Effect of renal function on the pharmacokinetics of LCZ696 (sacubitril/valsartan), an angiotensin receptor neprilysin inhibitor

Development and validation of a sensitive and simple LC-MS/MS method for simultaneous quantitation of valsartan, sacubitril and sacubitrilat in pediatric population

Pediatric heart failure (HF) is an important clinical disease with high hospitalization rates, morbidity, mortality and medical costs. Sacubitril/valsartan (also known as Entresto), was approved for the treatment of adult HF and is recently used in pediatrics. However, clinical therapy on children is more challenging than adults, and the pharmacokinetics of Entresto in children are still largely unknown and urgently needed. Herein, we aim to develop a simple and sensitive analytic method to monitor Entresto in pediatric patients, which is of great importance for individualized safe medication in children. Specifically, a liquid chromatography tandem mass spectrometry method for simultaneously quantification of valsartan, sacubitril and its bio-active metabolite sacubitrilat in human plasma has been developed and validated in pediatric patients. Plasma samples were pretreated with acetonitrile for protein precipitation. Elution was performed on X Select HSS T3 column (2.1 × 100 mm, 5 µm; Waters) column using an isocratic mobile phase process consisting of 0.1% formic acid aqueous solution and 0.1% formic acid acetonit rile with a total run time of 3.0 min. Valsartan-d3, sacubitrilin-d4 and sacubitrilat-d4 were used as the corresponding deuterium internal standards. According to the Bioanalytical Method Validation Guidance for Industry, the method was validated in the range of 0.5-5000 ng/mL. Intra- and inter-day accuracy of sacubitril,valsartan and sacubitrilat ranged from 93%- 108%, 98%- 109%, 91%- 102%, respectively, with relative standard deviation of precision ranging from 2.0% to 5.1%, 2.4%- 7.5%, 1,3%- 7.4%. The proposed method demonstrated good accuracy, precision and linearity. The matrix factors normalized by internal standard meet the acceptance criteria. The method was fully validated and applied in 39 children. Trough concentration of the three substances to be measured were: valsartan (11.3-938.0 ng/mL), sacubitril (0.5-395.5 ng/mL) and sacubitrilat (522.1-4890.0 ng/mL). Overall, this is the first study to simultaneously determined the plasma valsartan, sacubitril and sacubitrilat concentrations in children, which is believed to facilitate the clinical management of pediatric HF.

Angiotensin receptor neprilysin inhibitor in chronic heart failure and comorbidity management: Indian consensus statement

Heart failure (HF) is a significant public health concern characterized by notable rates of morbidity and mortality. Multimorbidity, ranging from 43% to 98% among HF patients, significantly impacts prognosis and treatment response. HF management requires a holistic approach, including guideline-directed medical therapy. Sacubitril/valsartan (angiotensin receptor neprilysin inhibitor [ARNI]) is a cornerstone of HF treatment, supported by robust evidence from large-scale clinical trials across different levels of left ventricular ejection fraction. The recommendations presented in this paper have been developed by a group of cardiologists in India who convened in expert opinion meetings to discuss the utilization of ARNI in chronic HF patients with five different comorbid conditions like type 2 diabetes mellitus (T2DM), chronic kidney disease, myocardial infarction (MI), obesity, and hypertension. Key focus areas include initiation, dose titration, and management across different HF phenotypes and comorbidities. Emphasis is placed on the efficacy of ARNI irrespective of glycemic status in the T2DM population, its role in HF patients with obesity, and addressing challenges related to renal function decline and hyperkalemia. Additionally, the document highlights ARNI's potential benefits in hypertensive and post-MI HF patients, alongside observations on the obesity paradox in HF prognosis. Overall, these recommendations aim to optimize ARNI therapy in HF patient populations with different comorbidities, addressing specific challenges and considerations to improve outcomes and quality of life.

Devastating Worsening Renal Function Following the Initiation of Sacubitril/Valsartan: Falling Between Two Stools

Previously prescribed antihypertensive agents were switched to the maximum dose of sacubitril/valsartan, without any upward titration, in two elderly hypertensive patients with chronic kidney disease who were hospitalized for treatment of congestive heart failure, in the hope of its decongestive, antihypertensive, and potential renoprotective actions. However, they quickly fell into oliguria and finally required hemodialysis. Sacubitril/valsartan should be initiated with careful attention in elderly patients with advanced renal dysfunction.

