Brand Name: Kerlone, Betoptic S
Generic Name: Betaxolol HCl
Betaxolol is a cardioselective (beta-1-adrenergic) receptor blocking agent. It does not have significant membrane-stabilizing (local anesthetic) activity and is devoid of intrinsic sympathomimetic action.
Ocular: When instilled in the eye, betaxolol reduces elevated as well as normal intraocular pressure, whether or not accompanied by glaucoma. When used as a solution, the onset of action occurs within 30 minutes and the maximal effect is usually attained approximately 2 hours after instillation. Although the time of onset of action, and time of maximal effect for the suspension have not been determined, controlled double masked studies show that the magnitude and duration of the ocular hypotensive effect of betaxolol 0.5% solution and betaxolol 0.25% suspension were clinically equivalent.
A single dose provides a 12-hour reduction in intraocular pressure (IOP) and twice daily administration maintains the IOP below 22 mm Hg in most patients.
Betaxolol has no effect on pupil size or accommodation.
Systemic: Ophthalmic betaxolol is virtually devoid of systemic effects. Following oral administration, the elimination half-life of betaxolol is 14 to 22 hours, and it is metabolized mainly to inactive substances which are excreted in the urine. Although betaxolol is absorbed systemically, ophthalmic doses do not ordinarily produce pharmacologically active tissue levels and thus, despite its cardioselective beta blocking activity, it has minimal, if any, effect on heart rate or blood pressure.
Betaxolol has a low affinity for β2-adrenergic receptors, and ophthalmic doses have no significant effect on pulmonary function as measured by forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and FEV1/FVC. Ophthalmic doses do not inhibit the effect of isoproterenol, a beta-adrenergic stimulant, on pulmonary function. Therefore, ophthalmic betaxolol may be used in the treatment of patients with glaucoma or ocular hypertension who have coexisting reactive airway disease.
For lowering intraocular pressure in the treatment of ocular hypertension or chronic open angle glaucoma. May be used alone or in combination with other IOP-lowering medication.
Patients who are receiving a beta-adrenergic blocking agent orally and ophthalmic betaxolol should be observed for a potential additive effect either on the intraocular pressure or on the known systemic effects of beta blockade.
Although ophthalmic betaxolol has demonstrated a low potential for systemic effects, it should be used with caution in patients with bradycardia, and those with diabetes (especially labile diabetes) because of possible masking of hypoglycemia. Consideration should be given to the gradual withdrawal of all beta-adrenergic blocking agents in patients suspected of developing thyrotoxicosis, and also prior to general anesthesia, because of the reduced ability of the heart to respond to beta-adrenergically mediated sympathetic reflex stimuli.
Betaxolol, a cardioselective beta-blocker, has produced only minimal effects in patients with reactive airway disease; however, caution should be exercised in the treatment of patients with excessive restriction of pulmonary function.
In patients with angle-closure glaucoma, the immediate treatment objective is to reopen the angle by constriction of the pupil with a miotic agent. Betaxolol has no effect on the pupil; therefore, ophthalmic betaxolol should be used with a miotic to reduce elevated intraocular pressure in angle-closure glaucoma.
As with the use of other antiglaucoma drugs, diminished responsiveness to ophthalmic betaxolol after prolonged therapy has been reported in some patients. However, in one long-term study in which 250 patients treated with betaxolol ophthalmic solution have been followed for up to 3 years, no significant difference in mean intraocular pressure has been observed after initial stabilization.
Although ophthalmic betaxolol used alone has little or no effect on pupil size, mydriasis resulting from concomitant therapy with epinephrine has been reported occasionally.
Close observation of the patient is recommended when a beta-blocker is administered to patients receiving oral beta-adrenergic blocking drugs, or catecholamine-depleting drugs such as reserpine, because of possible additive effects. Caution should be exercised in patients using concomitant adrenergic psychotropic drugs.
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