Levobunolol

Levobunolol is a non-cardioselective beta-adrenoceptor blocking agent, equipotent at both beta₁ and beta₂ receptors. Levobunolol is greater than 60 times more potent than its dextro isomer in its beta-blocking activity. In order to obtain the highest degree of beta-blocking potential without increasing the potential for direct myocardial depression, the levo isomer, levobunolol, is used. Levobunolol does not have significant local anaesthetic (membrane-stabilising) or intrinsic sympathomimetic activity. Levobunolol has shown to be as effective as Timolol in lowering intraocular pressure.

Levobunolol when instilled in the eye will lower elevated intraocular pressure as well as normal intraocular pressure, whether or not accompanied by glaucoma. Elevated intraocular pressure presents a major risk factor in the pathogenesis of glaucomatous field loss. The higher the level of intraocular pressure, the likelihood of optic nerve damage and visual field loss.

The primary mechanism of action of levobunolol in reducing intraocular pressure is most likely a decrease in aqueous humor production. Levobunolol reduces intraocular pressure with little or no effect on pupil size in contrast to the miosis which cholinergic agents are known to produce.

The blurred vision and night blindness often associated with miotics would not be expected with the use of levobunolol. Patients with cataracts avoid the inability to see around lenticular opacities caused by pupil constriction.

The onset of action with one drop of Betagan can be detected within one hour after instillation, with maximum effect seen between two and six hours. A significant decrease can be maintained for up to 24 hours following a single dose.

Not applicable.