Pharmacokinetics and pharmacodynamics of the vasopeptidase inhibitor, omapatrilat in healthy subjects

TaleNeprilysin and Neprilysin inhibition in chronic kidney disease

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is associated with increased risk of progression to end-stage kidney disease and cardiovascular events. There is limited evidence that available treatments have beneficial effects on cardiorenal outcomes in all people with nondiabetic CKD. Neprilysin inhibition (NEPi) is a new therapeutic strategy with potential to improve outcomes for patients with CKD.

RECENT FINDINGS

NEPi enhances the activity of the natriuretic peptide system producing natriuresis, diuresis and inhibition of the renin-angiotensin system and sympathetic nervous system. Sacubitril/valsartan is the first Angiotensin receptor-neprilysin inhibitor (ARNI) to be produced and has been shown to substantially improve cardiovascular outcomes in heart failure and delay progression of kidney disease in this population. Although ARNIs have not shown similar effects on kidney function in the short-to-medium term in people with CKD, they are associated with substantial reductions in cardiac biomarkers and blood pressure in CKD.

SUMMARY

These data suggest that NEPi with an ARNI could benefit patients with CKD by reducing the risk of cardiovascular disease and have the possibility of retarding the progression of CKD (hence delaying the need for renal replacement therapy).

Cardiovascular Outcomes with Sacubitril-Valsartan in Heart Failure: Emerging Clinical Data

One of the defining features of heart failure (HF) is neurohormonal activation. The renin-angiotensin-aldosterone-system (RAAS) and sympathetic nervous system (SNS) cause vasoconstriction and fluid retention and, in response, the secretion of natriuretic peptides (NPs) from volume and pressure-overloaded myocardium promotes vasodilation and diuresis. Inhibition of the RAAS with either angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) has been the cornerstone of medical treatment for HF with a reduced ejection fraction (HFrEF) but, until recently, it was unclear how the beneficial effects of NPs may be augmented in patients with HF. Neprilysin, a metalloproteinase widely distributed throughout the body, plays a role in degrading the gross excess of circulating NPs in patients with HF. Early studies of neprilysin inhibition suggested possible physiological benefits. In 2014, the PARADIGM-HF trial found that sacubitril-valsartan, a combination of the ARB valsartan, and the neprilysin inhibitor sacubitril, was superior to enalapril in patients with HFrEF, reducing the relative risk of cardiovascular (CV) death or first hospitalisation with HF by 20%. Almost half of the patients with HF symptoms have a “preserved” ejection fraction (HFpEF); however, the PARAGON-HF study found that sacubitril-valsartan in patients with LVEF ≥45% had no effect on CV death or first and recurrent hospitalisations with HF compared to valsartan. Guidelines across the world have changed to include sacubitril-valsartan for patients with HFrEF yet, nearly 6 years after PARADIGM-HF, there is still uncertainty as to when and in whom sacubitril-valsartan should be started. Furthermore, there may yet be subsets of patients with HFpEF who might benefit from treatment with sacubitril-valsartan. This review will describe the mechanisms behind the outcome benefit of sacubitril-valsartan in patients with HFrEF and to consider its future role in the management of patients with HF.

Cardiorenal and endocrine effects of synthetic canine BNP1-32 in dogs with compensated congestive heart failure caused by myxomatous mitral valve disease

Background

The effects of synthetic brain natriuretic peptide (BNP1‐32) on cardiorenal and renin angiotensin aldosterone system in dogs with naturally occurring congestive heart failure (CHF) are unknown.

Objectives

To evaluate the cardiorenal and endocrine effects of SC administered synthetic canine BNP1‐32, with or without furosemide, in dogs with CHF caused by myxomatous mitral valve disease (MMVD).

Animals

Seven client‐owned male dogs with compensated American College of Veterinary Internal Medicine stage C CHF caused by MMVD on chronic treatment with furosemide, benazepril, and pimobendan.

Methods

A single‐dose, crossover, pilot study. Each dog received a dose of BNP1‐32 (5 μg/kg), furosemide (2 mg/kg), and both BNP1‐32/furosemide (5 μg/kg and 2 mg/kg, respectively) SC with a 2‐week washout period among each treatment. Between‐ and within‐treatment effects were evaluated using linear mixed modeling with restricted maximum likelihood estimation and evaluation of least square differences.

