CVS Pharmacology: Drugs for Heart Failure

Introduction/Overview

Heart failure (HF) represents a global public health challenge, affecting millions of individuals worldwide and contributing substantially to morbidity, mortality, and healthcare utilization. The therapeutic landscape of HF has expanded dramatically over recent decades, with a growing array of pharmacologic agents that target distinct neurohormonal pathways, hemodynamic alterations, and myocardial remodeling processes. A comprehensive understanding of these agents is essential for clinicians and pharmacists alike, given the complexity of HF management and the necessity for individualized treatment plans.

Clinical relevance is underscored by the fact that pharmacologic therapy remains the cornerstone of HF treatment, with mortality reduction, symptom improvement, and hospitalization avoidance documented across multiple randomized controlled trials. Moreover, evolving evidence has introduced novel drug classes—such as sodium–glucose cotransporter‑2 (SGLT2) inhibitors and neprilysin inhibitors—that have reshaped guideline recommendations and patient outcomes. Understanding the pharmacodynamics, pharmacokinetics, therapeutic indications, and safety profiles of these drugs is therefore critical for optimizing patient care.

Learning objectives for this chapter include:

• Describe the principal drug classes used in heart failure management and their key pharmacologic properties.
• Explain the mechanisms by which these agents modulate neurohormonal activity, preload, afterload, and myocardial remodeling.
• Summarize the pharmacokinetic characteristics that influence dosing strategies and therapeutic monitoring.
• Identify common and serious adverse effects, as well as major drug–drug interactions and contraindications.
• Apply evidence-based considerations for special populations, including pregnant women, children, the elderly, and patients with renal or hepatic impairment.

Classification

1. Renin–Angiotensin–Aldosterone System (RAAS) Modulators

Agents that interfere with the RAAS pathway are foundational in HF therapy. They encompass angiotensin‑converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), and mineralocorticoid receptor antagonists (MRAs). The recently approved angiotensin receptor–neprilysin inhibitor (ARNI) combines an ARB with a neprilysin inhibitor, offering dual neurohormonal modulation.

2. β‑Adrenergic Blockers

These drugs attenuate sympathetic overactivation by blocking β‑adrenergic receptors, thereby reducing heart rate, myocardial contractility, and arrhythmogenic potential. Selective β1‑blockers predominate in HFrEF, whereas non‑selective agents have more limited roles.

3. Diuretics

Loop diuretics, thiazide‑like diuretics, and potassium‑sparing diuretics address volume overload and preload reduction. Loop diuretics are the mainstay for symptomatic relief, while thiazide‑like agents serve as adjunctive therapy, and potassium‑sparing diuretics provide sodium regulation with minimal potassium loss.

4. Aldosterone Antagonists

MRAs—spironolactone and eplerenone—block aldosterone receptors, mitigating sodium retention and myocardial fibrosis.

5. Digitalis Glycosides

Digoxin exerts positive inotropic effects and modulates conduction through Na⁺/K⁺‑ATPase inhibition, maintaining rhythm control in selected HF patients.

6. Vasodilators

Hydralazine and isosorbide dinitrate, either alone or in combination, reduce systemic vascular resistance and preload.

7. Sodium‑Glucose Cotransporter‑2 (SGLT2) Inhibitors

Initially developed for type 2 diabetes mellitus, SGLT2 inhibitors have demonstrated robust benefits in HF irrespective of diabetic status, via osmotic diuresis, natriuresis, and metabolic modulation.

8. Novel Agents

Vericiguat, a soluble guanylate cyclase stimulator, and other emerging therapies target cGMP pathways, offering potential in advanced HF.

Mechanism of Action

1. RAAS Modulators

ACE inhibitors block the conversion of angiotensin I to angiotensin II, thereby reducing vasoconstriction, aldosterone release, and sympathetic activation. ARBs competitively inhibit angiotensin II binding to AT1 receptors, attenuating downstream signaling. MRAs antagonize aldosterone binding to mineralocorticoid receptors in renal tubules and cardiac myocytes, curbing sodium reabsorption and fibrotic remodeling. ARNIs inhibit neprilysin, preventing degradation of natriuretic peptides, bradykinin, and adrenomedullin, while simultaneously blocking AT1 receptors, resulting in synergistic vasodilation, natriuresis, and antiproliferative effects.

2. β‑Adrenergic Blockers

Selective β1‑blockers competitively inhibit catecholamine binding at β1 receptors in the heart, decreasing intracellular cyclic AMP production, reducing calcium influx, and lowering myocardial oxygen demand. These changes translate into reduced arrhythmogenicity, improved ventricular remodeling, and extended survival in HFrEF.

