Safety of spironolactone in dogs with chronic heart failure because of degenerative valvular disease: a population-based, longitudinal study

Dose-exposure-response of CARDALIS® (benazepril/spironolactone) on the classical and alternative arms of the renin-angiotensin-aldosterone system in healthy dogs

BACKGROUND

Benazepril exhibits a dose-dependent effect on biomarkers of the circulating renin-angiotensin-aldosterone system (RAAS) in dogs.

HYPOTHESIS/OBJECTIVES

To characterize the dose-exposure-response relationship of a fixed-dose combination product including benazepril and spironolactone (CARDALIS®) on RAAS biomarkers in dogs.

ANIMALS

Eighteen purpose-bred healthy beagle dogs.

METHODS

Three groups of 6 dogs received different doses of CARDALIS® for 14 days following induction of RAAS activation by feeding a low-sodium diet: (a) benazepril 0.25 mg/kg + spironolactone 2 mg/kg PO q24h (label dose); (b) benazepril 0.25 mg/kg + spironolactone 2 mg/kg PO q12h; or (c) benazepril 0.5 mg/kg + spironolactone 4 mg/kg PO q12h. Blood samples were collected at baseline and serial time intervals after CARDALIS® dosing to measure serum RAAS biomarkers and plasma concentrations of active drug metabolites. Time-weighted averages for serum RAAS biomarkers after CARDALIS® dosing at steady state were compared between dosage groups using Wilcoxon rank-sum testing.

RESULTS

Compared to the label dose, the highest dose of CARDALIS® was associated with a 30% decrease in angiotensin II (P = .03), 94% increase in angiotensin 1-7 (P = .03), 71% decrease in surrogate activity of ACE (P = .002), and 116% increase in circulating aldosterone (P = .02). CARDALIS® was well-tolerated at all doses with no clinically relevant changes in renal values or serum electrolytes.

CONCLUSIONS AND CLINICAL IMPORTANCE

The combined CARDALIS® product leads to dose-dependent alterations of RAAS metabolites. These results could help inform clinical trials in dogs with heart disease.

Comprehensive characterization of the effect of mineralocorticoid receptor antagonism with spironolactone on the renin-angiotensin-aldosterone system in healthy dogs

OBJECTIVE

To characterize the dose-exposure-response effect of spironolactone on biomarkers of the classical and alternative arms of the renin-angiotensin-aldosterone system (RAAS) in healthy dogs.

ANIMALS

Ten healthy purpose-bred Beagle dogs.

PROCEDURES

Study dogs were randomly allocated to 2 spironolactone dosing groups (2 mg/kg PO q24hr, 4 mg/kg PO q24hr). The dogs received 7-day courses of spironolactone followed by a 14-day washout period in a crossover (AB/BA) design. Angiotensin peptides and aldosterone were measured in serum using equilibrium analysis, and plasma canrenone and 7-α-thiomethyl spironolactone (TMS) were quantified via liquid chromatography-mass spectrometry/mass spectroscopy (LC-MS/MS). Study results were compared before and after dosing and between groups.

RESULTS

Following spironolactone treatment, dogs had a significant increase in serum aldosterone concentration (P = 0.07), with no statistical differences between dosing groups. Significant increases in angiotensin II (P = 0.09), angiotensin I (P = 0.08), angiotensin 1-5 (P = 0.08), and a surrogate marker for plasma renin activity (P = 0.06) were detected compared to baseline following spironolactone treatment during the second treatment period only. Overall, changes from baseline did not significantly differ between spironolactone dosages. RAAS analytes were weakly correlated (R < 0.4) with spironolactone dosage and plasma canrenone or plasma TMS. There were no adverse clinical or biochemical effects seen at any spironolactone dosage during treatment.

CONCLUSIONS

Treatment with spironolactone increased serum aldosterone concentration in healthy dogs and impacted other biomarkers of the classical and alternative arms of the RAAS. There was no difference in effect on the RAAS between 2 and 4 mg/kg/day dosing. Dosage of 4 mg/kg/day was safe and well-tolerated in healthy dogs.

