Ivabradine is a heart rate-lowering medicine used to treat chronic heart failure and stable angina in patients with a resting heart rate of 70 beats per minute or more. It slows the heart rate without affecting blood pressure, cardiac contractility or the heart's electrical conduction beyond the sinus node. Ivabradine is listed on India's National List of Essential Medicines (NLEM).

Drug Class: Heart Rate-Lowering Medicine - How Ivabradine Slows the Heart

Ivabradine belongs to a unique class of medicines called selective sinus node inhibitors sometimes referred to as If-channel blockers. It is the only drug in this class currently available for clinical use. Unlike beta-blockers, calcium channel blockers and digoxin which also lower heart rate ivabradine works exclusively through a single, highly specific mechanism in the sinus node without affecting other electrical or mechanical properties of the heart.

Medical Uses

Doctors prescribe ivabradine for:

• Chronic heart failure with reduced ejection fraction (HFrEF): Indicated for symptomatic heart failure in patients already on maximally tolerated beta-blocker doses (or who cannot tolerate beta-blockers) and whose resting heart rate remains at or above 70 beats per minute. Studies showed that ivabradine significantly reduced cardiovascular death and hospitalisation for heart failure

• Stable angina pectoris: Reduces the frequency of angina episodes by slowing the heart rate and reducing myocardial oxygen demand; used as an add-on to beta-blockers when heart rate is insufficiently controlled or as an alternative when beta-blockers are contraindicated or not tolerated

• Inappropriate sinus tachycardia: Used when the sinus node fires abnormally fast at rest; it effectively reduces resting and exertional heart rate in IST.

How Ivabradine Works - Blocking the If Current in the Heart

The sinus node is the heart's natural pacemaker in the right atrium that generates regular electrical impulses that set the heart rate. These impulses are controlled by the funny current (If), carried by HCN (hyperpolarisation-activated cyclic nucleotide-gated) channels in sinus node cells. During each cardiac cycle these channels open after the heart muscle relaxes, allowing ions to slowly depolarise the cell until the next heartbeat is triggered. Ivabradine blocks HCN channels when they are open, slowing the rate at which sinus node cells reach the threshold for firing the next heartbeat. Because ivabradine acts exclusively within the sinus node, it lowers heart rate without affecting blood pressure, cardiac contractility or AV nodal conduction.

Available Forms and Strengths of Ivabradine

Ivabradine is available as oral tablets. Film-coated tablets are available in 2.5 mg, 5 mg and 7.5 mg strengths. The treating physician determines the starting dose for adults and may adjust it over time based on heart rate and how the patient responds. Ivabradine should be taken twice daily with meals, which helps ensure it's absorbed consistently and works as intended.

How to Take Ivabradine 

• Twice daily dosing: Ivabradine is given twice daily, morning and evening with meals at approximately 12-hour intervals; taking ivabradine on an empty stomach increases peak drug levels and may worsen visual disturbances (phosphenes)

• Swallow tablets whole: Tablets should be swallowed whole; crushing or chewing can affect drug absorption and tolerability

• Do not stop suddenly: While ivabradine does not have the dangerous rebound effect seen with beta-blockers it should not be discontinued abruptly without medical advice.

Dosage and Duration - How Much Ivabradine to Take

 Ivabradine dosage varies and depends on the underlying conditions:

• Heart failure: Start at 5 mg twice daily; after 2 weeks, increase to 7.5 mg twice daily if resting heart rate is above 60 beats per minute; reduce to 2.5 mg twice daily (or discontinue) if resting heart rate falls below 50 beats per minute

• Stable angina: Start at 5 mg twice daily; increase to 7.5 mg twice daily after 3 to 4 weeks if heart rate control is insufficient

• Elderly patients (over 75 years): Start at 2.5 mg twice daily; titrate cautiously; elderly patients are at higher risk of bradycardia with ivabradine

Common and Serious Side Effects

Common side effects are:

