Pentoxifylline for intermittent claudication

Nonalcoholic steatohepatitis: A comprehensive updated review of risk factors, symptoms, and treatment

Non-alcoholic steatohepatitis (NASH) is a subtype of nonalcoholic fatty liver disease and a progressive and chronic liver disorder with a significant risk for the development of liver-related morbidity and mortality. The complex and multifaceted pathophysiology of NASH makes its management challenging. Early identification of symptoms and management of patients through lifestyle modification is essential to prevent the development of advanced liver disease. Despite the increasing prevalence of NASH, there is no FDA-approved treatment for this disease. Currently, medications targeting metabolic disease risk factors and some antifibrotic medications are used for NASH patients but are not sufficiently effective. The beneficial effects of different drugs and phytochemicals represent new avenues for the development of safer and more effective treatments for NASH. In this review, different risk factors, clinical symptoms, diagnostic methods of NASH, and current treatment strategies for the management of patients with NASH are reviewed.

Pentoxifylline changes the balance of immune cell population in breast tumor-infiltrating lymphocytes

Immunotherapy utilizing tumor-infiltrating lymphocytes (TILs) is a promising approach for cancer treatment. Pentoxifylline (PTXF), a xanthine derivative, exhibits antitumor properties. This study aimed to investigate the impact of PTXF on the phenotype and function of TILs and splenocytes in a triple-negative breast cancer (TNBC) mouse model. TNBC was subcutaneously induced in BALB/c mice, followed by nine intraperitoneal injections of 100 mg/kg PTXF. TILs were then isolated by enzymatic digestion of tumors and cocultured with 4T1 cells. The proportion of regulatory T cells (Tregs) and cytotoxic T cells in TILs and splenocytes was assessed using flow cytometry. Transforming growth factor (TGF)-β and interferon (IFN)-γ production in TILs and splenocytes cultures was measured by ELISA. Relative expression of t-bet, foxp3, gata-3, and ror-γt in TILs and splenocytes was evaluated using real-time PCR. Tumor growth in PTXF-treated mice was significantly lower than that in the controls (P < 0.01). The frequency of regulatory and cytotoxic TILs in PTXF-treated mice was approximately half (P < 0.01) and twice (P < 0.05) that of the control group, respectively. The level of TGF-β and IFN-γ in the supernatant of PTXF-treated TILs was decreased and increased, respectively (P < 0.05). The relative expression of t-bet and foxp3 in the PTXF-treated mice compared to controls was increased and decreased, respectively (P < 0.05). Changes in the immune cell balance were less significant in the spleen compared to the TILs. PTXF treatment could limit the tumor growth and modify the regulatory-to-cytotoxic TILs ratio, as well as cytokine balance of TILs, in favor of antitumor responses.

Pharmacodynamic properties for inhibition of cAMP- and cGMP elimination by pentoxifylline remain unaltered in vitro during hypothermia

BACKGROUND

Rewarming from hypothermia is associated with severe complications, one of which is hypothermia-induced cardiac dysfunction. This condition is characterized by decreased cardiac output accompanied by increased total peripheral resistance. This contributes to mortality rate approaching 40%. Despite this, no pharmacological interventions are recommended for these patients below 30 °C. Raising the intracellular levels of cAMP and/or cGMP, through PDE3- and PDE5-inhibitors respectively, have showed the ability to alleviate hypothermia-induced cardiac dysfunction in vivo. Drugs that raise levels of both cAMP and cGMP could therefore prove beneficial in patients suffering from hypothermia-induced cardiac dysfunction.

METHODS

The unselective PDE-inhibitor pentoxifylline was investigated to determine its ability to reach the intracellular space, inhibit PDE3 and PDE5 and inhibit cellular efflux of cAMP and cGMP at temperatures 37, 34, 30, 28, 24 and 20 °C. Recombinant human PDE-enzymes and human erythrocytes were used in the experiments. IC₅₀-values were calculated at all temperatures to determine temperature-dependent changes.

RESULTS

At 20 °C, the IC₅₀-value for PDE5-mediated enzymatic breakdown of cGMP was significantly increased compared to normothermia (IC₅₀: 39.4 µM ± 10.9 µM vs. 7.70 µM ± 0.265 µM, p-value = 0.011). No other significant changes in IC₅₀-values were observed during hypothermia.

CONCLUSIONS

This study shows that pentoxifylline has minimal temperature-dependent pharmacodynamic changes, and that it can inhibit elimination of both cAMP and cGMP at low temperatures. This can potentially be effective treatment of hypothermia-induced cardiac dysfunction.

TRIAL REGISTRATION

Not applicable.

Pentoxifylline as a therapeutic option for pre-eclampsia: a study on its placental effects

BACKGROUND AND PURPOSE

Recently pentoxifylline, a non-selective phosphodiesterase inhibitor and adenosine receptor antagonist, has attracted much interest for the treatment of the increased vascular resistance and endothelial dysfunction in pre-eclampsia. We therefore investigated the placental transfer, vascular effects and anti-inflammatory actions of pentoxifylline in healthy and pre-eclamptic human placentas.

