Effects of perhexiline on symptomatic and hemodynamic responses to exercise in patients with angina pectoris

Advancements in pharmacotherapy for angina

INTRODUCTION

Angina pectoris is the most prevalent symptomatic manifestation of ischemic heart disease, frequently leads to a poor quality of life, and is a major cause of medical resource consumption. Since the early descriptions of nitrite and nitrate in the 19th century, there has been considerable advancement in the pharmacologic management of angina. Areas covered: Management of chronic angina is often challenging for clinicians. Despite introduction of several pharmacological agents in last few decades, a significant proportion of patients continue to experience symptoms (i.e., refractory angina) with subsequent disability. For the purpose of this review, we searched PubMed and Cochrane databases from inception to August 2016 for the most clinically relevant publications that guide current practice in angina therapy and its development. In this article, we briefly review the pathophysiology of angina and mechanism-based classification of current therapy. This is followed by evidence-based insight into the traditional and novel pharmacotherapeutic agents, highlighting their clinical usefulness. Expert opinion: Considering the wide array of available therapies with different mechanism efficacy and limiting factors, a personalized approach is essential, particularly for patients with refractory angina. Ongoing research with novel pharmacologic modalities is likely to provide new options for management of angina.

Experimental and early investigational drugs for angina pectoris

INTRODUCTION

Ischemic heart disease (IHD) is a major cause of death and disability among Western countries and angina pectoris is the most prevalent symptomatic manifestation. Strategies to improve management of chronic stable angina are a priority. Areas covered: A comprehensive review was conducted using the Medline and Cochrane databases as well as the clinical trial databases in the United States and Europe. Traditional therapies for angina will be discussed. This review particularly emphasizes investigational therapies for angina (including pharmacological agents, cell and gene based therapies, and herbal medications). Expert opinion: There has been renewed interest in older anti-angina agents (e.g., perhexiline, amiodarone, and phosphodiestrase-5 inhibitors). Other anti-inflammatory agents (e.g., allopurinol and febuxostat) are currently undergoing evaluation for angina therapy. Therapeutic angiogenesis continues to face some challenges. Future trials should evaluate the optimum patient population that would benefit from this form of therapy.

Angina treatments and prevention of cardiac events: an appraisal of the evidence

Angina pectoris is the symptomatic manifestation of transient myocardial ischaemia. At the most fundamental level, angina arises when myocardial oxygen demand exceeds the ability of the coronary circulation to provide adequate oxygen delivery to maintain normal myocardial metabolic function. In vivo, the balance of oxygen demand and delivery is a complex physiological process that can be altered by a variety of interventions. Lifestyle modification is a cornerstone of cardiovascular disease management, with or without angina. Additional pharmaceutical and physical interventions are usually applied to patients with angina. Mechanisms of action for these interventions include heart rate modulation, vascular smooth muscle relaxation, metabolic manipulation, revascularization, and others. A number of these interventions have overlapping mechanisms that target angina. Additionally, some interventions may directly or indirectly prevent or delay adverse outcomes such as myocardial infarction or death. This review summarizes current evidence for many applied ischaemia treatments documented to modify angina and comments on available evidence relating to improvement in cardiovascular outcomes.

Emerging therapies for the management of decompensated heart failure: from bench to bedside

While pharmaceutical innovation has been highly successful in reducing mortality in chronic heart failure, this has not been matched by similar success in decompensated heart failure syndromes. Despite outstanding issues over definitions and end points, we argue in this paper that an unprecedented wealth of pharmacologic innovation may soon transform the management of these challenging patients. Agents that target contractility, such as cardiac myosin activators and novel adenosine triphosphate-dependent transmembrane sodium-potassium pump inhibitors, provide inotropic support without arrhythmogenic increases in cytosolic calcium or side effects of more traditional agents. Adenosine receptor blockade may improve glomerular filtration and diuresis by exerting a direct beneficial effect on glomerular blood flow while vasopressin antagonists promote free water excretion without compromising renal function and may simultaneously inhibit myocardial remodeling. Urodilatin, the renally synthesized isoform of atrial natriuretic peptide, may improve pulmonary congestion via vasodilation and enhanced diuresis. Finally, metabolic modulators such as perhexiline may optimize myocardial energy utilization by shifting adenosine triphosphate production from free fatty acids to glucose, a unique and conceptually appealing approach to the management of heart failure. These advances allow optimism not only for the advancement of our understanding and management of decompensated heart failure syndromes but for the translational research effort in heart failure biology in general.

