Oculohypotensive effect of perindopril in acute and chronic models of glaucoma in rabbits

We studied the effect of perindopril (1%) on intraocular pressure (IOP) and compared it with the effect of pilocarpine, a therapeutic agent used in experimentally induced acute and chronic models of glaucoma in rabbits. Acute glaucoma was induced by intravenous administration of 5% glucose. Pretreatment with topical perindopril (1%) and pilocarpine (1%) prevented acute rise in IOP induced by intravenous administration of 5% glucose. For inducing chronic ocular hypertension in rabbits, 50 units of freshly prepared α-chymotrypsin in 0.1 mL of sterile saline was injected in the posterior chamber of the eye. Perindopril (1%) (35 ± 1.38 mm Hg to 22.45 ± 1.42 mm Hg) and pilocarpine (1%) (34.4 ± 0.81 mm Hg to 20.15 ± 0.69 mm Hg) produced a significant fall in IOP in these rabbits; pretreatment with indomethacin (prostaglandin synthesis inhibitor) did not affect the IOP-lowering action of perindopril (1%). Perindopril (2.71 × 10−7 mol/L) and neostigmine (1.49 × 10−7mol/L) inhibited true cholinesterase and pseudocholinesterase enzyme activity in blood. The cholinesterase enzyme inhibition by perindopril was comparable with that by neostigmine. In conclusion, our data suggest that perindopril reduced IOP in experimentally induced acute and chronic glaucoma in rabbits. One of the possible mechanisms of perindopril, apart from the inhibition of angiotensin-converting enzyme, may be inhibition of the enzyme cholinesterase.