EXPERIMENTAL APPROACH

The placental transfer and metabolism of pentoxifylline were studied using ex vivo placenta perfusion experiments. In wire myography experiments with chorionic plate arteries, pentoxifyllines vasodilator properties were investigated, focusing on the cGMP and cAMP pathways and adenosine receptors. Its effects on inflammatory factors were also studied in placental explants.

KEY RESULTS

Pentoxifylline transferred from the maternal to foetal circulation, reaching identical concentrations. The placenta metabolized pentoxifylline into its active metabolite lisofylline (M1), which was released into both circulations. In healthy placentas, pentoxifylline potentiated cAMP- and cGMP-induced vasodilation, as well as causing vasodilation by adenosine A₁ antagonism and via NO synthase and PKG. Pentoxifylline also reduced inflammatory factors secretion. In pre-eclamptic placentas, we observed that its vasodilator capacity was preserved, however not via NO-PKG but likely through adenosine signalling. Pentoxifylline neither potentiated vasodilation through cAMP and cGMP, nor suppressed the release of inflammatory factors from these placentas.

CONCLUSION AND IMPLICATIONS

Pentoxifylline is transferred across and metabolized by the placenta. Its beneficial effects on the NO pathway and inflammation are not retained in pre-eclampsia, limiting its application in this disease, although it could be useful for other placenta-related disorders. Future studies might focus on selective A₁ receptor antagonists as a new treatment for pre-eclampsia.

Are the Protean Effects of Pentoxifylline in the Therapy of Diabetes and Its Complications Still Relevant?

Pentoxifylline (Px) has protean effects that can be utilized in the therapy of diabetes and its complications. There have been well-documented but often inconclusive improvements in peripheral arterial disease, foot ulcers, peripheral neuropathy, nephropathy, retinopathy, ischemic heart disease and cerebrovascular disease. In addition, non-alcoholic steatosis and steatohepatitis, which are closely associated with insulin resistance and type 2 diabetes, have been shown to improve with pentoxifylline. Surprisingly, pentoxifylline modestly improves insulin resistance through improvements in capillary blood flow as well as beta cell function and decreased hepatic glucose production. The therapeutic effects of pentoxifylline are complementary to the effects of drugs such as blockers of the renin-angiotensin-aldosterone system when utilized in the therapy of diabetic nephropathy.

Novel Co-crystal of Pentoxifylline and Protocatechuic Acid Relieves Allodynia in Rat Models of Peripheral Neuropathic Pain and CRPS by Alleviating Local Tissue Hypoxia

Local tissue ischemic hypoxia is a peripheral process that can be targeted with topical treatment to alleviate pain under chronic pain conditions such as complex regional pain syndrome (CRPS) and peripheral neuropathic pain. We recently reported three novel salts and a co-crystal composed of vasoactive agents and antioxidant nutraceuticals, all of which produced potent topical anti-allodynic effects in the chronic postischemic pain (CPIP) rat model of CRPS. One of the products, pentx-pca, is a co-crystal synthesized from pentoxifylline (pentx) and protocatechuic acid (pca). Pentx-pca exhibited potent topical anti-allodynic effects in CPIP and rats with chronic constriction injury of the sciatic nerve exceeding effects produced individually by pentx and pca. We hypothesized that the anti-allodynic effects of pentx-pca in CPIP rats were due to its impact on local tissue oxygenation and subsequent oxygen-dependent mitochondrial respiration. Percutaneous tissue oxygen saturation (SaO₂) measurements taken from the hind paw of the CPIP rats revealed that anti-allodynic doses of topical pentx-pca increased local tissue SaO₂. Moreover, assessment of the oxygen-dependent mitochondrial function using a triphenyl tetrazolium chloride assay revealed that mitochondrial dysfunction significantly declined in the plantar muscle collected from CPIP rats topically treated with anti-allodynic doses of pentx-pca as compared to vehicle-treated CPIP rats. Furthermore, time-dependent resolution of plantar muscle mitochondrial dysfunction, that occurred in the CPIP rats at 6-week post procedure, paralleled the loss of the anti-allodynic response to topical treatment with pentx-pca. Our results indicated that pentx-pca produced potent anti-allodynic effects in the CPIP rat model of CRPS by alleviating peripheral tissue ischemia/hypoxia and downstream hypoxia-driven mitochondrial dysfunction.

Protocol for the Stimulating β3-Adrenergic Receptors for Peripheral Artery Disease (STAR-PAD) trial: a double-blinded, randomised, placebo-controlled study evaluating the effects of mirabegron on functional performance in patients with peripheral arterial disease

INTRODUCTION

There is currently only one approved medication effective at improving walking distance in people with intermittent claudication. Preclinical data suggest that the β₃-adrenergic receptor agonist (mirabegron) could be repurposed to treat intermittent claudication associated with peripheral artery disease. The aim of the Stimulating β₃-Adrenergic Receptors for Peripheral Artery Disease (STAR-PAD) trial is to test whether mirabegron improves walking distance in people with intermittent claudication.

