Intraocular Pressure Responses to Antiglaucoma Agents in Spontaneous Buphthalmic Rabbits

Abstract

In spontaneous ocular hypertensive buphthalmic rabbits, we have tested a representative agent of various pharmacological classes which are known to decrease intraocular pressure (IOP) by an action upon aqueous humour formation and/or outflow facility after topical instillation. Various concentrations of the α-adrenergic agonist, norepinephrine, the mixed α, β-adrenergic agonist, epinephrine, the β-adrenergic agonist, isoproterenol, and β-adrenergic antagonists, timolol and propranolol, as well as the cholinergic agent, pilocar-pine, resulted in a significant dose-related decrease in IOP of buphthalmic rabbits. The results demonstrate the utility of buphthalmic rabbits for the evaluation of the ocular hypotensive and potential antiglaucoma activity of pharmacological agents; however, difficulties encountered in breeding and maintaining these rabbits appear to preclude their routine use for large scale drug evaluation.

Effects of Timolol and of Timolol with Tamarind Seed Polysaccharide on Intraocular Pressure in Rabbits

“…Vareilles et al (1977) showed that topical administration of 0Á5% timolol reduced IOP in chymotrypsin-treated rabbit eyes and in water-loaded rabbits, and Bonomi et al (1979) showed that 0Á25±1% timolol reduced IOP in New Zealand White rabbits with betamethasone-induced ocular hypertension. Vareilles et al (1980) showed that 0Á01±1% timolol reduced IOP in buphthalmic rabbits. Liu et al (1983) found that topical timolol was more effective at reducing IOP in water-loaded pigmented rabbits than in water-loaded New Zealand White rabbits and Sugrue et al (1988) showed that topical application of 0Á01±0Á1% timolol reduced IOP in chymotrypsin-treated albino rabbit eyes.…”

Effects of Timolol and of Timolol with Tamarind Seed Polysaccharide on Intraocular Pressure in Rabbits

“…Vareilles et al (1977) showed that topical administration of 0Á5% timolol reduced IOP in chymotrypsin-treated rabbit eyes and in water-loaded rabbits, and Bonomi et al (1979) showed that 0Á25±1% timolol reduced IOP in New Zealand White rabbits with betamethasone-induced ocular hypertension. Vareilles et al (1980) showed that 0Á01±1% timolol reduced IOP in buphthalmic rabbits. Liu et al (1983) found that topical timolol was more effective at reducing IOP in water-loaded pigmented rabbits than in water-loaded New Zealand White rabbits and Sugrue et al (1988) showed that topical application of 0Á01±0Á1% timolol reduced IOP in chymotrypsin-treated albino rabbit eyes.…”

Timolol may inhibit aqueous humor secretion by cAMP-independent action on ciliary epithelial cells

“…An ocular hypotensive effect has also been reported in normotensive rabbits at very low timolol concentration [0.01% topical timolol (31)], but the effect is small. Second, ␤ 1 -adrenergic antagonists are effective in some models of ocular hypertension (6,61), although the high density of ␤-receptors in the ciliary process are predominantly of the ␤ 2 subtype. Third, D-timolol may be as effective as L-timolol (42) in decreasing aqueous flow, despite stereospecificity of the ␤-adrenergic receptors for the L-isomers (41,49).…”

Effects of Timolol and of Timolol with Tamarind Seed Polysaccharide on Intraocular Pressure in Rabbits

“…Vareilles et al (1977) showed that topical administration of 0Á5% timolol reduced IOP in chymotrypsin-treated rabbit eyes and in water-loaded rabbits, and Bonomi et al (1979) showed that 0Á25±1% timolol reduced IOP in New Zealand White rabbits with betamethasone-induced ocular hypertension. Vareilles et al (1980) showed that 0Á01±1% timolol reduced IOP in buphthalmic rabbits. Liu et al (1983) found that topical timolol was more effective at reducing IOP in water-loaded pigmented rabbits than in water-loaded New Zealand White rabbits and Sugrue et al (1988) showed that topical application of 0Á01±0Á1% timolol reduced IOP in chymotrypsin-treated albino rabbit eyes.…”

Timolol may inhibit aqueous humor secretion by cAMP-independent action on ciliary epithelial cells

“…An ocular hypotensive effect has also been reported in normotensive rabbits at very low timolol concentration [0.01% topical timolol (31)], but the effect is small. Second, ␤ 1 -adrenergic antagonists are effective in some models of ocular hypertension (6,61), although the high density of ␤-receptors in the ciliary process are predominantly of the ␤ 2 subtype. Third, D-timolol may be as effective as L-timolol (42) in decreasing aqueous flow, despite stereospecificity of the ␤-adrenergic receptors for the L-isomers (41,49).…”

Effects of Timolol and of Timolol with Tamarind Seed Polysaccharide on Intraocular Pressure in Rabbits

“…Vareilles et al (1977) showed that topical administration of 0Á5% timolol reduced IOP in chymotrypsin-treated rabbit eyes and in water-loaded rabbits, and Bonomi et al (1979) showed that 0Á25±1% timolol reduced IOP in New Zealand White rabbits with betamethasone-induced ocular hypertension. Vareilles et al (1980) showed that 0Á01±1% timolol reduced IOP in buphthalmic rabbits. Liu et al (1983) found that topical timolol was more effective at reducing IOP in water-loaded pigmented rabbits than in water-loaded New Zealand White rabbits and Sugrue et al (1988) showed that topical application of 0Á01±0Á1% timolol reduced IOP in chymotrypsin-treated albino rabbit eyes.…”

Timolol may inhibit aqueous humor secretion by cAMP-independent action on ciliary epithelial cells

“…An ocular hypotensive effect has also been reported in normotensive rabbits at very low timolol concentration [0.01% topical timolol (31)], but the effect is small. Second, ␤ 1 -adrenergic antagonists are effective in some models of ocular hypertension (6,61), although the high density of ␤-receptors in the ciliary process are predominantly of the ␤ 2 subtype. Third, D-timolol may be as effective as L-timolol (42) in decreasing aqueous flow, despite stereospecificity of the ␤-adrenergic receptors for the L-isomers (41,49).…”