3. Diuretics

Loop diuretics inhibit the Na⁺/K⁺/2Cl⁻ symporter in the thick ascending limb of Henle, resulting in increased excretion of sodium, chloride, and water, thereby decreasing preload. Thiazide‑like agents inhibit the Na⁺/Cl⁻ cotransporter in the distal convoluted tubule, contributing to mild natriuresis. Potassium‑sparing diuretics, such as amiloride and triamterene, block epithelial sodium channels or renal outer medullary potassium channels, promoting sodium excretion while preserving potassium.

4. Aldosterone Antagonists

By blocking mineralocorticoid receptors, MRAs reduce sodium reabsorption in the collecting ducts and inhibit pro‑fibrotic signaling pathways, thereby limiting myocardial stiffness and arrhythmogenic substrate.

5. Digitalis Glycosides

Digoxin competitively inhibits the Na⁺/K⁺‑ATPase, leading to intracellular sodium accumulation, which in turn elevates intracellular calcium via the Na⁺/Ca²⁺ exchanger. The resultant increase in intracellular calcium enhances myocardial contractility. Additionally, digoxin exerts vagomimetic effects, prolonging atrioventricular conduction and suppressing re‑entrant arrhythmias.

6. Vasodilators

Hydralazine directly relaxes arteriolar smooth muscle, lowering systemic vascular resistance. Isosorbide dinitrate releases nitric oxide, which activates guanylate cyclase, increasing cyclic GMP and promoting vasodilation. The combined effect reduces afterload and preload, improving cardiac output.

7. SGLT2 Inhibitors

These agents inhibit SGLT2 transporters in proximal renal tubules, reducing glucose and sodium reabsorption, inducing osmotic diuresis and natriuresis. The resultant volume depletion and decreased preload, along with reduced arterial stiffness, improve cardiac function. Additional metabolic effects, such as ketone body utilization and reduced oxidative stress, contribute to cardioprotection.

8. Vericiguat

Vericiguat stimulates soluble guanylate cyclase, augmenting cyclic GMP production independent of nitric oxide, thereby promoting vasodilation, reducing myocardial stress, and inhibiting maladaptive remodeling.

Pharmacokinetics

1. ACE Inhibitors

Orally administered ACE inhibitors are generally well absorbed, with bioavailability ranging from 30% to 90% depending on the agent. They undergo hepatic metabolism (omeprazole) or limited renal excretion. Half‑lives vary from 1 to 12 hours; dosing intervals are typically once or twice daily. Metabolites may retain activity, necessitating caution in renal dysfunction.

2. ARBs

ARBs exhibit high oral bioavailability and extensive first‑pass metabolism. Elimination occurs via hepatic metabolism and renal excretion of metabolites. Half‑lives range from 6 to 18 hours, permitting once‑daily dosing. Renal impairment may prolong exposure, requiring dose adjustment.

3. MRAs

Spironolactone is poorly absorbed, metabolized by the liver to active hydroxylated metabolites, and eliminated renally. Eplerenone has higher bioavailability and a shorter half‑life (~6 hours), allowing once‑daily dosing. Both agents require monitoring of serum potassium and renal function.

4. β‑Adrenergic Blockers

Selective β1‑blockers such as metoprolol and bisoprolol have high oral bioavailability, undergo hepatic metabolism, and possess half‑lives ranging from 3 to 12 hours. Non‑selective agents like carvedilol exhibit variable absorption and a longer half‑life (~7 hours). Renal impairment minimally affects exposure.

5. Diuretics

Loop diuretics (furosemide) are rapidly absorbed with bioavailability ~80%. They distribute extensively into extravascular compartments and are eliminated unchanged via the kidneys. Half‑life is short (~2 hours), necessitating multiple daily doses for sustained effect. Thiazide‑like diuretics exhibit higher bioavailability and longer half‑lives (~12–15 hours). Potassium‑sparing diuretics have variable absorption and are primarily excreted unchanged.

6. Digitalis Glycosides

Digoxin is absorbed with ~70% bioavailability, distributed widely (volume of distribution ~2–3 L/kg), and eliminated primarily via the kidneys. The half‑life ranges from 36 to 48 hours in adults. Food intake may delay absorption but does not alter extent.

7. Vasodilators

Hydralazine is absorbed slowly, with a half‑life of ~2–3 hours, and undergoes hepatic metabolism. Isosorbide dinitrate is rapidly absorbed, with a half‑life of ~1–3 hours, and is metabolized by first‑pass hepatic metabolism. Dosing intervals are typically hourly or twice daily to maintain therapeutic levels.