Management of Chronic Congestive Heart Failure Caused by Myxomatous Mitral Valve Disease in Dogs: A Narrative Review from 1970 to 2020

Simple Summary

Myxomatous mitral valve disease (MMVD) is the most common acquired cardiovascular disease in dogs. The progression of the disease and the increasing severity of valvular regurgitation cause a volume overload of the left heart, leading to left atrial and ventricular remodeling and congestive heart failure (CHF). The treatment of chronic CHF secondary to MMVD in dogs has not always been the same over time. In the last fifty years, the drugs utilized have considerably changed, as well as the therapeutic protocols. Some drugs have also changed their intended use. An analysis of the literature concerning the therapy of chronic heart failure in dogs affected by this widespread degenerative disease is not available; a synthesis of the published literature on this topic and a description of its current state of art are needed. To the authors’ knowledge, a review of this topic has never been published in veterinary medicine; therefore, the aim of this study is to overview the treatments of chronic CHF secondary to MMVD in dogs from 1970 to 2020 using the general framework of narrative reviews.

Abstract

The treatment of chronic congestive heart failure (CHF), secondary to myxomatous mitral valve disease (MMVD) in dogs, has considerably changed in the last fifty years. An analysis of the literature concerning the therapy of chronic CHF in dogs affected by MMVD is not available, and it is needed. Narrative reviews (NRs) are aimed at identifying and summarizing what has been previously published, avoiding duplications, and seeking new study areas that have not yet been addressed. The most accessible open-access databases, PubMed, Embase, and Google Scholar, were chosen, and the searching time frame was set in five decades, from 1970 to 2020. The 384 selected studies were classified into categories depending on the aim of the study, the population target, the pathogenesis of MMVD (natural/induced), and the resulting CHF. Over the years, the types of studies have increased considerably in veterinary medicine. In particular, there have been 43 (24.29%) clinical trials, 41 (23.16%) randomized controlled trials, 10 (5.65%) cross-over trials, 40 (22.60%) reviews, 5 (2.82%) comparative studies, 17 (9.60%) case-control studies, 2 (1.13%) cohort studies, 2 (1.13%) experimental studies, 2 (1.13%) questionnaires, 6 (3.40%) case-reports, 7 (3.95%) retrospective studies, and 2 (1.13%) guidelines. The experimental studies on dogs with an induced form of the disease were less numerous (49–27.68%) than the studies on dogs affected by spontaneous MMVD (128–72.32%). The therapy of chronic CHF in dogs has considerably changed in the last fifty years: in the last century, some of the currently prescribed drugs did not exist yet, while others had different indications.

Clinical efficacy of a benazepril and spironolactone combination in dogs with congestive heart failure due to myxomatous mitral valve disease: The BEnazepril Spironolactone STudy (BESST)

BACKGROUND

The renin-angiotensin-aldosterone system (RAAS), when chronically activated, is harmful and RAAS-suppressive drugs are beneficial in the treatment of congestive heart failure (CHF). Mineralocorticoid receptor antagonists are widely used in the treatment of CHF in people.

HYPOTHESIS/OBJECTIVES

To determine if a mineralocorticoid receptor antagonist (spironolactone) is beneficial and safe in CHF due to myxomatous mitral valve disease (MMVD) of varying severity, we hypothesized that, when combined with furosemide, a combination product (S+BNZ) containing the ACE inhibitor (ACE-I), benazepril, and spironolactone, would be superior to benazepril alone.

ANIMALS

Five hundred and sixty-nine client-owned dogs, with MMVD and CHF (ACVIM Stage C) of ≤10-days' duration.

