THE EFFECT OF TOPICAL DILTIAZEM ON THE INTRAOCULAR-PRESSURE IN BETAMETHASONE-INDUCED OCULAR HYPERTENSIVE RABBITS

The effect of calcium channel blockers (CCBs) on intraocular pressure (IOP) remains still controversial, although some preliminary reports s uggest that these drugs may be effective in the management of ocular h ypertension and low-tension glaucoma. The aim of the present work was to assess the effect of topical diltiazem on IOP in an animal model fo r glaucoma, the betamethasone-induced ocular hypertension in rabbits. IOP was measured with a manometrically calibrated applanation pneumato nograph. Ocular hypertension was produced in 120 rabbits by weekly sub conjunctival injection of a betamethasone suspension into the left eye . The experiments examining the ocular actions of diltiazem were carri ed out in two stages. In the first one, the ability of topical diltiaz em to prevent the rise in IOP induced by betamethasone was studied. In a second phase, the effect of topical diltiazem on IOP in betamethaso ne-induced ocular hypertensive rabbits was assessed. Diltiazem was top ically applied once daily for 5 days a week into the left eye. The eff ect of five different concentrations of diltiazem was evaluated to obt ain dose-response curves. Topical diltiazem was found to prevent in a dose-related fashion the betamethasone-induced IOP rise as well as to reduce IOP in rabbits made ocular hypertensive by weekly subconjunctiv al injection of betamethasone. Unilateral topical administration did n ot produce a clear effect on IOP in the untreated eye. This is the fir st report describing the ocular hypotensive action CCBs in an animal m odel for glaucoma. These findings are in agreement with preliminary ev idence suggesting that CCBs may have a beneficial effect in human ocul ar hypertension.