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Betaxon

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Betaxon

Betaxon

CLINICAL PHARMACOLOGY

Mechanism of Action

Levobetaxolol is a cardioselective (beta-1adrenergic) receptor blocking agent that does not have significant membrane-stabilizing (local anesthetic) activity and is devoid of intrinsic sympathomimetic action. Animal studies suggest levobetaxolol (S-isomer) is the more active enantiomer of betaxolol (racemate).

When instilled in the eye, BETAXON™ (levobetaxolol hydrochloride ophthalmic suspension) Ophthalmic Suspension has the action of reducing elevated intraocular pressure. Elevated IOP presents a major risk factor in glaucomatous field loss. The higher the level of IOP, the greater the likelihood of optic nerve damage and visual field loss.

Since racemic betaxolol and other beta-adrenergic antagonists have been shown to reduce intraocular pressure by a reduction of aqueous production as demonstrated by tonography and aqueous fluorophotometry, it is assumed that the mechanism of action of levobetaxolol is similar.

Pharmacodynamics

The intraocular pressure lowering effect of racemic betaxolol can generally be noted within 30 minutes and the maximal effect can usually be detected two hours after topical administration. It is assumed that the intraocular pressure lowering time profile of levobetaxolol is similar. A single dose provides approximately a 12-hour reduction in intraocular pressure.

Pharmacokinetics

BETAXON™ Ophthalmic Suspension 0.5% (levobetaxolol hydrochloride ophthalmic suspension) was dosed topically for 7 days to steady-state in 20 normal volunteers. An average maximal levobetaxolol plasma concentration (Cmax) of 0.5 0.14 ng/mL was reached about three hours after the last dose. The mean half-life of levobetaxolol was approximately 20 hours.

Clinical Studies

In two well-controlled clinical studies in which a total of 356 patients were dosed for three months, BETAXON (levobetaxolol hydrochloride ophthalmic suspension) &™ Ophthalmic Suspension produced clinically relevant reductions in IOP at a follow-up visit. At 8 AM after nighttime dosing (trough), IOP was reduced from baseline approximately 4 to 5 mmHg (16% to 21%). At 10AM, two hours after dosing (peak), IOP was reduced from baseline approximately 5 to 6 mmHg (20% to 23%).

In comparisons between BETAXON (levobetaxolol hydrochloride ophthalmic suspension) TM Ophthalmic Suspension 0.5% and non-cardioselective beta blockers in reactive airway subjects, BETAXON (levobetaxolol hydrochloride ophthalmic suspension) TM Ophthalmic Suspension is expected to demonstrate less effect on pulmonary function [FEV1 and Forced Vital Capacity (FVC)].

The cardiovascular effects of BETAXON™ (levobetaxolol hydrochloride ophthalmic suspension) Ophthalmic Suspension 0.5% and betaxolol ophthalmic solution 1% were compared in double-masked, crossover studies to timolol maleate ophthalmic solution 0.5%. Levobetaxolol and betaxolol were shown during exercise to have significantly less effect on heart rate and systolic blood pressure than timolol maleate.

Last reviewed on RxList: 3/30/2010
This monograph has been modified to include the generic and brand name in many instances.

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