METHODS AND ANALYSIS

The STAR-PAD trial is a Phase II, multicentre, double-blind, randomised, placebo-controlled trial of mirabegron versus placebo on walking distance in patients with PAD. A total of 120 patients aged ≥40 years with stable PAD and intermittent claudication will be randomly assigned (1:1 ratio) to receive either mirabegron (50 mg orally once a day) or matched placebo, for 12 weeks. The primary endpoint is change in peak walking distance as assessed by a graded treadmill test. Secondary endpoints will include: (i) initial claudication distance; (ii) average daily step count and total step count and (iii) functional status and quality of life assessment. Mechanistic substudies will examine potential effects of mirabegron on vascular function, including brachial artery flow-mediate dilatation; MRI assessment of lower limb blood flow, tissue perfusion and arterial stiffness and numbers and angiogenesis potential of endothelial progenitor cells. Given that mirabegron is safe and clinically available for alternative purposes, a positive study is positioned to immediately impact patient care.

ETHICS AND DISSEMINATION

The STAR-PAD trial is approved by the Northern Sydney Local Health District Human Research Ethics Committee (HREC/18/HAWKE/50). The study results will be published in peer-reviewed medical or scientific journals and presented at scientific meetings, regardless of the study outcomes.

TRIAL REGISTRATION NUMBER

ACTRN12619000423112; Results.

Phytochemicals as Therapeutic Interventions in Peripheral Artery Disease

Peripheral artery disease (PAD) affects over 200 million people worldwide, resulting in significant morbidity and mortality, yet treatment options remain limited. Among the manifestations of PAD is a severe functional disability and decline, which is thought to be the result of different pathophysiological mechanisms including oxidative stress, skeletal muscle pathology, and reduced nitric oxide bioavailability. Thus, compounds that target these mechanisms may have a therapeutic effect on walking performance in PAD patients. Phytochemicals produced by plants have been widely studied for their potential health effects and role in various diseases including cardiovascular disease and cancer. In this review, we focus on PAD and discuss the evidence related to the clinical utility of different phytochemicals. We discuss phytochemical research in preclinical models of PAD, and we highlight the results of the available clinical trials that have assessed the effects of these compounds on PAD patient functional outcomes.

β 3 Adrenergic Receptor Stimulation Promotes Reperfusion in Ischemic Limbs in a Murine Diabetic Model

Aims/Hypothesis: Peripheral arterial disease (PAD) is a major burden, resulting in limb claudication, repeated surgical interventions and amputation. There is an unmet need for improved medical management of PAD that improves quality of life, maintains activities of daily life and reduces complications. Nitric oxide (NO)/redox balance is a key regulator of angiogenesis. We have previously shown beneficial effects of a β₃ adrenergic receptor (β₃AR) agonist on NO/redox balance. We hypothesized that β₃AR stimulation would have therapeutic potential in PAD by promoting limb angiogenesis.

Methods: The effect of the β₃AR agonist CL 316,243 (1–1,000 nmol/L in vitro, 1 mg/kg/day s. c) was tested in established angiogenesis assays with human endothelial cells and patient-derived endothelial colony forming cells. Post-ischemia reperfusion was determined in streptozotocin and/or high fat diet-induced diabetic and non-diabetic mice in vivo using the hind limb ischemia model.

Results: CL 316,243 caused accelerated recovery from hind limb ischemia in non-diabetic and type 1 and 2 diabetic mice. Increased eNOS activity and decreased superoxide generation were detected in hind limb ischemia calf muscle from CL 316, 243 treated mice vs. controls. The protective effect of CL 316,243 in diabetic mice was associated with >50% decreases in eNOS glutathionylation and nitrotyrosine levels. The β₃AR agonist directly promoted angiogenesis in endothelial cells in vitro. These pro-angiogenic effects were β₃AR and NOS-dependent.

Conclusion/Interpretation:β₃AR stimulation increased angiogenesis in diabetic ischemic limbs, with demonstrable improvements in NO/redox balance and angiogenesis elicited by a selective agonist. The orally available β₃AR agonist, Mirabegron, used for overactive bladder syndrome, makes translation to a clinical trial by repurposing of a β₃AR agonist to target PAD immediately feasible.

PIMD: An Integrative Approach for Drug Repositioning Using Multiple Characterization Fusion

The accumulation of various types of drug informatics data and computational approaches for drug repositioning can accelerate pharmaceutical research and development. However, the integration of multi-dimensional drug data for precision repositioning remains a pressing challenge. Here, we propose a systematic framework named PIMD to predict drug therapeutic properties by integrating multi-dimensional data for drug repositioning. In PIMD, drug similarity networks (DSNs) based on chemical, pharmacological, and clinical data are fused into an integrated DSN (iDSN) composed of many clusters. Rather than simple fusion, PIMD offers a systematic way to annotate clusters. Unexpected drugs within clusters and drug pairs with a high iDSN similarity score are therefore identified to predict novel therapeutic uses. PIMD provides new insights into the universality, individuality, and complementarity of different drug properties by evaluating the contribution of each property data. To test the performance of PIMD, we use chemical, pharmacological, and clinical properties to generate an iDSN. Analyses of the contributions of each drug property indicate that this iDSN was driven by all data types and performs better than other DSNs. Within the top 20 recommended drug pairs, 7 drugs have been reported to be repurposed. The source code for PIMD is available at https://github.com/Sepstar/PIMD/.

