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Schistosomiasis is a neglected tropical disease mainly affecting the poorest tropical and subtropical areas of the world with the impressive number of roughly 200 million infections per year. Schistosomes are blood trematode flukes of the genus Schistosoma causing symptoms in humans and animals. Organ morbidity is caused by the accumulation of parasite eggs and subsequent development of fibrosis. If left untreated, schistosomiasis can result in substantial morbidity and even mortality. Praziquantel (PZQ) is the most effective and widely used compound for the treatment of the disease, in prevention and control programs in the last 30 years. Unfortunately, it has no effect on juvenile immature schistosomes and cannot prevent reinfection or interfere with the schistosome life cycle; moreover drug-resistance represents a serious threat. The search for an alternative or complementary treatment is urgent and drug repurposing could accelerate a solution. The anti-anginal drug perhexiline maleate (PHX) has been previously shown to be effective on larval, juvenile, and adult stages of S. mansoni and to impact egg production in vitro. Since PHX is a racemic mixture of R-(+)- and S-(-)-enantiomers, we designed and realized a stereoselective synthesis of both PHX enantiomers and developed an analytical procedure for the direct quantification of the enantiomeric excess also suitable for semipreparative separation of PHX enantiomers. We next investigated the impact of each enantiomer on viability of newly transformed schistosomula (NTS) and worm pairs of S. mansoni as well as on egg production and vitellarium morphology by in vitro studies. Our results indicate that the R-(+)-PHX is mainly driving the anti-schistosomal activity but that also the S-(-)-PHX possesses a significant activity towards S. mansoni in vitro., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Since Warburg's observation that most cancers exhibit elevated glycolysis, decades of research have attempted to reduce tumor glucose utilization as a therapeutic approach. Hexokinase (HK) activity is the first glycolytic enzymatic step; despite many attempts to inhibit HK activity, none has reached clinical application. Identification of HK isoforms, and recognition that most tissues express only HK1 while most tumors express HK1 and HK2, stimulated reducing HK2 activity as a therapeutic option. However, studies using HK2 shRNA and isogenic HK1 + HK2 - and HK1 + HK2 + tumor cell pairs demonstrated that tumors expressing only HK1, while exhibiting reduced glucose consumption, progressed in vivo as well as tumors expressing both HK1 and HK2. However, HK1 - HK2 + tumor subpopulations exist among many cancers. shRNA HK2 suppression in HK1 - HK2 + liver cancer cells reduced xenograft tumor progression, in contrast to HK1 + HK2 + cells. HK2 inhibition, and partial inhibition of both oxidative phosphorylation and fatty acid oxidation using HK2 shRNA and small-molecule drugs, prevented human liver HK1 - HK2 + cancer xenograft progression. Using human multiple myeloma xenografts and mouse allogeneic models to identify potential clinical translational agents, triple therapies that include antisense HK2 oligonucleotides, metformin, and perhexiline prevent progression. These results suggest an agnostic approach for HK1 - HK2 + cancers, regardless of tissue origin., (©2019 American Association for Cancer Research.)

The failing heart has an increased metabolic demand and at the same time suffers from impaired energy efficiency, which is a detrimental combination. Therefore, therapies targeting the energy-deprived failing heart and rewiring cardiac metabolism are of great potential, but are lacking in daily clinical practice. Metabolic impairment in heart failure patients has been well characterized for patients with reduced ejection fraction, and is coming of age in patients with 'preserved' ejection fraction. Targeting cardiomyocyte metabolism in heart failure could complement current heart failure treatments that do improve cardiovascular haemodynamics, but not the energetic status of the heart. In this review, we discuss the hallmarks of normal cardiac metabolism, typical metabolic disturbances in heart failure, and past and present therapeutic targets that impact on cardiac metabolism., (© 2016 The Authors. European Journal of Heart Failure © 2016 European Society of Cardiology.)

