Za Pharmacy
Drugs, Supplies and Delivery
Ivabradine
Ivabradine is a unique medication that selectively lowers heart rate without affecting myocardial contractility or vascular tone. It is primarily used in the management of chronic heart failure and angina pectoris, particularly in patients who cannot tolerate beta-blockers. This article synthesizes information from the British National Formulary (BNF), Lippincott Textbook of Pharmacology, and Lange Basic & Clinical Pharmacology to provide a detailed overview of ivabradine, including its mechanism, uses, dosing, side effects, precautions, and drug interactions.
Ivabradine selectively inhibits the If (funny) channels in the sinoatrial (SA) node, which are responsible for the pacemaker current that regulates heart rate. By blocking these channels, ivabradine:
- Reduces heart rate without affecting myocardial contractility or blood pressure.
- Improves myocardial oxygen supply by prolonging diastolic filling time, making it particularly useful in angina and heart failure (Lippincott, Lange).
Unlike beta-blockers, ivabradine does not affect bronchial smooth muscle or peripheral vascular resistance, making it a safer option for patients with asthma or peripheral vascular disease (BNF).
- Chronic Heart Failure:
- Indicated for patients with symptomatic heart failure with reduced ejection fraction (HFrEF) and a heart rate ≥75 beats per minute (bpm) despite optimal therapy, including beta-blockers (BNF).
- Chronic Stable Angina:
- Used in patients with normal sinus rhythm who are intolerant to or inadequately controlled by beta-blockers (Lippincott).
- Heart Failure:
- Initial dose: 5 mg twice daily, increased to 7.5 mg twice daily if heart rate remains above 60 bpm after 2 weeks (BNF).
- Angina:
- Initial dose: 5 mg twice daily, increased to 7.5 mg twice daily if needed (Lippincott).
Administration:
- Take with or without food.
- Avoid grapefruit juice, as it increases ivabradine levels and the risk of side effects (Lange).
- Common: Luminous phenomena (visual brightness, often described as "phosphenes"), bradycardia, and headache (Lippincott).
- Serious: Severe bradycardia, atrial fibrillation, and QT prolongation (BNF).
- Bradycardia: Avoid in patients with a resting heart rate <60 bpm before treatment (Lange).
- Pacemaker Dependency: Contraindicated in patients relying on pacemakers for rhythm control (BNF).
- Liver Impairment: Use with caution in moderate to severe hepatic impairment; dose adjustment may be necessary (Lippincott).
- Pregnancy and Lactation: Use only if benefits outweigh risks; limited data available (Lange).
- CYP3A4 Inhibitors (e.g., ketoconazole, erythromycin): Increase ivabradine levels, raising the risk of bradycardia and other side effects (BNF).
- Grapefruit Juice: Inhibits CYP3A4, increasing ivabradine bioavailability and risk of side effects (Lippincott).
- QT-Prolonging Drugs: Concurrent use may increase the risk of arrhythmias (Lange).
Ivabradine is the generic name for this medication. It is marketed under the brand name Procoralan® in some regions. Generic versions are also available, making it more accessible for patients.
