Plecanatide Improves Abdominal Bloating and Bowel Symptoms of Irritable Bowel Syndrome with Constipation

BACKGROUND

Bloating is a bothersome symptom in irritable bowel syndrome with constipation (IBS-C).

AIM

To evaluate plecanatide efficacy in patients with IBS-C stratified by bloating intensity.

METHODS

Pooled phase 3 data (2 randomized, controlled IBS-C trials) from adults treated with plecanatide 3 mg or placebo for 12 weeks were analyzed. Patients were stratified post-hoc by baseline bloating severity (11-point scale: mild [≤ 5] and moderate-to-severe [> 5]). Assessments included change from baseline in bloating, abdominal pain, and complete spontaneous bowel movement (CSBM) frequency. Abdominal pain and bloating composite responders were defined as patients with ≥ 30% improvement from baseline in both bloating and abdominal pain at Week 12.

RESULTS

At baseline, 1104/1436 patients with IBS-C (76.9%) reported moderate-to-severe bloating. In the moderate-to-severe bloating subgroup, plecanatide significantly reduced bloating severity versus placebo (least-squares mean change [LSMC]: - 1.7 vs - 1.3; P = 0.002), reduced abdominal pain (- 1.7 vs - 1.3; P = 0.006), and increased CSBM frequency (1.4 vs 0.8; P < 0.0001). In the mild bloating subgroup, significant improvements were observed with plecanatide versus placebo for abdominal pain (LSMC: - 1.3 vs - 1.0; P = 0.046) and CSBM frequency (2.0 vs 1.2; P = 0.003) but not bloating (- 0.9 vs - 0.8; P = 0.28). A significantly greater percentage of patients were abdominal pain and bloating composite responders with plecanatide versus placebo (moderate-to-severe bloating: 33.6% vs 26.8% [P = 0.02]; mild bloating: 38.4% vs 27.2% [P = 0.03]).

CONCLUSION

Plecanatide treatment improved IBS-C abdominal and bowel symptoms, including in those who present with moderate-to-severe bloating.

Plecanatide for the treatment of chronic idiopathic constipation and irritable bowel syndrome with constipation: Post hoc analyses of placebo-controlled trials in adults with severe constipation

BACKGROUND

Patients with chronic idiopathic constipation (CIC) and irritable bowel syndrome with constipation (IBS-C) often experience severe symptoms. The current aim was to evaluate plecanatide in adults with CIC or IBS-C with severe constipation.

METHODS

Data were analyzed post hoc from randomized, placebo-controlled trials (CIC [n = 2], IBS-C [n = 2]) of plecanatide 3 mg, 6 mg, or placebo administered for 12 weeks. Severe constipation was defined as no complete spontaneous bowel movements (CSBMs) and an average straining score ≥3.0 (CIC; 5-point scale) or ≥8.0 (IBS-C; 11-point scale) during a 2-week screening. Primary efficacy endpoints were durable overall CSBM responders (CIC: ≥3 CSBMs/week, plus increase from baseline of ≥1 CSBM/week, for ≥9 of 12 weeks, including ≥3 of the last 4 weeks) and overall responders (IBS-C: ≥30% reduction from baseline in abdominal pain and ≥1 CSBM/week increase for ≥6 of 12 weeks).

KEY RESULTS

Severe constipation was observed in 24.5% (646/2639) and 24.2% (527/2176) of CIC and IBS-C populations, respectively. The CIC durable overall CSBM response rate (plecanatide 3 mg, 20.9%; plecanatide 6 mg, 20.2%; placebo, 11.3%) and IBS-C overall response rate (plecanatide 3 mg, 33.0%; plecanatide 6 mg, 31.0%; placebo, 19.0%) were significantly greater with plecanatide versus placebo (p ≤ 0.01 for all). Median time to first CSBM in CIC and IBS-C populations were significantly shorter with plecanatide 3 mg versus placebo (p = 0.01 for both).

CONCLUSIONS AND INFERENCES

Plecanatide was effective in the treatment of severe constipation in adults with CIC or IBS-C.

Augmentation of natriuretic peptide (NP) receptor A and B (NPR-A and NPR-B) and cyclic guanosine monophosphate (cGMP) signalling as a therapeutic strategy in heart failure

INTRODUCTION

Heart failure is a complex, debilitating condition and despite advances in treatment, it remains a significant cause of morbidity and mortality worldwide. Therefore, the need for alternative treatment strategies is essential. In this review, we explore the therapeutic strategies of augmenting natriuretic peptide receptors (NPR-A and NPR-B) and cyclic guanosine monophosphate (cGMP) in heart failure.

AREAS COVERED

We aim to provide an overview of the evidence of preclinical and clinical studies on novel heart failure treatment strategies. Papers collected in this review have been filtered and screened following PubMed searches. This includes epigenetics, modulating enzyme activity in natriuretic peptide (NP) synthesis, gene therapy, modulation of downstream signaling by augmenting soluble guanylate cyclase (sGC) and phosphodiesterase (PDE) inhibition, nitrates, c-GMP-dependent protein kinase, synthetic and designer NP and RNA therapy.

EXPERT OPINION

The novel treatment strategies mentioned above have shown great potential, however, large randomized controlled trials are still lacking. The biggest challenge is translating the results seen in preclinical trials into clinical trials. We recommend a multi-disciplinary team approach with cardiologists, geneticist, pharmacologists, bioengineers, researchers, regulators, and patients to improve heart failure outcomes. Future management can involve telemedicine, remote monitoring, and artificial intelligence to optimize patient care.

