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Clinicians advise giving monotherapy a fair chance before switching treatment
If first-line glaucoma therapy to lower IOP is failing, then a clinician should consider switching medications within a drug class.
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With limited and often contradictory clinical data regarding glaucoma therapy choices, including when treatments should be changed and what constitutes a target IOP, clinicians have learned to treat patients on an individual basis.
Specialists say the key to effective glaucoma therapy is employing treatments that lower IOP with limited side effects. If medication is the first-line choice of treatment, maintaining patients on the fewest number of drugs is important because compliance issues become increasingly problematic when more than two glaucoma drugs are prescribed, according to experts contacted by Ocular Surgery News.
Beginning the therapy
Adjunctive therapy can be helpful in achieving target IOP, but before adding another drug, physicians said it is best to carefully assess use of the first prescribed glaucoma medication.
 Robert J. Noecker |
“You want something that’s efficacious,” Robert J. Noecker, MD, said. “The whole idea of having long-term success is to lower the eye pressure, and we try to do that with as few medications as possible.”
Louis B. Cantor, MD, suggested beginning therapy by prescribing one glaucoma medication selected on the patient’s individual ocular needs. If the first drug is not effective in reaching the target pressure, he suggested switching to another medication within the class to see if a different drug would be more effective.
The situation is similar to baseball, according to Dr. Cantor. If a baseball player is given only one chance to hit the ball, the chance of failure would be higher than the three strikes a batter is given. The same can be said for monotherapy, he said.
“Give monotherapy a few swings at the ball, at least, to see if you can connect,” he said. “At least get on base and get a good effect to start with, with monotherapy, and the best monotherapy that you can. Don’t abandon monotherapy too quickly.”
Monotherapy
The most common drug class used in first-line treatment is prostaglandin analogues, the clinicians said. While beta-blockers once filled that slot, they no longer dominate the field. Prostaglandin analogues have become more popular because they are a safe, strong topical medication, according to Dr. Noecker.
“The name of the game is to try to get away with as little medication as possible,” he said.
Other options available for first-line glaucoma therapy are laser and, in some cases, surgery, but many clinicians, especially in the United States, turn first to prostaglandin analogues as monotherapy, he said.
With first-line therapy, Dr. Noecker said he is aiming for a 30% to 40% reduction in IOP. He said he attempts to achieve IOP in the upper teens for mild glaucoma patients, the mid teens for moderate glaucoma patients and low teens for severe glaucoma patients.
He said he has found that patients exposed to previous ocular drugs seem to respond best to Lumigan (bimatoprost 0.03%, Allergan), while patients with dry eye seem to respond best to Travatan Z (travoprost 0.004%, Alcon).
According to Dr. Cantor, the main considerations driving monotherapy are efficacy and tolerability, and prostaglandin analogues meet those requirements. He said he usually starts patients on a prostaglandin analogue because of the limited side effects and excellent pressure lowering.
Steven T. Simmons, MD, also starts patients on a prostaglandin. He said he typically begins patients on Xalatan (latanoprost, Pfizer) or bimatoprost, depending on the pressure goal. If a patient is on latanoprost and IOP does not decrease by 20 mm Hg or if the patient does not achieve his target pressure, then Dr. Simmons switches patients to bimatoprost. If a patient still does not achieve optimum pressure, he adds a second medication or offers the option of laser trabeculoplasty.
“I’d say that about two-thirds of my patients choose the second medication at that time, and if the patients are on a prostaglandin, then I’ll add Alphagan (brimonidine tartrate, Allergan),” he said.
Switching within classes
 Louis B. Cantor |
Before patients are placed on two medications or have laser therapy or surgery, many physicians recommend switching to a different medication within the prostaglandin family. Dr. Noecker said he does not hesitate to switch patients if he believes the first prostaglandin is not adequately lowering pressure.
Sticking with monotherapy also makes sense because adding drugs can become expensive and cause compliance issues, Dr. Cantor said. He said by switching within the prostaglandin analogue class, physicians can keep patients off adjunctive therapy a little longer.
“Getting the first drug right and accepting that sometimes the drug we pick first isn’t going to be the perfect drug for that patient is important,” Dr. Cantor said.
Adjunctive therapy
If patients do not experience adequate pressure lowering after switching within a drug class, adjunctive therapy is often the next step, the physicians said. Choices for second-line therapy include beta-blockers, alpha-agonists and topical carbonic anhydrase inhibitors.
Dr. Noecker said he prefers using alpha-agonists because the current formulation is well-tolerated, systemically safe and efficacious. He said that while all three classes appear to have similar efficacy, in his experience he has found that topical carbonic anhydrase inhibitors are not as well-tolerated and beta-blockers have slightly more systemic implications. He said he would use beta-blockers last and, at that point, would consider combining different groups of medications.
He cautioned physicians to be careful when combining drug therapies. Research has shown that beta-blockers and prostaglandin analogues do not have a good additive effect, he said.
Dr. Cantor said adjunctive therapy should be started after exhausting all options with a single medication and assuring that patients cannot achieve target pressure without additional drugs.
“The time to begin adjunctive therapy, medically, is when you’re confident that you’ve got the most effective monotherapy for that patient and you’re still not at target pressure,” he said.
When starting adjunctive therapy, Dr. Simmons does monocular trials because he has found a great deal of variability in patients’ pressures on their primary therapy. Without monocular trials, variability can be difficult to determine when comparing the first drug’s efficacy with the second. He said fluctuations in diurnal curves could cause a patient’s IOP to be different at various times, and adding a second medication without adequate study of the first medication could result in adding an unnecessary second medication.
“I have instituted using monocular trials, as well as bringing people back to check their pressure, before I will institute a second therapy,” Dr. Simmons said.
For more information:
- Louis B. Cantor, MD, can be reached at 702 Rotary Circle, Indianapolis, IN 46202-5175; 317-274-8485; fax: 317-278-1007; e-mail: lcantor@iupui.edu. Dr. Cantor is a consultant for and receives research grants and honoraria from Allergan. He has received honoraria from Merck and research support from Alcon and Pfizer.
- Robert J. Noecker, MD, can be reached at the University of Pittsburgh Medical Center, Eye and Ear Institute, 203 Lothrop St., 8th Floor, Pittsburgh, PA 15213; 412-647-2200; fax: 412-647-5119; e-mail: noeckerrj@upmc.edu. Dr. Noecker is a consultant to Allergan and on the speaker’s bureau at Alcon.
- Steven T. Simmons, MD, can be reached at 1240 New Scotland Road, Slingerlands, NY 12159; 518-475-7300; fax: 518-475-9174; e-mail: glaucomaconsult@aol.com. Dr. Simmons is a consultant for Allergan, receives grant support from Alcon, and speaks for Merck.
- Alcon, maker of Travatan Z, can be reached at 6201 South Freeway, Fort Worth, TX 76134; 817-293-0450; fax: 817-568-6142; Web site: www.alconlabs.com. Allergan, maker of Lumigan and Alphagan, can be reached at P.O. Box 19534, Irvine, CA 92623; 714-246-4500; fax: 714-246-4971; Web site: www.allergan.com. Pfizer, maker of Xalatan, can be reached at 235 E. 42nd St. New York, NY 10017; 212-573-343; fax: 212-672-7926; Web site: www.pfizer.com.
- Erin L. Boyle is an OSN Staff Writer who covers all aspects of ophthalmology.