Results

Rapid absorption of BNP1‐32 and a corresponding rise in urinary cyclic guanosine monophosphate excretion was observed at 1‐2 hours after any treatment containing BNP1‐32 (P < .05). However, BNP1‐32 did not influence measured cardiorenal variables. Plasma aldosterone concentrations were below quantifiable levels in majority of the samples.

Conclusions and Clinical Importance

No beneficial cardiorenal effects were detected. It is possible that dogs with chronic CHF have a reduction in natriuretic peptide responsiveness.

Sacubitril/valsartan: A novel angiotensin receptor-neprilysin inhibitor

OBJECTIVE

To describe the efficacy, superiority and safety profile of the first-in-class angiotensin receptor-neprilysin inhibitor "Sacubitril/Valsartan" as compared to angiotensin-converting enzyme inhibitors (ACEi) and angiotensin II receptor blocker (ARB) in heart failure (HF) patients, reviewing data available from both clinical and pre-clinical studies. Evidences on health care utilization outcomes such as hospitalizations and emergency department visits were also evaluated.

MATERIAL (DATA SOURCE)

Sources: Medical literature on 'Sacubitril/Valsartan' and 'Angiotensin Receptor-Neprilysin Inhibitor' was identified by searching databases (including, but not limited to, PubMed, Embase and HighWire) for articles published since 1991, bibliographies from published literature, clinical trial registries/databases and websites (including those of regional regulatory agencies and the manufacturer). Additional information (including contributory unpublished data) was also requested from the companies developing the drug.

SEARCH STRATEGY

We conducted separate searches for each of the interventions of interest. The timeframe for both searches spanned the period from January 1991 to the most recently published data available and focused on PubMed, Embase and HighWire indexed articles. The search strategies included a combination of indexing terms as well as free-text terms included separately in 'Keywords' section. To supplement the above searches and ensure optimal and complete literature retrieval, we performed a manual check of the references of recent relevant reviews and meta-analysis. Searches were last updated on 12th July 2017.

SELECTION

Studies in patients with hypertension who received sacubitril/valsartan combination drug were included. Inclusion of studies was based mainly on the methods section of the trials. When available, large, well-controlled trials with appropriate statistical methodology was preferred. Relevant pharmacodynamics and pharmacokinetics data was also included.

DATA EVALUATION

Many clinical trials have been conducted comparing the efficacy of sacubitril/valsartan with other anti-hypertensives. The trials have shown sacubitril/valsartan to be more effective in improving symptoms and physical limitations, reducing the risk of cardiovascular (CV) death, HF hospitalization, and the overall mortality and morbidity compared to its counterparts.

CONCLUSION

Effective reduction of blood pressure to accepted goals is the key to reduce the risk of CV events and stroke. Dual inhibition of neprilysin and the angiotensin receptor with sacubitril/valsartan may represent an attractive and serendipitous therapeutic approach for a range of CV diseases, including hypertension and HF, in which vasoconstriction, volume overload and neuro-hormonal activation play a part in pathophysiology. Sacubitril/Valsartan appears to be more efficacious in reducing blood pressure than currently available ACEi and ARBs with a similar safety and tolerability profile. Besides, pleiotropic benefits like HbA_1c reduction, better eGFR progression and a greater decrease in blood pressure and serum creatinine levels make this drug a novel addition to the current hypertension armamentarium.

Pharmacodynamic and Pharmacokinetic Profiles of Sacubitril/Valsartan (LCZ696) in Patients with Heart Failure and Reduced Ejection Fraction

AIMS

Concomitant renin-angiotensin-aldosterone system blockade and natriuretic peptide system enhancement may provide unique therapeutic benefits to patients with heart failure and reduced ejection fraction (HFrEF). This study assessed the pharmacodynamics and pharmacokinetics of LCZ696 in patients with HFrEF.

METHODS

This was an open-label, noncontrolled single-sequence study. After a 24-h run-in period, patients (n = 30) with HFrEF (EF ≤ 40%; NYHA class II-IV) received LCZ696 100 mg twice daily (bid) for 7 days and 200 mg bid for 14 days, along with standard treatment for heart failure (HF) (except angiotensin-converting enzyme inhibitors [ACEIs] or angiotensin receptor blockers [ARBs]).