Pharmacologic blockade of the natriuretic peptide clearance receptor promotes weight loss and enhances insulin sensitivity in type 2 diabetes

While natriuretic peptides (NPs) are primarily known for their renal and cardiovascular actions, NPs stimulate lipolysis in adipocytes and induce a thermogenic program in white adipose tissue (WAT) that resembles brown fat. The biologic effects of NPs are negatively regulated by the NP clearance receptor (NPRC), which binds and degrades NPs. Knockout (KO) of NPRC protects against diet induced obesity and improves insulin sensitivity in obese mice. To determine if pharmacologic blockade of NPRC enhanced the beneficial metabolic actions of NPs in type 2 diabetes, we blocked NP clearance in a mouse model of type 2 diabetes using the specific NPRC ligand ANP(4-23). We found that treatment with ANP(4-23) caused a significant decrease in body weight by increasing energy expenditure and reducing fat mass without a change in lean body mass. The decrease in fat mass was associated with a significant improvement in insulin sensitivity and reduced serum insulin levels. These beneficial effects were accompanied by a decrease in infiltrating macrophages in adipose tissue, and reduced expression of inflammatory markers in both serum and WAT. These data suggest that inhibiting NP clearance may be an effective pharmacologic approach to promote weight loss and enhance insulin sensitivity in type 2 diabetes. Optimizing the therapeutic approach may lead to useful therapies for obesity and type 2 diabetes.

Natriuretic peptides in acute kidney injury - A sojourn on parallel tracks?

OBJECTIVE

The focus of this review was to elicit the mechanistic logic of the experimental and clinical study designs of natriuretic peptides (NP) in acute kidney injury (AKI) and to understand their respective outcomes.

METHODS

Online search of PubMed and manual review of articles. Randomized trials, observational and physiologic studies of NPs and AKI were extracted. Rationale, design and study outcomes were analyzed.

RESULTS

In experimental models of AKI, infusion of NP prevented post-ischemic fall in renal blood flow (RBF) or improvement in RBF, GFR, diuresis and natriuresis and demonstrated anti-inflammatory properties. NPs were most effective in the early stages of AKI, also in established phase of AKI but their effectiveness were limited to the time of infusion. Hypotension was a major side-effect. Based on these observations, preliminary clinical studies were performed which demonstrated improved urine output, RBF and GFR and reduced need for dialysis. However, randomized, controlled trials failed to demonstrate improvement in dialysis-free survival in different cohorts and study designs. Although NPs reduced the incidence of AKI in the postoperative period in cardiac surgery, it was not associated with improved long-term survival. In contrast to randomized trials, meta-analysis reported favorable results.

CONCLUSIONS

Reasons for the divergence of experimental and clinical outcomes of NPs in AKI are discussed in this review article.

CRRL269

RATIONALE

Acute kidney injury (AKI) has a high prevalence and mortality in critically ill patients. It is also a powerful risk factor for heart failure incidence driven by hemodynamic changes and neurohormonal activation. However, no drugs have been approved by the Food and Drug Administration. Endogenous pGC-A (particulate guanylyl cyclase A receptor) activators were reported to preserve renal function and improve mortality in AKI patients, although hypotension accompanied by pGC-A activators have limited their therapeutic potential.

OBJECTIVE

We investigated the therapeutic potential of a nonhypotensive pGC-A activator/designer natriuretic peptide, CRRL269, in a short-term, large animal model of ischemia-induced AKI and also investigated the potential of uCNP (urinary C-type natriuretic peptide) as a biomarker for AKI.

METHODS AND RESULTS

We first showed that CRRL269 stimulated cGMP generation, suppressed plasma angiotensin II, and reduced cardiac filling pressures without lowering blood pressure in the AKI canine model. We also demonstrated that CRRL269 preserved glomerular filtration rate, increased renal blood flow, and promoted diuresis and natriuresis. Further, CRRL269 reduced kidney injury and apoptosis as evidenced by ex vivo histology and tissue apoptosis analysis. We also showed, compared with native pGC-A activators, that CRRL269 is a more potent inhibitor of apoptosis in renal cells and induced less decreases in intracellular Ca2+ concentration in vascular smooth muscle cells. The renal antiapoptotic effects were at least mediated by cGMP/PKG pathway. Further, CRRL269 inhibited proapoptotic genes expression using a polymerase chain reaction gene array. Additionally, we demonstrated that AKI increased uCNP levels.

CONCLUSIONS

Our study supports developing CRRL269 as a novel renocardiac protective agent for AKI treatment.

Hormone treatments in congestive heart failure

The common ultimate pathological feature for all cardiovascular diseases, congestive heart failure (CHF), is now considered as one of the main public health burdens that is associated with grave implications. Neurohormonal systems play a critical role in cardiovascular homeostasis, pathophysiology, and cardiovascular diseases. Hormone treatments such as the newly invented dual-acting drug valsartan/sacubitril are promising candidates for CHF, in addition to the conventional medications encompassing beta receptor blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and mineralocorticoid receptor antagonists. Clinical trials also indicate that in CHF patients with low insulin-like growth factor-1 or low thyroid hormone levels, supplemental treatment with growth hormone or thyroid hormone seems to be cardioprotective; and in CHF patients with volume overload the vasopressin antagonists can relieve the symptoms superior to loop diuretics. Furthermore, a combination of selective glucocorticoid receptor agonist and mineralocorticoid receptor antagonist may be used in patients with diuretic resistance. Finally, the potential cardiovascular efficacy and safety of incretin-based therapies, testosterone or estrogen supplementation needs to be prudently evaluated in large-scale clinical studies. In this review, we briefly discuss the therapeutic effects of several key hormones in CHF.

