Perhexilene maleate in treatment of angina pectoris

Pleiotropic mechanisms of action of perhexiline in heart failure

INTRODUCTION

The re-purposing of the anti-anginal drug perhexiline (PHX) has resulted in symptomatic improvements in heart failure (HF) patients. The inhibition of carnitine palmitoyltransferase-1 (CPT-1) has been proposed as the primary mechanism underlying the therapeutic benefit of PHX. This hypothesis is contentious.

AREAS COVERED

We reviewed the primary literature and patent landscape of PHX from its initial development in the 1960s through to its emergence as a drug beneficial for HF. We focused on its physico-chemistry, molecular targets, tissue accumulation and clinical dosing.

EXPERT OPINION

Dogma that the beneficial effects of PHX are due primarily to potent myocardial CPT-1 inhibition is not supported by the literature and all available evidence point to it being extremely unlikely that the major effects of PHX occur via this mechanism. In vivo PHX is much more likely to be an inhibitor of surface membrane ion channels and also to have effects on other components of cellular metabolism and reactive oxygen species (ROS) generation across the cardiovascular system. However, the possibility that minor effects of PHX on CPT-1 underpin disproportionately large effects on myocardial function cannot be entirely excluded, especially given the massive accumulation of the drug in heart tissue.

A Controlled Multi-Centre Study of Hygroton® in the Treatment of Angina Pectoris

Following the reports of Floyd (1966) and Floyd & Domenet (1972) a study was conducted on the effect of adding 50 mg of chlorthalidone ( Hygroton®) or a matching placebo to the usual antianginal regime of 25 patients. The study was a double blind comparison between chlorthalidone 50 mg tablets and a matching placebo; each patient received both treatments. Chlorthalidone was found to be significantly better than placebo in both reducing the incidence of attacks and the consumption of glyceryl trinitrate. Chlorthalidone reduced the day-time anginal attack rate by 38% as compared with the placebo attack rate. This improvement is of the same order as that achieved by beta-adrenergic receptor blocking agents in similar types of trial. A marked variation in response was found between different types of patients. The earlier investigations with diuretics in angina are reviewed, and a possible explanation for the advantageous effect of chlorthalidone is offered.

Pharmacological and emerging therapies in the treatment of chronic angina

Chronic angina is a common manifestation of ischaemic heart disease. Medical treatments are the mainstay approach to reduce the occurrence of angina and improve patients' quality of life. This Series paper focuses on commonly used standard treatments (eg, nitrates, β blockers, and calcium-channel blockers), emerging anti-angina treatments (which are not available in all parts of the world), and experimental treatments. Although many emerging treatments are available, evidence is scarce about their ability to reduce angina and ischaemia.

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.

Impairment of sulfobromophthalein biliary excretion and inhibition of glutathione S-transferase activity induced by perhexiline maleate in rats

The effect of the antianginal agent perhexiline maleate (160 mg/kg i.g., daily for 4 days) on the biliary excretion of sulfobromophthalein (BSP) and BSP-glutathione and the hepatic activity of glutathione S-transferases was investigated in Wistar rats. Perhexiline maleate caused a significant reduction in the maximal biliary excretion of BSP (-28%). The decrease corresponded to a lowered excretion of the conjugated dye whereas the excretion of the parent compound did not change significantly. Administration of the drug caused no effect on the maximal biliary excretion of infused BSP-glutathione. Liver glutathione concentrations were similar in control and treated rats. Perhexiline maleate significantly reduced liver glutathione S-transferase activities toward BSP (-25%), 3,4-dichloronitrobenzene (DCNB) (-21%) and 1-chloro-3,4-dinitrobenzene (DNCB) (-27%). Kinetic studies of the enzyme in liver cytosol showed that perhexiline maleate induced an uncompetitive inhibition for the BSP substrate with a reduced Vmax and Km. The results indicate that the reduction in glutathione S-transferase activity plays an important role as a factor determining the impairment in the hepatobiliary transport of BSP caused by perhexiline maleate.

Antianginal efficacy of perhexiline maleate in patients refractory to beta-adrenoreceptor blockade

We performed a double-blind controlled crossover trial of perhexiline maleate versus identical placebo in daily doses of 100-400 mg in 20 male patients who were severely limited with angina pectoris despite therapy with beta-adrenoreceptor blockers. All patients had documented coronary artery disease and were awaiting coronary artery bypass grafting. Beta-blocker therapy was continued unchanged. A significant response compared to placebo was evident after 100 mg of perhexiline, and incremental therapeutic effects were evident up to 400 mg. The mean weekly angina rate fell from 18.2 +/- 2.8 basal to 6.2 +/- 1.5 on 200 mg (P less than 0.05) to 2.8 +/- 0.9 on 400 mg perhexiline (P less than 0.05). Nitroglycerin consumption fell in parallel. The mean exercise duration increased from 261 +/- 57 sec to 384 +/- 75 sec (P less than 0.05). Five patients became asymptomatic on perhexiline, and the number of pain-free days increased 100% (P less than 0.01) compared to placebo. No patient experienced hypotension or heart failure. This study shows that the addition of perhexiline to beta-adrenoreceptor antagonists in patients with severe angina pectoris is effective and represents an alternative therapy.

Morphological changes in CNS of rats treated with perhexiline maleate (pexid)

The basic cellular lesion in CNS of suckling rats treated with Pexid was studied by light and electron miroscopy. The most pronounced abnormality, the formation of various intracytoplasmic inclusions, was found in neurons, astrocytes, oligodendrocytes, ependymal cells, endothelial cells and fibroblasts. These abnormal inclusions were generally membrane-bound, although clearly non-membrane-bound inclusions were occasionally found. The several internal patterns of the inclusions were (1) lamellar, both concentric and parallel, (2) reticular and (3) crystalloid. These alterations were completely reversed following withdrawal of the drug. The structural characteristics of the abnormal inclusions in Pexid-treated animals were similar to those found with certain hypocholesterolemic, neuroleptic, anorectic, and antimalarial drugs. This suggests that the inclusions occurring within the cells of animals treated with any of these drugs may develop in a similar manner, and that the formation of such inclusions is likely to be a form of cellular reaction common to certain metabolic disturbances.

Perhexiline maleate in the treatment of angina pectoris in patients awaiting coronary artery bypass surgery

Twenty-five patients with angina pectoris due to coronary artery disease who had not responded to other medical therapy and on the waiting list for coronary bypass surgery were treated over a period of 4 weeks with perhexiline maleate (100 mg to 400 mg/day) in addition to their other therapy. There was an 80% reduction in the average number of both anginal attacks and nitroglycerin requirement when the pre-treatment week and the 4th week of perhexiline maleate therapy were compared (p less than 0.0001). Six of the patients had no anginal attacks at all and did not require sublingual nitro glycerin tablets during the 4th week of perhexiline maleate therapy.

Clinical evaluation of perhexiline maleate in patients with angina pectoris

This paper reports a double-blind trial of a new antianginal drug, perhexiline. Fifty-five patients suffering from angina pectoris were studied for periods of 12 or 24 weeks in a cross-over comparison against a placebo in four centres in the United Kingdom and Ireland. Perhexiline was effective in most patients as judged by reducing the number of anginal attacks in 84% and the consumption of glyceryl trinitrate tablets in 64%. The major side effect, dizziness, noted in one-third of the patients, may be dose/body-weight related. Perhexiline is a valuable new agent for the treatment of patients with angina, especially those who do not respond to other antianginal agents.