Overview
Xamoterol is a cardioselective beta-1 adrenergic receptor partial agonist used primarily for its inotropic effects in heart failure. It acts as an agonist when sympathetic tone is low and as an antagonist when sympathetic tone is high, providing a unique pharmacological profile.
Mechanism of Action
Xamoterol is a partial agonist at beta-1 adrenergic receptors in the heart. It has approximately 43% of the intrinsic sympathomimetic activity of isoprenaline. At low sympathetic tone, it acts as an agonist to increase cardiac contractility and heart rate. At high sympathetic tone (such as during exercise), it acts as an antagonist to prevent excessive cardiac stimulation.
Indications
- Chronic mild to moderate heart failure
- Management of symptoms in heart failure patients
Dosage
Typically 200 mg twice daily. Dosage should be individualized based on patient response and tolerance. Treatment should be initiated at lower doses and titrated upward.
Contraindications
- Severe or unstable heart failure
- Acute myocardial infarction
- Cardiogenic shock
- Severe bradycardia
- Heart block greater than first degree
- Hypersensitivity to xamoterol or related compounds
Side Effects
- Palpitations
- Tachycardia
- Dizziness
- Headache
- Nausea
- Fatigue
- Dyspnea
- Insomnia
- Muscle cramps
Interactions
- Calcium channel blockers (additive negative inotropic effects)
- Other beta-blockers (additive effects)
- Digoxin (potential additive effects on heart rate)
- Antiarrhythmic drugs
- Insulin and oral hypoglycemics (masking of hypoglycemic symptoms)