Pentoxifylline for intermittent claudication

BACKGROUND

Intermittent claudication (IC) is a symptom of peripheral arterial disease (PAD) and is associated with high morbidity and mortality. Pentoxifylline, one of many drugs used to treat IC, acts by decreasing blood viscosity, improving erythrocyte flexibility, and promoting microcirculatory flow and tissue oxygen concentration. Many studies have evaluated the efficacy of pentoxifylline in treating people with PAD, but results of these studies are variable. This is the second update of a review first published in 2012.

OBJECTIVES

To determine the efficacy of pentoxifylline in improving the walking capacity (i.e. pain-free walking distance and total (absolute, maximum) walking distance) of people with stable intermittent claudication, Fontaine stage II.

SEARCH METHODS

For this update, the Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases, and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 28 January 2020. There were no language restrictions.

SELECTION CRITERIA

We included all double-blind, randomised controlled trials (RCTs) comparing pentoxifylline versus placebo or any other pharmacological intervention in people with IC Fontaine stage II.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion, assessed the included studies, matched data and resolved disagreements by discussion. Review authors assessed the methodological quality of studies using the Cochrane 'Risk of bias' tool and collected results related to the outcomes of interest, pain-free walking distance (PFWD), total walking distance (TWD), ankle-brachial pressure index (ABI), quality of life (QoL) and side effects. Comparison of studies was based on duration and dose of pentoxifylline. We used GRADE criteria to assess the certainty of the evidence.

MAIN RESULTS

We identified no new eligible studies for this update. This review includes 24 studies with 3377 participants. Seventeen studies compared pentoxifylline versus placebo. The seven remaining studies compared pentoxifylline with flunarizine (one study), aspirin (one study), Gingko biloba extract (one study), nylidrin hydrochloride (one study), prostaglandin E1 (two studies), and buflomedil and nifedipine (one study). Risk of bias for the individual studies was generally unclear because there was a lack of methodological reporting for many of the included studies, especially regarding randomisation and allocation methods. Most included studies did not provide adequate information to allow selective reporting to be judged and did not report blinding of assessors. Heterogeneity between included studies was considerable with regards to multiple variables, including duration of treatment, dose of pentoxifylline, baseline walking distance and participant characteristics; therefore, pooled analysis for comparisons which included more than one study, was not possible. Pentoxifylline compared to placebo Of 17 studies comparing pentoxifylline with placebo, 11 reported PFWD and 14 reported TWD; the difference in percentage improvement in PFWD for pentoxifylline over placebo ranged from -33.8% to 73.9% and in TWD ranged from 1.2% to 155.9%. It was not possible to pool the data of the studies because data were insufficient and findings from individual trials were unclear. Most included studies suggested a possible improvement in PFWD and TWD for pentoxifylline over placebo (both low-certainty evidence). The five studies which evaluated pre-exercise ABI comparing pentoxifylline and placebo found no evidence of a difference (moderate-certainty evidence). Two of the three studies that evaluated QoL between people who received pentoxifylline and placebo were larger studies that used validated QoL tools and generally found no evidence of a difference between groups. One small, short-term study, which did not specify which QoL tool was used, reported improved QoL in the pentoxifylline group (moderate-certainty evidence). Pentoxifylline generally was well tolerated; the most commonly reported side effects consisted of gastrointestinal symptoms such as nausea (low-certainty evidence). Certainty of the evidence from this review was low or moderate, with downgrading due to risk of bias concerns, inconsistencies between studies and the inability to evaluate imprecision because meta-analysis could not be undertaken. The seven remaining studies compared pentoxifylline with either flunarizine, aspirin, Gingko biloba extract, nylidrin hydrochloride, prostaglandin E1, or buflomedil and nifedipine; data were too limited to allow any meaningful conclusions to be made.

AUTHORS' CONCLUSIONS

There is a lack of high-certainty evidence for the effects of pentoxifylline compared to placebo, or other treatments, for IC. There is low-certainty evidence that pentoxifylline may improve PFWD and TWD compared to placebo, but no evidence of a benefit to ABI or QoL (moderate-certainty evidence). Pentoxifylline was reported to be generally well tolerated (low-certainty evidence). Given the large degree of heterogeneity between the studies, the role of pentoxifylline for people with IC Fontaine class II remains uncertain.

