血管肽酶抑制剂的研究进展

目的阐述血管肽酶抑制剂(VPIs)的作用机制、构效关系以及临床研究等方面的进展。方法根据近期对VPIs的作用机制、构效关系以及研究开发现状的25篇相关文献进行整理和归纳。结果与结论数种血管肽酶抑制剂正在进行治疗高血压、心力衰竭等心血管疾病的临床试验。VPIs有望成为新一代治疗高血压和心力衰竭的药物。     

血管肽酶抑制剂新药研发的进展

血管肽酶抑制剂是单一结构的化合物分子,具有双重的抑制作用,即抑制血管紧张素转化酶和中性内肽酶的活性。能降低肾素–血管紧张素–醛固酮系统的活性,减少血管紧张素Ⅱ及醛固酮的生成;阻止中性内肽酶降解心房钠利尿肽、脑钠利尿肽等钠利尿肽及缓激肽,从而产生利尿排钠、增加血管舒张性的作用,其作用比单用血管紧张素转化酶抑制剂或中性内肽酶抑制剂更有效。主要概述了血管肽酶抑制剂的药理作用及新药研发情况。     

Novel angiotensin II inhibitors in cardiovascular medicine

Blockade of the renin-angiotensin-aldosterone cascade is now recognised as a very effective approach to treat hypertensive, heart failure and high cardiovascular risk patients and to retard the development of renal failure. The purpose of this review is to discuss the state of development of currently available drugs blocking the renin-angiotensin system, such as angiotensin converting enzyme (ACE) inhibitors, renin inhibitors and angiotensin II receptor antagonists, with a special emphasis on the results of the most recent trials conducted with AT₂ receptor antagonists in heart failure and Type 2 diabetes. In addition, the future perspectives of drugs with dual mechanisms of action, such as NEP/ACE inhibitors, also named vasopeptidase inhibitors, are presented.     

The potential role of angiotensin converting enzyme and vasopeptidase inhibitors in the treatment of diabetic neuropathy

Diabetic neuropathy is a debilitating disorder that occurs in more than 50 percent of patients with diabetes. Evidence suggests that there are at least five major pathways involved in the development of diabetic neuropathy: metabolic, vascular, immunologic, neurohormonal growth factor deficiency, and extracellular matrix remodeling. In light of the complicated etiologies, an effective treatment for diabetic neuropathy has not yet been identified. Hyperglycemia increases tissue angiotensin II, which induces oxidative stress, endothelial damage and other pathologies including vasoconstriction, thrombosis, inflammation and vascular remodeling. Angiotensin converting enzyme inhibition and/or blocking of the angiotensin II receptor are recognized as first line treatment for nephropathy and cardiovascular disease in diabetes patients. A new class of drug in late stages of development is vasopeptidase inhibitors. This drug inhibits both angiotensin converting enzyme activity and neutral endopeptidase. Neutral endopeptidase is a protease that degrades a number of biologically active peptides including vasoactive peptides. However, little information is available about the potential benefits of these drugs on diabetic neuropathy. Pre-clinical studies suggest that these drugs may be useful in treating diabetic complications involving vascular tissue. The purpose of this review is to evaluate the use of angiotensin converting enzyme and vasopeptidase inhibitors in the treatment of diabetic neuropathy.     

Towards triple vasopeptidase inhibitors for the treatment of cardiovascular diseases

