Cilostazol: treatment of intermittent claudication

In Vitro/In Vivo Correlation of Two Extended-Release Cilostazol Formulations

This study aims to evaluate and determine the correlation between in vitro release and in vivo pharmacokinetics of two extended-release dosage forms of Cilostazol. In vitro release profiles for two dosage forms, tablet and capsule, were analyzed under physiologically mimicked medium conditions using the paddle and basket USP release apparatus. A single-dose, two-period crossover study design in beagle dogs was applied for the pharmacokinetic study. The fed and fast effects were considered for evaluation. Pseudo gastric release medium transfer setup study from pH 1.2 to pH 6.8 (+0.5% SLS) and pH 1.2 to pH 6.8 (+1.0% SLS) demonstrated that Pletaal® SR 200 mg capsules have higher drug release rates than Cilostan® CR 200 mg tablets. Similarly, in vivo study showed Cilostazol concentration in plasma and AUC was lower under the fast state than the fed state. The ratio of least squared geometric mean values, Cmax, AUC0-t, and AUC0-inf of Cilostazol were 2.53-fold, 2.89-fold, and 2.87-fold higher for Pletaal® SR 200 mg capsules compared with Cilostan® CR 200 mg tablets, respectively. Correlation of in vitro/in vivo data indicated that Pletal® SR 200 mg capsules have better release and pharmacodynamic effect than Cilostan® CR 200 mg tablets.

Lifestyle Approach and Medical Therapy of Lower Extremity Peripheral Artery Disease

Lower extremity peripheral artery disease (PAD) is common among patients with several risk factors, such as elderly, smoking, hypertension, and diabetes mellitus. Notably, PAD is associated with a higher risk of cardiovascular complications. Non-invasive interventions are beneficial to improve morbidity and mortality among patients with PAD. Traditional risk factors like smoking, diabetes mellitus, hypertension, and dyslipidemia play a significant role in the development of PAD. Still, additional factors such as mental health, glycemic control, diet, exercise, obesity management, lipid-lowering therapy, and antiplatelet therapy have emerged as important considerations. Managing these factors can help improve outcomes and reduce complications in PAD patients. Antiplatelet therapy with aspirin or clopidogrel is recommended in PAD patients, with clopidogrel showing more significant benefits in symptomatic PAD individuals. Managing several risk factors is crucial for improving outcomes and reducing complications in patients with PAD. Further research is also needed to explore the potential benefits of novel therapies. Ultimately, a comprehensive approach to PAD management is essential for improving morbidity and mortality among patients with this condition.

The anti-platelet drug cilostazol enhances heart rate and interrenal steroidogenesis and exerts a scant effect on innate immune responses in zebrafish

RATIONALE

Cilostazol, an anti-platelet phosphodiesterase-3 inhibitor used for the treatment of intermittent claudication, is known for its pleiotropic effects on platelets, endothelial cells and smooth muscle cells. However, how cilostazol impacts the endocrine system and the injury-induced inflammatory processes remains unclear.

METHODS

We used the zebrafish, a simple transparent model that demonstrates rapid development and a strong regenerative ability, to test whether cilostazol influences heart rate, steroidogenesis, and the temporal and dosage effects of cilostazol on innate immune cells during tissue damage and repair.

RESULTS

While dosages of cilostazol from 10 to 100 μM did not induce any noticeable morphological abnormality in the embryonic and larval zebrafish, the heart rate was increased as measured by ImageJ TSA method. Moreover, adrenal/interrenal steroidogenesis in larval zebrafish, analyzed by whole-mount 3β-Hsd enzymatic activity and cortisol ELISA assays, was significantly enhanced. During embryonic fin amputation and regeneration, cilostazol treatments led to a subtle yet significant effect on reducing the aggregation of Mpx-expressing neutrophil at the lesion site, but did not affect the immediate injury-induced recruitment and retention of Mpeg1-expressing macrophages.

CONCLUSIONS

Our results indicate that cilostazol has a significant effect on the heart rate and the growth as well as endocrine function of steroidogenic tissue; with a limited effect on the migration of innate immune cells during tissue damage and repair.

