Ivabradine

Introduction Overview

Generic Name

ivabradine

Brand Name

Corlanor

Dosage Form

oral liquid (5 mg/5 mL), oral tablet (5 mg; 7.5 mg)

Drug Class

Miscellaneous cardiovascular agents

Pharmacokinetics

Absorption: Ivabradine is well absorbed from the gastrointestinal tract following oral administration. It exhibits peak plasma concentrations approximately 1 hour after dosing, indicating rapid absorption. Food intake slightly delays the time to peak concentration but does not significantly affect the bioavailability. The oral bioavailability is about 40%, attributable to first-pass metabolism in the liver and gut. Clinical studies also show that coadministration with food improves tolerability by reducing transient adverse effects related to rapid absorption.

Distribution: Ivabradine is extensively distributed throughout the body tissue with an apparent volume of distribution of approximately 70 liters. It is approximately 70% bound to plasma proteins, primarily albumin. The drug crosses into cardiac tissue effectively, facilitating its action on sinoatrial node tissues. Given its lipophilicity, ivabradine penetrates various tissues, but central nervous system penetration is minimal, limiting central adverse effects.

Metabolism: Ivabradine undergoes extensive hepatic metabolism primarily via the cytochrome P450 3A4 (CYP3A4) isoenzyme system. The major metabolic pathway is oxidative metabolism resulting in multiple inactive metabolites. The metabolism is subject to drug interactions with CYP3A4 inhibitors or inducers, which may increase or decrease ivabradine plasma levels, potentially leading to toxicity or therapeutic failure. Genetic polymorphisms of CYP3A4 can also influence metabolic clearance.

Elimination: The elimination half-life of ivabradine is approximately 2 hours; however, its effective heart rate-reducing action persists longer due to its active metabolites with half-lives of up to 11 hours. Ivabradine and its metabolites are primarily excreted in the urine (about 70%), with the remainder excreted via feces. Renal impairment moderately affects clearance, necessitating cautious dosing. Ivabradine does not accumulate significantly with repeated dosing in patients with normal renal and hepatic function.

Dosage Forms

Available Dosage Forms:
- Oral Liquid: 5 mg/5 mL solution provided in single-use plastic ampules.
- Oral Tablet: Immediate-release tablets available in 5 mg and 7.5 mg strengths.

Dosages for Adults and Adolescents:
- Adults with chronic heart failure: Initial dosing is 5 mg orally twice daily with meals. Based on clinical assessment after 2 weeks, dosage may be titrated by 2.5 mg increments to a maximum of 7.5 mg twice daily to achieve a resting heart rate of 50-60 bpm. Dose reduction is indicated for bradycardia symptoms or heart rates below 50 bpm.
- Special consideration for patients with conduction defects or risk of bradycardia: initiate at 2.5 mg twice daily.

Specific Patient Populations:
- Pediatric patients aged 6 months and older with stable symptomatic dilated cardiomyopathy heart failure:
- For those weighing less than 40 kg: initiate oral solution at 0.05 mg/kg twice daily with food. Dose adjustments made at 2-week intervals targeting a 20% heart rate reduction, not exceeding 0.2 mg/kg twice daily in infants less than 1 year, and 0.3 mg/kg twice daily in older children; maximum total dose capped at 7.5 mg per dose twice daily.
- For those 40 kg or greater: oral tablets at starting dose of 2.5 mg twice daily with titration up to 7.5 mg twice daily.
- Patients with hepatic or renal impairment may require dosage adjustments; however, severe hepatic impairment is a contraindication.
- Use caution in elderly patients; clinical monitoring is advised.

Administration Recommendations:
- Ivabradine is to be taken twice daily with food to optimize absorption and minimize gastrointestinal discomfort.
- Avoid grapefruit or grapefruit juice due to CYP3A4 inhibition which can elevate plasma levels leading to increased side effects.
- Oral liquid should be dosed using the provided dosing syringe and used immediately after opening the ampule to ensure accuracy and stability.