Cardiovascular diseases (CDs) are among the most encountered pathologies in western countries; with obesity reaching pandemic proportions, they are soon to become a worldwide problem. High blood pressure is the main risk factor for CDs, and its tight control is an imperative for the treatment of complications such as renal diseases, heart failure, and atherosclerosis. Blood homeostasis and vascular tone are regulated through at least 3 major closely interrelated pathways in which zinc metallopeptidases modulate the concentration of vasoactive mediators. Those extensively studied vasopeptidases were therefore rapidly targeted with specific inhibitors in order to control the levels of vasoconstrictors [angiotensin II (AII) and endothelin-1 (ET-1)] and vasodilators [bradykinin (BK) and atrial natriuretic peptide (ANP)], thereby controlling blood pressure. The first class of inhibitors to be developed were against angiotensin-converting enzyme (ACE), recently followed by dual inhibitors of ACE/neprylisin (NEP), NEP/endothelin-converting enzyme (ECE), and finally triple ACE/NEP/ECE inhibitors. The dual and triple inhibitors are defined as vasopeptidase inhibitors (VPI). In addition to their ability to effectively lower blood pressure in hypertensive patients, drugs targeting these enzymes also displayed antiinflammatory and antifibrotic activities. The major point emerging from recent studies undertaken to improve the management of CDs is that the combined action of different therapeutic strategies (ie, simultaneous modulation of several neurohumoral mediators) shows better results than conservative therapeutic approaches. In this review, we historically present the advances made in the comprehension of the different mechanisms of blood pressure regulation and some of the drugs that arose from this understanding.     

A review of vasopeptidase inhibitors: a new modality in the treatment of hypertension and chronic heart failure.

Vasopeptidase inhibitors are a group of agents capable of inhibiting neutral endopeptidase and angiotensin-converting enzymes, which leads to potentiation of natriuretic peptide actions and suppression of the renin-angiotensin-aldosterone system. With this distinctively characteristic mechanism, these agents have emerged as a new drug class for management of hypertension and heart failure. Several vasopeptidase inhibitors are under clinical investigation. Omapatrilat is the most studied agent in this class. Clinical studies of omapatrilat in hypertension have consistently shown the agent's effectiveness in a variety of patient populations. In patients with heart failure, omapatrilat significantly improved neurohormonal and hemodynamic status. Long-term effects of omapatrilat in patients with heart failure recently were compared with those of conventional therapy in a large phase II trial. Results of the study appear promising. Large clinical trials are ongoing, and additional information regarding safety and efficacy from these studies may help define the place in therapy for this agent.     

Vasopeptidase inhibition for blood pressure control: emerging experience

Vasopeptidase inhibition is a novel treatment approach in cardiovascular disease such as hypertension and heart failure. Since the inhibition of the angiotensin-converting enzyme (ACE) turned out to represent a very successful principle in the treatment of hypertension in numerous large scale clinical studies, their results encouraged attempts to inhibit other key enzymes in the regulation of vascular tone as well--such as the neutral endopeptidase (NEP). Similar to ACE, NEP is an endothelial cell surface metalloproteinase, which is involved in the degradation of several regulatory peptides including the natriuretic peptides and thus augments vasodilatation and natriuresis through increased levels of atrial natriuretic peptide (ANP). By simultaneous inhibition of the RAS and potentiation of the natriuretic peptide system, combined NEP/ACE inhibitors--the so called vasopeptidase inhibitors--reduce vasoconstriction and enhance vasodilatation, therefore, decreasing peripheral vascular resistance and blood pressure. Based on these considerations, numerous preclinicial studies with vasopeptidase inhibitors were performed and revealed promising results in experimental hypertension. Correspondingly, large scale clinical studies in patients with hypertension are on the way. Their preliminary results indicate that combined inhibition of ACE and NEP by vasopeptidase inhibitors represents an effective strategy in the treatment of hypertension and other cardiovascular disease such as heart failure. However, clinical data also suggest that the incidence of angioedema may increase on vasopeptidase inhibition. Therefore, careful evaluation of the safety of this promising therapeutic principle in large scale clinical studies is mandatory before vasopeptidase inhibition may be considered a novel option in the treatment of cardiovascular disease.     

