Effect of Oral Losartan Potassium Administration on Intraocular Pressure in Normotensive and Glaucomatous Human Subjects

Abstract

The effects of the type 1 angiotensin II receptor antagonist Losartan potassium on intraocular pressure (IOP) were studied. Four groups of subjects were analysed: group A, ten controls; group B, ten patients with essential arterial hypertension and with IOP within the normal range; group C, ten patients with primary open angle glaucoma (POAG), but without essential arterial hypertension; group D, ten patients with arterial hypertension and POAG. The study design was held in a randomized crossover double-blind fashion. Systolic and diastolic arterial pressure, heart rate, pupil diameter, IOP and total outflow facility were recorded at baseline and at 1hr intervals up to 6hr, following the oral administration of 50mg of Losartan potassium and/or placebo. The alternative treatment was given a week later. Drug administration significantly reduced IOP in all subjects. No variation in heart rate and pupil diameter was observed during the follow-up period. Blood pressure dropped only in arterial hypertensive patients (groups B and D). Total outflow facility increased significantly in all groups. Placebo did not induce any variation in all groups. These findings demonstrate that the mechanism by which Losartan potassium reduces intraocular pressure is not mediated by a decrease in blood pressure, but rather it is more specific, confirming the role of the renin-angiotensin system also in the regulation of intraocular pressure in man.