■ A dorzolamide-timolol fixed combination dosed 3 times a day (TDS) has a superior IOP-lowering effect than the same agent dosed twice daily (BID) in patients with primary open-angle glaucoma (POAG). According to a study published in the Journal of Drug Assessment, the 2 strategies had comparable safety profiles.

Pakravan et al reported on a prospective, interventional case series that included newly diagnosed POAG patients. Patients who were taking the combination drug (Cosopt; Bausch + Lomb) BID for 1 month were switched to TDS dosing for an another month. The investigators performed (and continued to monitor) comprehensive ophthalmic examinations and checked diurnal IOP, blood pressure (BP), and 24-hour heart rate (HR) at baseline, 1 month, and 2 months.

There were 31 patients with POAG who completed the study, and they had a mean baseline IOP of 23.1±3.15 mmHg. Intraocular pressure decreased significantly to 16.5±2.21 mmHg at 1 month (P<.0001) and 13.9±2.23 mmHg at 2 months (P<.0001). The researchers reported that month-2 IOP was significantly lower than month 1 (P=.0004). Although dorzolamide-timolol fixed-combination dosed BID significantly reduced mean 24-hour systolic BP and mean 24-hour HR from baseline (P<.0001), these measures remained unchanged when the drug was dosed TDS (P=.62), Pakravan et al reported.

“Cosopt BID reduced the IOP by almost 28% from the baseline ... Increasing the dose of the medication to three times a day provided further IOP reduction by 12% and delivered a 40% reduction from the baseline,” wrote the investigators. Fixed-combination drugs are an attractive alternative because more than 50% of glaucoma patients require more than 1 drop for IOP control, and there is a direct correlation between the number of medications and adherence to therapy, the researchers added.