Many conditions culminate in heart failure (HF), a multi-organ systemic syndrome with an intrinsically poor prognosis. Pharmacotherapeutic agents that correct neurohormonal dysregulation and haemodynamic instability have occupied the forefront of developments within the treatment of HF in the past. Indeed, multiple trials aimed to validate these agents in the 1980s and early 1990s, resulting in a large and robust evidence-base supporting their use clinically. An established treatment paradigm now exists for the treatment of HF with reduced ejection fraction (HFrEF), but there have been very few notable developments in recent years. HF remains a significant health concern with an increasing incidence as the population ages. We may indeed be entering the surgical era for HF treatment, but these therapies remain expensive and inaccessible to many. Newer pharmacotherapeutic agents are slowly emerging, many targeting alternative therapeutic pathways, but with mixed results. Metabolic modulation and manipulation of the nitrate/nitrite/nitric oxide pathway have shown promise and could provide the answers to fill the therapeutic gap between medical interventions and surgery, but further definitive trials are warranted. We review the significant evidence base behind the current medical treatments for HFrEF, the physiology of metabolic impairment in HF, and discuss two promising novel agents, perhexiline and nitrite., (© 2016 The Authors. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Objectives: Patients undergoing cardiac surgery require adequate myocardial protection. Manipulating myocardial metabolism may improve the extent of myocardial protection. Perhexiline has been shown to be an effective anti-anginal agent due to its metabolic modulation properties by inhibiting the uptake of free fatty acids into the mitochondrion, and thereby promoting a more efficient carbohydrate-driven myocardial metabolism. Metabolic modulation may augment myocardial protection, particularly in patients with left ventricular hypertrophy (LVH) known to have a deranged metabolic state and are at risk of poor postoperative outcomes. This study aimed to evaluate the role of perhexiline as an adjunct in myocardial protection in patients with LVH secondary to aortic stenosis (AS), undergoing an aortic valve replacement (AVR)., Methods: In a multicentre double-blind randomized controlled trial of patients with AS undergoing AVR ± coronary artery bypass graft surgery, patients were randomized to preoperative oral therapy with either perhexiline or placebo. The primary end point was incidence of inotrope use to improve haemodynamic performance due to a low cardiac output state during the first 6 h of reperfusion, judged by a blinded end points committee. Secondary outcome measures included haemodynamic measurements, electrocardiographic and biochemical markers of new myocardial injury and clinical safety outcome measures., Results: The trial was halted early on the advice of the Data Safety and Monitoring Board. Sixty-two patients were randomized to perhexiline and 65 to placebo. Of these, 112 (54 perhexiline and 48 placebo) patients received the intervention, remained in the trial at the time of the operation and were analysed. Of 110 patients who achieved the primary end point, 30 patients (16 perhexiline and 14 placebo) had inotropes started appropriately; there was no difference in the incidence of inotrope usage OR of 1.65 [confidence interval (CI): 0.67-4.06] P = 0.28. There was no difference in myocardial injury as evidenced by electrocardiogram odds ratio (OR) of 0.36 (CI: 0.07-1.97) P = 0.24 or postoperative troponin release. Gross secondary outcome measures were comparable between the groups., Conclusions: Perhexiline as a metabolic modulator to enhance standard myocardial protection does not provide an additional benefit in haemodynamic performance or attenuate myocardial injury in the hypertrophied heart secondary to AS. The role of perhexiline in cardiac surgery is limited., (© The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Type 2 diabetes mellitus escalates the risk of heart failure partly via its ability to induce a cardiomyopathic state that is independent of coronary artery disease and hypertension. Although the pathogenesis of diabetic cardiomyopathy has yet to be fully elucidated, aberrations in cardiac substrate metabolism and energetics are thought to be key drivers. These aberrations include excessive fatty acid utilisation and storage, suppressed glucose oxidation and impaired mitochondrial oxidative phosphorylation. An appreciation of how these abnormalities arise and synergise to promote adverse cardiac remodelling is critical to their effective amelioration. This review focuses on disturbances in myocardial fuel (fatty acids and glucose) flux and energetics in type 2 diabetes, how these disturbances relate to the development of diabetic cardiomyopathy and the potential therapeutic agents that could be used to correct them., (© The Author(s) 2015.)