Asia-Pacific Consensus Statement on the Management of Peripheral Artery Disease: A Report from the Asian Pacific Society of Atherosclerosis and Vascular Disease Asia-Pacific Peripheral Artery Disease Consensus Statement Project Committee

BACKGROUND

Peripheral artery disease (PAD) is the most underdiagnosed, underestimated and undertreated of the atherosclerotic vascular diseases despite its poor prognosis. There may be racial or contextual differences in the Asia-Pacific region as to epidemiology, availability of diagnostic and therapeutic modalities, and even patient treatment response. The Asian Pacific Society of Atherosclerosis and Vascular Diseases (APSAVD) thus coordinated the development of an Asia-Pacific Consensus Statement (APCS) on the Management of PAD.

OBJECTIVES

The APSAVD aimed to accomplish the following: 1) determine the applicability of the 2016 AHA/ACC guidelines on the Management of Patients with Lower Extremity Peripheral Artery Disease to the Asia-Pacific region; 2) review Asia-Pacific literature; and 3) increase the awareness of PAD.

METHODOLOGY

A Steering Committee was organized to oversee development of the APCS, appoint a Technical Working Group (TWG) and Consensus Panel (CP). The TWG appraised the relevance of the 2016 AHA/ACC PAD Guideline and proposed recommendations which were reviewed by the CP using a modified Delphi technique.

RESULTS

A total of 91 recommendations were generated covering history and physical examination, diagnosis, and treatment of PAD-3 new recommendations, 31 adaptations and 57 adopted statements. This Asia-Pacific Consensus Statement on the Management of PAD constitutes the first for the Asia-Pacific Region. It is intended for use by health practitioners involved in preventing, diagnosing and treating patients with PAD and ultimately the patients and their families themselves.

Diagnosis and Management of Peripheral Artery Diseases

Распространенность заболеваний периферических артерий (ЗПА) во всем мире достигает порядка 200 миллионов человек. Самым частым клиническим проявлением ЗПА является перемежающая хромота, возникающая вследствие недостаточного кровоснабжения пораженной конечности. В настоящем обзоре литературы обобщены и систематизированы последние достижения в области диагностики и лечения пациентов с перемежающей хромотой. Тщательный сбор анамнеза и физикальное обследование являются первоочередными мероприятиями для установления предварительного диагноза и направлены на дифференциацию сосудистых и нейрогенных причин перемежающей хромоты. Лодыжечно-плечевой индекс относится к наиболее часто используемым методам скрининга и диагностики ЗПА. Основу лечения составляют четыре взаимодополняющих подхода: немедикаментозное и лекарственное лечение для купирования симптомов хронической ишемии, фармакотерапия для вторичной профилактики сердечно-сосудистых осложнений, открытая или эндоваскулярная реваскуляризация для увеличения дистанции безболевой ходьбы. Недавнее исследование COMPASS продемонстрировало преимущества комбинированного применения 2,5 мг ривароксабана дважды в день и аспирина в части снижения уровня неблагоприятных сердечно-сосудистых событий, при этом отмечался более высокий риск геморрагических осложнений. На сегодняшний день цилостазол является единственным препаратом, обладающим доказанной терапевтической эффективностью в отношении перемежающей хромоты. Программы лечебной физкультуры под наблюдением врача либо в домашних условиях способствуют улучшению коллатерального кровообращения и увеличивают дистанцию ходьбы без боли. Назначение высоких доз статинов и антитромбоцитарных препаратов абсолютно обосновано всем пациентам с ЗПА. Ингибиторы ангиотензин-превращающего фермента обеспечивают дополнительное снижение кардиоваскулярных рисков, в особенности у пациентов с сахарным диабетом и артериальной гипертензией.

The prevalence of peripheral artery disease (PAD) worldwide reaches about 200 million people. The most frequent clinical manifestation of PAD is intermittent claudication, which occurs due to insufficient blood supply to the affected limb. This literature review summarizes and systematizes recent advances in the diagnosis and treatment of patients with intermittent claudication.Thorough case history collection and physical examination are the primary measures for making a preliminary diagnosis, which is aimed at differentiating the vascular and neurogenic causes of intermittent claudication. The ankle-shoulder index is one of the most commonly used methods for screening and diagnosing PAD. The basis of treatment consists of four complementary approaches: non-pharmacological and pharmacological treatment for the relief of symptoms of chronic ischemia, pharmacotherapy for the secondary prevention of cardiovascular complications, open or endovascular revascularization to increase the distance of pain-free walking. A recent COMPASS study demonstrated the benefits of combining 2.5 mg of rivaroxaban twice daily with aspirin in reducing adverse cardiovascular events, however there was a higher risk of hemorrhagic complications. Today, cilostazol is the only drug with proven therapeutic effectiveness against intermittent claudication. Physical therapy programs under the supervision of a doctor or at home help to improve collateral blood circulation and increase the walking distance without pain. The administration of high doses of statins and antiplatelet drugs is absolutely justified in all patients with PAD. Angiotensin converting enzyme inhibitors provide an additional reduction in cardiovascular risks, especially in patients with diabetes and hypertension.

