Greater IOP reduction achieved with once-daily vs. twice-daily fixed combination drops
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Once-daily fixed combination bimatoprost, timolol and brimonidine more effectively reduced peak IOP compared with a twice-daily regimen in patients with primary open-angle glaucoma, according to a study in the Journal of Glaucoma.
“The importance of our results is that we can have better efficacy while potentially enhancing adherence by requiring fewer drops per day,” Bianca Nicolela Susanna, MD, of the department of ophthalmology at ABC Foundation School of Medicine in Santo André, Brazil, and colleagues wrote. “Furthermore, it reduces the cost of the treatment as one bottle of medication should last twice as long with only one instillation compared to two per day.”
In a randomized clinical trial, 30 patients (average age, 70 years) with primary open-angle glaucoma instilled bimatoprost 0.01%, brimonidine tartrate 0.15% and timolol maleate 0.5% (Triplenex, Allergan) once daily in one eye and twice daily in the opposite eye for 90 days.
Patients participated in four water drinking tests to measure peak IOP, taken before starting the drops (WDT0) and monthly during treatment (WTD1, WTD2 and WTD3).
From WDT0 to WDT3, the mean peak IOP reduction in the once-daily group was 6.1 mm Hg compared with 4.3 mm Hg in the twice-daily group (P = .023). The once-daily group also had a higher mean peak IOP reduction over all water drinking tests (5.9 mm Hg vs. 4.46 mm Hg, P = .006).
Researchers further observed that most eyes (n = 24 in both groups) achieved IOP less than 18 mm Hg at WDT3, with six eyes in the once-daily group recording IOP less than 10 mm Hg compared with only one patient in the twice-daily group.
Study limitations included a small sample size, short-term follow-up and the possibility of incorrect instillation of drops.
“Additional studies should assess the long-term efficacy of once-daily use of [triple-fixed combination] and the possibility of fewer side effects, with lower costs, less ocular toxicity, ocular discomfort and likely greater adherence,” the authors wrote.
Perspective
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I’m a big fan of fixed combination glaucoma medications. They improve compliance and reduce exposure to preservatives – two factors known to undermine glaucoma treatment. In the U.S., our commercially available fixed combos include only two medication components, while other countries enjoy more options. Susanna and colleagues investigate the use of a triple combo drop (bimatoprost 0.01%, brimonidine 0.15% and timolol 0.5%, marketed in other countries as Triplenex by Allergan) either once or twice a day. They cleverly use the WDT as a surrogate for diurnal IOP determination.
In a small (60 eyes of 30 patients) randomized clinical trial, they found that this medication was more effective when dosed once daily rather than twice daily. This is no surprise, as we know that once daily prostaglandin analog (PGA) treatment is more effective than twice daily treatment. Further, there have been small patient series showing that twice daily PGA treatment can cause sudden IOP spikes, near 40 mm Hg.
So, is it possible to enjoy the IOP-lowering effects of three medications in a once daily regimen? If you can get one drop to do the work of 6 drops, sign me up. We are a long way from showing that this is the case, however, but one can hope.
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