Oncogenic activation of NOTCH1 signaling plays a central role in the pathogenesis of T-cell acute lymphoblastic leukemia, with mutations on this signaling pathway affecting more than 60% of patients at diagnosis. However, the transcriptional regulatory circuitries driving T-cell transformation downstream of NOTCH1 remain incompletely understood. Here we identify Hairy and Enhancer of Split 1 (HES1), a transcriptional repressor controlled by NOTCH1, as a critical mediator of NOTCH1-induced leukemogenesis strictly required for tumor cell survival. Mechanistically, we demonstrate that HES1 directly downregulates the expression of BBC3, the gene encoding the PUMA BH3-only proapoptotic factor in T-cell acute lymphoblastic leukemia. Finally, we identify perhexiline, a small-molecule inhibitor of mitochondrial carnitine palmitoyltransferase-1, as a HES1-signature antagonist drug with robust antileukemic activity against NOTCH1-induced leukemias in vitro and in vivo., (© 2015 by The American Society of Hematology.)

Objectives: Perhexiline is thought to modulate metabolism by inhibiting mitochondrial carnitine palmitoyltransferase-1, reducing fatty acid uptake and increasing carbohydrate utilization. This study assessed whether preoperative perhexiline improves markers of myocardial protection in patients undergoing coronary artery bypass graft surgery and analysed its effect on the myocardial metabolome., Methods: In a prospective, randomized, double-blind, placebo-controlled trial, patients at two centres were randomized to receive either oral perhexiline or placebo for at least 5 days prior to surgery. The primary outcome was a low cardiac output episode in the first 6 h. All pre-specified analyses were conducted according to the intention-to-treat principle with a statistical power of 90% to detect a relative risk of 0.5 and a conventional one-sided α-value of 0.025. A subset of pre-ischaemic left ventricular biopsies was analysed using mass spectrometry-based metabolomics., Results: Over a 3-year period, 286 patients were randomized, received the intervention and were included in the analysis. The incidence rate of a low cardiac output episode in the perhexiline arm was 36.7% (51/139) vs 34.7% (51/147) in the control arm [odds ratio (OR) 0.92, 95% confidence interval (CI) 0.56-1.50, P = 0.74]. Perhexiline was associated with a reduction in the cardiac index at 6 h [difference in means 0.19, 95% CI 0.07-0.31, P = 0.001] and an increase in inotropic support in the first 12 h (OR 0.55, 95% CI 0.34-0.89, P = 0.015). There were no significant differences in myocardial injury with troponin-T or electrocardiogram, reoperation, renal dysfunction or length of stay. No difference in the preischaemic left ventricular metabolism was identified between groups on metabolomics analysis., Conclusions: Preoperative perhexiline does not improve myocardial protection in patients undergoing coronary surgery and in fact reduced perioperative cardiac output, increasing the need for inotropic support. Perhexiline has no significant effect on the mass spectrometry-visible polar myocardial metabolome in vivo in humans, supporting the suggestion that it acts via a pathway that is independent of myocardial carnitine palmitoyltransferase inhibition and may explain the lack of clinical benefit observed following surgery., Clinicaltrialsgov Id: NCT00845364., (© The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery.)