The Nitric Oxide System in Peripheral Artery Disease: Connection with Oxidative Stress and Biopterins

Peripheral artery disease (PAD) pathophysiology extends beyond hemodynamics to include other operating mechanisms, including endothelial dysfunction. Oxidative stress may be linked to endothelial dysfunction by reducing nitric oxide (NO) bioavailability. We aimed to investigate whether the NO system and its regulators are altered in the setting of PAD and to assess the relationship between NO bioavailability and oxidative stress. Sera from 35 patients with intermittent claudication (IC), 26 patients with critical limb ischemia (CLI), and 35 non-PAD controls were analyzed to determine levels of tetrahydrobiopterin (BH4), dihydrobiopterin (BH2), nitrate/nitrite (nitric oxides, or NOx), arginine, citrulline, asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), and the oxidative stress markers 8-Oxo-2′-deoxyguanosine (8-OHdG), 4-hydroxynonenal (4-HNE), advanced glycation end products (AGEs), and protein carbonyls. NOx was significantly lower in IC and CLI patients compared to controls in association with elevated oxidative stress, with the greatest NOx reductions observed in CLI. Compared with controls, IC and CLI patients had reduced BH4, elevated BH2, and a reduced BH4/BH2 ratio. SDMA, the arginine/SDMA ratio, and the arginine/ADMA ratio were significantly higher in CLI patients. The NO system and its regulators are significantly compromised in PAD. This dysregulation appears to be driven by increased oxidative stress and worsens as the disease progresses from claudication to CLI.

Systemic administration of pentoxifylline attenuates the development of hypertension in renovascular hypertensive rats

There is evidence to suggest that hypertension involves a chronic low-grade systemic inflammatory response; however, the underlying mechanisms are unclear. To further understand the role of inflammation in hypertension, we used a rat renovascular model of hypertension in which we administered the TNF-α synthesis inhibitor pentoxifylline (PTX, 30 mg/kg/day) in the drinking water for 60 days. In conscious rats, PTX administration significantly attenuated the development of hypertension (systolic blood pressure, PTX: 145 ± 8 vs. vehicle (Veh): 235 ± 11 mmHg, after 38 days of treatment, P < 0.05, N = 5/group). This attenuation in hypertension was coupled with a decrease in the low-frequency spectra of systolic blood pressure variability (PTX: 1.23 ± 0.2 vs Veh: 3.05 ± 0.8 arbitrary units, P < 0.05, N = 5/group). Furthermore, systemic PTX administration decreased c-Fos expression within the hypothalamic paraventricular nucleus (PTX: 17 ± 4 vs. Veh: 70 ± 13 cells, P < 0.01, N = 5, PVN) and increased the total number of microglial branches (PTX: 2129 ± 242 vs. Veh: 1415 ± 227 branches, P < 0.05, N = 4/group). Acute central injection of PTX (20 μg) under urethane anesthesia caused a small transient decrease in blood pressure but did not change renal sympathetic nerve activity. Surprisingly, we found no detectable basal levels of plasma TNF-α in either PTX- or vehicle-treated animals. These results suggest that inflammation plays a role in renovascular hypertension and that PTX might act both peripherally and centrally to prevent hypertension.

How To Assess a Claudication and When To Intervene

PURPOSE OF THE REVIEW

Peripheral artery disease (PAD) affects close to 200 million people worldwide. Claudication is the most common presenting symptom for patients with PAD. This review summarizes the current diagnostic and treatment options for patients with claudication. Comprehensive history and physical examination in order to differentiate between claudication secondary to vascular disease vs. neurogenic causes is paramount for initial diagnosis. Ankle-brachial index is the most commonly used test for screening and diagnostic purposes. Treatment consists of four different approaches, which are best utilized in combination: non-pharmacological treatment for claudication improvement, pharmacological treatment for claudication improvement, pharmacological treatment for secondary risk reduction, and interventional treatment for claudication improvement.

RECENT FINDINGS

Cilostazol is the only Food and Drug Administration (FDA)-approved agent for symptomatic treatment of claudication. Supervised exercise programs provide the maximum benefit for claudication improvement, but home-based exercise programs are an alternative. High-intensity statins and an antiplatelet agent should be prescribed to all patients with PAD. Angiotensin-converting-enzyme inhibitors can provide additional risk reduction, especially in patients with diabetes or hypertension. Rivaroxaban of low dosage (2.5 mg twice daily) in combination with aspirin further decreases cardiovascular risk, but this reduction comes at the cost of higher bleeding risk. Peripheral artery disease (PAD) is a form of atherosclerotic disease that affects hundreds of millions of people worldwide-one of its most common manifestations is intermittent claudication (IC), which results from insufficient blood flow to meet the metabolic demands of an affected extremity. This paper reviews the current literature regarding the workup, diagnosis, diagnostic modalities, treatment options, and management of intermittent claudication.

Pentoxifylline versus Steroid Therapy for Idiopathic Sudden Sensorineural Hearing Loss with Diabetes

OBJECTIVES

To compare the efficacy of pentoxifylline with that of conventional steroid therapy in diabetic patients with idiopathic sudden sensorineural hearing loss (ISSNHL) and to compare blood sugar levels during hospitalization.