Practical Recommendations for the Use of Angiotensin Receptor-Neprilysin Inhibitors (ARNI) in Heart Failure: Insights from Indian Cardiologists

Heart failure is a significant public health concern characterized by notable rates of morbidity and mortality. Despite the presence of guideline-directed medical therapy (GDMT), its utilization remains inadequate. This practical recommendation paper focuses on the utilization of angiotensin receptor-neprilysin inhibitor (ARNI) as a pivotal treatment for heart failure with reduced ejection fraction (HFrEF), heart failure with preserved ejection fraction (HFpEF), and heart failure with improved ejection fraction (HFimpEF). The recommendations presented in this paper have been developed by a group of cardiologists in India who convened six advisory board meetings to discuss the utilization of ARNI in the management of heart failure. The paper emphasizes the importance of accurate biomarkers for diagnosing heart failure, particularly N-terminal pro-B-type natriuretic peptide (NT-proBNP) and B-type natriuretic peptide (BNP), which are commonly used. Additionally, the paper advocates the use of imaging, specifically echocardiography, in diagnosing and monitoring heart failure patients. Moreover, the paper highlights the role of ARNI in heart failure management, with numerous clinical trials that have demonstrated its effectiveness in reducing cardiovascular death or heart failure hospitalization, enhancing quality of life, and diminishing the risk of ventricular arrhythmias. This practical recommendation paper offers valuable insights into the utilization of ARNI in the management of heart failure, aiming to enhance the implementation of GDMT and ultimately alleviate the burden of heart failure on society.

Sacubitril/Valsartan in Dialysis Patients: Update on Current Perspectives

Sacubitril/Valsartan is a combination of neprilysin inhibitor and angiotensin II receptor blocker that proved its own efficacy and safety in heart failure patients to ameliorate cardiovascular morbidity and mortality compared to angiotensin II-converting enzyme inhibitors alone. However, end-stage renal disease patients have not been included in the randomized controlled trials, so the beneficial effects as well as the risk profile of this association remain still undefined in these patients. Only observational studies on this drug association have been carried out in end-stage renal disease patients investigating mostly biohumoral or echocardiographic markers. Therefore, its application is still controversial and not free of complications due to the potential risk of hypotension and hyperkaliemia. The efficacy to improve biohumoral markers and cardiac function in dialysis patients and the potential application especially in those patients with severe and resistant hypertension and/or left ventricular dysfunction could be crucial in end-stage renal disease patients. Ongoing long-term randomized controlled trials should thoroughly define the effective benefits and/or adverse effects in patients on substitutive treatment.

Efficacy and safety of sacubitril/valsartan after switching from azilsartan in hemodialysis patients with hypertension

This study assessed the efficacy and safety of sacubitril/valsartan in 23 hemodialysis patients with hypertension (mean age 70 years; male 69.6%) after switching from azilsartan, an angiotensin receptor blocker. Both at baseline and 3 months after the start of sacubitril/valsartan treatment, home blood pressure (BP), BP values during hemodialysis, and N-terminal pro-brain natriuretic peptide (NT-proBNP) level were measured. The mean dosage of azilsartan was 30 ± 10 mg/day at baseline and that of sacubitril/valsartan after 3 months of treatment was 204 ± 64 mg/day. After 3 months, significant reductions in mean morning home BP (155 ± 17/80 ± 12 to 147 ± 16/76 ± 11 mmHg), mean nighttime home systolic BP (153 ± 19 to 144 ± 16 mmHg), and median (IQRs) NT-proBNP level [8124 (2620-13 394) to 6271 (1570-9591) pg/mL] were observed (all P < .05), whereas BP values during hemodialysis did not change significantly. In hemodialysis patients, except for hypotension, sacubitril/valsartan was generally well tolerated, effectively controlled out-of-office BP, and improved NT-proBNP.

Application of Angiotensin Receptor–Neprilysin Inhibitor in Chronic Kidney Disease Patients: Chinese Expert Consensus

Chronic kidney disease (CKD) is a global public health problem, and cardiovascular disease is the most common cause of death in patients with CKD. The incidence and prevalence of cardiovascular events during the early stages of CKD increases significantly with a decline in renal function. More than 50% of dialysis patients die from cardiovascular disease, including coronary heart disease, heart failure, arrhythmia, and sudden cardiac death. Therefore, developing effective methods to control risk factors and improve prognosis is the primary focus during the diagnosis and treatment of CKD. For example, the SPRINT study demonstrated that CKD drugs are effective in reducing cardiovascular and cerebrovascular events by controlling blood pressure. Uncontrolled blood pressure not only increases the risk of these events but also accelerates the progression of CKD. A co-crystal complex of sacubitril, which is a neprilysin inhibitor, and valsartan, which is an angiotensin receptor blockade, has the potential to be widely used against CKD. Sacubitril inhibits neprilysin, which further reduces the degradation of natriuretic peptides and enhances the beneficial effects of the natriuretic peptide system. In contrast, valsartan alone can block the angiotensin II-1 (AT1) receptor and therefore inhibit the renin–angiotensin–aldosterone system. These two components can act synergistically to relax blood vessels, prevent and reverse cardiovascular remodeling, and promote natriuresis. Recent studies have repeatedly confirmed that the first and so far the only angiotensin receptor–neprilysin inhibitor (ARNI) sacubitril/valsartan can reduce blood pressure more effectively than renin–angiotensin system inhibitors and improve the prognosis of heart failure in patients with CKD. Here, we propose clinical recommendations based on an expert consensus to guide ARNI-based therapeutics and reduce the occurrence of cardiovascular events in patients with CKD.