8. SGLT2 Inhibitors

Agents such as dapagliflozin and empagliflozin have high oral bioavailability (>90%), are extensively metabolized by CYP2C8 and CYP3A4, and are excreted primarily via the kidneys. Half‑lives range from 12 to 17 hours, permitting once‑daily dosing. Renal impairment reduces drug exposure and therapeutic effect, requiring dose adjustment or discontinuation in severe cases.

9. Vericiguat

Vericiguat displays high oral bioavailability (~75%), is metabolized by CYP3A4, and has a half‑life of approximately 30 hours, allowing once‑daily dosing. Renal and hepatic impairment may modestly reduce clearance but generally do not necessitate dose modification.

Therapeutic Uses/Clinical Applications

1. Reduced Ejection Fraction (HFrEF)

ACE inhibitors, ARBs, MRAs, β‑blockers, and ARNIs constitute the cornerstone of guideline‑directed medical therapy for HFrEF, aiming to reduce mortality, hospitalizations, and improve functional capacity. Loop diuretics provide symptomatic relief from congestion. Digitalis glycosides are reserved for symptomatic control and rate or rhythm management in atrial fibrillation. SGLT2 inhibitors have become integral for reducing HF hospitalizations and mortality in this population.

2. Preserved Ejection Fraction (HFpEF)

Evidence supports the use of ARNI (sacubitril/valsartan) and SGLT2 inhibitors in HFpEF to reduce hospitalizations and improve quality of life. Diuretics remain essential for symptom control. β‑blockers are generally reserved for comorbid conditions such as ischemic heart disease or arrhythmias.

3. Advanced or Refractory HF

Vericiguat and other novel agents may be considered for patients with worsening HF despite optimal therapy. Hydralazine and isosorbide dinitrate combinations are particularly beneficial in black patients with HFrEF, reducing mortality and hospitalization rates.

4. Off‑Label Uses

SGLT2 inhibitors are increasingly employed in non‑diabetic HF patients to leverage diuretic and cardioprotective effects. Digitalis glycosides may be used in selected cases for rate control in atrial fibrillation, although newer agents (e.g., AV‑block) are preferred. Hydralazine–isosorbide combinations are sometimes prescribed in patients intolerant to ACE inhibitors or ARBs.

Adverse Effects

1. ACE Inhibitors

Common side effects include cough, hyperkalemia, hypotension, and angioedema. Rare but serious reactions encompass interstitial lung disease and severe hypertension. Black box warnings pertain to pregnancy‑associated fetal toxicity and angioedema risk.

2. ARBs

Side effects mirror ACE inhibitors but lack cough and are associated with hyperkalemia, hypotension, and renal impairment. Angioedema is uncommon but documented.

3. MRAs

Spironolactone is linked to gynecomastia, menstrual irregularities, and hyperkalemia. Eplerenone has a lower incidence of endocrine side effects but shares hyperkalemia risk. Renal dysfunction may precipitate life‑threatening hyperkalemia.

4. β‑Adrenergic Blockers

Adverse reactions include bradycardia, hypotension, fatigue, and bronchospasm (particularly with non‑selective agents). Heart failure patients may experience transient worsening of dyspnea due to negative inotropy.

5. Diuretics

Loop diuretics can cause electrolyte disturbances (hypokalemia, hyponatremia, hypomagnesemia), dehydration, ototoxicity (at high doses), and renal dysfunction. Thiazide‑like diuretics are associated with hyperglycemia, hyperuricemia, and hypokalemia. Potassium‑sparing agents predispose to hyperkalemia and metabolic alkalosis.

6. Digitalis Glycosides

Digitalis toxicity manifests as nausea, vomiting, visual disturbances, arrhythmias, and seizures. Hyperkalemia and hypokalemia can potentiate toxicity. Monitoring of serum levels is essential.

7. Vasodilators

Hydralazine is linked to lupus‑like syndrome, rash, and headache. Isosorbide dinitrate may cause headaches, hypotension, and tolerance development.

8. SGLT2 Inhibitors

Common side effects include genital mycotic infections, urinary tract infections, dehydration, and hypotension. Rare events encompass euglycemic ketoacidosis and Fournier’s gangrene.

9. Vericiguat

Adverse effects are generally mild and include headache, dizziness, and hypotension. No severe safety signals have emerged to date.

Drug Interactions

1. ACE Inhibitors / ARBs / MRAs

Potentiation of hyperkalemia with potassium‑sparing diuretics, potassium supplements, or nonsteroidal anti‑inflammatory drugs (NSAIDs). Co‑administration with diuretics may exacerbate hypotension.

2. β‑Adrenergic Blockers

Combined use with calcium channel blockers (particularly non‑selective agents) can precipitate severe bradycardia and heart block. Interaction with digoxin may enhance inotropic effects and risk of arrhythmia.