MATERIALS AND METHODS

Medical charts were retrospectively reviewed for all diabetic patients admitted to one institution for ISSNHL between 2000 and 2015. We analyzed 298 cases; 50 patients received pulse steroid treatment (steroid group) and 248 received intravenous administration of pentoxifylline only (pentoxifylline group). Hearing change was evaluated by comparing the initial hearing tests with follow-up hearing tests for up to 3 months. Blood sugar levels were also compared between the 2 groups.

RESULTS

At 3 months post-treatment, the degree of hearing recovery was similar between the 2 groups. The pure-tone average was improved from baseline by 17.9±21.2 dB in the steroid group and 18.9±20.7 dB in the pentoxifylline group (p=0.776); hearing recovery rates were also similar (40% vs 39.1%; p=0.826). During hospitalization, average fasting blood sugar levels were higher (203.9±92.0 vs 174.4±54.8 mg/dL; p=0.033) and acute hyperglycemia was more common (48.0% vs 33.1%; p=0.044) with steroid versus pentoxifylline treatment.

CONCLUSION

Hearing recovery rates did not significantly differ between steroid and pentoxifylline treatment in diabetic patients with ISSNHL, but pentoxifylline appeared to be associated with better blood sugar control.

A Small Group Randomized Double-Blind Placebo-Controlled Study to Evaluate the Efficacy of Daily Pentoxifylline in the Management of Patients With Erectile Dysfunction with Suboptimal Treatment Response to Sildenafil

Introduction

Several studies have reaffirmed the use of regular pentoxifylline therapy in increasing the penile brachial pressure index in men affected by erectile dysfunction when compared to placebo.

Aim

The aim of this study was to evaluate the efficacy of pentoxifylline as an adjunctive treatment for patients with erectile dysfunction.

Methods

This study was a single center, prospective, randomized, double-blind, placebo-controlled trial. Subjects were recruited between April 2014 and November 2016 from the National University Hospital, Singapore. The combination therapy group was given pentoxifylline 400 mg thrice daily orally and the monotherapy group was given placebo capsules thrice daily orally. Both groups continued their on-demand 100 mg sildenafil. The treatment duration was 8 weeks. Efficacy was measured via the International Index of Erectile Function (IIEF-5) questionnaire at the eighth week. Differences in mean IIEF-5 score and the domains of the IIEF at 8 weeks between the 2 treatment groups were compared using independent sample t-test.

Main Outcome Measure

Baseline IIEF-5 and the IIEF-15 score vs post-therapy IIEF-5 and the IIEF-15 score.

Results

50 patients were randomized into 2 groups. Patients in the 2 groups were comparable in terms of the demographic and clinical characteristics, comorbidities, and baseline IIEF-5 scores. The mean IIEF-5 score post-therapy of the combination therapy group vs the monotherapy group was 14.11 and 14.87, respectively. There was no significant difference between the outcomes of these 2 groups (unadjusted mean difference -0.76; 95% CI -4.01 to 2.49; P = .641) and the outcomes are the same even after adjusting for baseline IIEF-5 scores. There was a significant improvement in the “overall satisfaction” portion of the IIEF score for the combination therapy group as compared to the monotherapy group (unadjusted mean difference 0.12; 95% CI -1.49 to 1.25) and even after adjustment for baseline scores (adjusted mean difference 1.11; 95% CI 0.10 to 2.12; P = .032) the improvement is significant.

Conclusion

Our trial suggests that the use of combination therapy does not improve the management of patients compared to monotherapy.

Law YXT, Tai BC, Tan YQ et al. A Small Group Randomized Double-Blind Placebo-Controlled Study to Evaluate the Efficacy of Daily Pentoxifylline in the Management of Patients With Erectile Dysfunction with Suboptimal Treatment Response to Sildenafil. Sex Med 2019;8:14–20.

[Conservative treatment of chronic lower limb ischemia in ambulatory practice (in Russian only)]

Peripheral artery disease is still one of the most important surgical problems. General surgeons treat the majority of patients with chronic lower limb ischemia due to the lack of specialized surgical care. Current methods for risk factors adjustment, exercise therapy and the most common drugs for intermittent claudication management are reviewed in the article. The effect of these medicines on subjective (pain-free walking distance, maximal walking distance, etc.) and objective (ankle-brachial index) parameters and the incidence of complications are analyzed.

Growth factors for angiogenesis in peripheral arterial disease

BACKGROUND

Peripheral artery disease (PAD) is associated with a high clinical and socioeconomic burden. Treatments to alleviate the symptoms of PAD and decrease the risks of amputation and death are a high societal priority. A number of growth factors have shown a potential to stimulate angiogenesis. Growth factors delivered directly (as recombinant proteins), or indirectly (e.g. by viral vectors or DNA plasmids encoding these factors), have emerged as a promising strategy to treat patients with PAD.

OBJECTIVES

To assess the effects of growth factors that promote angiogenesis for treating people with PAD of the lower extremities.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Specialised Register (June 2016) and CENTRAL (2016, Issue 5). We searched trial registries for details of ongoing or unpublished studies. We also checked the reference lists of relevant publications and, if necessary, tried to contact the trialists for details of the studies.