Evaluating sacubitril/valsartan as a treatment option for heart failure with reduced ejection fraction and preserved ejection fraction

INTRODUCTION

Sacubitril/valsartan is the first-in-class angiotensin-receptor neprilysin inhibitor approved in 2015 for the treatment of heart failure with reduced ejection fraction (HFrEF). On 16 February 2021, the Food and Drug Administration acknowledged that "Benefits are most clearly evident in patients with left ventricular ejection fraction below normal," thus potentially extending the use in subjects with heart failure and preserved ejection fraction (HFpEF).

AREAS COVERED

The authors outline the regulatory history, pharmacokinetics, pharmacodynamics, and risk-benefit profile of sacubitril/valsartan in HFrEF and HFpEF. A critical cross-trial comparison is presented, including sodium-glucose cotransporter 2 inhibitors (SGLT2i), together with an insight into the latest European Society of Cardiology guidelines, where the new category of heart failure with mildly reduced ejection fraction is introduced.

EXPERT OPINION

Sacubitril/valsartan is a foundation of the pharmacological armamentarium in HFrEF to counteract the neuro-hormonal changes and reverse cardiac remodeling, together with beta-blockers, SGLT2i and mineralocorticoid receptor antagonists. The optimal sequence algorithm is an evolving issue, and the authors provide the reader with their personal perspective. A multidisciplinary management is encouraged to minimize the therapeutic inertia and manage tolerability issues, thus supporting adherence. Pragmatic trials, pharmacovigilance, and high-quality real-world evidence are crucial toward personalized safe prescribing of sacubitril/valsartan.

Pharmacokinetics and Pharmacodynamics of Sacubitril/Valsartan in Maintenance Hemodialysis Patients with Heart Failure

BACKGROUND

Heart failure (HF) is one of the main comorbidities in patients receiving maintenance hemodialysis (HD). Sacubitril/valsartan (SAC/VAL) is widely used in HF patients with reduced ejection fraction (HFrEF) or HF mid-range ejection fraction (HFmrEF). However, the pharmacokinetic (PK) and pharmacodynamic properties of SAC/VAL in HD patients with HF remain uncertain.

OBJECTIVES

This study aimed to analyze the efficacy and PK properties of SAC/VAL in HD patients with HFrEF or HFmrEF.

METHODS

HD patients with HFrEF or HFmrEF were treated with SAC/VAL 50 or 100 mg twice a day (BID) and the concentrations of valsartan and LBQ657 (active metabolite of SAC) were determined by high-performance liquid chromatography-tandem mass spectrometry during HD and on the days between HD sessions (interval days). N-terminal-pro B-type natriuretic peptide and high-sensitivity troponin T were measured, and left ventricular ejection fraction (LVEF) was evaluated by echocardiography.

RESULTS

The mean maximum plasma concentrations (Cmax) of LBQ657 and VAL on the interval days were 15.46 ± 6.01 and 2.57 ± 1.23 mg/L, respectively. Compared with previous values in patients with severe renal impairment and healthy volunteers, these levels both remained within the safe concentration ranges during treatment with SAC/VAL 100 mg BID. Moreover, SAC/VAL significantly improved LVEF in HD patients with HFrEF or HFmrEF (p < 0.05).

CONCLUSIONS

HD did not remove the SAC metabolite LBQ657 or VAL in patients with HF. However, SAC/VAL 100 mg BID was safe and effective in patients undergoing HD.