3. Diuretics

Loop diuretics with NSAIDs may diminish diuretic efficacy and increase renal injury risk. Thiazide diuretics with sulfonylureas may increase hypoglycemia risk.

4. Digitalis Glycosides

Concurrent use of quinidine or amiodarone can increase serum digoxin levels. Drugs affecting renal excretion (e.g., ACE inhibitors, ARBs) may also raise digoxin concentration.

5. Vasodilators

Hydralazine with β‑blockers may blunt expected blood pressure reduction. Isosorbide dinitrate with phosphodiesterase‑5 inhibitors (e.g., sildenafil) carries risk of profound hypotension.

6. SGLT2 Inhibitors

Co‑administration with diuretics may increase hypotension. Insulin or sulfonylureas may increase hypoglycemia risk.

7. Vericiguat

Concurrent use with potent CYP3A4 inhibitors or inducers may alter exposure; caution is advised. Interaction with nitrates is not well characterized but may influence hypotension.

Special Considerations

1. Pregnancy and Lactation

ACE inhibitors, ARBs, MRAs, and digitalis glycosides carry teratogenic potential or fetal toxicity; thus, they are contraindicated in pregnancy. Hydralazine and isosorbide dinitrate are relatively safer options for hypertension management during pregnancy. SGLT2 inhibitors lack comprehensive data but are generally avoided due to limited evidence. Lactation safety is variable; monitoring is advised when agents are used.

2. Pediatric Population

Evidence for most HF agents in children is limited. β‑blockers and diuretics are utilized under specialist supervision. ACE inhibitors and ARBs have limited pediatric indications. SGLT2 inhibitors are not approved for use in children.

3. Geriatric Population

Older adults are more susceptible to orthostatic hypotension, electrolyte disturbances, and drug accumulation. Dose titration should be cautious, with frequent monitoring of renal function, electrolytes, and blood pressure. Cognitive impairment may affect adherence.

4. Renal Impairment

ACE inhibitors, ARBs, MRAs, and SGLT2 inhibitors require dose adjustments or avoidance in severe chronic kidney disease (CKD). Diuretics are essential for fluid management but may cause diuretic resistance. Renal function should be monitored regularly, with adjustments based on estimated glomerular filtration rate (eGFR).

5. Hepatic Impairment

Hepatic metabolism of many HF agents (e.g., ACE inhibitors, ARBs, β‑blockers, SGLT2 inhibitors) can be affected. Dose reduction or avoidance is warranted in advanced liver disease. Monitoring of liver function tests is recommended.

Summary/Key Points

• Pharmacologic therapy remains the backbone of heart failure management, with evidence‑based agents targeting neurohormonal pathways, preload, afterload, and myocardial remodeling.
• RAAS modulators, β‑adrenergic blockers, diuretics, MRAs, and novel agents such as ARNIs, SGLT2 inhibitors, and vericiguat each possess distinct mechanisms and clinical indications.
• Adverse effect profiles necessitate vigilance for hyperkalemia, hypotension, electrolyte disturbances, and drug interactions, particularly in patients with renal impairment or polypharmacy.
• Special populations require tailored dosing, monitoring, and, when appropriate, alternative therapeutic strategies to mitigate risk.
• Ongoing research continues to refine HF pharmacotherapy, underscoring the importance of staying current with emerging evidence and guideline updates.

References

1. Opie LH, Gersh BJ. Drugs for the Heart. 9th ed. Philadelphia: Elsevier; 2021.
2. Golan DE, Armstrong EJ, Armstrong AW. Principles of Pharmacology: The Pathophysiologic Basis of Drug Therapy. 4th ed. Philadelphia: Wolters Kluwer; 2017.
3. Katzung BG, Vanderah TW. Basic & Clinical Pharmacology. 15th ed. New York: McGraw-Hill Education; 2021.
4. Brunton LL, Hilal-Dandan R, Knollmann BC. Goodman & Gilman's The Pharmacological Basis of Therapeutics. 14th ed. New York: McGraw-Hill Education; 2023.
5. Whalen K, Finkel R, Panavelil TA. Lippincott Illustrated Reviews: Pharmacology. 7th ed. Philadelphia: Wolters Kluwer; 2019.
6. Trevor AJ, Katzung BG, Kruidering-Hall M. Katzung & Trevor's Pharmacology: Examination & Board Review. 13th ed. New York: McGraw-Hill Education; 2022.
7. Rang HP, Ritter JM, Flower RJ, Henderson G. Rang & Dale's Pharmacology. 9th ed. Edinburgh: Elsevier; 2020.