METHODS

After initial stabilization, dogs were randomized into a positive-controlled, double-blind, multicenter trial, to receive furosemide plus S+BNZ or furosemide plus benazepril. The primary outcome variable was the percentage of dogs reaching cardiac endpoint before Day 360. Cardiac endpoint was defined as cardiac death or euthanasia, recurrence of pulmonary edema, necessity for nonauthorized cardiac drug(s) or a furosemide dosage >8 mg/kg/d.

RESULTS

A significantly lower percentage of dogs treated with S+BNZ reached the primary outcome variable by Day 360 (OR = 0.56; 95% CI, 0.32-0.98; P = .04) and risk of dying or worsening from cardiac causes, was significantly reduced (HR = 0.73; 95% CI = 0.59-0.89, P = .002) vs benazepril alone. Adverse events, potentially associated with treatment, were rare and equal between groups.

CONCLUSION AND CLINICAL IMPORTANCE

The combination of S+BNZ is effective, safe, and superior to benazepril alone, when used with furosemide for the management of mild, moderate or severe CHF caused by MMVD in dogs.

Prospective clinical trial evaluating spironolactone in Doberman pinschers with congestive heart failure due to dilated cardiomyopathy

INTRODUCTION/OBJECTIVES

Whether the aldosterone antagonist spironolactone has beneficial survival effects in dogs with dilated cardiomyopathy (DCM) is not known. The primary objective of the study was to evaluate the effect of spironolactone, when added to conventional therapy, on survival time in Doberman pinschers with congestive heart failure (CHF) due to DCM.

ANIMALS

Sixty-seven client-owned Doberman pinschers with CHF due to DCM.

MATERIALS AND METHODS

The trial design was prospective, randomized, blinded, and placebo controlled. Dogs were randomized to receive 50-75 mg of spironolactone twice daily (n = 34) or a placebo (n = 33), in addition to standard CHF therapy. Follow-up visits were targeted every 1-6 weeks until endpoint. Quality-of-life questionnaire and physical examination were performed at every visit, while renal biochemistry, ECG, echocardiography, and thoracic radiography were reassessed as needed. The primary endpoint was time to cardiac death, defined as death or euthanasia from CHF or sudden death.

RESULTS

Median time to primary endpoint in the spironolactone group (183 days) was not statistically significantly different than that for the placebo group (124 days) (p = 0.254). The development of atrial fibrillation (AF) was significantly less frequent in the spironolactone group (n = 7) than the placebo group (n = 15, p = 0.037).

CONCLUSIONS

While median time to cardiac death in the spironolactone group was not statistically significantly different than that in the placebo group, adding spironolactone to conventional therapy resulted in reduced occurrence of AF.

Effect of spironolactone and benazepril on furosemide-induced diuresis and renin-angiotensin-aldosterone system activation in normal dogs

Background

Diuretic braking during furosemide continuous rate infusion (FCRI) curtails urine production.

Hypothesis

Renin‐angiotensin‐aldosterone system (RAAS) activation mediates braking, and RAAS inhibition will increase urine production.

Animals

Ten healthy purpose‐bred male dogs.

Methods

Dogs received placebo, benazepril, or benazepril and spironolactone PO for 3 days before a 5‐hour FCRI (0.66 mg/kg/h) in a 3‐way, randomized, blinded, cross‐over design. Body weight (BW), serum creatinine concentration (sCr), serum electrolyte concentrations, PCV, and total protein concentration were measured before PO medications, at hours 0 and 5 of FCRI, and at hour 24. During the FCRI, water intake, urine output, urine creatinine concentration, and urine electrolyte concentrations were measured hourly. Selected RAAS components were measured before and after FCRI. Variables were compared among time points and treatments.

Results

Diuretic braking and urine production were not different among treatments. Loss of BW, hemoconcentration, and decreased serum chloride concentration occurred during FCRI with incomplete recovery at hour 24 for all treatments. Although unchanged during FCRI, sCr increased and serum sodium concentration decreased at hour 24 for all treatments. Plasma aldosterone and angiotensin‐II concentrations increased significantly at hour 5 for all treatments, despite suppressed angiotensin‐converting enzyme activity during benazepril background treatment.