Mechanism Of Action

Ivabradine exerts its pharmacological effects primarily by selectively inhibiting the funny (If) current, a mixed sodium-potassium inward current, located in the sinoatrial (SA) node pacemaker cells. This current is responsible for the spontaneous depolarization during the diastolic phase that determines the heart rate. By selectively blocking the If channels, ivabradine slows the spontaneous diastolic depolarization, leading to a reduction in heart rate without affecting myocardial contractility or intracardiac conduction.

At the cellular level, ivabradine penetrates the sinoatrial node cells and binds to the open state of the If channels preferentially when the membrane potential is within the diastolic range. This binding causes a decrease in pacemaker activity, which prolongs the diastolic depolarization phase. Unlike beta-blockers or calcium channel blockers, ivabradine does not influence adrenergic signaling pathways or intracellular calcium handling, allowing it to specifically lower heart rate without negative inotropic or lusitropic effects.

Biochemically, ivabradine operates by modulating the channel gating kinetics, reducing the likelihood of channel opening during diastole, thus lowering the spontaneous action potential firing rate. This leads to prolongation of the cardiac cycle and reduction in myocardial oxygen demand due to slower heart rates. The clinical implication is an improved balance between myocardial oxygen supply and demand, particularly beneficial in conditions like heart failure where excessive heart rate contributes to pathophysiology.

Comparatively, ivabradine differs from beta-adrenergic blockers and calcium channel blockers which have broad effects on cardiac conduction and contractility. Ivabradine's unique mechanism provides a targeted heart rate reduction option with minimal hemodynamic effects, making it useful in patients intolerant to beta-blockers. Clinical trials such as the SHIFT study have demonstrated ivabradine's efficacy in reducing hospitalization for heart failure by improving symptoms and preventing disease progression, thereby underscoring its role in cardiovascular therapeutic regimens.

Pharmacological Actions

Selective inhibition of the If current in sinoatrial node cells, resulting in heart rate reduction
Slows spontaneous pacemaker activity without affecting myocardial contractility or conduction pathways
Reduces myocardial oxygen consumption by decreasing heart rate, improving myocardial oxygen balance
Acts primarily on the electrical activity of the heart with minimal effects on blood pressure
Improves symptoms and reduces hospitalization risk in chronic heart failure patients in sinus rhythm
Does not exert negative inotropic or lusitropic effects, preserving myocardial contractility
Demonstrates cardioselective action with negligible effects on other cardiac ion channels
Does not alter intracardiac conduction, mitigating the risk of atrioventricular block
Shown to improve exercise tolerance and quality of life in patients with stable angina in clinical studies
May be combined with beta-blockers or used when beta-blockers are contraindicated or not tolerated
Potential to reduce arrhythmogenicity by stabilizing heart rate dynamics
Produces transient visual side effects due to inhibition of retinal Ih channels without long-term toxicity
Exhibits a dose-dependent effect on heart rate reduction, allowing flexible dose titration
Metabolized by CYP3A4, requiring vigilance for pharmacokinetic interactions

Therapeutic Or Clinical Uses

Management of chronic stable heart failure with reduced left ventricular ejection fraction (LVEF ≤35%) in adults with resting heart rate ≥70 bpm in sinus rhythm
Reduction of risk of hospitalization for worsening heart failure in symptomatic patients with stable chronic heart failure
Treatment of stable symptomatic heart failure due to dilated cardiomyopathy in pediatric patients aged 6 months and older
Off-label or investigational use for heart rate control in patients who are intolerant or have contraindications to beta-blockers
Adjunct therapy in chronic heart failure to improve clinical outcomes when combined with standard treatments
Potential use in management of inappropriate sinus tachycardia by selective heart rate reduction
Investigation for benefits in ischemic heart disease by reducing myocardial oxygen demand through heart rate control
Alternative therapy for patients with angina pectoris where beta-blockers are not suitable
Part of comprehensive cardiovascular management plans tailored to patients infeasible for or unresponsive to conventional therapies
Supports optimization of cardiac workload without compromising blood pressure or myocardial contractility
Used in the context of sinus rhythm only; contraindicated in atrial fibrillation or other arrhythmias
Improves exercise capacity and symptom burden in chronic heart failure patients
Can be employed in pediatric cardiology for specific heart failure etiologies with careful dosing and monitoring