Dual Antiplatelet Therapy: A Concise Review for Clinicians

Dual antiplatelet therapy (DAPT) combines two antiplatelet agents to decrease the risk of thrombotic complications associated with atherosclerotic cardiovascular diseases. Emerging data about the duration of DAPT is being published continuously. New approaches are trying to balance the time, benefits, and risks for patients taking DAPT for established cardiovascular diseases. Short-term dual DAPT of 3-6 months, or even 1 month in high-bleeding risk patients, is equivalent in terms of efficacy and effectiveness compared to long-term DAPT for patients who experienced percutaneous coronary intervention in an acute coronary syndrome setting. Prolonged DAPT beyond 12 months reduces stent thrombosis, major adverse cardiovascular events, and myocardial infarction rates but increases bleeding risk. Extended DAPT does not significantly benefit stable coronary artery disease patients in reducing stroke, myocardial infarction, or cardiovascular death. Ticagrelor and aspirin reduce cardiovascular events in stable coronary artery disease with diabetes but carry a higher bleeding risk. Antiplatelet therapy duration in atrial fibrillation patients after percutaneous coronary intervention depends on individual characteristics and bleeding risk. Antiplatelet therapy is crucial for post-coronary artery bypass graft and transcatheter aortic valve implantation; Aspirin (ASA) monotherapy is preferred. Antiplatelet therapy duration in peripheral artery disease depends on the scenario. Adding vorapaxar and cilostazol may benefit secondary prevention and claudication, respectively. Carotid artery disease patients with transient ischemic attack or stroke benefit from antiplatelet therapy and combining ASA and clopidogrel is more effective than ASA alone. The optimal duration of DAPT after carotid artery stenting is uncertain. Resistance to ASA and clopidogrel poses an incremental risk of deleterious cardiovascular events and stroke. The selection and duration of antiplatelet therapy in patients with cardiovascular disease requires careful consideration of both efficacy and safety outcomes. The use of combination therapies may provide added benefits but should be weighed against the risk of bleeding. Further research and clinical trials are needed to optimize antiplatelet treatment in different patient populations and clinical scenarios.

Peripheral arterial disease: A small and large vessel problem

Peripheral arterial disease (PAD) is one clinical manifestation of systemic atherosclerosis and is very common. Despite its prevalence, PAD remains underdiagnosed, undertreated, and understudied. The most common symptom in patients with PAD is intermittent claudication (IC), or pain in the lower extremities with walking or exertion, which is relieved after a short period of rest. Many patients with confirmed PAD are asymptomatic or have symptoms other than IC. Regardless of symptoms, patients with PAD have poor cardiovascular outcomes. PAD has largely been viewed a disease of large vessel atherosclerosis but what is becoming clear is that arterial plaques and occlusions are only one piece of the puzzle. Recent work has shown that abnormalities in the microvasculature contribute to the outcome of patients with PAD. From the perspective of the leg, limitation in blood flow is not the only problem as patients have a myriad of other problems, including muscle fibrosis, neuropathic changes, changes in the cellular respiration machinery and dysfunction of the small vessels that perfuse skeletal muscle and the supporting structures. Supervised exercise training remains one of the most effective tool to treat patients with PAD, however, the mechanisms behind its effectiveness are still being elucidated and use of structured exercise programs is not widespread. Medical therapy to treat systemic atherosclerosis is underutilized in patients with PAD. Invasive therapies are used only when patients with PAD have reached an advanced stage. While invasive strategies are effective in some patients with PAD, these strategies are costly, carry risk, and many patients are not amenable to invasive therapy. Appreciating the complex pathophysiology of PAD will hopefully spur new research and development of effective therapies for PAD.

Do Patients With Arterial Occlusive Disease of Different Etiologies Benefit Equally From Cilostazol?

BACKGROUND

Cilostazol is a guideline-recommended drug that improves intermittent claudication and quality of life in patients with chronic atherosclerotic peripheral arterial disease. The drug is used for most etiologies of arterial occlusive diseases in clinical practice. This study aimed to evaluate whether patients benefit equally from cilostazol regardless of etiology.

