Around-the-clock intraocular pressure reduction with once-daily application of latanoprost by itself or in combination with timolol

Objective: To determine whether once-daily, in the morning, topical application of the new ocular hypotensive prostaglandin analogue, latanoprost, yields nocturnal intraocular pressure (IOP) reduction similar to its diurnal IOP reducing efficacy. Study Design and Patients: Placebo-controlled, randomized, and double-masked study on hospitalized patients with ocular hypertension or glaucoma. Patients in group 1 (n=9) were maintained on twice-daily applications of 0.5% timolol maleate. Patients in group 2 (n=10) terminated their timolol treatment 3 weeks before the beginning of the study. In both groups the test drug (0.005% latanoprost) and its vehicle (placebo) was applied by hospital staff every morning for 9 days. Measurements: After 4 days of ambulatory treatment, patients were hospitalized, and IOP values were obtained in the supine and sitting positions with a handheld electronic tonometer (Tone-Pen XL, Bio-Rad, Glendale, Calif) and a Goldmann's applanation tonometer, covering every 2-hour interval, around the clock, but not more than at four time points per day during a 5-day period. Results: The mean nocturnal IOPs (Goldmann's applanation tonometer) collected for 5 days were mean +/- SEM 17.9 +/- 0.6 vs 20.2 +/- 0.6 mm Hg and 16.8 +/- 0.3 vs 20.6 +/- 0.5 mm Hg for the study vs the control eyes in group 1 and group 2, respectively. These nocturnal IOP reductions were statistically significant (P<.001, two-tailed paired Student's t test). The differences between diurnal and nocturnal IOP reductions (handheld electronic or Goldmann's applanation tonometer) were minimal (<0.3 mm Hg) and statistically not significant (P>.31, two-tailed paired Student's t test). Conclusion: Once-daily latanoprost treatment provides uniform circadian (around-the-clock) IOP reduction by itself, or in combination with timolol.