Angiotensin receptor-neprilysin inhibitor in patients with heart failure and chronic kidney disease

Despite significant advances in the management of heart failure with reduced ejection fraction (HFrEF), there remains an enormous health problem with high morbidity and mortality over the last few decades. The neprilysin inhibitor enhances the activity of natriuretic peptides, producing vasodilation, natriuresis, and diuresis. Angiotensin receptor blockers inhibit the renin-angiotensin-aldosterone system. Sacubitril/valsartan, a first-in-class angiotensin receptor-neprilysin inhibitor (ARNI), has been shown to improve cardiovascular outcomes in HFrEF and delay the progression of chronic kidney disease (CKD) in patients with HFrEF. The PARADIGM-HF study showed a reduction in diuretic need in the ARNI group. While the use of diuretics is effective in volume control in patients with HFrEF, their use has the potential to adversely affect renal function. Therefore, ARNI therapy could benefit patients with heart failure and CKD by reducing cardiovascular morbidity and mortality and possibly retarding the progression of CKD, although more clinical evidence is required in patients with severe CKD and end-stage renal disease.

Disease-modifier Drugs in Patients with Advanced Heart Failure: How to Optimize Their Use?

Therapy based on disease-modifier drugs is among the required criteria to diagnose advanced heart failure (AdvHF). Nevertheless, several conditions, such as hospitalization, hypotension, renal dysfunction, electrolyte abnormalities, medical inertia, and patients' adherence, can make the maintenance of optimal medical therapy in patients with AdvHF challenging. Moreover, in recent years, new classes of drugs able have been shown to be able to further modify the natural history of heart failure with reduced ejection fraction, but they are still not widely adopted. This article discusses the optimal use of disease-modifier drugs in patients with AdvHF as well as the possible usefulness of the new therapeutic opportunities.

Sacubitril/valsartan in patients with heart failure with reduced ejection fraction with end-stage of renal disease

Aims

Sacubitril/valsartan (SV) reduced heart failure hospitalization and cardiovascular mortality compared with enalapril in the Prospective Comparison of ARNI with ACE‐I to Determine Impact on Global Mortality and Morbidity in Heart Failure trial. However, this trial excluded patients with end stage of renal disease (ESRD); thus, the efficacy and safety of SV in heart failure with reduced ejection fraction (HFrEF) with ESRD remains uncertain.

Methods and results

We retrospectively analysed the clinical and laboratory data of 501 HFrEF patients who administered with SV from March 2017 to April 2019 in a single tertiary university hospital. A total of 23 HFrEF patients with ESRD on dialysis [58.3% non‐ischaemic heart failure; left ventricular ejection fraction (LVEF): 29.7 ± 4.4%] were included in this study. At baseline and follow‐up visit, we evaluated cardiovascular biomarkers such as high‐sensitive troponin T (hsTnT), soluble ST2 (sST2), echocardiographic parameters, and clinical and adverse events. The mean dose of SV was 90 ± 43 mg/day at baseline and 123 ± 62 mg/day at last follow‐up (follow‐up duration: median 132 days). The level of hsTnT was significantly reduced from 236.2 ± 355.3 to 97.0 ± 14.0 pg/mL (P = 0.002), and the sST2 level was significantly reduced from 40.4 ± 44.0 to 19.6 ± 14.1 ng/mL (P = 0.005). LVEF was significantly improved from 29.7 ± 4.4% to 40.8 ± 10.4% (P = 0.002). During the follow‐up, up‐titration, down‐titration, and maintenance of SV dosing were observed in 7 (30%), 5 (21.7%), and 11 patients (47.8%), respectively. SV down‐titration group had adverse events including symptomatic hypotension (systolic blood pressure <100 mmHg) (n = 4) and dizziness (n = 1), but they did not discontinue SV therapy.

Conclusions

We found that SV could safely reduce the hsTnT and sST2 levels and improve LVEF in HFrEF patients with ESRD. As far as we know, this is the first study to show the efficacy and safety of SV in HFrEF with ESRD on dialysis. Larger prospective, long‐term follow‐up study should be warranted.

Do plasma neprilysin activity and plasma neprilysin concentration predict cardiac events in chronic kidney disease patients?

Background

Since the introduction of sacubitril/valsartan in clinical cardiology, neprilysin has become a major target for heart failure treatment. Plasma neprilysin concentration has been discussed as a novel biomarker that predicts cardiac events. Natriuretic peptides may inhibit plasma neprilysin. As they accumulate in chronic kidney disease (CKD), we hypothesized that high plasma neprilysin loses its predictive role in CKD patients.

Methods

We measured plasma levels of neprilysin concentration, neprilysin activity and brain natriuretic peptide (BNP) in 542 CKD G2-G4 patients within the CARE FOR HOMe study. Patients were followed for predefined endpoints of hospitalization for acute decompensated heart failure and incident atherosclerotic cardiovascular events.

Results

During 5.1 ± 2.1 years, 63 patients had acute decompensated heart failure and 125 patients had incident atherosclerotic cardiovascular events. In both Kaplan-Meier and multivariate Cox regression analyses, high plasma BNP and low, rather than elevated, neprilysin activity predicted future hospitalization for acute decompensated heart failure; neprilysin concentration was not predictive. Furthermore, only BNP was an independent predictor of incident atherosclerotic cardiovascular events.

