Ivabradine

Heart Failure in Adults

Ivabradine is primarily used to reduce the risk of hospitalization in adults with stable, symptomatic chronic heart failure. It is typically prescribed for patients who meet specific criteria, including:

• A left ventricular ejection fraction (a measure of how well the heart pumps blood) of 35% or lower.
• A resting heart rate of at least 70 beats per minute.
• Symptoms that persist despite taking other standard heart medications.

It is often used in combination with other heart failure treatments or as an alternative for patients who cannot tolerate beta-blockers or who are already taking the maximum tolerated dose of a beta-blocker.

Heart Failure in Children

This medication is also used for children aged 6 months and older. It is indicated for the treatment of stable symptomatic heart failure caused by dilated cardiomyopathy, a condition where the heart muscle becomes enlarged and weakened.

Chronic Stable Angina

In certain regions, ivabradine is used to manage symptoms of chronic stable angina (chest pain). It is generally used for patients who have a normal heart rhythm but cannot take beta-blockers, or for those whose symptoms are not sufficiently controlled by beta-blockers alone.

Mechanism of Action

Ivabradine belongs to a class of medications called hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blockers. It works by targeting the sinoatrial node, which is the part of the heart that acts as a natural pacemaker to control the heart rate.

The medication works through the following process:

• Targeting electrical currents: Ivabradine blocks a specific electrical current in the pacemaker cells of the heart. This current is responsible for starting each heartbeat.
• Slowing the heart rate: By blocking this current, the medication increases the time between heartbeats, effectively slowing down the heart rate.
• Improving heart function: When the heart beats more slowly, it has more time to fill with blood. This allows the heart to pump blood more efficiently throughout the body.

Ivabradine is unique because it lowers the heart rate without affecting the strength of the heart's contraction or significantly impacting blood pressure.

Common Side Effects

The most frequently reported side effects of ivabradine include:

• Visual phenomena (phosphenes): A temporary increase in brightness in parts of the visual field, often triggered by sudden changes in light intensity.
• Slow heart rate (bradycardia): A pulse that is slower than normal.
• High blood pressure (hypertension): Increased blood pressure readings.
• Dizziness: Feeling lightheaded or unsteady.
• Blurred vision: General changes in visual clarity.

Serious Side Effects

Contact a healthcare provider immediately if you experience any of the following serious symptoms:

• Severe bradycardia: Symptoms such as fainting, extreme fatigue, or significant dizziness.
• Heart rhythm problems: Feeling like your heart is racing, pounding, or skipping beats (atrial fibrillation).
• Respiratory issues: New or worsening shortness of breath.
• Chest pain: Pressure or discomfort in the chest.
• Allergic reactions: Severe skin rash, itching, swelling of the face, lips, or tongue, or difficulty breathing.

Visual changes usually occur within the first two months of treatment and may resolve on their own during or after stopping the medication. Use caution when driving or operating machinery in situations where light intensity may change suddenly.

Heart Rate and Rhythm Risks

Ivabradine can cause a significantly slow heart rate (bradycardia) or increase the risk of developing atrial fibrillation, a type of irregular heart rhythm. Healthcare providers typically monitor heart rate and rhythm regularly during treatment. The risk of a slow heart rate is higher in individuals taking other medications that slow the heart, such as beta-blockers or certain calcium channel blockers.

Pregnancy and Fetal Harm

Based on animal studies, ivabradine may cause harm to a developing fetus. It is generally recommended that individuals who can become pregnant use effective contraception while taking this medication. If pregnancy occurs, the medication should be discontinued.

Visual Disturbances

Many people taking ivabradine experience temporary visual changes known as phosphenes. These are described as brief flashes of light or enhanced brightness in parts of the visual field. These effects are usually mild and often resolve on their own during treatment or after stopping the medication.

Contraindications

Ivabradine is not recommended for individuals with certain medical conditions, including:

• Acute decompensated heart failure.
• Very low blood pressure (hypotension).
• Specific heart rhythm disorders like sick sinus syndrome or high-degree heart block, unless a pacemaker is in place.
• Severe liver impairment.
• A resting heart rate that is already very slow before starting treatment.

Drug Interactions

Certain medications can significantly increase the levels of ivabradine in the body, leading to a higher risk of side effects. This medication should not be used with strong CYP3A4 inhibitors, such as certain antifungal or antiviral drugs.

Pregnancy

Ivabradine can cause fetal harm when taken during pregnancy. Research in animals has shown that the medication may lead to heart and skeletal birth defects. Because of these risks, healthcare providers typically advise against using ivabradine during pregnancy.

Individuals of reproductive potential should use effective contraception while taking this medication. If you suspect you are pregnant or plan to become pregnant, consult your healthcare provider to discuss alternative treatment options.

Breastfeeding

It is currently unknown if ivabradine is present in human breast milk. However, animal studies have demonstrated that the drug is excreted in milk. To avoid the risk of serious adverse reactions in a nursing infant, breastfeeding is generally not recommended during treatment with ivabradine. You should talk to your doctor about the risks and benefits of breastfeeding versus continuing the medication.

Available Forms

Ivabradine is provided in the following oral formulations:

• Film-coated tablets: These are solid tablets intended to be swallowed whole.
• Oral solution: This is a liquid form of the medication, which may be used for pediatric patients or individuals who have difficulty swallowing solid tablets.

FDA Approval and Indications

Ivabradine was first approved by the U.S. Food and Drug Administration (FDA) in April 2015. It is indicated to reduce the risk of hospitalization for worsening heart failure in adult patients with stable, symptomatic chronic heart failure. Eligible patients must have a left ventricular ejection fraction (LVEF) of 35% or less, be in sinus rhythm with a resting heart rate of 70 beats per minute or higher, and be on the highest tolerated dose of beta-blockers or have a contraindication to them.

In April 2019, the FDA expanded the approved use to include pediatric patients aged 6 months and older who have stable symptomatic heart failure due to dilated cardiomyopathy.

Regulatory Status and Safety Information

Ivabradine is available only by prescription. It does not currently have a boxed warning or a Risk Evaluation and Mitigation Strategy (REMS) program. However, the FDA has monitored the drug for potential safety concerns since its release. In 2016, the FDA identified a potential signal of serious risk for bradycardia (slow heart rate) and atrial fibrillation based on reports in the FDA Adverse Event Reporting System (FAERS), which led to updated safety information in the drug's official labeling.

Initial FDA Approval

The U.S. Food and Drug Administration (FDA) first approved ivabradine in April 2015. It was approved to reduce the risk of hospitalization in adults with stable, symptomatic chronic heart failure. This approval is specific to patients who have a left ventricular ejection fraction (a measure of how much blood the heart pumps out) of 35% or less. Additionally, patients must be in a normal heart rhythm (sinus rhythm) and have a resting heart rate of at least 70 beats per minute. The medication is intended for use in patients who are already taking the highest dose of beta-blockers they can tolerate or those who cannot take beta-blockers.

Pediatric Approval

In April 2019, the FDA expanded the approval of ivabradine to include children aged 6 months and older. It is used to treat stable symptomatic heart failure caused by dilated cardiomyopathy, a condition where the heart's main pumping chamber becomes enlarged and weakened. Like the adult indication, pediatric use requires the patient to be in sinus rhythm with an elevated heart rate.

Regulatory Classification

Ivabradine is the first medication in a class of drugs known as hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blockers. During its initial review, the FDA granted the drug priority review and fast-track status because it provided a new way to manage heart failure by slowing the heart rate without affecting blood pressure or the strength of the heart's contraction.