Effect of fluoxetine on intraocular pressure in the rabbit

The effects of fluoxetine, which is a selective inhibitor of serotonin reup take (SSRI) have been studied on the intraocular pressure (IOP) in the rabb it. IOP was measured using a Perkins tonometer. Intravenous administration of fluoxetine (6.0 mg kg(-1)) significantly increased IOP by 7.2 +/- 1.3 mm Hg (P < 0.001). Fluoxetine administration also reduced the amount of urine excreted during the 24 hr, and increased the urine concentration of 5-hydro xyindole acetic acid (5-HIAA). Topical preadministration of ketanserin prev ented a rise in IOP, without there being any effects on the other parameter s examined. These findings indicate that intravenous administration of fluoxetine is ab le to raise IOP, through increased plasma levels of serotonin, which is con firmed by elevated 5-HIAA urine excretion and reduction in diuresis. Ketans erin, a specific 5-HT2A antagonist, counteracts the IOP increase brought ab out by fluoxetine, thus emphasizing the role of serotonin in the regulation of IOP and stressing the importance of including ophthalmological examinat ion in the protocol of depressed patients undergoing SSRI therapy. (C) 2000 Academic Press.