Conclusions

In line with experimental studies, high natriuretic peptides may inhibit neprilysin activity in CKD. Therefore, high neprilysin activity and concentrations are not predictors of adverse cardiovascular outcome in CKD patients. Thus neprilysin inhibitors should be implemented with caution in patients with advanced CKD.

Renal effects of Sacubitril/Valsartan in heart failure with reduced ejection fraction: a real life 1-year follow-up study

Real-life data confirming the favourable renal outcome in patients with heart failure (HF) treated with Sacubitril/Valsartan, previously found in several trials (RCTs), are still scant. We evaluated the renal effects of Sacubitril/Valsartan in a real-life sample of HF patients. Observational analysis of 54 consecutive outpatients affected by HF with reduced ejection fraction (HFrEF) and clinical indication for Sacubitril/Valsartan. Patients were evaluated at baseline (T0) and after six (T6) and twelve (T12) months after initiating Sacubitril/Valsartan and compared with a group of 30 historical controls. Mean age: 65.5 ± 11.7 years. Older patients: 29 (53.7%). Mean baseline estimated glomerular filtration rate (eGFR): 59.4 ± 19.2 ml/min/1.73 m2. Patients with chronic kidney disease (CKD), defined by an eGFR < 60 ml/min/1.73 m2, were 29 (53.7%). Sacubitril/Valsartan was less titrated in both older patients and patients with CKD. There were no changes in diuretics during follow-up. Systolic blood pressure (BP) decreased during follow-up (p = 0.014), while left ventricular ejection fraction (LVEF) slighly increased (p < 0.001). Renal function improved after 12 months compared to historical controls (p for interaction < 0.001) and a greater benefit was found in subjects aged < 65 years (p for interaction = 0.002) and patients with CKD (p for interaction = 0.009). A statistically (p = 0.009), but not clinically significant increase in serum potassium was also found, regardless of age and CKD. This is the first study focused on the renal effects of Sacubitril/Valsartan in HFrEF patients followed for 12 months in a real-life clinical context. The improved eGFR, despite lower BP, represents an important confirmation outside the peculiar world of RCTs.

A validated RP-HPLC method for the evaluation of the influence of grapefruit juice on liver S9 activation of sacubitril

Grapefruit juice inhibits esterase enzyme. Therefore, a possible interaction with ester prodrugs should be taken into consideration. In this study, the influence of grapefruit juice on sacubitril (SAC) rat liver S9 activation by esterase enzyme was evaluated. An RP-HPLC method was developed and validated for estimation of SAC in rat liver S9 fraction using a C₁₈ Cyano column as stationary phase and acetonitrile-sodium di-hydrogen phosphate buffer (0.02 m, pH 4 adjusted by o-phosphoric acid, 40:60, v/v), as mobile phase at a flow rate of 1 mL/min and UV detection at 254 nm. The method was successfully applied to an in vitro study in which SAC was incubated with rat liver S9 fraction prepared from rats that had previously ingested grapefruit juice for a week. The calculated SAC concentration after incubation was compared with that of SAC incubated with rat liver S9 fraction from the rat control group. The statistical significance between the results of test and control incubation sets was assessed. In conclusion, the current study demonstrated that grapefruit juice decreased SAC hydrolysis, hence delaying its activation to sacubitrilat (active form) in gut lumen. Based on this food-drug interaction, it may be required that grapefruit juice should be consumed with caution in patients receiving SAC.

Clinical Pharmacokinetics of Sacubitril/Valsartan (LCZ696): A Novel Angiotensin Receptor-Neprilysin Inhibitor