Objectives: The aim of this study was to determine whether short-term treatment with perhexiline improves cardiac energetics, left ventricular function, and symptoms of heart failure by altering cardiac substrate utilization., Background: Perhexiline improves exercise capacity and left ventricular ejection fraction (LVEF) in patients with heart failure (HF). (31)P cardiac magnetic resonance spectroscopy can be used to quantify the myocardial phosphocreatine/adenosine triphosphate ratio. Because improvement of HF syndrome can improve cardiac energetics secondarily, we investigated the effects of short-term perhexiline therapy., Methods: Patients with systolic HF of nonischemic etiology (n = 50, 62 ± 1.8 years of age, New York Heart Association functional class II to IV, LVEF: 27.0 ± 1.44%) were randomized to receive perhexiline 200 mg or placebo for 1 month in a double-blind fashion. Clinical assessment, echocardiography, and (31)P cardiac magnetic resonance spectroscopy were performed at baseline and after 1 month. A substudy of 22 patients also underwent cross-heart blood sampling at completion of the study to quantify metabolite utilization., Results: Perhexiline therapy was associated with a 30% increase in the phosphocreatine/adenosine triphosphate ratio (from 1.16 ± 0.39 to 1.51 ± 0.51; p < 0.001) versus a 3% decrease with placebo (from 1.36 ± 0.31 to 1.34 ± 0.31; p = 0.37). Perhexiline therapy also led to an improvement in New York Heart Association functional class compared with placebo (p = 0.036). Short-term perhexiline therapy did not change LVEF. Cross-heart measures of cardiac substrate uptake and respiratory exchange ratio (which reflects the ratio of substrates used) did not differ between patients who received perhexiline versus placebo., Conclusions: Perhexiline improves cardiac energetics and symptom status with no evidence of altered cardiac substrate utilization. No change in LVEF is seen at this early stage. (Metabolic Manipulation in Chronic Heart Failure; NCT00841139)., (Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Currently, there are no effective medical treatment options to prevent the formation of heterotopic bones in fibrodysplasia ossificans progressiva (FOP). By the drug repositioning strategy, we confirmed that perhexiline maleate (Pex) potentially ameliorates heterotopic ossification in model cells and mice. Here, we conducted a prospective study to assess the efficacy and safety of Pex in the treatment of FOP patients., Methods: FOP patients in this open-label single-center study were treated with Pex for a total of 12 months, and followed up for 12 consecutive months after medication discontinuation. The safety of the treatment was assessed regularly by physical and blood examinations. The efficacy of Pex for preventing heterotopic ossifications was evaluated by the presence of flare-ups, measurements of serum bone markers, and changes in the total bone volume calculated by the three-dimensional computed tomography (3D-CT) images., Results: Five patients with an average age of 23.4 years were enrolled. Within safe doses of Pex administration in each individual, there were no drug-induced adverse effects during the medication phase. Three patients showed no intense inflammatory reactions during the study period, while two patients had acute flare-ups around the hip joint without evidence of trauma during the medication phase. In addition, one of them became progressively incapable of opening her mouth over the discontinuation phase. Serum levels of alkaline phosphatase (ALP) and bone specific ALP (BAP) were significantly and synchronously increased with the occurrence of flare-ups. Volumetric 3D-CT analysis demonstrated a significant increase in the total bone volume of Case 2 (378 cm(3)) and Case 3 (833 cm(3)) during the two-year study period., Conclusions: We could not prove the efficacy of oral Pex administration in the prevention of heterotopic ossifications in FOP. Serum levels of ALP and BAP appear to be promising biomarkers for monitoring the development of ectopic ossifications and efficacy of the therapy. Quantification of change in the total bone volume by whole body CT scanning could be a reliable evaluation tool for disease progression in forthcoming clinical trials of FOP.

Background: Heart failure is a major cause of morbidity and mortality in society. Current medical therapy centres on neurohormonal modulation with angiotensin converting enzyme inhibitors and β-blockers. There is growing evidence for the use of metabolic manipulating agents as adjunctive therapy in patients with heart failure. We aim to determine the effect of perhexiline on cardiac energetics and alterations in substrate utilisation in patients with non-ischaemic dilated cardiomyopathy., Methods: A multi-centre, prospective, randomised double-blind, placebo-controlled trial of 50 subjects with non-ischaemic dilated cardiomyopathy recruited from University Hospital Birmingham NHS Foundation Trust and Cardiff and Vale NHS Trust. Baseline investigations include magnetic resonance spectroscopy to assess cardiac energetic status, echocardiography to assess left ventricular function and assessment of symptomatic status. Subjects are then randomised to receive 200 mg perhexiline maleate or placebo daily for 4 weeks with serum drug level monitoring. All baseline investigations will be repeated at the end of the treatment period. A subgroup of patients will undergo invasive investigations with right and left heart catheterisation to calculate respiratory quotient, and mechanical efficiency. The primary endpoint is an improvement in the phosphocreatine to adenosine triphosphate ratio at 4 weeks. Secondary end points are: i) respiratory quotient; ii) mechanical efficiency; iii) change in left ventricular (LV) function., Trial Registration: ClinicalTrials.gov: NCT00841139 ISRCTN: ISRCTN72887836.