Side Or Adverse Effects

Bradycardia and associated symptoms such as fatigue, dizziness, or syncope due to excessive heart rate reduction
Visual disturbances including phosphenes, transient enhanced brightness, seeing halos around lights, and kaleidoscopic effects
Hypertension or increased blood pressure episodes possibly related to autonomic regulation shifts
Atrial fibrillation occurrence, requiring monitoring given ivabradine’s use in sinus rhythm patients
Headache, sometimes severe, potentially linked to vascular or neurological mechanisms
Pounding or irregular heartbeats and palpitations
Dose-dependent nausea and gastrointestinal discomfort
Light sensitivity or photophobia affecting vision comfort especially during initial treatment period
Chest tightness or angina exacerbation in rare cases
Rare allergic reactions such as hives, facial swelling, or respiratory difficulties
Possible worsening of underlying conduction disorders like sick sinus syndrome if uncorrected or unmonitored
Visual symptoms usually transient and reversible upon dose adjustment or discontinuation
Fatigue and tiredness which may affect quality of life in some patients
Hypotension is uncommon but can occur particularly in patients with preexisting low blood pressure
Local irritation or taste disturbance with oral liquid formulation use

Precautions

Use cautiously with patients who have pre-existing bradycardia or conduction abnormalities
Avoid in patients with heart conditions such as sick sinus syndrome, sinoatrial block, or third-degree AV block without pacemaker
Monitor heart rate regularly to maintain target range (50-60 bpm) and prevent profound bradycardia
Adjust dose or discontinue if symptoms of slow heart rate develop, including dizziness or syncope
Use with caution in patients with mild to moderate hepatic impairment; contraindicated in severe liver disease
Avoid concomitant use with strong CYP3A4 inhibitors or inducers to prevent adverse pharmacokinetic interactions
Educate patients about possible visual side effects and advise caution with activities requiring visual acuity
Monitor blood pressure as hypertension may be exacerbated or new onset during treatment
Avoid abrupt discontinuation to prevent rebound tachycardia or worsening heart failure symptoms
Advise women of childbearing potential to use effective contraception due to potential teratogenic effects
Not recommended during pregnancy and breastfeeding due to lack of safety data and potential harm
Avoid grapefruit and grapefruit juice as they increase ivabradine plasma levels via CYP3A4 inhibition
Monitor for new or worsening arrhythmias including atrial fibrillation
Exercise caution with co-administration of other heart rate or rhythm modifying agents such as beta-blockers, digoxin, amiodarone
Educate patients to report any symptoms of heart rhythm disturbance such as palpitations, chest discomfort, dizziness, or syncope

Warnings

Contraindicated in patients with severe liver disease due to risk of accumulation and toxicity
Avoid use in patients with very low resting heart rate or hypotension to prevent hemodynamic compromise
Not to be used in patients with sick sinus syndrome, sinoatrial block, or third-degree AV block without pacemaker support
May cause serious heart rhythm problems including bradycardia, atrial fibrillation, and arrhythmias requiring monitoring
Use cautiously in patients dependent on pacemaker; contraindicated if pacemaker controls heart rate
Risk of fetal harm and premature birth; pregnancy prevention advised during treatment
Visual disturbances may impair driving or operating machinery; advise caution
Avoid concomitant use with potent CYP3A4 inhibitors such as azole antifungals, macrolide antibiotics to prevent toxic plasma levels
Excessive heart rate lowering may precipitate heart failure decompensation or ischemic events in susceptible patients
Discontinue upon signs of serious allergic reaction such as angioedema or anaphylaxis
Risk of hospitalizations or adverse cardiac events if used inappropriately outside indicated heart failure population
Careful patient selection essential, focusing on those in sinus rhythm with elevated baseline heart rate
Regular ECG monitoring recommended during treatment to detect conduction disturbances
Not indicated for treatment of blood pressure or arrhythmias other than sinus tachycardia-related heart failure
Avoid in combination with other negative chronotropic agents without cardiac specialist oversight