METHODS

Patients on cilostazol were divided into 4 groups according to arterial occlusive disease etiology: (1) atherosclerosis, (2) diabetic angiopathy, (3) embolism/thrombosis, and (4) Buerger disease. Patients' maximum walking distance, ankle-brachial index score and distal tissue oxygen saturation (Sto2), clinical improvement onset time, ability to reach maximum benefit time, vascular surgeries, and wounds were compared before they started cilostazol and after 12 months. Results were evaluated at a statistical significance of P < .05.

RESULTS

In 194 patients, 307 target extremities were evaluated in the 4 disease groups. After cilostazol use, maximum walking distance, ankle-brachial index score, and distal Sto2 increased significantly in all groups (P < .001), but distal Sto2 in the diabetic angiopathy and Buerger disease groups was significantly lower than in the atherosclerosis group (P < .001). Ankle-brachial index and distal Sto2 differences in the Buerger disease group were significantly lower (both P < .001). The vascular surgery counts decreased significantly in the atherosclerosis and embolism/thrombosis groups (P = .019 and P = .004, respectively).

CONCLUSION

Patients with nonatherosclerotic arterial occlusive disease also benefit from cilostazol, but patients with Buerger disease or diabetic angiopathy seem to benefit less. Combining cilostazol with anticoagulant or antiaggregant agents and closer monitoring of these patients may produce better results.

Update on Cilostazol: A Critical Review of Its Antithrombotic and Cardiovascular Actions and Its Clinical Applications

Cilostazol, a phosphodiesterase III inhibitor, has vasodilating and antiplatelet properties with a low rate of bleeding complications. It has been used over the past 25 years for improving intermittent claudication in patients with peripheral artery disease (PAD). Cilostazol also has demonstrated efficacy in patients undergoing percutaneous revascularization procedures for both PAD and coronary artery disease. In addition to its antithrombotic and vasodilating actions, cilostazol also inhibits vascular smooth muscle cell proliferation via phosphodiesterase III inhibition, thus mitigating restenosis. Accumulated evidence has shown that cilostazol, due to its "pleiotropic" effects, is a useful, albeit underutilized, agent for both coronary artery disease and PAD. It is also potentially useful after ischemic stroke and is an alternative in those who are allergic or intolerant to classical antithrombotic agents (eg, aspirin or clopidogrel). These issues are herein reviewed together with the pharmacology and pharmacodynamics of cilostazol. Large studies and meta-analyses are presented and evaluated. Current guidelines are also discussed, and the spectrum of cilostazol's actions and therapeutic applications are illustrated.

K-134, a phosphodiesterase 3 inhibitor, reduces vascular inflammation and hypoxia, and prevents rupture of experimental abdominal aortic aneurysms

Objective

Abdominal aortic aneurysm (AAA) is a chronic inflammatory disease, which frequently results in fatal rupture; however, no pharmacologic treatment exists to inhibit AAA growth and prevent rupture. In this study, we investigated whether K-134, a novel phosphodiesterase 3 inhibitor, could limit the progression and rupture of AAA using multiple experimental models.

Methods

A hypoperfusion-induced AAA rat model was developed by inserting of a small catheter and via tight ligation of the infrarenal aorta. Rats were fed with a 0.15% K-134-containing diet (K-134(+) group) or a normal diet (K-134(-) group) from 7 days before the experiment to 28 days after model creation (pretreatment protocol). After the administration period, elastin fragmentation, macrophage infiltration, reactive oxygen species expression, matrix metalloproteinase levels, aneurysmal tissue hypoxia, and adventitial vasa vasorum (VV) stenosis were assessed. In the delayed treatment protocol, rats with AAA >3 mm were randomly divided to K-134(+) or K-134(-) group 7 days after model creation, and the effect of K-134 on suppressing preexisting AAA was examined. Further, elastase-induced rat model and angiotensin II-infused ApoE^-/- mouse model were also used to examine the ability of K-134 to prevent rupture.