Conclusions

The neurohormonal profile during FCRI supports RAAS mediation of diuretic braking in this model. Background treatment with benazepril with or without spironolactone did not mitigate braking, but was well tolerated. Delayed changes in sCr and serum sodium concentration and incomplete recovery of hydration indicators caused by furosemide hold implications for clinical patients.

Aldosterone and the mineralocorticoid receptor in renal injury: A potential therapeutic target in feline chronic kidney disease

There is a growing body of experimental and clinical evidence supporting mineralocorticoid receptor (MR) activation as a powerful mediator of renal damage in laboratory animals and humans. Multiple pathophysiological mechanisms are proposed, with the strongest evidence supporting aldosterone-induced vasculopathy, exacerbation of oxidative stress and inflammation, and increased growth factor signalling promoting fibroblast proliferation and deranged extracellular matrix homeostasis. Further involvement of the MR is supported by extensive animal model experiments where MR antagonists (such as spironolactone and eplerenone) abrogate renal injury, including ischaemia-induced damage. Additionally, clinical trials have shown MR antagonists to be beneficial in human chronic kidney disease (CKD) in terms of reducing proteinuria and cardiovascular events, though current studies have not evaluated primary end points which allow conclusions to made about whether MR antagonists reduce mortality or slow CKD progression. Although differences between human and feline CKD exist, feline CKD shares many characteristics with human disease including tubulointerstitial fibrosis. This review evaluates the evidence for the role of the MR in renal injury and summarizes the literature concerning aldosterone in feline CKD. MR antagonists may represent a promising therapeutic strategy in feline CKD.

The renin-angiotensin-aldosterone system and its suppression

Chronic activation of the renin-angiotensin-aldosterone system (RAAS) promotes and perpetuates the syndromes of congestive heart failure, systemic hypertension, and chronic kidney disease. Excessive circulating and tissue angiotensin II (AngII) and aldosterone levels lead to a pro-fibrotic, -inflammatory, and -hypertrophic milieu that causes remodeling and dysfunction in cardiovascular and renal tissues. Understanding of the role of the RAAS in this abnormal pathologic remodeling has grown over the past few decades and numerous medical therapies aimed at suppressing the RAAS have been developed. Despite this, morbidity from these diseases remains high. Continued investigation into the complexities of the RAAS should help clinicians modulate (suppress or enhance) components of this system and improve quality of life and survival. This review focuses on updates in our understanding of the RAAS and the pathophysiology of AngII and aldosterone excess, reviewing what is known about its suppression in cardiovascular and renal diseases, especially in the cat and dog.

Short-Term Efficacy and Safety of Torasemide and Furosemide in 366 Dogs with Degenerative Mitral Valve Disease: The TEST Study

BACKGROUND

Furosemide is the only loop diuretic recommended by the ACVIM consensus guidelines for treatment of congestive heart failure (CHF) in dogs related to degenerative mitral valve disease (DMVD). Torasemide is another potent loop diuretic with a longer half-life and a higher bioavailability.

OBJECTIVES

(1) To demonstrate that torasemide given once a day (q24h) is noninferior to furosemide given twice a day (q12h) for treating dogs with CHF; (2) and to compare the effect of the 2 drugs on the time to reach a composite cardiac endpoint "spontaneous cardiac death, euthanasia due to heart failure or CHF class worsening."

ANIMALS

A total of 366 dogs with CHF attributable to DMVD.

METHODS

Analysis of 2 prospective randomized single-blinded reference-controlled trials was performed. Dogs orally received either torasemide q24h (n = 180) or furosemide q12h (n = 186) in addition to standard CHF therapy over 3 months. The primary efficacy criterion was the percentage of dogs with treatment success assessed in each study. The time to reach the composite cardiac endpoint was used as secondary criterion in the overall population.