RESULTS

On Day 21, significant increases were observed in the plasma biomarkers indicative of neprilysin and RAAS inhibition (ratio-to-baseline: cyclic guanosine monophosphate [cGMP], 1.38; renin concentration and activity, 3.50 and 2.27, respectively; all, P < 0.05). Plasma NT-proBNP levels significantly decreased at all the time points on Days 7 and 21; plasma aldosterone and endothelin-1 levels significantly decreased on Day 21 (all, P < 0.05). Following administration of LCZ696, the Cmax of sacubitril (neprilysin inhibitor prodrug), LBQ657 (active neprilysin inhibitor), and valsartan were reached within 0.5, 2.5, and 2 h. Between 100- and 200-mg doses, the Cmax and AUC0-12 h for sacubitril and LBQ657 were approximately dose-proportional while that of valsartan was less than dose-proportional.

CONCLUSIONS

Treatment with LCZ696 for 21 days was well tolerated and resulted in plasma biomarker changes indicative of neprilysin and RAAS inhibition in patients with HF. The pharmacokinetic exposure of the LCZ696 analytes in patients with HF observed in this study is comparable to that observed in the pivotal Phase III study.

Spotlight on valsartan-sacubitril fixed-dose combination for heart failure: the evidence to date

Heart failure is a global problem with elevated prevalence, and it is associated with substantial cardiovascular morbidity and mortality. Treating heart-failure patients has been a very challenging task. This review highlights the main pharmacological developments in the field of heart failure with reduced ejection fraction, giving emphasis to a drug that has a dual-acting inhibition of the neprilysin and renin–angiotensin–aldosterone system. Neprilysin is an enzyme that participates in the breakdown of biologically active natriuretic peptides and several other vasoactive compounds. The inhibition of neprilysin has been a therapeutic target for several drugs tested in cardiovascular disease, mainly for heart failure and/or hypertension. However, side effects and a lack of efficacy led to discontinuation of their development. LCZ696 is a first-in-class neprilysin- and angiotensin-receptor inhibitor that has been developed for use in heart failure. This drug is composed of two molecular moieties in a single crystalline complex: a neprilysin-inhibitor prodrug (sacubitril) and the angiotensin-receptor blocker (valsartan). The PARADIGM-HF trial demonstrated that this drug was superior to an angiotensin-converting enzyme inhibitor (enalapril) in reducing mortality in patients with heart failure with reduced ejection fraction. The ability to block the angiotensin receptor and augment the endogenous natriuretic peptide system provides a distinctive mechanism of action in cardiovascular disease.

Role of neprilysin inhibitor combinations in hypertension: insights from hypertension and heart failure trials

Neprilysin is a neutral endopeptidase and its inhibition increases bioavailability of natriuretic peptides, bradykinin, and substance P, resulting in natriuretic, vasodilatatory, and anti-proliferative effects. In concert, these effects are prone to produce a powerful ventricular unloading and antihypertensive response. LCZ696 (Valsartan/sacubitril) is a first-in-class angiotensin II-receptor neprilysin inhibitor. LCZ696 is a novel drug not only for the treatment of heart failure but it is also likely to be a useful antihypertensive drug and may have a preferential effect on systolic pressure. This review discusses (i) the mechanism of action, pharmacokinetics, and pharmacodynamics of this novel drug, (ii) the efficacy, safety, and tolerability of LCZ696 in treatment of hypertension from the available trials, (iii) evidence from other contemporary trials on combined Neprilysin inhibitors, (iv) future trials and areas of research to identify hypertensive patient populations that would most benefit from LCZ696.

How First-Time-in-Human Studies Are Being Performed: A Survey of Phase I Dose-Escalation Trials in Healthy Volunteers Published Between 1995 and 2004

First-time-in-human studies are small, time-lagged dose-escalation studies including volunteer subjects evaluating safety and tolerability. There is little consensus in the design of a first-time-in-human study, and it is difficult to get an overview of studies performed. One hundred five studies comprising 3323 healthy volunteers published in the 5 major clinical pharmacology journals since 1995 were analyzed. The average trial was placebo controlled, double blind including 32 subjects at 5 dose levels but with great variation in cohort size and dose-escalation method. The parallel single-dose design was the most common design, with the crossover designs being more frequent in the early publications. Despite discussions on the optimization of phase I trials, little seems to be happening. The development of study designs and evaluation methods for cancer trials is extensive, but formal statistically based methods and more scientific study designs are unusual in phase I dose-escalation trials in healthy volunteers.