Oral treatment with plecanatide or dolcanatide attenuates visceral hypersensitivity via activation of guanylate cyclase-C in rat models

AIM

To investigate the effects of plecanatide and dolcanatide on maintenance of paracellular permeability, integrity of tight junctions and on suppression of visceral hypersensitivity.

METHODS

Transport of fluorescein isothiocyanate (FITC)-dextran was measured to assess permeability across cell monolayers and rat colon tissues. Effects of plecanatide and dolcanatide on the integrity of tight junctions in Caco-2 and T84 monolayers and on the expression and localization of occludin and zonula occludens-1 (ZO-1) were examined by immunofluorescence microscopy. Anti-nociceptive activity of these agonists was evaluated in trinitrobenzene sulfonic acid (TNBS)-induced inflammatory as well as in non-inflammatory partial restraint stress (PRS) rat models. Statistical significance between the treatment groups in the permeability studies were evaluated using unpaired t-tests.

RESULTS

Treatment of T84 and Caco-2 monolayers with lipopolysaccharide (LPS) rapidly increased permeability, which was effectively suppressed when monolayers were also treated with plecanatide or dolcanatide. Similarly, when T84 and Caco-2 monolayers were treated with LPS, cell surface localization of tight junction proteins occludin and ZO-1 was severely disrupted. When cell monolayers were treated with LPS in the presence of plecanatide or dolcanatide, occludin and ZO-1 were localized at the cell surface of adjoining cells, similar to that observed for vehicle treated cells. Treatment of cell monolayers with plecanatide or dolcanatide without LPS did not alter permeability, integrity of tight junctions and cell surface localization of either of the tight junction proteins. In rat visceral hypersensitivity models, both agonists suppressed the TNBS-induced increase in abdominal contractions in response to colorectal distension without affecting the colonic wall elasticity, and both agonists also reduced colonic hypersensitivity in the PRS model.

CONCLUSION

Our results suggest that activation of GC-C signaling might be involved in maintenance of barrier function, possibly through regulating normal localization of tight junction proteins. Consistent with these findings, plecanatide and dolcanatide showed potent anti-nociceptive activity in rat visceral hypersensitivity models. These results imply that activation of GC-C signaling may be an attractive therapeutic approach to treat functional constipation disorders and inflammatory gastrointestinal conditions.

Safety and tolerability of plecanatide in patients with chronic idiopathic constipation: long-term evidence from an open-label study

OBJECTIVE

This multi-center, fixed-dose, open-label study evaluated the long-term safety and tolerability of once-daily oral plecanatide for the treatment of adults with chronic idiopathic constipation (CIC).

METHODS

Eligible patients completed a phase 2b or phase 3 double-blind study of plecanatide, or had not previously been treated with plecanatide. Enrolled patients received plecanatide (3 or 6 mg) for up to 72 weeks. Safety and tolerability were assessed by the incidence, nature, and severity of spontaneously reported treatment-emergent adverse events (TEAEs). Patients also completed Patient Global Assessment questionnaires, which included measures of treatment satisfaction and the desire to continue treatment.

RESULTS

There were 2370 patient exposures in this study, with the vast majority (90.5%) receiving treatment with plecanatide 6 mg. At the time of study closure, 1932 (81.5%) had completed or were still receiving study drug. TEAEs were qualitatively and quantitatively similar to those observed in prior double-blind studies. The most common TEAEs were diarrhea (7.1%) and urinary tract infection (2.2%). TEAEs leading to discontinuation occurred in 5.3% of patients, with diarrhea leading to discontinuation in 3.1%. Most TEAEs were mild/moderate in severity and were generally considered not related to plecanatide treatment. At the end of treatment, the median score for treatment satisfaction was 4.0 (quite satisfied), and the median score for treatment continuation was 4.0 (quite likely).

CONCLUSIONS

Long-term treatment of adults with CIC demonstrated that plecanatide was safe and well tolerated, with low TEAE and discontinuation rates. Patients indicated satisfaction and a desire to continue with plecanatide treatment.

2018 New Drug Update

Five new drugs marketed within the last year, which are used for medical problems often experienced by the elderly, have been selected for consideration in this review. The uses and most important properties of these agents are discussed, and a rating for each new drug is determined using the New Drug Comparison Rating system developed by the author (DAH). Advantages, disadvantages, and other important information regarding each new drug are identified and used as the basis for determining the rating. The drugs include an anticoagulant, an antiparkinson agent, an agent for tardive dyskinesia, an agent for psoriasis, and an agent for constipation. The drugs reviewed are betrixaban, safinamide mesylate, valbenazine tosylate, guselkumab, and plecanatide.

Natriuretic Peptides: The Case of Prostate Cancer

Cardiac natriuretic peptides have long been known to act as main players in the homeostatic control of blood pressure, salt and water balance. However, in the last few decades, new properties have been ascribed to these hormones. A systematic review of English articles using MEDLINE Search terms included prostate cancer, inflammation, cardiac hormones, atrial natriuretic peptide, and brain natriuretic peptide. Most recent publications were selected. Natriuretic peptides are strongly connected to the immune system, whose two branches, innate and adaptive, are finely tuned and organized to kill invaders and repair injured tissues. These peptides control the immune response and act as anti-inflammatory and immune-modulatory agents. In addition, in cancers, natriuretic peptides have anti-proliferative effects by molecular mechanisms based on the inhibition/regulation of several pathways promoting cell proliferation and survival. Nowadays, it is accepted that chronic inflammation is a crucial player in prostate cancer development and progression. In this review, we summarize the current knowledge on the link between prostate cancer and inflammation and the potential use of natriuretic peptides as anti-inflammatory and anticancer agents.