Sacubitril/valsartan (LCZ696) is indicated for the treatment of heart failure with reduced ejection fraction. Absorption of sacubitril/valsartan and conversion of sacubitril (prodrug) to sacubitrilat (neprilysin inhibitor) was rapid with maximum plasma concentrations of sacubitril, sacubitrilat, and valsartan (angiotensin receptor blocker) reaching within 0.5, 1.5-2.0, and 2.0-3.0 h, respectively. With a two-fold increase in dose, an increase in the area under the plasma concentration-time curve was proportional for sacubitril, ~1.9-fold for sacubitrilat, and ~1.7-fold for valsartan in healthy subjects. Following multiple twice-daily administration, steady-state maximum plasma concentration was reached within 3 days, showing no accumulation for sacubitril and valsartan, while ~1.6-fold accumulation for sacubitrilat. Sacubitril is eliminated predominantly as sacubitrilat through the kidney; valsartan is eliminated mainly by biliary route. Drug-drug interactions of sacubitril/valsartan were evaluated with medications commonly used in patients with heart failure including furosemide, warfarin, digoxin, carvedilol, levonorgestrel/ethinyl estradiol combination, amlodipine, omeprazole, hydrochlorothiazide, intravenous nitrates, metformin, statins, and sildenafil. Co-administration with sacubitril/valsartan increased the maximum plasma concentration (~2.0-fold) and area under the plasma concentration-time curve (1.3-fold) of atorvastatin; however, it did not affect the pharmacokinetics of simvastatin. Age, sex, or ethnicity did not affect the pharmacokinetics of sacubitril/valsartan. In patients with heart failure vs. healthy subjects, area under the plasma concentration-time curves of sacubitril, sacubitrilat, and valsartan were higher by approximately 1.6-, 2.1-, and 2.3-fold, respectively. Renal impairment had no significant impact on sacubitril and valsartan area under the plasma concentration-time curves, while the area under the plasma concentration-time curve of sacubitrilat correlated with degree of renal function (1.3-, 2.3-, 2.9-, and 3.3-fold with mild, moderate, and severe renal impairment, and end-stage renal disease, respectively). Moderate hepatic impairment increased the area under the plasma concentration-time curves of valsartan and sacubitrilat ~2.1-fold.

From ARB to ARNI in Cardiovascular Control

Coexistence of hypertension, diabetes mellitus and chronic kidney disease synergistically aggravates the risk of cardiovascular and renal morbidity and mortality. These high-risk, multi-morbid patient populations benefit less from currently available anti-hypertensive treatment. Simultaneous angiotensin II type 1 receptor blockade and neprilysin inhibition (‘ARNI’) with valsartan/sacubitril (LCZ696) might potentiate the beneficial effects of renin-angiotensin-aldosterone inhibition by reinforcing its endogenous counterbalance, the natriuretic peptide system. This review discusses effects obtained with this approach in animals and humans. In animal models of hypertension, either alone or in combination with myocardial infarction or diabetes, ARNI consistently reduced heart weight and cardiac fibrosis in a blood pressure-independent manner. Additionally, LCZ696 treatment reduced proteinuria, focal segmental glomerulosclerosis and retinopathy, thus simultaneously demonstrating favourable effects on microvascular complications. These results were confirmed in patient populations. Besides blood pressure reductions in hypertensive patients and greatly improved (cardiovascular) mortality in heart failure patients, ventricular wall stress and albuminuria were reduced particularly in diabetic patients. The exact underlying mechanism remains unknown, but may involve improved renal haemodynamics and reduced glomerulosclerosis, e.g. related to a rise in natriuretic peptide levels. However, the assays of these peptides are hampered by methodological artefacts. Moreover, since sacubitrilat is largely renally cleared, drug accumulation may occur in patients with impaired renal function and thus hypotension is a potential side effect in patients with chronic kidney disease. Further caution is warranted since neprilysin also degrades endothelin-1 and amyloid beta in animal models. Accumulation of the latter may increase the risk of Alzheimer’s disease.

Neprilysin inhibition and endothelin-1 elevation: Focus on the kidney

Increasing the degree of renin-angiotensin system (RAS) blockade by combining ≥2 RAS blockers marginally increases efficacy, but results in more side effects. Hence, interference with other systems is currently being investigated, like potentiation of natriuretic peptides with neprilysin inhibitors. However, the neprilysin inhibitor thiorphan was recently found to increase endothelin-1 when administered to TGR(mREN2)27 (Ren2) rats on top of RAS blockade. Here we investigated whether this effect is thiorphan-specific, by comparing the neprilysin inhibitors thiorphan and sacubitril, administered by osmotic minipumps at a low or high dose for 7 days, in Ren2 rats. Plasma and urinary levels of endothelin-1, atrial and brain natriuretic peptide (ANP, BNP) and their second messenger cyclic guanosine 3'5' monophosphate (cGMP) were monitored. No significant differences were found in the plasma concentrations of endothelin-1, cGMP, ANP and BNP after treatment, although plasma ANP tended to be higher in the high-dose thiorphan treatment group and the low- and high-dose sacubitril treatment groups, compared with vehicle. Urinary endothelin-1 increased in the low-dose thiorphan and high-dose sacubitril groups, compared with baseline, although significance was reached for the former only. Urinary cGMP rose significantly in the high-dose sacubitril treatment group compared with baseline. Both urinary endothelin-1 and cGMP were significantly higher in the high-dose sacubitril group compared with the low-dose sacubitril group. In conclusion, endothelin-1 upregulation occurs with both thiorphan and sacubitril, and is particularly apparent in neprilysin-rich organs like the kidney. High renal neprilysin levels most likely also explain why sacubitril increased cGMP in urine only.

