Betaxolol is a cardioselective beta-1 adrenergic receptor antagonist (beta-blocker) formulated as an ophthalmic solution for topical use in the eye. In the Indian market, the 0.5% w/v concentration is the standard and primary strength used for the management of chronic open-angle glaucoma and ocular hypertension. It reduces elevated and normal intraocular pressure (IOP) with minimal effect on pulmonary and cardiovascular parameters due to its relative beta-1 selectivity, making it a preferred choice for patients with mild reactive airway disease where non-selective beta-blockers are contraindicated.
Adult: One drop (approx. 0.05 mL of 0.5% solution) instilled into the affected eye(s) twice daily, approximately 12 hours apart.
Note: 1. Wash hands. 2. Tilt head back. 3. Gently pull lower eyelid down to form a pouch. 4. Instill one drop into the pouch without touching the dropper tip to eye, fingers, or any surface. 5. Close eyes gently. 6. Apply pressure with a finger to the tear duct (nasolacrimal occlusion) for 1-2 minutes to reduce systemic absorption. 7. If using other eye drops, wait at least 5-10 minutes between applications.
Betaxolol is a competitive antagonist at beta-1 adrenergic receptors. In the eye, it reduces the production of aqueous humor by the ciliary body. The exact mechanism is not fully elucidated but is believed to involve inhibition of adenylate cyclase and reduction of cyclic AMP (cAMP) in ciliary epithelial cells, leading to decreased aqueous inflow.
Pregnancy: Pregnancy Category C (US FDA). Animal studies have shown adverse effects. There are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus. Systemic beta-blockers have been associated with fetal bradycardia, hypoglycemia, and intrauterine growth restriction.
Driving: May cause transient blurred vision, dizziness, or fatigue after instillation. Patients should not drive or operate machinery until their vision is clear and they are sure the medication does not affect them adversely.
| Other Systemic Beta-Blockers (e.g., Metoprolol, Atenolol) | Additive bradycardia, hypotension, AV block, and heart failure risk. | Major |
| Calcium Channel Blockers (especially Verapamil, Diltiazem) | Potentiates negative inotropic and chronotropic effects; risk of severe bradycardia and heart failure. | Major |
| Digoxin | Additive effects on AV conduction, increasing risk of bradycardia and block. | Moderate |
| Insulin & Oral Hypoglycemics | May mask tachycardia (a warning sign of hypoglycemia) and potentially prolong hypoglycemia. | Moderate |
| Catecholamine-depleting drugs (e.g., Reserpine) | Additive hypotensive and bradycardic effects; may cause vertigo or syncope. | Moderate |
| NSAIDs (e.g., Indomethacin) | May theoretically reduce the intraocular pressure-lowering effect of betaxolol. | Minor |
| Adrenergic Agonists (e.g., Epinephrine in local anesthetics) | Potential for hypertension and bradycardia due to unopposed alpha-action. | Moderate |
| Clonidine | Potentiates rebound hypertension if clonidine is withdrawn while on beta-blocker. | Major |