RESULTS

Torasemide was noninferior to furosemide (Ptorasemide  - Pfurosemide  = +7%; 95% CI [-8%; +22%] and Ptorasemide  - Pfurosemide  = +1%; 95% CI [-12%; +14%], respectively, in Study 1 and Study 2). Torasemide (median dose = 0.24 mg/kg/d q24h; range = 0.10-0.69 mg/kg/d) was associated with a 2-fold reduction in the risk of reaching the composite cardiac endpoint (adjusted HR = 0.47; 95% CI = 0.27-0.82; P = 0.0077) as compared with furosemide (median dose = 1.39 mg/kg q12h; range = 0.70-6.30 mg/kg q12h).

CONCLUSIONS AND CLINICAL IMPORTANCE

Torasemide q24h is an effective oral diuretic in dogs with CHF.

Treatment of dogs with compensated myxomatous mitral valve disease with spironolactone-a pilot study

OBJECTIVES

Spironolactone improves outcome in dogs with advanced myxomatous mitral valve disease (MMVD). Its efficacy in preclinical MMVD is unknown. The hypothesis was the administration of spironolactone to dogs with compensated MMVD demonstrating risk factors for poorer prognosis will decrease the rate of disease progression. The aim was to provide pilot data to evaluate preliminary effects and sample size calculation for a definitive clinical trial.

ANIMALS

Twenty-five client-owned dogs with MMVD with at least one of the following; left atrial to aortic ratio (LA:Ao) ≥ 1.5, normalized left ventricular internal diameter in diastole ≥ 1.6), N-terminal pro-B-type natriuretic peptide (NT-proBNP) > 550 pmol/L, cardiac troponin I > 0.025 ng/mL.

METHODS

Prospective, single-center, equally randomized, placebo-controlled, double-blinded, parallel grouped pilot study. No dogs were receiving medications for cardiac disease before the enrollment.

RESULTS

Twelve dogs received placebo; 13 received spironolactone. One dog in the spironolactone group died suddenly, 1 developed congestive heart failure, and 2 received suboptimal spironolactone doses. At enrollment, NT-proBNP was significantly higher in the spironolactone group (p=0.005). Left atrial to aortic ratio (p=0.002) and left ventricular internal diameter in diastole (p=0.005) increased over time in the placebo group, but not the spironolactone group; the change did not differ significantly between groups. The change in biomarker concentrations did not differ significantly between groups; there was a tendency toward an increase in NT-proBNP over time in the placebo group. Enrollment of 76 dogs would be necessary to demonstrate a difference in the change in LA:Ao over 6 months between the groups.

CONCLUSIONS

Preliminary results support undertaking a larger clinical trial of treatment of dogs with preclinical MMVD with spironolactone.

Safety of Benazepril in 400 Azotemic and 110 Non-Azotemic Client-Owned Cats (2001-2012)

This retrospective study examined cats after initiation of benazepril therapy to determine the frequency of systemic hypotension or elevations in serum creatinine and/or potassium. Medical records review identified azotemic and non-azotemic cats prescribed benazepril. Blood pressure was recorded at the first available time after initiation of therapy. No cats experienced documented systolic systemic hypotension (<90 mmHg). Serum creatinine, and potassium when available, were recorded at baseline and in time windows after initiation of treatment: 1-30 days and 31-60 days. Blood chemistry results were screened for hyperkalemia (≥6.0 mEq/L). During the first 2 mo after starting benazepril therapy, there was a low incidence (3.7%) and clinically insignificant magnitude of hyperkalemia. Serum creatinine increases of greater than 30% from baseline were noted. This change was found in 11.0% of cats during the first 30 days of therapy and in 13.7% of cats from days 31-60 after initiation of therapy. The long-term survival of the cats that had >30% increases in creatinine from baseline was not statistically different from the survival of those that did not experience these increases, which suggests this finding may not be a reason to discontinue therapy. Benazepril appeared safe in a heterogeneous population of cats.