Plecanatide: First Global Approval

Plecanatide (Trulance^TM) is an oral guanylate cyclase-C agonist that is being developed by Synergy Pharmaceuticals for the treatment of gastrointestinal disorders, such as chronic idiopathic constipation (CIC) and irritable bowel syndrome with constipation (IBS-C). It is a synthetic analogue of human uroguanylin, a 16 amino acid peptide that regulates ion and fluid transport in the gastrointestinal tract. In January 2017, plecanatide received its first global approval in the USA for the treatment of adult patients with CIC. Plecanatide is undergoing phase III investigation in IBS-C. This article summarizes the milestones in the development of plecanatide leading to this first approval in CIC.

$850 Per Bowel Movement?! Hard To Justify That Cost

Constipation can be a serious and painful problem, and we shouldn't dismiss other people's suffering. On the other hand there's a danger when new medications are compared against placebo rather than against over-the-counter products with a history of effectiveness.

Hospital Policies for Treatment of Acute Decompensated Heart Failure

Background:

It is unclear to what extent hospitals use guidelines or protocols in treating acute decompensated heart failure (ADHF) and whether nesiritide is included in these guidelines or protocols.

Objective:

To assess the formulary status of currently used drugs, therapeutic guidelines, and perceptions about the appropriateness of treatment of ADHF in community hospitals.

Methods:

A Web-based survey of pharmacy directors at community hospitals that were part of a national group purchasing organization was conducted.

Results:

One hundred seven hospitals participated in the survey (response rate 47.1%). Diuretics such as furosemide and bumetanide were more commonly included (100% and 94.4%, respectively) on hospital formularies than was torsemide (69.2%). Dopamine and dobutamine were more common (94.4% each) on the formulary than was milrinone (68.2%), Nitroprusside and nitroglycerin were listed on the formularies of more than 90% of participating institutions, while nesiritide was listed on the formularies in only 48.6% of hospitals and was placed on restricted status in 36.4% of hospitals. Guidelines for care of patients with ADHF were used in the emergency department (ED), inpatient care units, and outpatient clinics in 18.6%, 43.0%, and 8.5% of hospitals, respectively. Overall, ADHF care, including general treatment as well as specific use of nesiritide, was deemed appropriate in the majority of patients, but nearly twice as many respondents perceived the management of ADHF and specific use of nesiritide as inappropriate in the ED compared with inpatient treatment. Only 41.1% of the respondents reported following Braunwald recommendations for the use of nesiritide.

Conclusions:

A sizable percentage of responding community hospitals do not have guidelines for treatment of ADHF despite the existence of such guidelines in the literature. There are opportunities for improvement in the general treatment of ADHF as well as for the use of nesiritide in ADHF, especially in the ED or observation unit versus inpatient units.

Combination of drugs acting on the natriuretic system and the renin-angiotensin system in heart failure

Conventional diuretic agents are very effective agents in relieving volume overload and congestive symptoms in chronic heart failure (CHF). However, they are associated with activation of the renin-angiotensin system (RAS) and the sympathetic nervous system and a reduction in glomerular filtration rate, all of which have been associated with adverse outcomes in CHF. Therefore, there is an increasing interest in drugs that target the natriuretic system without neurohormonal activation and deterioration of renal function. In this review, we will discuss the underlying rationale and evidence behind currently pursued strategies that target the natriuretic system. This includes the administration of natriuretic peptides (NPs) and strategies that potentiate the NP system, such as neutral endopeptidase inhibition. We will also highlight some potentially important interactions of these strategies with drugs that target the RAS.

Natriuretic peptides in cardiovascular diseases: current use and perspectives

The natriuretic peptides (NPs) family, including atrial, B-type, and C-type NPs, is a group of hormones possessing relevant haemodynamic and anti-remodelling actions in the cardiovascular (CV) system. Due to their diuretic, natriuretic, vasorelaxant, anti-proliferative, and anti-hypertrophic effects, they are involved in the pathogenic mechanisms leading to major CV diseases, such as heart failure (HF), coronary artery disease, hypertension and left ventricular hypertrophy, and cerebrovascular accidents. Blood levels of NPs have established predictive value in the diagnosis of HF, as well as for its prognostic stratification. In addition, they provide useful clinical information in hypertension and in both stable and unstable coronary artery disease. Structural abnormalities of atrial natriuretic peptide gene (NPPA), as well as genetically induced changes in circulating levels of NPs, have a pathogenic causal link with CV diseases and represent emerging markers of CV risk. Novel NP-based therapeutic strategies are currently under advanced clinical development, as they are expected to contribute to the future management of hypertension and HF. The present review provides a current appraisal of NPs' clinical implications and a critical perspective of the potential therapeutic impact of pharmacological manipulation of this class of CV hormones.