Negotiating renal dysfunction when treating patients with heart failure

INTRODUCTION

Chronic kidney disease (CKD) is one of the most prevalent comorbidities in HF, and no specific treatment is still available for the so-called cardiorenal syndrome. Areas covered: The aim of this review is to describe the interaction of heart and kidney function and the consequences of cardiorenal syndrome, focusing on the use of available therapeutics. Expert commentary: The presence of CKD has been associated with adverse outcomes in HF regardless of ejection fraction. On the other hand, cardiovascular events are the most common causes of morbidity and mortality among CKD patients, reflecting the close pathophysiological crosstalk between these organs. Multiple mechanisms are involved in the development of cardiorenal syndrome, including hemodynamic, neurohormonal and inflammatory mediators. The management of several HF drugs is a challenge in the presence of CKD mainly due to blunted diuretic response and increased risk of worsening of kidney function. Therefore, finding a balance between the optimization of cardiac and renal outcomes is a real negotiation in the everyday clinical practice.

Erratum to: Clinical Pharmacokinetics of Sacubitril/Valsartan (LCZ696): A Novel Angiotensin Receptor-Neprilysin Inhibitor

Sacubitril/valsartan (LCZ696) is indicated for the treatment of heart failure with reduced ejection fraction. Absorption of sacubitril/valsartan and conversion of sacubitril (prodrug) to sacubitrilat (neprilysin inhibitor) was rapid with maximum plasma concentrations of sacubitril, sacubitrilat, and valsartan (angiotensin receptor blocker) reaching within 0.5, 1.5-2.0, and 2.0-3.0 h, respectively. With a twofold increase in dose, an increase in the area under the plasma concentration-time curve was proportional for sacubitril, ~1.9-fold for sacubitrilat, and ~1.7-fold for valsartan in healthy subjects. Following multiple twice-daily administration, steady-state maximum plasma concentration was reached within 3 days, showing no accumulation for sacubitril and valsartan, while ~1.6-fold accumulation for sacubitrilat. Sacubitril is eliminated predominantly as sacubitrilat through the kidney; valsartan is eliminated mainly by biliary route. Drug-drug interactions of sacubitril/valsartan were evaluated with medications commonly used in patients with heart failure including furosemide, warfarin, digoxin, carvedilol, levonorgestrel/ethinyl estradiol combination, amlodipine, omeprazole, hydrochlorothiazide, intravenous nitrates, metformin, statins, and sildenafil. Co-administration with sacubitril/valsartan increased the maximum plasma concentration (~2.0-fold) and area under the plasma concentration-time curve (1.3-fold) of atorvastatin; however, it did not affect the pharmacokinetics of simvastatin. Age, sex, or ethnicity did not affect the pharmacokinetics of sacubitril/valsartan. In patients with heart failure vs. healthy subjects, area under the plasma concentration-time curves of sacubitril, sacubitrilat, and valsartan were higher by approximately 1.6-, 2.1-, and 2.3-fold, respectively. Renal impairment had no significant impact on sacubitril and valsartan area under the plasma concentration-time curves, while the area under the plasma concentration-time curve of sacubitrilat correlated with degree of renal function (1.3-, 2.3-, 2.9-, and 3.3-fold with mild, moderate, and severe renal impairment, and end-stage renal disease, respectively). Moderate hepatic impairment increased the area under the plasma concentration-time curves of valsartan and sacubitrilat ~2.1-fold.

Transport properties of valsartan, sacubitril and its active metabolite (LBQ657) as determinants of disposition

1. The potential for drug-drug interactions of LCZ696 (a novel, crystalline complex comprising sacubitril and valsartan) was investigated in vitro. 2. Sacubitril was shown to be a highly permeable P-glycoprotein (P-gp) substrate and was hydrolyzed to the active anionic metabolite LBQ657 by human carboxylesterase 1 (CES1b and 1c). The multidrug resistance-associated protein 2 (MRP2) was shown to be capable of LBQ657 and valsartan transport that contributes to the elimination of either compound. 3. LBQ657 and valsartan were transported by OAT1, OAT3, OATP1B1 and OATP1B3, whereas no OAT- or OATP-mediated sacubitril transport was observed. 4. The contribution of OATP1B3 to valsartan transport (73%) was appreciably higher than that by OATP1B1 (27%), Alternatively, OATP1B1 contribution to the hepatic uptake of LBQ657 (∼70%) was higher than that by OATP1B3 (∼30%). 5. None of the compounds inhibited OCT1/OCT2, MATE1/MATE2-K, P-gp, or BCRP. Sacubitril and LBQ657 inhibited OAT3 but not OAT1, and valsartan inhibited the activity of both OAT1 and OAT3. Sacubitril and valsartan inhibited OATP1B1 and OATP1B3, whereas LBQ657 weakly inhibited OATP1B1 but not OATP1B3. 6. Drug interactions due to the inhibition of transporters are unlikely due to the redundancy of the available transport pathways (LBQ657: OATP1B1/OAT1/3 and valsartan: OATP1B3/OAT1/3) and the low therapeutic concentration of the LCZ696 analytes.