Results

K-134 prevented AAA rupture and significantly improved survival in the pretreatment protocol (P < .01). In the K-134(+) group, elastin degeneration was prevented; macrophage infiltration and reactive oxygen species production were significantly decreased. At 14 days, the enzymatic activity of matrix metalloproteinase-9 was significantly decreased. Further, K-134 inhibited intimal hyperplasia and VV stenosis. Expressions of hypoxic markers, hypoxia-inducible factor-1α, and pimonidazole, in the aneurysmal wall were also attenuated. In the delayed treatment protocol, K-134 also improved survival of rats with preexisting AAA. Similarly, in the elastase-induced rat model and angiotensin II-infused ApoE^-/- mouse model, K-134 inhibited rupture and significantly improved survival (P < .01).

Conclusions

K-134 prevented the rupture of AAA and improved survival through suppressing inflammatory reaction. The inhibition of intimal hyperplasia in the adventitial VV may be associated with reduced hypoxia in the aneurysmal tissue. (JVS–Vascular Science 2020;1:219-32.)

Clinical Relevance

This study shows that K-134, a novel phosphodiesterase 3 inhibitor, suppressed abdominal aortic aneurysm (AAA) rupture. Considering that K-134 had already undergone a phase Ⅱ study in the United States for claudication in peripheral artery occlusive disease patients with good tolerance, K-134 may become a promising new therapeutic option for AAAs and could undergo clinical trials for patients with small AAA.

The Impact of Chronic Kidney Disease on Peripheral Artery Disease and Peripheral Revascularization

Chronic kidney disease (CKD) is a clinical condition characterized by high morbidity and mortality. Globally, CKD is also increasing in prevalence and incidence. The two principal kidney measures namely estimated glomerular filtration rate (eGFR) and albuminuria have been found to be predictors of renal and cardiovascular (CV) endpoints including peripheral artery disease (PAD). The prevalence of PAD was increased in CKD patients and, particularly, in patients with more severe CKD stages. Despite the fact that revascularization strategies are suitable in CKD patients in similar fashion to non-CKD patients, few CKD patients underwent these procedures. In fact, if it is true that revascularization improves prognosis in PAD patients irrespective of baseline eGFR, it was also demonstrated that CKD patients, who underwent revascularization, were at higher risk for amputations, mortality, re-intervention and perioperative complications. With the present review article, we have examined the association between CKD, PAD and peripheral revascularization highlighting data about epidemiology, pathophysiologic mechanisms, and results from previous observational and intervention studies. We have also examined the future perspectives and challenges of research around the association between CKD and PAD.

A new simple method for quantification of cilostazol and its active metabolite in human plasma by LC-MS/MS: Application to pharmacokinetics of cilostazol associated with CYP genotypes in healthy Chinese population

A simple, sensitive, and fully automated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous quantification of cilostazol (CIL) and its active metabolite, 3,4-dehydro cilostazol (CIL-M), in human plasma. Plasma samples were processed by protein precipitation in 2 mL 96-deep-well plates, and all liquid transfer steps were performed through robotic liquid handling workstation, enabling the whole procedure fast, compared to the reported methods. Separation of analytes was successfully achieved on a UPLC BEH C₁₈ column (2.1 × 100 mm, 1.7 μm) with mobile phase A (5 mM ammonium formate containing 0.1% formic acid) and mobile phase B (methanol) at a flow rate of 0.30 mL min^-1 . The total run time was 3.5 min per sample. Mass spectrometric detection was conducted by electrospray ion source in positive ion multiple reaction monitoring mode. Calibration curves were linear over the concentration range of 1.0-800 ng·mL^-1 for CIL and 0.05-400 ng·mL^-1 for CIL-M. The coefficient of variation for the assay's precision was 12.3%, and the accuracy was 88.8-99.8%. It was fully validated and successfully applied to assess the influence of CYP genotypes on the pharmacokinetics of CIL after oral administration of 50 mg tablet formulations of CIL to healthy Chinese volunteers. The results suggest that, in Chinese population, the genotype of CYP3A5 affects the plasma exposure of CIL.