Gastrointestinal pain: unraveling a novel endogenous pathway through uroguanylin/guanylate cyclase-C/cGMP activation

The natural hormone uroguanylin regulates intestinal fluid homeostasis and bowel function through activation of guanylate cyclase-C (GC-C), resulting in increased intracellular cyclic guanosine-3',5'-monophosphate (cGMP). We report the effects of uroguanylin-mediated activation of the GC-C/cGMP pathway in vitro on extracellular cGMP transport and in vivo in rat models of inflammation- and stress-induced visceral hypersensitivity. In vitro exposure of intestinal Caco-2 cells to uroguanylin stimulated bidirectional, active extracellular transport of cGMP into luminal and basolateral spaces. cGMP transport was significantly and concentration dependently decreased by probenecid, an inhibitor of cGMP efflux pumps. In ex vivo Ussing chamber assays, uroguanylin stimulated cGMP secretion from the basolateral side of rat colonic epithelium into the submucosal space. In a rat model of trinitrobenzene sulfonic acid (TNBS)-induced visceral hypersensitivity, orally administered uroguanylin increased colonic thresholds required to elicit abdominal contractions in response to colorectal distension (CRD). Oral administration of cGMP mimicked the antihyperalgesic effects of uroguanylin, significantly decreasing TNBS- and restraint stress-induced visceromotor response to graded CRD in rats. The antihyperalgesic effects of cGMP were not associated with increased colonic spasmolytic activity, but were linked to significantly decreased firing rates of TNBS-sensitized colonic afferents in rats in response to mechanical stimuli. In conclusion, these data suggest that the continuous activation of the GC-C/cGMP pathway along the intestinal tract by the endogenous hormones guanylin and uroguanylin results in significant reduction of gastrointestinal pain. Extracellular cGMP produced on activation of GC-C is the primary mediator in this process via modulation of sensory afferent activity.

[Natriuretic peptides. History of discovery, chemical structure, mechanism of action and the removal routes. Basis of diagnostic and therapeutic use]

Natriuretic peptides (NP) are the group of proteins synthesized and secreted by the mammalian heart. All the NP are synthesized from prohormones and have 17-amino acid cyclic structures containing two cysteine residues linked by internal disulphide bond. They are characterized by a wide range of actions, mainly through their membrane receptors. The NP regulate the water and electrolyte balance, blood pressure through their diuretic, natriuretic, and relaxating the vascular smooth muscles effects. They also affect the endocrine system and the nervous system. The neurohormonal regulation of blood circulation results are mainly based on antagonism with renin--angiotensin--aldosterone system. The NP representatives are: atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), C-type natriuretic peptide (CNP), urodilatine and (DNP) Dendroaspis natriuretic peptide, not found in the human body. According to the guidelines of the European Society of Cardiology determination of NT-proBNP level have found a use in the diagnosis of acute and chronic heart failure, risk stratification in acute coronary syndromes and pulmonary embolism. There are reports found in the literature, that demonstrate the usefulness of NT-proBNP determination in valvular, atrial fibrillation, and syncopes. Recombinant human ANP--Carperitid and BNP--Nesiritid, have already found a use in the adjunctive therapy of dyspnea in acute heart failure.

Gastrointestinal hormones: uroguanylin-a new gut-derived weapon against obesity?

A recent report has identified uroguanylin as an endocrine signal that exerts a physiological role in energy homeostasis, adding another factor to the gut–brain axis. From a clinical point of view, several observations highlight the uroguanylin–guanylyl cyclase C pathway as a potential therapeutic target for the development of antiobesity drugs.

Insights into natriuretic peptides in heart failure: an update

Natriuretic peptides (NPs) secreted by the heart in response to volume overload are pleiotropic molecules with vasodilating, diuretic, natriuretic, antiproliferative, and antifibrotic actions. Functioning of the NP system is altered in congestive heart failure (CHF), suggesting that support of the NP system might be beneficial in treatment of acute and chronic CHF. Several approaches alone or in combination with other pharmacologic therapies have been shown to enhance function of the NP system: direct administration of native and designer NPs, inhibition of degradation of NPs and their second messenger (cyclic guanosine monophosphate ), and stimulation of cGMP generation. Despite increasing numbers of studies using NPs in therapy of acute and chronic CHF, several controversies regarding safety, efficacy, and dosing of NPs need to be addressed. Moreover, further research is warranted to identify the stages and etiologies of CHF that may profit from NP therapy.

Natriuretic peptides for guiding heart failure therapy

Use of natriuretic peptide to guide heart failure therapy represents a promising option. Although natriuretic peptides provide accurate diagnostic and independent incremental prognostic information, their use to gauge and titrate therapy is not yet fully realized.

Natriuretic peptides and therapeutic applications

Since the discovery of atrial natriuretic factor by de Bold et al., there has been tremendous progress in our understanding of the physiologic, diagnostic and therapeutic roles of the natriuretic peptides (NPs) in health and disease. Natriuretic peptides are endogenous hormones that are released by the heart in response to myocardial stretch and overload. Three mammalian NPs have been identified and characterized, including atrial natriuretic peptide (ANP or atrial natriuretic factor), B-type natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). In addition, Dendroaspis natriuretic peptide (DNP) has been isolated from the venom of Dendroaspis angusticeps (the green mamba snake), and urodilatin from human urine. These peptides are structurally similar and they consist of a 17-amino-acid core ring and a cysteine bridge. Both ANP and BNP bind to natriuretic peptide receptor A (NPR-A) that are expressed in the heart and other organs. Activation of NPR-A generates an increase in cyclic guanosine monophosphate, which mediates natriuresis, inhibition of renin and aldosterone, as well as vasorelaxant, anti-fibrotic, anti-hypertrophic, and lusitropic effects. The NP system thus serves as an important compensatory mechanism against neurohumoral activation in heart failure. This provides a strong rationale for the use of exogenous NPs in the management of acutely decompensated heart failure. In this article, the therapeutic applications of NPs in the acute heart failure syndromes are reviewed. Emerging therapeutic agents and areas for future research are discussed.