Pharmacokinetics and pharmacodynamics of LCZ696, a novel dual-acting angiotensin receptor-neprilysin inhibitor (ARNi)

Angiotensin receptor blockade and neprilysin (NEP) inhibition together offer potential benefits for the treatment of hypertension and heart failure. LCZ696 is a novel single molecule comprising molecular moieties of valsartan and NEP inhibitor prodrug AHU377 (1:1 ratio). Oral administration of LCZ696 caused dose-dependent increases in atrial natriuretic peptide immunoreactivity (due to NEP inhibition) in Sprague-Dawley rats and provided sustained, dose-dependent blood pressure reductions in hypertensive double-transgenic rats. In healthy participants, a randomized, double-blind, placebo-controlled study (n = 80) of single-dose (200-1200 mg) and multiple-dose (50-900 mg once daily for 14 days) oral administration of LCZ696 showed that peak plasma concentrations were reached rapidly for valsartan (1.6-4.9 hours), AHU377 (0.5-1.1 hours), and its active moiety, LBQ657 (1.8-3.5 hours). LCZ696 treatment was associated with increases in plasma cGMP, renin concentration and activity, and angiotensin II, providing evidence for NEP inhibition and angiotensin receptor blockade. In a randomized, open-label crossover study in healthy participants (n = 56), oral LCZ696 400 mg and valsartan 320 mg were shown to provide similar exposure to valsartan (geometric mean ratio [90% confidence interval]: AUC(0-infinity) 0.90 [0.82-0.99]). LCZ696 was safe and well tolerated. These data support further clinical development of LCZ696, a novel, orally bioavailable, dual-acting angiotensin receptor-NEP inhibitor (ARNi) for hypertension and heart failure.

Effects of vasopeptidase inhibition on renal function and tubuloglomerular feedback in spontaneously hypertensive rats

Vasopeptidase inhibitors are a novel class of antihypertensive agents that concomitantly inhibit angiotensin converting enzyme and neutral endopeptidase. Our purpose was to investigate the effects of omapatrilat, a vasopeptidase inhibitor, on renal function and tubuloglomerular feedback (TGF) response in anesthetized 9-10-week-old spontaneously hypertensive rats (SHR). Intravenous injection of omapatrilat at 10 micromol/kg decreased systemic blood pressure and renal vascular resistance. Renal plasma flow was unchanged, whereas glomerular filtration rate (GFR) and filtration fraction (FF) were reduced. Increased urinary sodium excretion of tubular origin was observed. These parameters remained unaltered with vehicle treatment. Micropuncture study revealed that the maximal reduction of early proximal flow rate (EPFR) induced by orthograde perfusion of Henle's loop with artificial tubular fluid (ATF) was significantly reduced by omapatrilat treatment (28.5+/-3.1% vs. 72.0+/-2.8% of control) and was not significantly changed in the vehicle-treated group (vehicle 70.8+/-1.7% vs. control 71.0+/-2.1%). EPFR at zero perfusion was comparable between omapatrilat and vehicle treatment (29.7+/-2.2 vs. 31.3+/-2.1 nl/min, respectively). Luminal perfusion of 10(-4) mol/l 7-nitroindazole in ATF abrogated the blunting of TGF response by omapatrilat but elicited no change in the vehicle-treated group. The suppression of the TGF mechanism and the reduction in FF suggest that omapatrilat respectively dilates the afferent and efferent arterioles. Under such conditions, reduction of GFR may indicate a fall in intraglomerular pressure. The restoration of nitric oxide signaling in the juxtaglomerular apparatus of SHR seems to participate in the inhibition of TGF by omapatrilat. These findings suggest that omapatrilat may provide a novel approach to the treatment of systemic and glomerular hypertension.

Vasopeptidase inhibitor restores the balance of vasoactive hormones in progressive nephropathy

BACKGROUND

The mechanism(s) underlying greater renoprotection of combined blockade of angiotensin-converting enzyme (ACE) and neutral endopeptidase (NEP) by vasopeptidase over ACE inhibitors are ill defined. We previously found that progressive renal disease is associated with increased renal synthesis of endothelin-1 (ET-1) in the face of reduced generation of renal nitric oxide (NO) in the remnant kidney model. Here we compared changes in urinary excretion of ET-1 and nitrite/nitrate, markers of renal ET-1, and NO synthesis, respectively, and urinary cGMP, an indirect index of renal atrial natriuretic peptide (ANP) synthesis, after administration of vasopeptidase or ACE inhibitor in rats with renal mass reduction (RMR).

