Overview
Ivabradine is a selective sinus node If channel inhibitor that reduces heart rate without affecting myocardial contractility, conduction velocity, or blood pressure. It is used for chronic heart failure and chronic stable angina.
Mechanism of Action
Selectively inhibits the If (funny) current in the sinoatrial node, reducing spontaneous depolarization and heart rate without affecting other cardiac parameters.
Indications
- Chronic heart failure (NYHA Class II-IV) with systolic dysfunction
- Chronic stable angina pectoris in patients with normal sinus rhythm
Dosage
Initial: 5 mg twice daily with meals. May increase to 7.5 mg twice daily after 2 weeks if needed. Maximum: 7.5 mg twice daily.
Contraindications
- Sick sinus syndrome
- Sinoatrial block
- Heart rate <60 bpm before treatment
- Cardiogenic shock
- Acute myocardial infarction
- Severe hypotension (<90/50 mmHg)
- Pacemaker dependence
- Severe hepatic impairment
- Concomitant use with strong CYP3A4 inhibitors
- Pregnancy
Side Effects
- Bradycardia
- Phosphenes (visual disturbances)
- Headache
- Dizziness
- Hypertension
- Atrial fibrillation
- First-degree AV block
- Vertigo
- Nausea
- Constipation
Interactions
- Strong CYP3A4 inhibitors (ketoconazole, clarithromycin) - contraindicated
- Moderate CYP3A4 inhibitors (verapamil, diltiazem) - reduce ivabradine dose
- QT-prolonging drugs
- Heart rate-lowering agents (beta-blockers, digoxin)