[Natriuretic peptides: their role in diagnosis and therapy]

Cardiac natriuretic peptide hormones, atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP), are synthesized and secreted by the heart, producing several biological effects, such as natriuresis, vasorelaxation and hypotension. During the last decade these peptides, especially BNP, have received increasing attention as potential markers of cardiovascular disease. Their measurements can be used to diagnose heart failure, including diastolic dysfunction, and using them has been shown to save money. BNP levels can enable the differentiation between dyspnoic patients secondary to ventricular dysfunction and subjects with primary respiratory disorders. Moreover, there is good evidence that natriuretic peptides may have a diagnostic role in arterial hypertension, acute coronary syndromes, pulmonary hypertension, some valvular heart disease and some disorders affecting other systems (diabetes or thyroid disorders). In this paper we discuss the clinical utility of assessment of natriuretic peptide hormones in the diagnosis of various clinical conditions and their use as pharmacological agents.

Guanylin peptides and colorectal cancer (CRC)

Agonists of guanylyl-C receptor, such as guanylin/uroguanylin, are correlated not only with the intestinal cell epithelial physiology but also with the colorectal cancer tumorigenesis. Activation of the second intracellular messenger cyclic guanosine monophosphate by guanylyl cyclase-C receptor results in a complex intracellular signalling cascade involving the phosphodiesterase, the ion channels and the protein kinase. After an analytical review of relevant new knowledge, new diagnostic and therapeutic approaches for colorectal cancer are discussed.

Emerging drugs for acute and chronic heart failure: current and future developments

Heart failure continues to be a major public health issue. Although angiotensin-converting enzyme inhibitors and beta-adrenergic blockers have been broadly used as evidence-based therapies in heart failure, morbidity and mortality remains high. Furthermore, treatment for acute decompensated heart failure and diastolic heart failure (or 'heart failure with preserved ejection fraction') is far from perfect. This review provides a broad overview of some of the novel compounds under investigation for the treatment of heart failure. Novel strategies include drugs that aim to alleviate congestion and improve hemodynamics, drugs that preserve renal function, drugs that reduce arterial and myocardial stiffness, drugs that module myocardial contractility, drugs that affect metabolic and hormonal balance, and drugs that act on existing and novel physiologic targets.

Effect of nesiritide infusion duration on renal function in acutely decompensated heart failure patients

BACKGROUND

Nesiritide, a synthetic B-type natriuretic peptide, is used for the treatment of patients with acutely decompensated heart failure. Although nesiritide has been reported to worsen renal function, as reflected by significant elevations in serum creatinine (SCr), the impact of infusion duration on renal function has not been evaluated.

OBJECTIVE

To investigate the effect of nesiritide infusion duration (< 24 h vs > or = 24 h) on worsening renal function in patients with acutely decompensated heart failure.

METHODS

Medical records of hospitalized patients receiving nesiritide were retrospectively reviewed, and 84 consecutive charts of patients with acute decompensated heart failure and available renal function tests were identified for the study. SCr and blood urea nitrogen (BUN) were documented at baseline and during infusion. Worsening renal function was defined as an increase in SCr of 0.5 mg/dL or more or BUN 10 mg/dL or more from baseline.

RESULTS

Univariate analysis showed a significant association between nesiritide infusion duration of 24 hours or more (26.1% vs 2.6%; p = 0.003), high diuretic doses (61.5% vs 32.4%; p = 0.045), and baseline SCr (2.0 +/- 0.8 vs 1.5 +/- 0.7 mg/dL; p = 0.04) with increases in SCr of 0.5 mg/dL or more. However, only infusion duration of 24 hours or more was statistically significant on multivariate analysis, after adjusting for baseline SCr (OR 10.46; 95% CI 1.26 to 86.72; p = 0.03). Longer duration of infusion was also a consistent variable in both univariate and multivariate analysis when elevated BUN was evaluated (34.8 vs 2.6%; p < 0.001 and OR 19.73; 95% CI 2.47 to 157.46; p = 0.005, respectively).

CONCLUSIONS

Nesiritide infusion of 24 hours or more appears to be significantly associated with elevated markers of worsening renal function in patients with acutely decompensated heart failure compared with infusion of less than 24 hours; however, prospective studies are needed to corroborate this finding.

Prevention of Acute Renal Failure

Acute renal failure (ARF) comprises a family of syndromes that is characterized by an abrupt and sustained decrease in the glomerular filtration rate. In the ICU, ARF is most often due to sepsis and other systemic inflammatory states. ARF is common among the critically ill and injured and significantly adds to morbidity and mortality of these patients. Despite many advances in medical technology, the mortality and morbidity of ARF in the ICU continue to remain high and have not improved significantly over the past 2 decades. Primary strategies to prevent ARF still include adequate hydration, maintenance of mean arterial pressure, and minimizing nephrotoxin exposure. Diuretics and dopamine have been shown to be ineffective in the prevention of ARF or improving outcomes once ARF occurs. Increasing insight into mechanisms leading to ARF and the importance of facilitating renal recovery has prompted investigators to evaluate the role of newer therapeutic agents in the prevention of ARF.

Current and novel pharmacological approaches to renal insufficiency in heart failure

Renal insufficiency is becoming an increasingly common and devastating comorbidity in both acute and chronic heart failure settings. Part of the problem is due to the lack of insight into the underlying pathophysiology of salt and water balance leading to the congestive states. This review summarizes our current understanding regarding the cause and consequences of renal insufficiency in patients with heart failure, and addresses some of the limitations of current therapeutic strategies. Based on these limitations, this paper will explore the ongoing efforts to develop novel drug therapeutics to prevent or ameliorate renal impairment in patients with heart failure. These include natriuretic peptides and other vasodilators, adenosine receptor antagonists, and vasopressin receptor antagonists all currently undergoing late-stage clinical trials.

