BETAXON
Clinical safety rating: caution
Comprehensive clinical and safety monograph for BETAXON (BETAXON).
Selective beta-1 adrenergic receptor antagonist; reduces intraocular pressure by decreasing aqueous humor production through inhibition of beta-1 receptors in the ciliary epithelium.
| Metabolism | Hepatic metabolism primarily via CYP2D6; undergoes extensive first-pass metabolism. |
| Excretion | Primarily renal (40-50% unchanged) and fecal (30-40% as metabolites); biliary excretion contributes minimally. |
| Half-life | Terminal elimination half-life is 12-18 hours; prolonged in renal impairment (up to 36 hours). |
| Protein binding | 95-98% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | 0.8-1.2 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral: 75-90% (first-pass metabolism minimal). |
| Onset of Action | Oral: 1-2 hours; Intravenous: 5-10 minutes. |
| Duration of Action | 6-12 hours; extended in hepatic or renal dysfunction. |
0.25% ophthalmic solution, 1 drop in the affected eye(s) twice daily.
| Dosage form | SUSPENSION/DROPS |
| Renal impairment | No dose adjustment required for renal impairment. |
| Liver impairment | Use with caution in severe hepatic impairment; no specific dose adjustment guidelines available. |
| Pediatric use | Not established; safety and efficacy in pediatric patients have not been determined. |
| Geriatric use | No specific dose adjustment recommended; use with caution due to potential for increased systemic absorption and adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for BETAXON (BETAXON).
| Breastfeeding | Betaxolol is excreted into human breast milk. The milk-to-plasma (M/P) ratio is approximately 0.5-0.6. Infant exposure is estimated at <10% of the maternal weight-adjusted dose. Monitor infant for signs of beta-blockade (bradycardia, hypotension, hypoglycemia). Use with caution in breastfeeding mothers, especially with preterm or low-birth-weight infants. |
| Teratogenic Risk | Betaxolol is a beta-1 selective adrenergic receptor blocker. In animal studies, beta-blockers have been associated with embryotoxicity and fetal growth restriction at high doses. Human data are limited. First trimester: Risk of congenital anomalies is low based on available data; however, beta-blockers cross the placenta. Second and third trimesters: Exposure may cause fetal bradycardia, hypoglycemia, and reduced placental perfusion, leading to intrauterine growth restriction. Use only if benefit outweighs risk and consider fetal monitoring. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to betaxolol or any component of the formulation; sinus bradycardia; second- or third-degree AV block; cardiogenic shock; overt heart failure; bronchial asthma or severe COPD.
| Precautions | May exacerbate asthma, COPD, and other bronchospastic diseases; may mask symptoms of hypoglycemia in diabetic patients; may cause bradycardia and heart block; may potentiate muscle weakness in myasthenia gravis; may cause corneal anesthesia; use with caution in patients with sinus node dysfunction or heart failure. |
| Food/Dietary | No significant food interactions reported. Avoid excessive alcohol consumption as it may enhance hypotensive effects. |
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| Fetal Monitoring | Maternal: Monitor heart rate, blood pressure, and signs of bronchospasm. Fetal: Ultrasound for fetal growth and amniotic fluid volume, fetal heart rate monitoring (especially during third trimester). Neonatal: Observe for bradycardia, hypoglycemia, and respiratory depression for 48-72 hours postpartum. |
| Fertility Effects | Limited data. Beta-blockers may seldom cause erectile dysfunction in males, but effects on female fertility are unknown. No direct evidence of impaired fertility in humans. Animal studies have not shown significant fertility impairment. |
| Clinical Pearls | Betaxolol is a cardioselective beta-1 blocker with intrinsic sympathomimetic activity (ISA) and membrane-stabilizing activity. Predominantly used for hypertension and glaucoma. In ocular form, minimal systemic absorption but can trigger bronchospasm in asthmatics due to beta-2 blockade at high doses. Use cautiously in diabetes (may mask hypoglycemia) and in patients with bradycardia or heart block. Avoid abrupt cessation in coronary artery disease. Dose adjustment needed in severe hepatic impairment. |
| Patient Advice | Do not stop taking this medication suddenly without consulting your doctor, especially if you have heart disease; sudden stop can worsen chest pain or cause a heart attack. · Take exactly as prescribed, usually once daily with or without food. For eye drops, shake well before use and apply pressure to the inner corner of the eye (nasolacrimal occlusion) for 1-2 minutes to reduce systemic absorption. · Betaxolol may mask signs of low blood sugar (tachycardia, palpitations); monitor blood glucose carefully if diabetic. · Avoid driving or operating heavy machinery until you know how this medication affects you; it may cause dizziness or fatigue. · Tell your doctor if you experience unusual weight gain, swelling, shortness of breath, or slow/irregular heartbeat. · If you have asthma or COPD, use with caution and report any worsening breathing difficulty immediately. |