Background: Hypertrophic cardiomyopathy patients exhibit myocardial energetic impairment, but a causative role for this energy deficiency in the pathophysiology of hypertrophic cardiomyopathy remains unproven. We hypothesized that the metabolic modulator perhexiline would ameliorate myocardial energy deficiency and thereby improve diastolic function and exercise capacity., Methods and Results: Forty-six consecutive patients with symptomatic exercise limitation (peak Vo(2) <75% of predicted) caused by nonobstructive hypertrophic cardiomyopathy (mean age, 55±0.26 years) were randomized to perhexiline 100 mg (n=24) or placebo (n=22). Myocardial ratio of phosphocreatine to adenosine triphosphate, an established marker of cardiac energetic status, as measured by (31)P magnetic resonance spectroscopy, left ventricular diastolic filling (heart rate normalized time to peak filling) at rest and during exercise using radionuclide ventriculography, peak Vo(2), symptoms, quality of life, and serum metabolites were assessed at baseline and study end (4.6±1.8 months). Perhexiline improved myocardial ratios of phosphocreatine to adenosine triphosphate (from 1.27±0.02 to 1.73±0.02 versus 1.29±0.01 to 1.23±0.01; P=0.003) and normalized the abnormal prolongation of heart rate normalized time to peak filling between rest and exercise (0.11±0.008 to -0.01±0.005 versus 0.15±0.007 to 0.11±0.008 second; P=0.03). These changes were accompanied by an improvement in primary end point (peak Vo(2)) (22.2±0.2 to 24.3±0.2 versus 23.6±0.3 to 22.3±0.2 mL · kg(-1) · min(-1); P=0.003) and New York Heart Association class (P<0.001) (all P values ANCOVA, perhexiline versus placebo)., Conclusions: In symptomatic hypertrophic cardiomyopathy, perhexiline, a modulator of substrate metabolism, ameliorates cardiac energetic impairment, corrects diastolic dysfunction, and increases exercise capacity. This study supports the hypothesis that energy deficiency contributes to the pathophysiology and provides a rationale for further consideration of metabolic therapies in hypertrophic cardiomyopathy.

Aims: The objective of this study is to report on our 5-year collective experience on the use of perhexiline in the UK, in patients with chronic heart failure (CHF) and/or refractory angina with respect to 'real-life' drug side effects and toxicity, therapeutic drug level monitoring, 5 year mortality outcomes and predictors of response to perhexiline therapy., Methods and Results: Data on clinical history, perhexiline monitoring, follow-up, and mortality were retrospectively collated from centralized perhexiline databases from two tertiary referral centres. A total of 151 patients were on perhexiline therapy at two UK tertiary referral centres. At 3-4 months, 68.8% of patients had drug level within the therapeutic range and 20.8% were above the therapeutic range. A total of 58.9% of patients reported to have felt better on the perhexiline (responders). The presence of refractory angina was an independent predictor of response to perhexiline therapy (odds ratio 2.84, 95% confidence interval 1.28-6.32, P = 0.01). Five-year mortality was non-significantly different between patients with refractory angina, CHF, or both (20.5, 31.0, and 38.4%, P = 0.20, respectively)., Conclusion: Perhexiline therapy provides symptomatic relief in the majority of patients with minimal side effects or toxicity. Careful therapeutic level monitoring for dose titration is important to prevent acute and chronic toxicity. Patients with refractory angina were more likely to be responders.

Background: Several therapies commonly used for the treatment of acute heart failure syndromes (AHFS) present some well-known limitations and have been associated with an early increase in the risk of death. There is, therefore, an unmet need for new pharmacologic agents for the early management of AHFS that may improve both short- and long-term outcomes., Aim: To review the recent evidence on emerging pharmacologic therapies in AHFS., Methods: A systematic search of peer-reviewed publications was performed on MEDLINE, EMBASE and Clinical Trials.gov from January 1990 to August 2007. The results of unpublished or ongoing trials were obtained from presentations at national and international meetings and pharmaceutical industry releases. Bibliographies from these references were also reviewed, as were additional articles identified by content experts., Results: Cumulative data from large studies and randomised trials suggest that therapies with innovative mechanisms of action may safely and effectively reduce pulmonary congestion or improve cardiac performance in AHFS patients., Conclusion: Some investigational agents for the management of AHFS are able to improve haemodynamics and/or clinical status. In spite of these promising findings, no new agent has demonstrated a clear benefit in terms of long-term clinical outcomes compared to placebo or conventional therapies.

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.