Metabolic approaches to the treatment of ischemic heart disease: the clinicians' perspective

This review article discusses pharmacological approaches to optimizing myocardial metabolism during ischemia. Fatty acids are the main fuel for the healthy heart, with a lesser contribution coming from the oxidation of glucose and lactate. Myocardial ischaemia dramatically alters fuel metabolism, causing an accelerated rate of glucose conversion to lactate and a switch from lactate uptake by the heart to lactate production. This causes a dramatic disruption in cell homeostasis (e.g. lactate accumulation and a decrease in pH and ATP). Paradoxically, moderately ischemic tissue (approximately 50% of normal flow) continues to derive most of its energy (50-70%) from the oxidation of fatty acids despite a high rate of lactate production. This ischaemia-induced disruption in cardiac metabolism can be minimized by metabolic agents that reduce fatty acid oxidation and increase the combustion of glucose and lactate, resulting in clinical benefit to the ischemic patient. Agents that inhibit fatty acid beta-oxidation, such as ranolazine and trimetazidine, have proven to be effective in the treatment of stable angina. Treatment of acute myocardial infarction patients with an infusion of the glucose-insulin-potassium, which results in suppression of myocardial fatty acid oxidation and greater glucose combustion, has proven effective in reducing mortality. These metabolic therapies are free of direct hemodynamic or chronotropic effects, and thus are well positioned for use alongside traditional agents such as beta-adrenergic receptor antagonists or calcium channel antagonists.

Systematic review of the efficacy and safety of perhexiline in the treatment of ischemic heart disease

Perhexiline was introduced about 30 years ago and rapidly gained a reputation for efficacy in the management of angina pectoris. However, hepatic and neurological adverse effects associated with perhexiline administration led to a marked decline in its use. The drug was originally classified as a coronary vasodilator, and later as a calcium channel antagonist, but recent data suggests that it acts as a cardiac metabolic agent, through inhibition of the enzyme, carnitine palmitoyltransferase-1 (CPT-1). Given the drug's unique anti-ischemic action and favorable hemodynamic profile, together with an improved understanding of the mechanisms underlying the adverse effects of the drug and the clear clinical need for additional therapies in refractory patients, perhexiline is currently being re-appraised as a potentially useful agent in the management of severe myocardial ischemia. Perhexiline is being considered for registration or re-registration in a number of countries and is being evaluated in a large-scale clinical trial in elderly patients with aortic stenosis and myocardial ischemia. This systematic review examines the evidence from available published literature in relation to the efficacy and tolerability of perhexiline in the treatment of cardiac disease. While there is a lack of well designed controlled trials using objective end-points to determine efficacy (almost all trials used a crossover design, included small numbers of patients and had limited statistical analysis of results), there is consistency in the data available that perhexiline is considerably more effective than placebo when used as monotherapy. Furthermore, it affords additional symptom relief in those already receiving maximal conventional anti-anginal therapy. However, there is a paucity of trials demonstrating the efficacy of low dosages of perhexiline (100 to 200 mg/day) in patients with refractory angina pectoris. Available evidence also suggests that the incidence of adverse events can be minimised, and the efficacy maintained, by keeping plasma perhexiline concentrations within a therapeutic range (150 to 600 micro g/L)

Treatment of variant angina pectoris with perhexilene maleate

Three patients with variant angina pectoris resistant to therapy with nitrates and propranolol were treated with perhexilene maleate. Two patients had normal coronary arteries with documented coronary artery spasm, while the third patient had a fixed coronary artery obstruction. In all three patients, attacks of variant angina pectoris disappeared following institution of therapy with perhexilene maleate. When the dose of this drug was decreased to 100 mg per day or less, symptoms reappeared in all patients. Reinstitution of therapeutic doses of perhexilene maleate once again resulted in complete control of symptoms. Perhexilene maleate is therefore a useful agent for the treatment of variant angina pectoris.

Effects of perhexiline maleate on coronary flow distribution in the ischemic canine myocardium

Intravenous perhexiline maleate in a canine preparation with fixed coronary flow increases coronary diastolic pressure. It also redistributes coronary flow so as to preserve endocardial flow. Myocardial oxygen consumption was reduced and lactate uptake enhanced by the drug. It had no effect upon the threshold for ischemic-induced left ventricular failure.