Evaluation of Drug-Drug Interaction Potential Between Sacubitril/Valsartan (LCZ696) and Statins Using a Physiologically Based Pharmacokinetic Model

Sacubitril/valsartan (LCZ696) has been approved for the treatment of heart failure. Sacubitril is an in vitro inhibitor of organic anion-transporting polypeptides (OATPs). In clinical studies, LCZ696 increased atorvastatin C_max by 1.7-fold and area under the plasma concentration-time curve by 1.3-fold, but had little or no effect on simvastatin or simvastatin acid exposure. A physiologically based pharmacokinetics modeling approach was applied to explore the underlying mechanisms behind the statin-specific LCZ696 drug interaction observations. The model incorporated OATP-mediated clearance (CL_int,T) for simvastatin and simvastatin acid to successfully describe the pharmacokinetic profiles of either analyte in the absence or presence of LCZ696. Moreover, the model successfully described the clinically observed drug effect with atorvastatin. The simulations clarified the critical parameters responsible for the observation of a low, yet clinically relevant, drug-drug interaction DDI between sacubitril and atorvastatin and the lack of effect with simvastatin acid. Atorvastatin is administered in its active form and rapidly achieves C_max that coincide with the low C_max of sacubitril. In contrast, simvastatin requires a hydrolysis step to the acid form and therefore is not present at the site of interactions at sacubitril concentrations that are inhibitory. Similar models were used to evaluate the drug-drug interaction risk for additional OATP-transported statins which predicted to maximally result in a 1.5-fold exposure increase.

Sacubitril/Valsartan (LCZ696) in Heart Failure

It has been known since the 1990s that long-term morbidity and mortality is improved in patients with heart failure with reduced ejection fraction (HFrEF) by treatments that target the renin-angiotensin-aldosterone system (RAAS). It has also long been thought that enhancement of the activity of natriuretic peptides (NPs) could potentially benefit patients with HFrEF, but multiple attempts to realize this benefit had failed over the years - until 2014, when a large, phase III, randomized, controlled clinical trial (PARADIGM-HF) was completed comparing sacubitril/valsartan with enalapril, a well-established treatment for HFrEF. Sacubitril/valsartan (formerly known as LCZ696) is a first-in-class angiotensin receptor neprilysin inhibitor (ARNI) that simultaneously suppresses RAAS activation through blockade of angiotensin II type 1 receptors and enhances vasoactive peptides including NPs through inhibition of neprilysin, the enzyme responsible for their degradation. In PARADIGM-HF, patients with HFrEF treated with sacubitril/valsartan had 20% less risk for cardiovascular death or hospitalization for heart failure (the primary endpoint), 20% less risk for cardiovascular death, 21% less risk for first hospitalization for heart failure, and 16% less risk for death from any cause, compared with enalapril (all p < 0.001). Concerning tolerability, the sacubitril/valsartan group had higher proportions of patients with hypotension and nonserious angioedema but lower proportions with renal impairment, hyperkalemia, and cough, compared with the enalapril group. The use of sacubitril/valsartan has been endorsed by the latest heart failure treatment guidelines in Europe and the USA. This chapter reviews the discoveries, scientific reasoning, and clinical evidence that led to the development of sacubitril/valsartan, the first novel therapy in a new drug class to improve survival in HFrEF in the last 15 years.

Angiotensin Receptor-Neprilysin Inhibition

The novel combination sacubitril/valsartan represents a new therapeutic approach in the management of heart failure. With the simultaneous blockage of the enzyme neprilysin (by sacubitril) and angiotensin II receptors (by valsartan), this combination reduces the degradation of natriuretic peptides and other counterregulatory peptide systems while avoiding the deleterious effect of angiotensin II receptors activation and thereby encompasses a beneficial impact of 2 important neurohormonal pathways activated in heart failure. As opposed to previously tested neprilysin inhibitors, sacubitril/valsartan represents a more effective method in reducing morbidity and mortality in heart failure, while preserving a safety profile comparable to well-established, standard, angiotensin-converting enzyme inhibitor's therapy.