Aims: CYP2D6 protein expression is determined by the number of functional CYP2D6 alleles. It is also higher in individuals with at least one CYP2D6*2 allele. This study has investigated the effect of the number of functional CYP2D6 alleles and the influence of CYP2D6*2 alleles on plasma perhexiline concentrations in patients administered a standard loading regimen over 3 days., Methods: Eighteen patients with myocardial ischaemia who were not taking any drugs known to inhibit CYP2D6 metabolism in vivo commenced treatment with 200 mg of perhexiline twice per day. On the fourth day, blood was drawn for genotyping and the measurement of trough plasma concentrations of perhexiline and its major metabolite, cis-OH-perhexiline., Results: The only genotypic CYP2D6 poor metabolizer had a trough plasma perhexiline concentration of 2.70 mg l-1 and no detectable cis-OH-perhexiline. The mean+/-SD trough plasma perhexiline concentration in patients with one functional allele was significantly higher (0.63+/-0.31 mg l-1, n=8, P=0.05) than in patients with two functional alleles (0.37+/-0.17 mg l-1, n=9). Conversely, the mean metabolic ratio was significantly lower in patients with one functional allele (2.90+/-1.76, P<0.01) compared with patients with two functional alleles (6.52+/-3.26). Patients with at least one CYP2D6*2 allele had a lower plasma perhexiline concentration (0.20+/-0.09 mg l-1, n=5, P<0.001) and a higher metabolic ratio (7.86+/-2.51, P<0.01) than the non-poor metabolizer patients with no CYP2D6*2 alleles (0.62+/-0.23 mg l-1 and 3.55+/-2.54, respectively, n=12)., Conclusion: Patients with only one functional allele and not CYP2D6*2 have diminished CYP2D6 metabolic capacity for perhexiline.

Aims: Perhexiline is an antianginal agent that displays both saturable and polymorphic metabolism via CYP2D6. The aim of this study was to determine whether perhexiline produces clinically significant inhibition of CYP2D6-catalysed metabolism in angina patients., Methods: The effects of perhexiline on CYP2D6-catalysed metabolism were investigated by comparing urinary total dextrorphan/dextromethorphan metabolic ratios following a single dose of dextromethorphan (16.4 mg) in eight matched control patients not taking perhexiline and 24 patients taking perhexiline. All of the patients taking perhexiline had blood drawn for CYP2D6 genotyping as well as to measure plasma perhexiline and cis-OH-perhexiline concentrations., Results: Median (range) dextrorphan/dextromethorphan metabolic ratios were significantly higher (P < 0.0001) in control patients, 271.1 (40.3-686.1), compared with perhexiline-treated patients, 5.0 (0.3-107.9). In the perhexiline-treated group 10/24 patients had metabolic ratios consistent with poor metabolizer phenotypes; however, none was a genotypic poor metabolizer. Interestingly, 89% of patients who had phenocopied to poor metabolizers had only one functional CYP2D6 gene. There was a significant negative linear correlation between the log of the dextrorphan/dextromethorphan metabolic ratio and plasma perhexiline concentrations (r(2) = 0.69, P < 0.0001). Compared with patients with at least two functional CYP2D6 genes, those with one functional gene were on similar perhexiline dosage regimens but had significantly higher plasma perhexiline concentrations, 0.73 (0.21-1.00) vs. 0.36 (0.04-0.69) mg l(-1) (P = 0.04), lower cis-OH-perhexiline/perhexiline ratios, 2.85 (0.35-6.10) vs. 6.51 (1.84-11.67) (P = 0.03), and lower dextrorphan/dextromethorphan metabolic ratios, 2.51 (0.33-39.56) vs. 11.80 (2.90-36.93) (P = 0.005)., Conclusions: Perhexiline significantly inhibits CYP2D6-catalysed metabolism in angina patients. The plasma cis-OH-perhexiline/perhexiline ratio may help to both phenotype patients and predict those in whom perhexiline may be most likely to cause clinically significant metabolic inhibition.

Antianginal drugs that exert their anti-ischaemic effects primarily by altering myocardial metabolism have recently attracted attention. They have the potential to relieve symptoms in patients with refractory angina who are already on "optimal" medical therapy and have disease that is not amenable to revascularisation, making these drugs an attractive addition to therapy, particularly for the elderly population. In some cases, they may even be used as first-line treatment. These drugs increase glucose metabolism at the expense of free-fatty-acid metabolism, enhancing oxygen efficiency during myocardial ischaemia. Whilst they have been demonstrated to reduce ischaemia in several clinical trials, their use remains limited. This review aims to draw attention to these "metabolic" antianginal drugs while surveying the evidence supporting their use and mode of action. Four metabolic antianginal drugs are reviewed: perhexiline, trimetazidine, ranolazine, and etomoxir. We also discuss the metabolic actions of glucose-insulin-potassium and beta-blockers and describe myocardial metabolism during normal and ischaemic conditions. The potential of these metabolic agents may extend beyond the treatment of ischaemia secondary to coronary artery disease. They offer significant promise for the treatment of symptoms occurring due to inoperable aortic stenosis, hypertrophic cardiomyopathy, and chronic heart failure.