METHODS

Twenty-one days after 5/6 nephrectomy, after the onset of hypertension and overt proteinuria, rats were divided in 3 groups (N= 7-8) and given daily by gavage: vehicle, the vasopeptidase inhibitor AVE7688 (3 mg/kg bid), or enalapril (5 mg/kg bid) until day 90. Normal rats (N= 5) served as control rats.

RESULTS

Systolic blood pressure in RMR rats was equally controlled by AVE7688 and enalapril. AVE7688 resulted in a significant antiproteinuric effect, with urinary protein levels being reduced on average by 83% in respect to vehicle (88 +/- 28 vs. 518 +/- 27 mg/day, P < 0.0001). Enalapril achieved a 47% reduction in proteinuria (277 +/- 81 mg/day, P < 0.01 vs. vehicle) to levels that remained higher (P < 0.01), however, than those after AVE7688. Renal function impairment and glomerular and tubular changes were significantly (P < 0.05 vs. vehicle) ameliorated by AVE7688, and partially affected by enalapril. AVE7688 reduced the abnormal urinary excretion of ET-1 of RMR animals (98 +/- 8 vs. vehicle: 302 +/- 50 pg/24 h, P < 0.001) more than enalapril (159 +/- 14 pg/24 h, P < 0.05 vs. AVE7688). Consistently, AVE7688 was more effective than enalapril in augmenting renal synthesis of NO (2487 +/- 267 and 1519 +/- 217 vs. vehicle: 678 +/- 71 nmol/15 h; P < 0.001, AVE7688 vs. vehicle, P < 0.01 AVE7688 vs. enalapril). AVE7688 significantly increased urinary cGMP (78 +/- 6 vs. vehicle 45 +/- 9 nmol/24 h; P < 0.01).

CONCLUSION

The superior renoprotection achieved by AVE7688 over enalapril in progressive renal injury is due to the correction of the altered balance of vasoconstrictor/vasodilator mediators in the kidney.

Synovial fluid levels and serum pharmacokinetics in a large animal model following treatment with oral glucosamine at clinically relevant doses

OBJECTIVE

To examine the concentration of glucosamine in the synovial fluid and its pharmacokinetics in serum in a large animal model following dosing with glucosamine HCl at clinically relevant levels.

METHODS

Eight adult female horses were studied. After an overnight fast, glucosamine HCl (20 mg/kg of body weight) was administered by either nasogastric (NG) intubation or intravenous (IV) injection. Blood samples were collected before dosing and at 5, 15, 30, 60, 120, 180, 240, 360, 480, and 720 minutes after dosing. Synovial fluid samples were collected from the radiocarpal joints 48 hours before dosing and at 1 and 12 hours after dosing. Glucosamine was assayed by fluorophore-assisted carbohydrate electrophoresis.

RESULTS

The maximum concentration of glucosamine in serum reached approximately 300 muM ( approximately 50 microg/ml) following IV dosing and approximately 6 microM (approximately 1 microg/ml) following NG dosing. Synovial fluid concentrations reached 9-15 microM with IV dosing and 0.3-0.7 microM with NG dosing, and remained elevated (range 0.1-0.7 microM) in most animals even at 12 hours after dosing. Following NG dosing, the median serum maximal concentration of 6.1 microM (range 4.38-7.58) was attained between 30 minutes and 4 hours postdose. The mean apparent volume of distribution was 15.4 liters/kg, the mean bioavailability was 5.9%, and the mean elimination half-life was 2.82 hours.

CONCLUSION

Clinically relevant dosing of glucosamine HCl in this large monogastric animal model results in serum and synovial fluid concentrations that are at least 500-fold lower than those reported to modify chondrocyte anabolic and catabolic activities in tissue and cell culture experiments. We conclude that the apparent therapeutic benefit of dietary glucosamine on pain and joint space width in humans and animals may be secondary to its effects on nonarticular tissues, such as the intestinal lining, liver, or kidney, since these may be exposed to much high levels of glucosamine following ingestion.