drug approved was brimonidine ophthalmic solution 0.15% (Alphagan P, Allergan). To offset the limiting side effects associated with Alphagan, such as allergic conjunctivitis and ocular pruritus, the concentration for the new agent has been decreased from 0.2% to 0.15% and the preservative changed from benzalkonium chloride (BAC) to Purite.
Simmons feels Alphagan P's main advantage will be in its role as an adjunctive agent. "More than 50% of glaucoma patients require more than one medicine to control their disease. So to have an excellent agent available without BAC gives Alphagan P tremendous strength," Simmons said.
Tammy Chernin. FDA clears several ophthalmic drops for glaucoma in a row. Drug Topics 2001;8:20.