Aims: To examine whether the prophylactic antianginal agent perhexiline potentiates platelet responsiveness to nitric oxide (NO) in patients with stable angina pectoris (SAP) and acute coronary syndromes (ACS: unstable angina pectoris or non-Q-wave myocardial infarction)., Methods and Results: Blood samples were obtained from patients before and after initiation of treatment with perhexiline. ADP-induced platelet aggregation and its inhibition by the NO donor sodium nitroprusside (SNP) were determined via impedance aggregometry in whole blood (WB) and platelet-rich plasma (PRP). Intraplatelet cGMP content was assayed by RIA, and superoxide (O(2)(-)) level by lucigenin-derived chemiluminescence. In patients with ACS not receiving perhexiline (n=12), platelet responsiveness to SNP did not vary significantly over the first 3 days post admission to hospital. Therapy with perhexiline for 3 days was associated with increases in SNP-induced inhibition of aggregation from 29+/-2% to 43+/-4% (n=50,P <0.001) in WB and from 20+/-5% to 42+/-7% (n=12, P<0.01) in PRP. Resolution of symptomatic ischaemia (n=39) was associated with significantly greater (P<0.01) increases than non-resolution (n=11). Similar increases in SNP responsiveness (P<0.001) occurred following institution of perhexiline therapy in patients with SAP (n=30), associated with a 85% decrease in anginal frequency. Treatment with perhexiline potentiated the cGMP-elevating effects of SNP in platelets (n=9,P =0.03). Although perhexiline did not alter whole blood O(2)(-) concentration ex vivo, it inhibited (P<0.01) O(2)(-) release from neutrophils in vitro., Conclusion: Perhexiline potentiates platelet responsiveness to NO both in SAP and ACS patients; in the latter group this improvement was predictive of resolution of ischaemic symptoms. The predominant mechanism of perhexiline effect is an increase in platelet cGMP responsiveness. Perhexiline also may reduce the potential for NO clearance by neutrophil-derived O(2)(-).

Despite large gains in the medical and surgical treatment of angina pectoris in the past two decades, many patients are refractory to conventional medical therapy and are unsuitable for a first or, more commonly, repeat coronary revascularization procedure. We evaluated the efficacy of perhexiline maleate, a drug with an antianginal mechanism of action in humans that is as yet unknown, by using a randomized double-blind placebo-controlled crossover design in 17 patients with refractory angina who continued to receive maximal antianginal therapy, typically including nitrates, a beta-blocker, and a calcium channel antagonist. In view of perhexiline's potential for hepatic and neurological toxicity, plasma drug levels were monitored and maintained in the 150-600 ng/ml range. Sixty-three percent of patients were judged perhexiline responders by objective exercise testing criteria, as compared with 18% of patients on placebo (p less than 0.05). By blinded review of subjective measures of anginal frequency and severity, 65% of patients noted an improvement while on perhexiline, whereas no patient identified the placebo phase with improvement. Side effects observed in 29% of patients were minor and related to transient elevations of blood levels of more than 600 ng/ml; no patient suffered hemodynamic or cardiac conduction abnormalities attributable to perhexiline. With attention to the pharmacokinetics of perhexiline's elimination in individual patients, this novel antianginal agent seems to be safe and effective and deserves further evaluation in patients already receiving maximal antianginal therapy who are not candidates for revascularization procedures.

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.

In a preliminary study which lasted 14 weeks, an anti-anginal preparation, perhexiline maleate (Pexid), was prescribed in a dosage of 200 mg twice a day to 7 patients who were suffering from cardiac arrhythmias associated with ischaemic heart disease. There was a significant reduction in ventricular extrasystoles during the 4th and 8th weeks of the study in 6 of the patients who had multiple ventricular ectopic beats. In 4 of these patients, an effective anti-arrhythmic response was maintained until the end of the study. These findings confirm other studies regarding the efficacy of the preparation in reducing ventricular extrasystoles in patients with cardiac ischaemia.