SELECTION CRITERIA

We included randomised controlled trials comparing growth factors (delivered directly or indirectly) with no intervention, placebo or any other intervention not based on the growth factor's action in patients with PAD of the lower extremities. The primary outcomes were limb amputation, death and adverse events. The secondary outcomes comprised walking ability, haemodynamic measures, ulceration and rest pain.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials and assessed the risk of bias. We used outcomes of the studies at low risk of bias for the main analysis and of all studies in the sensitivity analyses. We calculated odds ratios (OR) for dichotomous outcomes and mean differences for continuous outcomes with 95% confidence intervals (CI). We evaluated statistical heterogeneity using the I2 statistic and Cochrane's Q test. We conducted meta-analysis for the overall effect and for each growth factor as a subgroup analysis using OR in a fixed-effect model. We evaluated the robustness of the results in a sensitivity analysis using risk ratio (RR) and/or a random-effects model. We also assessed the quality of the evidence for each outcome.

MAIN RESULTS

We included 20 trials in the review and used 14 studies (on approximately 1400 participants) with published results in the analyses. Six published studies compared fibroblast growth factors (FGF), four studies hepatocyte growth factors (HGF) and another four studies vascular endothelial growth factors (VEGF), versus placebo or no therapy. Six of these studies exclusively or mainly investigated participants with intermittent claudication and eight studies exclusively participants with critical limb ischaemia. Follow-up generally ranged from three months to one year. Two small studies provided some data at 2 years and one of them also at 10 years.The direction and size of effects for growth factors on major limb amputations (OR 0.99, 95% CI 0.71 to 1.38; 10 studies, N = 1075) and death (OR 0.99, 95% CI 0.69 to 1.41; 12 studies, N = 1371) at up to two years are uncertain. The quality of the evidence is low due to risk of bias and imprecision (at one year, moderate-quality evidence due to imprecision). However, growth factors may decrease the rate of any limb amputations (OR 0.56, 95% CI 0.31 to 0.99; 6 studies, N = 415). The quality of the evidence is low due to risk of bias and selective reporting.The direction and size of effects for growth factors on serious adverse events (OR 1.09, 95% CI 0.79 to 1.50; 13 studies, N = 1411) and on any adverse events (OR 1.10, 95% CI 0.73 to 1.64; 4 studies, N = 709) at up to two years are also uncertain. The quality of the evidence is low due to risk of bias and imprecision (for serious adverse events at one year, moderate-quality evidence due to imprecision).Growth factors may improve haemodynamic measures (low-quality evidence), ulceration (very low-quality evidence) and rest pain (very low-quality evidence) up to one year, but they have little or no effect on walking ability (low-quality evidence). We did not identify any relevant differences in effects between growth factors (FGF, HGF and VEGF).

AUTHORS' CONCLUSIONS

The results of this review do not support the use of therapy with the growth factors FGF, HGF or VEGF in people with PAD of the lower extremities to prevent death or major limb amputation or to improve walking ability. However, the use of these growth factors may improve haemodynamic measures and decrease the rate of any limb amputations (probably due to preventing minor amputations) with an uncertain effect on adverse events; an improvement of ulceration and rest pain is very uncertain. New trials at low risk of bias are needed to generate evidence with more certainty.

Pentoxifylline inhibits pulmonary inflammation induced by infrarenal aorticcross-clamping dependent of adenosine receptor A2A

Infrarenal aortic cross-clamping (IAC) is commonly used during infrarenal vascular operations. Prolonged IAC causes ischemia-reperfusion injury to local tissues, resulting in the release of inflammatory cytokines and acute lung injury (ALI). Pentoxifylline (PTX) is a clinically used drug for chronic occlusive arterial diseases and exerts protective effects against ALI induced by various factors in experimental models. In this study, we evaluated the protective effects of PTX in a rat model of IAC. Wistar rats underwent IAC for 2 h, followed by 4 h reperfusion. PTX alone, or in combination with ZM-241385 (an adenosine receptor A2A antagonist) or CGS-21680 (an A2A agonist), was pre-administered to rats 1 h prior to IAC, and the severity of lung injury and inflammation were examined. Administration of PTX significantly attenuated ALI induced by IAC, evidenced by reduced histological scores and wet lung contents, improved blood gas parameters, decreased cell counts and protein amounts in bronchoalveolar lavage fluids, and inhibition of MPO activity and ICAM-1 expression in lung tissues, and lower plasma levels of TNF-α, IL-6, IL-1β and soluble ICAM-1. ZM-241385 significantly abrogated, while CGS-21680 slightly enhanced, the effects of PTX in ameliorating ALI and inhibiting pulmonary inflammation. In exploration of the mechanisms, we found that PTX stimulated IL-10 production through the phosphorylation of STAT3, and A2A receptor participated in this regulation. The study indicates PTX plays a protective role in IAC-induced ALI in rats by inhibiting pulmonary inflammation through A2A signaling pathways.