Pharmacological modulation of the natriuretic peptide system

The natriuretic peptide (NP) system is a cardioprotective hormonal system that fails to meet its cardioprotective end point during the development of cardiovascular complications such as hypertension and heart failure. The use of NPs or orally-active drugs that enhance the function of the NP system, are being explored for the treatment of such disorders. Much of the recent research has focused on vasopeptidase inhibitors that can inhibit neutral endopeptidase (NEP) and angiotensin-converting enzyme (ACE) and thereby augment NP signalling while attenuating the renin–angiotensin–aldosterone system. These drugs offer several beneficial effects over conventional ACE inhibitors but the vasoactive peptide bradykinin, which is partly responsible for their beneficial effects, leads to serious side effects such as angioedema. The hope that these compounds will replace conventional drugs is fading away but they might be useful in targeted refractory populations immune to conventional drugs. The trends from the recent published patents suggest that pharmaceutical companies are exploring new strategies that include inhibition of endothelin-converting enzyme along with ACE and/or NEP. This comprehensive review will address the patents as well as basic and clinical pharmacology of leading compounds that exploit various strategies to modulate the NP system. This includes recombinant NPs, NP receptor ligands, vasopeptidase inhibitors and novel molecules that offer new strategic insights into the modulation of the NP system for the treatment of cardiovascular complications.     

Omapatrilat: clinical pharmacology

Omapatrilat is the most clinically advanced member of a new class of cardiovascular agents known as vasopeptidase inhibitors. Omapatrilat acts by inhibiting two key enzymes responsible for blood pressure regulation: neutral endopeptidase and angiotensin-converting enzyme. Omapatrilat provides dose-related reductions in systolic and diastolic blood pressure with an excellent trough-to-peak ratio after once-daily administration. The reduction in blood pressure is proportional to baseline blood pressure. Used in monotherapy, omapatrilat controls hypertension in more than 65% of patients treated and reduces blood pressure to a greater extent than existing agents. Furthermore, omapatrilat exhibits an excellent tolerability profile. Therefore, this drug represents an important new approach for treating a wide range of patients, including those who are difficult to control, such as elderly patients with isolated systolic hypertension and patients with diabetes. The results of early clinical trials in patients with congestive heart failure have shown that omapatrilat not only improves symptoms but also reduces the risk of and hospitalization and death when compared with ACE inhibitors alone. These results indicate that vasopeptidase inhibition is a promising new strategy in the treatment of hypertension and cardiac diseases.     

Comparison of a vasopeptidase inhibitor with neutral endopeptidase and angiotensin-converting enzyme inhibitors on bradykinin metabolism in the rat coronary bed

The in vitro effects of omapatrilat, a dual vasopeptidase inhibitor that simultaneously inhibits neutral endopeptidase (NEP) and angiotensin-converting enzyme (ACE), on exogenous bradykinin metabolism after a single passage through the coronary bed were compared with that of a NEP inhibitor (retrothiorphan, 25 nM), an ACE inhibitor (enalaprilat, 130 nM), and omapatrilat (25 nM). Bradykinin and inhibitors were infused into isolated Langendorff rat hearts perfused at 1 ml/min followed by reperfusion at 10 ml/min. Residual bradykinin was quantified in the coronary effluent by enzyme-linked immunosorbent assay to calculate bradykinin recovery and its kinetic parameters (Vmax/Km). Bradykinin degradation rate at 1 ml/min was 4.56 +/- 0.39 1/min per gram without inhibitors and was significantly reduced to 2.57 +/- 0.19 1/min per gram in the presence of enalaprilat, to 2.97 +/- 0.38 1/min per gram with retrothiorphan, to 1.82 +/- 0.17 1/min per gram with both enalaprilat and retrothiorphan, and to 1.14 +/- 0.35 1/min per gram with omapatrilat. In a second set of experiments, the effect of a 14-day treatment of rats with either ACE inhibitors (enalapril, quinapril, and ramipril), a NEP inhibitor (candoxatril), or omapatrilat on exogenous bradykinin metabolism was studied in Langendorff perfused hearts isolated from these long-term treated rats. In untreated rats, bradykinin degradation at a coronary perfusion of 1 ml/min was 4.35 +/- 0.41 1/min per gram. This value was reduced by 30% for the NEP inhibitor, by 50% for all ACE inhibitors, and by 75% for omapatrilat. All inhibitors administered either short term or long term significantly reduced bradykinin degradation during a single passage through the coronary bed. However, omapatrilat administration resulted in the greatest protection from bradykinin breakdown than ACE or NEP inhibitors alone.     