We conducted a double-blind, crossover study into the effect of 100 mg of perhexiline maleate twice daily on the response to exercise of 15 patients with proven ischemic heart disease. Patients were evaluated by bicycle ergometry, on three occasions, before treatment and after 2 weeks of treatment with placebo or perhexiline. Patients were able to exercise for a longer period as shown by comparing perhexiline to pretreatment (mean change, 54.9%; p less than 0.001) and placebo values (38.9%; p less than 0.001). An increase in work performed while taking perhexiline was demonstrated when compared to pretreatment (mean change, 29.7%; p less than 0.001) and placebo (26.3%; p less than 0.001). An increase in heart rate at maximal exercise was observed when compared to pretreatment (mean change, 9.7%; p less than 0.01) and placebo (8.8%; p less than 0.01). A reduction in heart rate for a given workload was obtained when compared to pretreatment (mean change, 7.0%; p less than 0.005) and placebo (2.9%; p less than 0.01). An increase in resting systolic blood pressure while taking perhexiline was shown when compared to pretreatment (mean change, 12.8%; p less than 0.02) and placebo measurements (8.5%; p less than 0.05). Perhexiline in a dose of 200 mg daily is effective against angina pectoris and significantly increases exercise tolerance. The likelihood of side effects may be decreased by using this dosage regimen.

A random single-blind study of oxprenolol against perhexiline has been undertaken in angina pectoris. Both drugs were effective in treatment (P less than 0.01) but perhexiline was better than oxprenolol (P less than 0.05), 12 of the 14 patients preferring perhexiline. Offset against this was the greater incidence of side effects with perhexiline, including one patient who later developed peripheral neuropathy. Despite the greater efficacy of perhexiline, it is suggested that side effects should preclude its routine prescription as a drug of first choice in angina pectoris. It should remain of value in the special situations of resistant angina and angina with heart failure or bronchospasm, when its use should be carefully monitored for these side effects.

The effectiveness of perhexiline maleate in the suppression of ventricular ectopic activity has been studied in 10 patients after myocardial infarction. Before treatment all patients exhibited frequent ectopic beats, i.e. more than 8 per hour. Numerous Holter magnetic tape recordings were made over a 9 - 10-month period of treatment. During the entire period of monitoring significant suppression of ectopic activity was observed in 5 patients and transient suppression in 4, of whom 3 subsequently showed a transient increase. The drug was discontinued in 1 patient because of nausea, anorexia and weight loss. No other adverse effects were encountered.

The authors report the cases of 2 patients who died from cirrhosis after receiving perhexiline maleate, a drug widely used in Europe for the treatment of angina pectoris. Perhexiline maleate had been ingested for 24 and 28 mo, respectively. Manifestations of cirrhosis included jaundice, hepatic encephalopathy, ascites, and portal hypertension. Associated manifestations of intolerance to perhexiline maleate included peripheral neuropathy in 1 patient and marked weight loss in both. Histologic lesions resembled those observed in patients with alcoholic liver disease. Ultrastructural lesions included numerous enlarged lysosomes containing myeloid figures. Histochemical stains demonstrated increased phospholipid content of the hepatocytes. These findings are consistent with the view that prolonged administration of perhexiline maleate may induce both histologic lesions resembling those of alcoholic liver disease and ultrastructural and histochemical lesions resembling those of phospholipidosis.

The effects of drugs were evaluated in 47 cases with variant angina (VA), 19 with resting angina showing ST depression (RA), and 84 with unstable angina (UA). In VA patients, calcium antagonists were effective in 87.1% of the cases, while other drugs were effective in 56.3%. The difference was statistically significant. In RA patients, calcium antagonists were effective in 80.0% of the cases and other drugs in 44.4%. Nifedipine was effective in all 5 cases with coronary stenosis of more than 75.0%. All cases of RA had multiple vessel disease and nifedipine was effective in 80.0% of the patients. Nifedipine was effective in 83.3% of VA cases showing ST elevation during an exercise test, and was particularly effective in all patients having attacks only at rest. The effects of nifedipine were confirmed in 83.3% of UA cases. These results indicate that calcium antagonists are effective in VA, RA, and UA.