New Therapeutic Options For Glaucoma
BY WILLIAM TOWNSEND, OD
I recently spoke at the Cornea, Contact Lenses and Contemporary Care Conference, held annually by the University of Houston College of Optometry, about new glaucoma medications.
Allergan has developed a new anti-glaucoma drug that it expects to release in 2001. AGN 192024 (Lumigan 0.03%) is a prostamide, which Allergan describes as a "naturally occurring substance found in ocular tissues, representing newly-discovered intrinsic factors for IOP regulation."
Lumigan is currently in Phase III clinical trials. Early studies show that when Lumigan is administered once a day, its pressure lowering in the morning (35 percent) is comparable to timolol 0.5% and is slightly better than timolol later in the day. Some adverse events encountered with Lumigan include ocular itching, conjunctival hyperemia and eyelash growth, noted in less than five percent of patients treated.
Travatan is Alcon's prostaglandin analog for which the Texas-based company hopes to gain approval in 2001. Like Pharmacia-Upjohn's Xalatan (latanoprost), the most frequently prescribed glaucoma drug in the United States, Travatan is prescribed once daily at bedtime. Xalatan takes up to four weeks to manifest its pressure-lowering effects, but Alcon reports that maximal pressure lowering occurs with Travatan in about two weeks. Like Xalatan, Travatan produces a pressure reduction of about 30 percent. Alcon also reports that its new product is especially effective in treating blacks with glaucoma. Travatan shares common side effects with Xalatan, including mild hyperemia, lash growth and iris pigment changes reported in five percent of cases with Xalatan and three percent with Travatan.
Pharmacia-Upjohn expects to soon announce approval of its long-awaited combination drug, Xalcom. This medication will contain timolol 0.5% and latanoprost 0.005% in concentrations equivalent to independent use of the two medications. Xalcom will cost about the same as taking the two drops separately. Avoid prescribing the medication for individuals with contraindications to either drug. It will be recommended as a once-aday, morning-dosed medication. Its greatest advantage will be the convenience and increased compliance associated with once-daily dosing. Pharmacia-Upjohn looks for FDA approval in early 2001.
Alcon is conducting trials of Betaxon, its new cardio-selective beta-blocker. Betaxon is a 0.5% levo isomer of Alcon's popular Betoptic S. Betaxon's increased concentration not only improves pressure-lowering characteristics, but can smooth troughs and peaks leading to consistent pressures throughout the day. The currently available product, Betoptic S, though not as effective in lowering pressure as timolol and other non-selective beta-blockers, possesses vasorelaxing and neuroprotective attributes that make it valuable in treating glaucoma. Betaxon shares these attributes, and its profile is similar to that of timolol. Allergy to Betaxon is reportedly low, but like all beta-blockers, it should be avoided in patients with compromised pulmonary function. Approval of Betaxon is expected this year.
CIBA Vision's Rescula (unoprostone isopropyl 0.15%) received FDA approval in late 2000.
In the past two decades, the management of glaucoma has been enhanced tremendously by the introduction of new pharmaceutical products. In the near future, we may even be treating the neuropathy that causes glaucoma, rather than the pressure.
Dr. Townsend is in private practice in Canyon, Texas, and is a consultant at the Amarillo VA Medical Center. E-mail him at email@example.com