Betaxolol Hydrochloride

Trade Names:Betoptic- Solution 5.6 mg (equivalent to 5 mg base) per mL (0.5%)

Trade Names:Betoptic-S- Suspension 2.8 mg (equivalent to 2.5 mg base) per mL (0.25%)

Trade Names:Kerlone- Tablets 10 mg- Tablets 20 mg

Pharmacology

Blocks beta receptors, primarily affecting cardiovascular system (decreases heart rate, cardiac contractility, and BP) and lungs (promotes bronchospasm). Ophthalmic use reduces IOP, probably by reducing aqueous production.

Pharmacokinetics

Absorption

Bioavailability is about 89%, C _max is about 21.6% ng/mL (10 mg dose), and T _max is about 3 h.

Distribution

Approximately 50% protein bound.

Metabolism

Metabolized in liver to inactive metabolites.

Elimination

The t _½ is 14 to 22 h. More than 80% is recovered in urine as betaxolol and metabolites; about 15% excreted as unchanged drug.

Onset

24 h.

Within 30 min.

Peak

7 to 14 days.

2 h.

Duration

12 h.

Special Populations

In moderate to severe impairment, Cl is decreased significantly. In those undergoing dialysis, the t _½ and AUC are approximately doubled. Dosage adjustment required for those with severe renal function impairment and those undergoing dialysis.

The t _½ may be prolonged but Cl is unchanged. Dosage adjustments not needed.

Elimination may be decreased. Dosage adjustment required.

Indications and Usage

Hypertension.

Lowering IOP; ocular hypertension; chronic open-angle glaucoma.

Contraindications

Hypersensitivity to beta-blockers; sinus bradycardia; greater than first-degree heart block; CHF unless secondary to tachyarrhythmia treatable with beta-blockers; overt cardiac failure; cardiogenic shock.

Dosage and Administration

PO 10 to 20 mg/day.

PO Reduce initial dose to 5 mg/day.

Ophthalmic 1 to 2 drops twice daily in affected eye(s). Consider concomitant therapy if IOP is not at satisfactory level.

Storage/Stability

Store oral form in cool location. Store ophthalmic form at room temperature. Do not freeze.

Drug Interactions

May enhance or reverse antihypertensive effect; potentially life-threatening situations may occur, especially on withdrawal.

Some agents may impair antihypertensive effect.

May increase postural hypotension.

May increase effects of both drugs.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Hypotension; bradycardia; CHF; cold extremities; second- or third-degree heart block; arrhythmias; syncope.

CNS

Insomnia; fatigue; dizziness; depression; lethargy; drowsiness; forgetfulness; headache.

Dermatologic

Rash; hives; alopecia.

EENT

Dry eyes; blurred vision; tinnitus; slurred speech; dry mouth; sore throat. Ophthalmic use may cause eye discomfort or stinging; tearing; keratitis; blepharoptosis; visual disturbances; diplopia; ptosis.

GI

Nausea; vomiting; diarrhea; constipation.

Genitourinary

Impotence; painful, difficult, or frequent urination.

Hematologic

Agranulocytosis; thrombocytopenic purpura.

Hepatic

Elevated LFTs.

Metabolic

Acidosis; diabetes; hypercholesterolemia; hyperlipidemia; increased LDH; hypokalemia.

Respiratory

Bronchospasm; dyspnea; wheezing.

Miscellaneous

Weight changes; fever; facial swelling; muscle weakness. Ophthalmic betaxolol may produce the same adverse drug reactions seen with systemic use; antinuclear antibodies may develop.

Precautions

Pregnancy

Category C .

Lactation

Excreted in breast milk.

Children

Safety and efficacy not established.

Elderly

Dosage reduction may be necessary.

Renal Function

Use with caution.

Hepatic Function

Use with caution.

Anaphylaxis

Deaths have occurred with anaphylactic reactions to beta-blockers; aggressive therapy may be required.

Angle-closure glaucoma

To effectively reduce elevated IOP in angle-closure glaucoma, use with miotic agent.

Cessation of therapy

Gradually withdraw over about 2 wk. Carefully observe patients and allow minimal physical activity.

CHF

Cautiously administer in patients whose CHF is controlled by digitalis and diuretics.

Diabetes mellitus

May mask symptoms of hypoglycemia (eg, tachycardia, BP changes). May potentiate insulin-induced hypoglycemia.

Nonallergic bronchospastic disease (eg, chronic bronchitis, emphysema)

In general, beta-blockers are not given to patients with bronchospastic diseases.

Peripheral vascular disease

May precipitate or aggravate symptoms of arterial insufficiency.

Systemic absorption

Ophthalmic betaxolol may produce same adverse reactions seen with systemic use because of absorption.

Thyrotoxicosis

May mask clinical signs (eg, tachycardia) of developing or continuing hyperthyroidism. Abrupt withdrawal may exacerbate symptoms of hyperthyroidism, including thyroid storm.

Overdosage

Symptoms

Bradycardia, CHF, hypotension, bronchospasm, hypoglycemia.

Patient Information

• Explain that full effectiveness of drug may not occur for up to 1 to 2 wk after initiation of therapy and that dosage will be tapered slowly before stopping to prevent adverse effects (eg, hypotension, tachycardia, anxiety, angina, MI).
• Teach patient how to monitor pulse before taking oral medication, and advise to contact health care provider if pulse remains less than 50 bpm.
• Inform patients with diabetes to monitor blood glucose level closely.
• Advise patient that ophthalmic solution may cause initial burning or stinging when first instilled in eye.
• Instruct patient to inform health care provider of any scheduled surgery or dental work; dosage may need to be gradually tapered (and ophthalmic solution discontinued) before surgery or treatment.
• Explain that measurements of IOP will need to be performed on a regular basis to assess the therapeutic effect of the ophthalmic medication.
• Instruct patient to report the following symptoms to health care provider: dizziness, decreased pulse, shortness of breath, confusion, rash, or any unusual bleeding.
• Instruct patient not to take OTC medications (including diet aids, cold or nasal preparations [alpha-adrenergic stimulants]) without consulting health care provider.
• Advise patient that drug may cause drowsiness, and to use caution while driving or performing other tasks requiring mental alertness.

Copyright © 2009 Wolters Kluwer Health.