EyeWorld Asia-Pacific September 2012 Issue

55 September 2012 EWAP PhArmA The appeal of fixed glaucoma combinations W hen it comes to glaucoma medications, the use of fixed combination glaucoma drugs is very common, according to Tarek Shaarawy, MD , University of Geneva, Switzerland, and associate executive vice president, World Glaucoma Association. Dr. Shaarawy pegs the need for these as encompassing more than 50% of cases. “It’s a minority of patients that can be controlled after a couple of years of therapy on one molecule,” he said. Gary D. Novack, PhD, president, PharmaLogic Development Inc., San Rafael, Calif., USA, concurs. “The rule of thumb in America is that about half the patients who are on therapy are on monotherapy,” he said. “That means that the other half are on multiple therapy.” Combination punch While practitioners can simply prescribe two separate medications, offering a fixed combination agent may be very appealing, finds Reay H. Brown, MD, in private practice, Atlanta, Ga., USA. He cites compliance as likely being enhanced with such medications. “The major advantage is that they only have to use one bottle and one drop, let’s say twice a day, rather than two bottles and two separate drops twice a day,” Dr. Brown said. “I think the more that you can reduce the burden, the more likely people are to be compliant.” Dr. Shaarawy likewise finds that convenience is very Dynamic duos: Combination glaucoma agents getting results by Maxine Lipner Senior EyeWorld Contributing Editor important. “People can comply better with one bottle than two,” he said. He also pegs the potential for side effects as a key factor. “If you give them two bottles and each bottle has its own preservative then it becomes a double amount of preservative that you bombard the surface of the eye with,” he said. “That would potentially create ocular surface disease.” A study that Dr. Novack worked on together with Alan L. Robin, MD, and other fellow investiga- tors substantiates the compliance issue. In the study, published in the October 2007 issue of the Ameri- can Journal of Ophthalmology, the aim was to consider the adherence of subjects to using a once-daily prostaglandin agent or to using two-drug therapy. The findings showed that while patients readily adhered to taking one medication, with a mean coverage of 97.2%, this dropped to 85.6% when the second agent was part of the equa- tion. “When we added the two bot- tles, the compliance fell off,” Dr. Novack said. “So there is data that the more complicated regimens are harder for the patient to follow.” Current combos Presently, combination glaucoma medications in the U.S. are limited to three: Combigan (brimonidine tartrate/timolol maleate ophthalmic solution, Allergan, Irvine, Calif., USA), Cosopt (dorzolamide/timolol, Merck, Whitehouse Station, NJ, USA), and now Cosopt PF (preservative-free dorzolamide/ timolol, Merck), which got the FDA nod in February. Most of the combinations in Europe are carbonic anhydrase inhibitors with beta blockers, according to Dr. Shaarawy. In addition, there are prostaglandin combinations available outside of the U.S. The prostaglandin beta blocker combination is dubbed Xalacom (latanoprost/ timolol, Pfizer, New York, NY, USA), according to Dr. Novack. A second prostaglandin combination available in Europe is Ganfort (bimatoprost/timolol, Allergan), and a third is DuoTrav (travoprost/ timolol, Alcon, Fort Worth, Texas, USA/Hünenberg, Switzerland). One weakness Dr. Shaarawy finds is the common link for all the combinations—the beta blocker, timolol. “All combination therapies have a beta blocker, and a good percentage of our patients has a contraindication to using a beta blocker,” he said. “That is the main drawback to using them in those cases.” Dr. Brown agrees that beta blockers can be problematic. “The beta blocker has the contraindications of asthma or any sort of breathing issues like emphysema or chronic obstructive pulmonary disease,” he said. Also, any allergic intolerance to brimonidine or dorzolamide can factor in to the decision of which combination agent to choose. In addition, Dr. Shaarawy finds that the combinations differ in terms of how individual patients react. It becomes a question of trial and error. “What is important for the general ophthalmologist to remember is that if this combination doesn’t work with this patient, it might work with another,” Dr. Shaarawy said. “So individual responses to a fixed combination are very important not to discard.” However, for the most part he finds that there are no dramatic differences from one fixed glaucoma combination to another that would push a physician toward a particular product. The preservative-free Cosopt, however, enjoys a bit of a special niche. “For a person who has an ocular surface disease, you would probably go for a combination that is preservative free like Cosopt-S, which is available in Europe,” Dr. Shaarawy said. This was recently approved in the U.S. under the Cosopt PF label. Dr. Brown also pegs those with allergies as more amenable to a preservative-free approach. “Patients who have had more problems with allergy would certainly be more appropriate for the preservative-free medication,” Dr. Brown said. “It’s probably more expensive, which is the only drawback.” He has just started using the preservative-free product. “I think that it’s always good to have as few extraneous chemicals as possible,” he said. “But it’s a balance between cost and benefit.” Dr. Shaarawy has found that the preservative-free product appeals to the sensibilities of many of his patients. In his experience, however, there are two caveats. continued on page 56