Betaxolol

BRAND NAMES

Common brand names for Betaxolol include Kerlone (oral tablets for hypertension) and Betoptic(eye drops for glaucoma). These brands may vary by country, and formulations are available for both systemic and ocular use.

MECHANISM OF ACTION

Betaxolol works by selectively blocking beta-1 adrenergic receptors in the heart and eyes. This reduces the effects of adrenaline and noradrenaline, leading to decreased heart rate and cardiac output, which lowers blood pressure, and reduced aqueous humor production in the eyes, lowering intraocular pressure in glaucoma patients.

PHARMACOKINETICS

Absorption

Betaxolol is well absorbed after oral administration, with peak blood levels occurring within 1–2 hours. When used as eye drops, only a small portion is systemically absorbed, primarily through the nasolacrimal duct, resulting in lower overall blood levels compared to oral dosing.

Distribution

Betaxolol is widely distributed throughout the body. About 60–70% of the drug binds to plasma proteins, while the remaining portion is free and pharmacologically active. It also crosses the placenta and may enter breast milk, so caution is advised during pregnancy and lactation.

Metabolism

Betaxolol is partially metabolized in the liver by hepatic enzymes into inactive metabolites. A portion of the drug is excreted unchanged by the kidneys, so both liver and kidney function can affect its elimination and overall drug levels.

Excretion

Betaxolol is primarily excreted through the urine, with about 50–60% of an oral dose eliminated unchangedby the kidneys. The remaining portion is excreted as inactive metabolites. 

PHARMACODYNAMICS

Betaxolol’s pharmacodynamics involve selective beta-1 receptor blockade, which reduces heart rate, cardiac output, and renin release, lowering blood pressure. In the eyes, it decreases aqueous humor production, reducing intraocular pressure and helping prevent optic nerve damage in glaucoma.

ADMINISTRATION

Betaxolol can be administered orally as tablets for hypertension or topically as eye drops for glaucoma. Oral tablets are taken once or twice daily with or without food, while eye drops are typically applied one or two times daily in the affected eye(s), following the doctor’s instructions.

DOSAGE AND STRENGTH

• Oral tablets (for hypertension): Usually 10–20 mg once daily, may be increased up to 40 mg daily based on response.

• Eye drops (for glaucoma): Typically 0.25% or 0.5% solution, applied 1 drop in the affected eye once or twice daily.

FOOD INTERACTIONS

Betaxolol has minimal food interactions, though alcohol may increase dizziness or low blood pressure, and high-fat meals can slightly delay absorption. 

DRUG INTERACTIONS

• Other blood pressure medications (e.g., calcium channel blockers, ACE inhibitors) – may cause excessive blood pressure lowering.

• Antiarrhythmics – can increase the risk of slow heart rate or heart block.

• Insulin or oral diabetes drugs – may mask symptoms of low blood sugar.

• NSAIDs – may reduce the blood pressure–lowering effect of Betaxolol.

• Other beta-blockers – can increase risk of bradycardia or hypotension.

CONTRAINDICATIONS

Betaxolol is contraindicated in patients with severe bradycardia, heart block greater than first degree, cardiogenic shock, or overt heart failure. It should also be avoided in individuals with severe asthma or chronic obstructive pulmonary disease (COPD) due to the risk of bronchospasm and in those with a known allergy to beta-blockers.

SIDE EFFECTS

• Fatigue

• Dizziness

• Slow heart rate (bradycardia)

• Low blood pressure (hypotension)

• Cold hands or feet

• Eye irritation

• Burning

• Stinging

• Blurred vision

• Shortness of breath

• Depression

• Worsening heart failure can occur, especially with oral use.

TOXICITY

Betaxolol toxicity can result from overdose or excessive use, leading to severe bradycardia, hypotension, heart block, or heart failure. Other signs may include dizziness, fainting, shortness of breath, and fatigue. Immediate medical attention is required in cases of suspected overdose.