• Phosphenes (visual brightness phenomena): Transient flashes of light or bright spots triggered by sudden changes in light intensity (moving from a dark room to bright sunlight); occur because HCN channels are also present in the retina

• Bradycardia (slow heart rate): The risk is higher when ivabradine is combined with other heart rate-lowering drugs

• Atrial fibrillation: Ivabradine increases the risk of new-onset atrial fibrillation; patients should be monitored for palpitations or an irregular pulse; ivabradine must be discontinued if atrial fibrillation develops

• Gastrointestinal side effects: Nausea, diarrhoea, abdominal discomfort; usually mild and transient

Precautions: Who Should Use Ivabradine with Caution?

• Patients with atrial fibrillation or flutter: Contraindicated in pre-existing AF or flutter; must be stopped if AF develops during treatment

• Patients with a resting heart rate below 70 beats per minute before starting treatment: Ivabradine should not be initiated; further slowing increases the risk of symptomatic bradycardia

• Patients with sick sinus syndrome or sinoatrial block: These conditions predispose to dangerous bradycardia; ivabradine is contraindicated

• Patients taking strong CYP3A4 inhibitors (ketoconazole, clarithromycin, itraconazole, grapefruit juice): These drugs can dramatically increase ivabradine blood levels, causing severe bradycardia

• Pregnant women: Ivabradine is contraindicated in pregnancy; women of childbearing potential should use effective contraception

Drug Interactions and Important Safety Considerations

• Strong CYP3A4 inhibitors (ketoconazole, itraconazole, clarithromycin, erythromycin, grapefruit juice): Significantly increase ivabradine blood levels; co-administration is contraindicated

• Strong CYP3A4 inducers (rifampicin, phenytoin and carbamazepine): Can significantly reduce ivabradine blood levels; dose adjustment may be needed in TB patients

• Non-dihydropyridine calcium channel blockers (verapamil, diltiazem): Co-administration is contraindicated; both drugs lower heart rate and the combination can cause severe bradycardia

• Beta-blockers: Concurrent use is generally safe and is the recommended combination in heart failure when heart rate remains above 70 beats per minute on maximally tolerated beta-blocker doses

• Digoxin: Both drugs slow the sinus rate; concurrent use increases the risk of bradycardia.

Ivabradine vs Beta-Blockers 

Key differences are:

• Mechanism: Beta-blockers block adrenaline receptors throughout the body whereas ivabradine acts exclusively on HCN channels in the sinus node, lowering heart rate without affecting blood pressure, cardiac contractility, bronchial smooth muscle or glucose metabolism

• Respiratory and metabolic safety: Beta-blockers carry a risk of bronchospasm in patients with asthma or COPD and can cause weight gain, blunt hypoglycaemia warning signs and worsen insulin resistance. However ivabradine has none of these effects, making it preferable in patients with respiratory disease or diabetes

• Clinical role: Beta-blockers are first-line therapy for heart failure, angina and hypertension whereas ivabradine is used as an add-on or alternative when beta-blockers are contraindicated, not tolerated or insufficient to control heart rate; ivabradine cannot treat hypertension and is never used as first-line therapy alone.

FAQs

1. What is ivabradine used for?

   Ivabradine is used to treat chronic heart failure with reduced ejection fraction in patients with a resting heart rate of 70 beats per minute or more who are on maximally tolerated beta-blocker doses (or cannot tolerate beta-blockers). It is also used for stable angina and off-label for inappropriate sinus tachycardia.

2. How is ivabradine different from beta-blockers for the heart?

   Ivabradine slows the heart rate by blocking HCN channels in the sinus node, without affecting adrenaline receptors, blood pressure, cardiac contractility, lung function or glucose metabolism. Beta-blockers lower both heart rate and blood pressure and can worsen asthma and mask hypoglycaemia. Ivabradine is safer in patients with asthma, COPD and diabetes.

3. Can ivabradine lower blood pressure?

   No ivabradine does not meaningfully lower blood pressure. Its mechanism is confined to HCN channels in the sinus node and does not involve vasodilation or adrenoreceptor blockade. It can slow the heart rate without causing further hypotension but cannot be used as an antihypertensive agent.