The future of angiotensin II inhibition in cardiovascular medicine

Drugs, which interfere with the renin-angiotensin-aldosterone cascade such as angiotensin converting enzyme (ACE) inhibitors, have been available to clinicians for more than 20 years. They are now recognized as a very effective approach to treat patients with hypertension, heart failure, diabetic and non-diabetic chronic renal failure or patients with a high cardiovascular risk. The recent development of angiotensin II (Ang II) receptor antagonist has enabled to improve significantly the tolerability profile of this group of drugs while maintaining a high clinical efficacy. Yet, with the availability of Ang II receptor antagonists, new questions have arisen. Is it still possible to gain in efficacy with newer agents? What is the future of drugs such as neutral endopeptidase (NEP)/ACE inhibitors or renin inhibitors? The first objective of this review is to discuss the clinical implications of several large clinical trials that have been published recently with ACE inhibitors and Ang II receptor antagonists such as ALLHAT, LIFE, OPTIMAAL, Val-Heft, SCOPE, and more recently, CHARM, VALIANT and VALUE. With these trials, we can now define more precisely the role of these blockers of the renin-angiotensin system in the management of patients with cardiovascular complications. The second part of this review is devoted to new drugs interfering with the renin-angiotensin system. We discuss the recent results obtained with NEP/ACE inhibitors also named vasopeptidase inhibitors. Several compounds were or are in development but the experience with omapatrilat has blunted the enthusiasms for these compounds. Yet, vasopeptidase inhibitors remain very effective antihypertensive drugs and there is a great therapeutic potential for these agents provided one can define more accurately the risk/benefit ratio and the clinical indications. Finally, we present the recent data obtained with SPP 100, a new renin inhibitor that is actually under clinical development. SPP 100 has a sufficient bioavailability to induce a sustained blockade of the renin-angiotensin system when given orally to normal subjects. Recent studies have shown that SPP 100 lowers blood pressure in hypertensive patients as effectively as an Ang II receptor antagonist.     

Bradykinin B2 receptors as a target in diabetic nephropathy

Diabetic nephropathy is the leading cause of chronic renal failure in countries in the western world. Human polymorphism studies have suggested a nephroprotective effect that is mediated by bradykinin B2 receptors. Angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers have an additive nephroprotective effect in patients with diabetes, which may be due to ACE-inhibitor-mediated increases in the levels of bradykinin. There is also evidence from studies conducted in genetically altered mice to suggest that bradykinin is nephroprotective. Finally, evidence from animal models of nephropathy indicates that some of the beneficial effects of ACE inhibitors and vasopeptidase inhibitors are due to the action of bradykinin at B2 receptors. These data establish that stimulation of bradykinin B2 receptors is a target in diabetic nephropathy, and should provide impetus for the development of non-peptide, selective bradykinin B2 agonists.     

New developments in the pharmacological treatment of chronic heart failure

In recent years, rapid growth in the understanding of the pathophysiology of chronic heart failure has allowed for insights into many potential new therapeutic strategies. Yet until now, despite sound biological basis for efficacy and success in early-Phase studies, novel agents have not stood up to the scrutiny of late-Phase clinical trials. Indeed, remarkably negative results have been observed for vasopeptidase inhibitors, endothelin receptor antagonists and agents which block immune activation. However, efficacy data from other novel agents are still awaited, including the selective aldosterone receptor antagonist eplerenone, arginine vasopressin inhibitors, erythropoietin and hydroxy-methyl-glutaryl coenzyme A reductase inhibitors. Other classes of drugs which may enter clinical development include cardiac metabolic agents, matrix metalloproteinase inhibitors and advanced glycation end product antagonists. That the mortality and morbidity of patients with chronic heart failure remain unacceptably high makes the ongoing commitment to exploration of new drug therapies for the condition critical.     

