A1,
A2,
B,
C1,
C2,
D,
E,
F,
G-H,
I-K,
L,
M,
N,
O,
P1,
P2,
Q-R,
S,
T,
U-V,
W-Z
Betaxon Pharmacology, Pharmacokinetics, Studies, Metabolism - Levobetaxolol
Betaxon Pharmacology, Pharmacokinetics, Studies, Metabolism - Levobetaxolol
CLINICAL PHARMACOLOGY
Levobetaxolol is a cardioselective (beta-1-adrenergic) 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™ 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. In two well-controlled clinical
studies in which a total of 356 patients were dosed for three months, BETAXON™
Ophthalmic Suspension produced clinically relevant reductions in IOP at all
follow-up visits. At 8 AM after nighttime dosing (trough), IOP was reduced from
baseline approximately 4 to 5 mmHg (16% to 21%). At 10 AM, two hours after dosing
(peak), IOP was reduced from baseline approximately 5 to 6 mmHg (20% to 23%).
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. 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 of intraocular
pressure.
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 (C 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.
In comparisons between BETAXON™ Ophthalmic Suspension and non-cardioselective
beta blockers in reactive airway subjects, BETAXON™ Ophthalmic Suspension is
expected to demonstrate less effect on pulmonary function [FEV 1 and
Forced Vital Capacity (FVC)].
The cardiovascular effects of BETAXON™ 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.
top