Literature review and meta-analysis of the efficacy of cilostazol on limb salvage rates after infrainguinal endovascular and open revascularization

BACKGROUND

Current clinical guidelines recommend the use of cilostazol in the treatment of patients with infrainguinal peripheral artery disease (PAD) who experience intermittent claudication. However, the role of cilostazol therapy in patients with advanced PAD and critical limb ischemia (CLI) remains unclear. To conduct a meta-analysis of randomized controlled trials and cohort studies that evaluated the effect of cilostazol vs standard antiplatelet therapy on limb-related and arterial patency-related outcomes. We also reviewed literature pertinent to the effect of cilostazol on wound healing in patients with advanced PAD.

METHODS

We performed a MEDLINE, EMBASE, COCHRANE (CENTRAL), SCOPUS, and US Clinical Trials database search for all trials and studies since 1999 that compared cilostazol with standard antiplatelet therapy in the setting of infrainguinal PAD revascularization procedures (endovascular or open). Aggregate data was collected from four randomized control trials and six retrospective cohort studies. The end point incidence ratios and treatment effects were generated from each study and reported as hazard ratios (HR) using a random-effect model. We also reviewed 10 studies that evaluated the effect of cilostazol on wound healing in patients with advanced PAD.

RESULTS

From more than 25,000 total patients, 3136 patients met our inclusion criteria. All patients had at least lifestyle-impacting intermittent claudication, and more than 50% met the definition of CLI (Rutherford class ≥4). Patient age range was 53 to 83 years, and the majority were male (66%). The mean follow-up time averaged 2 years across all studies. Meta-analysis revealed that cilostazol treatment favored amputation-free survival (hazard ratio [HR], 0.79; 95% confidence interval [CI], 0.69-0.91), limb salvage rate (HR, 0.42; 95% CI, 0.27-0.66), decreased repeat revascularization (risk ratio [RR], 0.44; 95% CI, 0.37-0.52), and decreased restenosis (RR, 0.68; 95% CI, 0.61-0.76). Cilostazol treatment also increased freedom from target lesion revascularization (RR, 1.35; 95% CI, 1.21-1.53) with no difference in all-cause mortality. Effective wound healing was found to be an inconsistent outcome measure in patients receiving cilostazol therapy.

CONCLUSIONS

We observed that cilostazol therapy has a beneficial impact on all limb-related and arterial patency-related outcomes, but no effect on all-cause mortality in patients with advanced PAD and CLI undergoing revascularization procedures. Additional studies are needed to evaluate the effect of cilostazol therapy on wound healing in patients with advanced PAD.

Sulodexide improves pain-free walking distance in patients with lower extremity peripheral arterial disease: A systematic review and meta-analysis

Peripheral arterial disease is associated with very high cardiovascular risk. The main symptom is intermittent claudication, which strongly affects the quality of life. Therefore, treatment goals in peripheral arterial disease consist of the reduction of cardiovascular events and the relief of symptoms. An increase in pain-free walking distance, evaluated based on the Initial Claudication Distance, was also a strong positive prognostic factor in patients with peripheral arterial disease. Our objective was to reassess whether sulodexide is effective in improving Initial Claudication Distance. For this, we searched the literature according to the PRISMA checklist for double blind clinical trials assessing the improvement in the Initial Claudication Distance after 90 days of standard therapeutic regimen with sulodexide in adult patients with peripheral arterial disease. We found and assessed for bias in 11 studies eligible for review and meta-analysis. Data extracted from those studies favoured the sulodexide group, showing an overall difference in Initial Claudication Distance of +68.9 (CI 95%; ± 11.9 m) at the end of treatment (p < 0.001). According to this review, sulodexide is effective in improving Initial Claudication Distance and consequently the quality of life in patients with peripheral arterial disease. Further studies are needed to assess the effects of this drug on disease progression in asymptomatic patients with peripheral arterial disease.

