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Dosage/Direction for Use
Oral Hypertension Adult: Initially, 10 mg once daily, may increase to 20 mg/day after 1-2 wk if needed. Elderly: Initially, 5 mg/day. Renal impairment: Severe or on dialysis: Initially, 5 mg/day, may increase by increments of 5 mg every 2 wk. Max: 20 mg/day. Ophthalmic Open-angle glaucoma Adult: As 0.25% or 0.5% drops: Instill 1 drop bid. Ophthalmic Ocular hypertension Adult: As 0.25% or 0.5% drops: Instill 1 drop bid. |
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Administration
May be taken with or without food.
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Contraindications
Sick sinus syndrome, severe bradycardia, cardiogenic shock, uncontrolled cardiac failure, 2nd or 3rd degree AV block, severe bronchial asthma, severe COPD, metabolic acidosis, untreated phaeochromocytoma, severe peripheral arterial disease.
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Special Precautions
Patients w/ bronchospastic disease, DM, corneal disease. May mask signs of hyperthyroidism and acute hypoglycaemia. Avoid abrupt withdrawal as it may exacerbate angina, MI, ventricular arrhythmias and precipitate thyroid storm. Patients undergoing surgery involving general anaesth. Renal and hepatic impairment. Pregnancy and lactation. Monitoring Parameters Monitor BP, pulse and baseline renal function.
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Adverse Reactions
Eye discomfort (stinging and burning), bradycardia, palpitation, chest pain, oedema, insomnia, fatigue, lethargy, nausea, dyspepsia, diarrhoea, arthralgia, paraesthesia, dyspnoea, pharyngitis, antinuclear antibody positive, cold extremities.
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Overdosage
Symptoms: Symptomatic bradycardia, bronchospasm, hypotension and acute cardiac failure. Management: Perform gastric lavage. Administer IV atropine sulfate to induce vagal blockade; dopamine, dobutamine or norepinephrine for hypotension and glucagon for refractory cases; isoprenaline HCl and aminophylline for bronchospasm; conventional therapy w/ digitalis, diuretics and oxygen for acute cardiac failure.
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Drug Interactions
Increased risk of bradycardia w/ digitalis glycosides. May cause mydriasis w/ epinephrine. Potential additive effect w/ oral Ca channel blockers, β-adrenergic blockers, antiarrhythmics (including amiodarone), parasympathomimetics, guanethidine. Increased risk of myocardial depression and hypotension w/ peripheral muscle relaxants (e.g. tubocurarine).
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Food Interaction
May increase plasma level w/ alcohol.
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Lab Interference
May interfere result w/ glaucoma screening test (oral).
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Action
Betaxolol is a cardioselective β-blocker which has greater affinity for β1-receptors and has little or no effect on β2-receptors. It lacks intrinsic sympathomimetic but has little membrane-stabilising activity. It also causes the reduction of intraocular pressure by decreasing the production of aqueous humour.
Onset: 1-1.5 hr (oral). Absorption: Completely absorbed from the GI tract. Oral bioavailability: Approx 90%. Distribution: Crosses the placenta and is distributed into the breast milk. Plasma protein binding: Approx 50%. Metabolism: Undergoes minimal first-pass metabolism. Excretion: Via urine (approx 15% as unchanged drug). Elimination half-life: 14-22 hr. |
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Storage
Ophthalmic: Store between 15-25°C. Oral: Store between 15-25°C.
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CIMS Class
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ATC Classification
S01ED02 - betaxolol ; Belongs to the class of beta blocking agents. Used in the treatment of glaucoma.
C07AB05 - betaxolol ; Belongs to the class of selective beta-blocking agents. Used in the treatment of cardiovascular diseases. |