Contraindication

Known hypersensitivity to ivabradine or any formulation components
Severe hepatic impairment due to impaired drug metabolism and elimination
Resting heart rate less than 50 beats per minute prior to treatment initiation
Symptomatic bradycardia or sick sinus syndrome without pacemaker
Third-degree atrioventricular (AV) block in patients without a functioning pacemaker
Presence of sinoatrial block or other significant conduction disorders without pacemaker support
Acute decompensated heart failure or patients with worsening heart failure symptoms
Hypotension (low blood pressure) that is symptomatic or severely reduced
Pacemaker dependence controlling heart rate
Pregnancy due to potential fetal harm and lack of safety data
Concomitant use with potent CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin) due to risk of increased plasma levels
Concurrent use with other heart rate limiting drugs that may lead to excessive bradycardia without medical supervision
Patients with atrial fibrillation or other non-sinus rhythms
Severe renal impairment not explicitly contraindicated but use with caution and clinical monitoring advised
Breastfeeding mothers due to unknown excretion in breast milk and potential infant exposure

Drug Interactions

Significant interactions with CYP3A4 inhibitors such as ketoconazole, clarithromycin, and ritonavir which increase ivabradine plasma levels leading to bradycardia risk
Co-administration with CYP3A4 inducers (e.g., rifampin, St. John's wort) can reduce ivabradine efficacy by lowering concentration
Additive negative chronotropic effects when combined with beta-blockers, calcium channel blockers (verapamil, diltiazem), digoxin, or amiodarone, increasing bradycardia risk
Interactions with antiarrhythmic drugs such as amiodarone elevate risk of severe bradycardia or AV block
Concurrent use with antihypertensive drugs might enhance hypotensive effects and necessitate dose adjustments
Potential interaction with antiviral agents used in HIV or hepatitis C treatment that affect hepatic enzymes
Avoid grapefruit or grapefruit juice as it inhibits CYP3A4, significantly increasing ivabradine plasma levels
Possible interaction with other medications metabolized by CYP3A4, necessitating careful monitoring and possible dose modification
Drugs that prolong QT interval may have additive electrophysiological effects when used with ivabradine
Co-administration with St. John's wort may decrease plasma levels by CYP3A4 induction leading to reduced therapeutic effect
Monitoring required when used alongside antidepressants or antipsychotics that may affect cardiac conduction
Caution with antifungal medications such as itraconazole due to CYP3A4 inhibition
Interactions with certain antibiotics (macrolides, fluoroquinolones) that can affect CYP3A4 pathway
Careful patient monitoring is essential with polypharmacy in cardiovascular or infectious disease contexts
Adjustments or alternative therapies may be required to optimize safety and efficacy

Preparations Of The Drug

Oral solution preparation: 5 mg per 5 mL dosing ampules designed for pediatric and adult patients having difficulty swallowing tablets
Immediate-release tablets available in 5 mg and 7.5 mg strengths designed for precise dose titration
Single-use plastic ampules for oral liquid, intended for measurement accuracy and maintenance of stability
Film-coated tablets ensuring stability and bioavailability upon oral administration
Dosing devices such as syringes provided to facilitate accurate liquid measurement
Packaging designed to protect drug from moisture, heat, and light with storage at room temperature
Multiple unit packaging to support titration and gradual dose adjustments, particularly in heart failure management
Foil pouch packaging for liquid ampules to preserve drug integrity until use
Single-dose ampules intended for immediate use after opening to prevent degradation
Instructions included for both adult and pediatric dosing regimens
Available under brand name Corlanor with brand-specific labeling and prescribing information
Formulations intended for twice-daily dosing with food to enhance absorption and minimize GI side effects
Inclusion of patient information leaflets detailing administration techniques, precautions, and side effects
Compatibility information available for co-administration with other cardiovascular agents
Approved by regulatory authorities with clear guidance on storage, handling, and disposal