New developments in the pharmacological treatment of chronic heart failure

In recent years, rapid growth in the understanding of the pathophysiology of chronic heart failure has allowed for insights into many potential new therapeutic strategies. Yet until now, despite sound biological basis for efficacy and success in early-Phase studies, novel agents have not stood up to the scrutiny of late-Phase clinical trials. Indeed, remarkably negative results have been observed for vasopeptidase inhibitors, endothelin receptor antagonists and agents which block immune activation. However, efficacy data from other novel agents are still awaited, including the selective aldosterone receptor antagonist eplerenone, arginine vasopressin inhibitors, erythropoietin and hydroxy-methyl-glutaryl coenzyme A reductase inhibitors. Other classes of drugs which may enter clinical development include cardiac metabolic agents, matrix metalloproteinase inhibitors and advanced glycation end product antagonists. That the mortality and morbidity of patients with chronic heart failure remain unacceptably high makes the ongoing commitment to exploration of new drug therapies for the condition critical.     

The kidney in congestive heart failure: renal adverse event rate of treatment.

In this paper we review the effect of medical treatment on renal function in patients with congestive heart failure. We have examined data from the large-scale heart failure studies with angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, calcium channel blockers, beta-receptor blockers, an aldosterone antagonist, and a vasopeptidase inhibitor. Renal outcome was reported in almost all of the studies with angiotensin-converting enzyme inhibitors. Despite concern about renal adverse events with drugs in this class, they seem to be safe in patients with congestive heart failure. In contrast, we did not find any report about renal function in patients treated with beta-receptor blockers for congestive heart failure.     

New therapies for the treatment of congestive heart failure

Heart failure is characterized by sodium and fluid retention, sympathetic overactivity, parasympathetic withdrawal, vasoconstrictor activation and cytokine elevation. New therapies for heart failure attempt to control neurohormonal activation and limit progressive left ventricular dysfunction. Nesiritide (human B-type natriuretic peptide) is a recently approved new vasodilator that has been given to almost 1,000 patients in numerous clinical investigations; it belongs to a new class of heart failure drugs known as natriuretic peptides. Nesiritide decreases pulmonary capillary wedge pressure, systemic vascular resistance, mean right atrial pressure and pulmonary artery pressure, while improving cardiac index, stroke volume and heart failure symptoms. Many endothelin receptor antagonists are in various stages of development. Early clinical studies have demonstrated beneficial cardiovascular hemodynamic effects. Other new drugs for heart failure also include calcium sensitizers, neutral endopeptidase and vasopeptidase inhibitors, aldosterone receptor antagonists, vasopressin antagonists and cytokine inhibitors. All are being actively investigated and many show significant promise as beneficial therapies in the treatment of heart failure.     

Neuroendocrine activation as a target of modern chronic heart failure pharmacotherapy

At present, a constant progress in pathophysiology understanding and treatment of the chronic heart failure (CHF) is arising. The current CHF pharmacotherapy is complex, involving factors affecting the renin-angiotensin-aldosterone system (RAAS), beta-blockers, diuretics and vasodilatators. There are also significant efforts to introduce in CHF pharmacology novel therapeutic strategies, based on the other neurohormonal mechanisms activated in CHF. They include vasopressin receptor antagonists (VRA; vaptans), endothelin receptor antagonists (ERA; sentans), agents relating to the natriuretic peptides system (neutral endopeptidase inhibitors; NEPI and vasopeptidase inhibitors; VPI) and anticytokines agents (anti TNF-alpha immunoglobulin or TNF-alpha scavenger receptor; Etanercept). In this article we briefly describe the modem approach to CHF systemic treatment.     

Phosphodiesterase inhibitors

Phosphodiesterases are a diverse family of enzymes that hydrolyse cyclic nucleotides and thus play a key role in regulating intracellular levels of the second messengers cAMP and cGMP, and hence cell function. Theophylline and papaverine have historically been used therapeutically and are known to be weak inhibitors of PDE, but to what extent this contributed toward their clinical efficacy was poorly defined. However, the discovery of 11 isoenzyme families and our increased understanding of their function at the cell and molecular level provides an impetus for the development of isoenzyme selective inhibitors for the treatment of various diseases. This review focuses on the development of PDE3 inhibitors for congestive heart failure, PDE4 inhibitors for inflammatory airways disease and most successfully, PDE5 inhibitors for erectile dysfunction.