Clinical outcomes of extended endovascular recanalization of 16 consecutive Buerger’s disease patients

Objective

Buerger’s disease is one of the worst diseases causing peripheral artery occlusions (especially lower extremity) with increased morbidity and mortality. Endovascular treatment of the diseased arteries gains preference over bypass surgery nowadays. Here, we aimed to present the clinical outcomes of 16 consecutive Buerger’s disease patients underwent extended endovascular recanalization which is a new technique to restore direct blood flow to at least one foot artery, with the performance of angioplasty for each tibial and foot artery obstructions.

Methods

A total of 16 consecutive patients with confirmed diagnosis of Buerger’s disease that percutaneously treated in our center between February 2014 and March 2018 were included in the study. The mean age of the patients was 44.25 ± 4.28 ranging from 36 to 50 years. After physical examination and complementary diagnostic tests, performance of extended angioplasty for occluded arteries was intended to restore direct blood flow to at least one of the blow-the-knee arteries.

Results

A successful extended endovascular treatment was performed in 20 of 22 limbs, achieving a technical success of 91%. All patients were successfully discharged without any complication. Mean follow-up duration was 21.43 ± 7.08 months. Reintervention was performed in one patient and minor amputation was needed in one of the failed limbs. Limb salvage rate was 100%. A significant difference was observed based on Rutherford classification, ankle brachial index, direct blood flow to foot, presence of ulcer and rest pain when compared before and after the intervention.

Conclusion

We showed successful extended endovascular recanalization of Buerger’s disease patients with a high technical success rate and sustained clinical improvement. Extended endovascular recanalization could be a therapeutic option in Buerger’s disease patients, since they are not good candidates for surgery.

Current therapies and investigational drugs for peripheral arterial disease

Peripheral artery disease (PAD) is associated with elevated morbidity and mortality with cardiovascular (CV) disease. The guideline recommends smoking cessation and antiplatelet/antithrombotic drugs for asymptomatic and symptomatic PAD patients. It also recommends that PAD patients with critical limb ischemia (CLI) should be considered to receive endovascular and open surgical treatment for limb salvage. Although PAD patients with CLI receive these treatments, they are sometimes unable to deliver sufficient blood flow to eliminate their symptoms. Thus specific strategies are needed to promote enough blood flow. To establish the effective method, many investigations have been performed using cell-based therapy. Endothelial progenitor cells, mononuclear cells and mesenchymal stem cells have been well investigated in clinical settings. To induce angiogenesis, vascular endothelial growth factor, fibroblast growth factor and hepatocyte growth factor (HGF) have also been transfected in PAD patients. Among them, HGF is the most promising factor because it can induce angiogenesis without the induction of vascular inflammation and increased permeability. In this review article, we summarize current treatments and investigational drugs of PAD.

Multidisciplinary approach to the diagnosis and management of patients with peripheral arterial disease

Peripheral arterial disease (PAD) is frequently diagnosed after permanent damage has occurred, resulting in a high rate of morbidity, amputation, and loss of life. Early and ongoing diagnosis and treatment is required for this progressive disease. Lifestyle modifications can prevent or delay disease progression and improve symptoms. Limb-sparing endovascular interventions can restore circulation based on appropriate diagnostic testing to pinpoint vascular targets, and intervention must occur as early as possible to ensure optimal clinical outcomes. An algorithm for the diagnosis and management of PAD was developed to enable a collaborative approach between the family practice and primary care physician or internist and various specialists that may include a diabetologist, endocrinologist, smoking cessation expert, hypertension and lipid specialist, endovascular interventionalist, vascular surgeon, orthopedist, neurologist, nurse practitioner, podiatrist, wound healing expert, and/or others. A multidisciplinary team working together has the greatest chance of providing optimal care for the patient with PAD and ensuring ongoing surveillance of the patient’s overall health, ultimately resulting in better quality of life and increased longevity for patients with PAD.