Novel therapeutic directions for the natriuretic peptides in cardiovascular diseases: what's on the horizon

Remarkable advances have occurred since the discovery of ANP. The field of the natriuretic peptides has moved beyond their role as regulators of renal function. Growing evidence has now established the natriuretic peptides as regulators of myocardial structure and function as well as in cardiovascular regulation. Further, they emerge as being products not only of the cardiomyocyte but also of the cardiac fibroblast. Studies in vitro and in vivo have clearly established these cardiac hormones as antihypertrophic and antifibrotic. Further, indications such as cardioprotection for acute myocardial infarction, chronic therapy with oral BNP for hypertension and next generation peptides such as DNP-like peptides for acute heart failure may be in the near future. Novel therapeutic strategies to be tested in clinical trials in humans with cardiovascular disease are clearly on the horizon.

[Natriuretic peptides: anything new in cardiology?]

Twenty-five years after the first publication of the strong natriuretic effect of rat cardiac atria extract, natriuretic peptides play an important part in everyday, not only cardiological, practice. In the current review the authors briefly describe the role of natriuretic peptides (ANP, BNP, and CNP) in clinical practice, concentrating on the possibilities of their therapeutic use. They also summarize their role in the mechanisms of endogenous cardioprotection and regulation of LVH, which is the endpoint of many cardiovascular pathologies.

Cardiovascular and metabolic effects of natriuretic peptides

Natriuretic peptides (NP) are essential in mammals to regulate blood volume and pressure. The functional roles of NP are not limited to natriuresis and diuresis. Several peripheral and central actions of the peptides have been characterized. Studies on transgenic mice have revealed their key function in the regulation of cardiomyocyte growth. Plasma NP levels increase in patients with cardiovascular disorders and heart failure. They represent useful clinical markers for clinicians to diagnose heart diseases. The recent discovery of their potent lipolytic action in adipose tissue is a breakthrough in cardiovascular medicine. This new function of NP in the regulation of lipid metabolism offers interesting questions in the field of obesity, diabetes and cardiovascular diseases. This review will briefly describe the effects of NP on the cardiovascular system and lipid metabolism.

The natriuretic peptide system: kidney and cardiovascular effects

PURPOSE OF REVIEW

The natriuretic peptide (NP) system is primarily an endocrine system that maintains fluid and pressure homeostasis by modulating cardiac and renal function. The physiologic functions of the NP system in healthy humans and in patients with cardiovascular disease are not fully understood. NP levels are elevated in patients with heart failure (HF) and other cardiac diseases; measurement of NPs may be used in the clinical setting to aid diagnosis and prognosis. In addition, synthetic NPs such as nesiritide are available for use in management of patients with acutely decompensated congestive HF.

RECENT FINDINGS

Not only do NPs modulate volume and pressure homeostasis, but they also exert important anti-proliferative, anti-fibrotic effects in the heart. Thus, NPs may prove useful for prevention of remodeling after myocardial infarction and in advanced HF. BNP is emerging as an important biomarker in patients with HF and other cardiovascular diseases, such as pulmonary hypertension and atherosclerotic vascular disease. Elevated NP levels may serve as an early warning system to help to identify patients at high risk for cardiac events. Recombinant human ANP (carperitide) and BNP (nesiritide) are useful for management of acutely decompensated HF; these drugs are also being investigated for myocardial and renal protection in the setting of cardiac surgery and for prevention of cardiac remodeling.

SUMMARY

The clinical application of NPs is expanding rapidly. Recent basic science and clinical research findings continue to improve our understanding of the NP system and guide use of ANP and BNP as biomarkers and as therapeutic agents.

Natriuretic peptides, their receptors, and cyclic guanosine monophosphate-dependent signaling functions

Natriuretic peptides are a family of structurally related but genetically distinct hormones/paracrine factors that regulate blood volume, blood pressure, ventricular hypertrophy, pulmonary hypertension, fat metabolism, and long bone growth. The mammalian members are atrial natriuretic peptide, B-type natriuretic peptide, C-type natriuretic peptide, and possibly osteocrin/musclin. Three single membrane-spanning natriuretic peptide receptors (NPRs) have been identified. Two, NPR-A/GC-A/NPR1 and NPR-B/GC-B/NPR2, are transmembrane guanylyl cyclases, enzymes that catalyze the synthesis of cGMP. One, NPR-C/NPR3, lacks intrinsic enzymatic activity and controls the local concentrations of natriuretic peptides through constitutive receptor-mediated internalization and degradation. Single allele-inactivating mutations in the promoter of human NPR-A are associated with hypertension and heart failure, whereas homozygous inactivating mutations in human NPR-B cause a form of short-limbed dwarfism known as acromesomelic dysplasia type Maroteaux. The physiological effects of natriuretic peptides are elicited through three classes of cGMP binding proteins: cGMP-dependent protein kinases, cGMP-regulated phosphodiesterases, and cyclic nucleotide-gated ion channels. In this comprehensive review, the structure, function, regulation, and biological consequences of natriuretic peptides and their associated signaling proteins are described.