4. What are the visual side effects of ivabradine (phosphenes)?

   Phosphenes are transient flashes of light or bright spots in the visual field that occur in some patients on ivabradine and are triggered by sudden changes in light intensity (such as moving from a dark room into bright sunlight) because HCN channels are also present in the retina. They are harmless, not associated with structural eye damage and usually improve with continued treatment or dose reduction.

5. Why is ivabradine used in heart failure patients?

   In heart failure, a persistently elevated heart rate worsens outcomes. Ivabradine slows heart rate without lowering blood pressure, easing the heart's workload in patients with chronic heart failure. It's typically added when beta-blockers alone aren't enough to control heart rate particularly in those with reduced ejection fraction.

6. Can ivabradine be used with beta-blockers at the same time?

   Ivabradine is specifically designed to be used alongside beta-blockers in heart failure patients whose heart rate remains above 70 beats per minute despite maximally tolerated beta-blocker doses. The combination is well tolerated with close heart rate monitoring; ivabradine must not be combined with verapamil or diltiazem.

7. What is the brand name Ivabrad and what does it contain?

   Ivabrad is an Indian brand name for ivabradine, manufactured by Serdia Pharmaceuticals (now Sanofi), available in 2.5 mg, 5 mg and 7.5 mg film-coated tablets. Other Indian brands include Ivarich (Intas), Ivabid (Sun Pharma), and Corlanor (Cipla) all contain the same active substance with identical indications and dosing.

8. Who should not take ivabradine?

   Ivabradine should not be taken by patients with atrial fibrillation or flutter, sick sinus syndrome or sinoatrial block, a resting heart rate below 70 beats per minute, severe hepatic impairment or during pregnancy. Patients taking strong CYP3A4 inhibitors (ketoconazole, clarithromycin, itraconazole) or verapamil or diltiazem should also avoid ivabradine.

9. Does ivabradine affect the rhythm of the heart?

   Ivabradine does not directly affect cardiac rhythm and does not block sodium, potassium or calcium channels in the working myocardium or the AV node. However it is associated with an increased risk of new-onset atrial fibrillation; patients should be monitored for palpitations or an irregular pulse, and ivabradine must be discontinued if atrial fibrillation develops.

10. Is ivabradine safe for patients with atrial fibrillation?

    Ivabradine is contraindicated in patients with atrial fibrillation. It works exclusively on HCN channels in the sinus node and in atrial fibrillation, the sinus node is bypassed by chaotic electrical activity; ivabradine has no meaningful rate-controlling effect and must be stopped if AF develops.

References

1. Swedberg K, Komajda M, Böhm M, et al (SHIFT Investigators). Ivabradine and outcomes in chronic heart failure (SHIFT): a randomised placebo-controlled study. Lancet. 2010;376(9744):875–85. https://doi.org/10.1016/S0140-6736(10)61198-1

2. Fox K, Ford I, Steg PG, et al (BEAUTIFUL Investigators). Ivabradine for patients with stable coronary artery disease and left-ventricular systolic dysfunction (BEAUTIFUL). Lancet. 2008;372(9641):807–16. https://doi.org/10.1016/S0140-6736(08)61170-8

3. Fox K, Ford I, Steg PG, et al (SIGNIFY Investigators). Ivabradine in stable coronary artery disease without clinical heart failure. N Engl J Med. 2014;371(12):1091–9. https://doi.org/10.1056/NEJMoa1406430

4. McDonagh TA, Metra M, Adamo M, et al. 2021 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure. Eur Heart J. 2021;42(36):3599–726. https://doi.org/10.1093/eurheartj/ehab368

5. Cohn JN, Tognoni G. A randomised trial of the angiotensin-receptor blocker valsartan in chronic heart failure (Val-HeFT). N Engl J Med. 2001;345(23):1667–75. https://doi.org/10.1056/NEJMoa010713