Effect of daily topical ethacrynic acid on aqueous humor dynamics in monkeys

We determined the effect of 1.5% ethacrynic acid (ECA) in ointment on intraocular pressure (IOP) and outflow facility following 5 days of topical treatment in ocular normotensive cynomolgus monkeys. Twelve monkeys received a 1 cm strip of ointment containing ECA in one eye but without ECA in the other once daily for 5 days. On Day 1 and Day 5 IOP was measured immediately before and 1 and 3 h after treatment. Outflow facility (perfusion) was determined 3.5 h after treatment on Day 5. The ECA-vehicle IOP differences averaged -2.8 +/- 0.8 (S.E.M) (p < 0.01), -1.7 +/- 0.6 (p < 0.02) and -3.7 +/- 0.7 mm Hg (p < 0.001), equivalent to IOP reductions of 21 +/- 6% (p < 0.01), 13 +/- 5% (p < 0.02) and 26 +/- 5% (p < 0.002) respectively, at 0, 1 and 3 h respectively after treatment on Day 5. Facility averaged 40 +/- 15% higher (p < 0.03) in the ECA-treated compared to the vehicle-treated eyes 4 h after treatment on Day 5.