Natriuretic peptides: novel therapeutic targets in heart failure

Since the discovery of the cardiac hormone atrial natriuretic peptide by de Bold and colleagues in 1981, the field of natriuretic peptides has significantly advanced with translation of new knowledge to the clinical practice of heart failure. This new knowledge builds on the importance of cardiorenal mechanisms that contribute to optimal cardiovascular regulation. Recent investigations by our group and others have also established the direct myocardial actions of the natriuretic peptides, broadening their therapeutic potential beyond renal mechanisms. Indeed, a potential therapeutic target is cardiac remodeling and fibrosis based on the unique cardiorenal and humoral protective properties that natriuretic peptides possess. We review new insights into the natriuretic peptide system and specifically focus on the possible role of natriuretic peptides as a new therapeutic strategy to limit cardiac remodeling and fibrosis to delay worsening of cardiac function and the progression of heart failure.

Four peptide hormones' specific decrease (up to 97%) of human prostate carcinoma cells

BACKGROUND

Mortality from prostate cancer remains a significant problem with current treatment(s), with an expected 30 350 deaths from prostate cancer in 2005. Long-acting natriuretic peptide, vessel dilator, kaliuretic peptide and atrial natriuretic peptide have significant anticancer effects in breast and pancreatic adenocarcinomas. Whether these effects are specific and whether they have anticancer effects in prostate adenocarcinoma cells has not been determined.

MATERIALS AND METHODS

These peptide hormones were evaluated to determine if they have specific anticancer effects in human prostate adenocarcinomas.

RESULTS

Dose-response curves revealed a significant (P < 0.05) decrease in human prostate cancer number with each tenfold increase in the concentration from 1 microM to 1000 microM (i.e. 1 mM) of these four peptide hormones. There was a 97.4%, 87%, 88% and 89% (P < 0.001 for each) decrease in prostate cancer cells secondary to vessel dilator, long-acting natriuretic peptide, kaliuretic peptide and atrial natriuretic peptide, respectively, at their 1-mM concentrations within 24 h, without any proliferation in the 3 days following this decrease. These same hormones decreased DNA synthesis from 68% to 89% (P < 0.001). When utilized with their respective antibodies their ability to decrease prostate adenocarcinoma cells or inhibit their DNA synthesis was completely blocked. Western blots revealed that for the first time natriuretic peptide receptors (NPR) A- and C- were present in prostate cancer cells.

CONCLUSIONS

These results indicate that these peptide hormones' anticancer effects are specific. Furthermore, they have very potent effects of eliminating up to 97% of prostate cancer cells within 24 h of treatment.

Natriuretic Peptides and the Dialysis Patient

The natriuretic peptide family consists of four structurally similar, but genetically distinct molecules with pronounced cardiovascular and renal actions. They are counterregulatory hormones playing an important role in fluid volume homeostasis. Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) cause diuresis, natriuresis, and vasodilatation. C-type natriuretic peptide (CNP) has antimitogenic effects and causes vascular smooth muscle relaxation. Dendroaspis natriuretic peptide (DNP) shares many of the actions of ANP and BNP, but its function in humans is not yet fully understood. Natriuretic peptides have been extensively investigated as biochemical markers of the fluid state. Levels are elevated in disease conditions characterized by fluid overload and are closely related to survival in various cardiac disease states. In the dialysis population, BNP correlates significantly with cardiac function, whereas ANP is sensitive to volume changes during dialysis. However, changes in concentration do not predict achievement of euvolemia, and short half-life, combined with complicated assay techniques, make ANP a less than satisfactory tool for assessing hydration. BNP is a superior prognosticator for risk stratification in dialysis patients, and serial estimations will help in the identification of occult cardiac disease.

The emerging role of natriuretic peptides in the diagnosis and treatment of decompensated heart failure

B-type natriuretic peptide (BNP) is a cardiac neurohormone and is released as prepro BNP and then enzymatically cleaved to the N-terminal proBNP (NT-proBNP) and BNP upon ventricular myocyte stretch. Blood measurements of BNP and NT-proBNP have been used to identify patients with heart failure (HF). Clinical considerations for these tests include their half-lives in plasma, dependence on renal function for clearance, interpretation of their units of measure, and the rapid availability of the test results. The BNP assay is currently used as a diagnostic and prognostic aid in HF. In general, a BNP level below 100 pg/mL excludes acutely decompensated HF. Recombinant, human BNP (nesiritide) is an approved intravenous treatment for acute, decompensated HF. This paper reviews the literature concerning the use of this peptide as a diagnostic test and as an intravenous therapy.

[Acute dyspnea in the emergency room: the utility of troponin, natriuretic, procalcitonin and D-dimers]

In emergency, some "low cost" biological tests are too often systematically performed while others are not prescribed because they are considered "too expensive". Good practices for biological testing are in fact the real means for saving money. Here, in order to help for defining those good practices, we review emergency medical approach and, as an example, specify findings concerning the clinical utility of key blood analyses in patients with acute dyspnea. Emergency laboratory testing is usefull when it contributes to establish the diagnosis or to evaluate comorbidity or to stratify disease severity. In a given emergency context, clinical utility must be anticipated according to a bayesian approach with an estimation of the post-test probabilities using the likelihood ratios (estimated from literature) and the pretest probabilities (established by examination at the bedside). The likelihood ratio is the best criterion for diagnostic accuracy of a biological test. According to this criterion, troponin, natriuretic peptides, procalcitonin and D-dimers are four "costly" markers but which can significantly contribute to the etiologic diagnosis of an acute dyspnea. Troponin, natriuretic peptides and procalcitonin are also prognostic markers and are valuable parameters for stratifying disease severity according to their initial value and their plasmatic kinetic during the clinical course of the disease. In conclusion, it is not only the cost of the test but overall the potential impact of its result on the management of the patient's care which makes the decision of performing the test or not.