Pharmacological Treatment and Current Management of Peripheral Artery Disease

Patients with peripheral artery disease (PAD) are at heightened risk of both systemic cardiovascular adverse events, as well as limb-related morbidity. The optimal management of patients with PAD requires a comprehensive treatment strategy incorporating both lifestyle changes, including smoking cessation and exercise, as well as optimal medical therapy. Pharmacological therapies for patients with PAD are targeted both at modifying broad risk factors for major adverse cardiovascular events, as well as reducing limb-related morbidity. Observational data suggest that indicated pharmacological treatments are greatly underutilized in PAD, underscoring the need for improvements in patient identification and care delivery. Ongoing trials of novel therapies in patients with PAD will further inform pharmacological strategies to reduce both systemic cardiovascular risk and limb-related morbidity.

Antiplatelet strategy for acute ischemic stroke: A mini review

Transient ischemic attacks and minor ischemic strokes have a high risk of an unstable clinical course in the initial 48-72 h after symptom onset. Early antiplatelet treatment is recommended to treat most patients with acute ischemic stroke because few patients can be treated with thrombolysis due to the limit of strict indications, such as a time window. Antiplatelets aim to prevent recurrence or deterioration of stroke. The guidelines recommend the use of aspirin in the acute stage based on two clinical trials. However, some patients still developed recurrence or deterioration of stroke despite timely aspirin administration. Thus, the question remains unclear whether another effective and safe antiplatelet strategy for the treatment of acute ischemic stroke exists. Growing evidence shows that combination antiplatelets may be superior to mono antiplatelets in the treatment of acute ischemic stroke.

Practice-based evidence: profiling the safety of cilostazol by text-mining of clinical notes

BACKGROUND

Peripheral arterial disease (PAD) is a growing problem with few available therapies. Cilostazol is the only FDA-approved medication with a class I indication for intermittent claudication, but carries a black box warning due to concerns for increased cardiovascular mortality. To assess the validity of this black box warning, we employed a novel text-analytics pipeline to quantify the adverse events associated with Cilostazol use in a clinical setting, including patients with congestive heart failure (CHF).

METHODS AND RESULTS

We analyzed the electronic medical records of 1.8 million subjects from the Stanford clinical data warehouse spanning 18 years using a novel text-mining/statistical analytics pipeline. We identified 232 PAD patients taking Cilostazol and created a control group of 1,160 PAD patients not taking this drug using 1:5 propensity-score matching. Over a mean follow up of 4.2 years, we observed no association between Cilostazol use and any major adverse cardiovascular event including stroke (OR = 1.13, CI [0.82, 1.55]), myocardial infarction (OR = 1.00, CI [0.71, 1.39]), or death (OR = 0.86, CI [0.63, 1.18]). Cilostazol was not associated with an increase in any arrhythmic complication. We also identified a subset of CHF patients who were prescribed Cilostazol despite its black box warning, and found that it did not increase mortality in this high-risk group of patients.

CONCLUSIONS

This proof of principle study shows the potential of text-analytics to mine clinical data warehouses to uncover 'natural experiments' such as the use of Cilostazol in CHF patients. We envision this method will have broad applications for examining difficult to test clinical hypotheses and to aid in post-marketing drug safety surveillance. Moreover, our observations argue for a prospective study to examine the validity of a drug safety warning that may be unnecessarily limiting the use of an efficacious therapy.

Diagnosis and treatment of peripheral arterial disease in CKD patients

Peripheral arterial disease (PAD) is a cardiovascular disease risk equivalent and is a common problem in chronic kidney disease patients. Unlike in the general population, PAD in CKD occurs due to medial calcification as opposed to intimal atherosclerotic process. PAD intervention should be performed in select symptomatic patients, as described by the guidelines, and CVD risk factor modification should occur in all CKD patient, regardless of the presence of PAD. As a discipline, Interventional Nephrology has emerged out of a desire to create better outcomes for our patients and to "fix a problem." The core values of our discipline have evolved out of this fundamental desire to meet an unmet clinical need, to provide insight into a disease state specific to our patients, and to offer clinical/academic excellence in doing so. We must endeavor to follow a similar path in our approach to PAD. The purpose of this review is to educate interventional nephrologists in the diagnosis and treatment of PAD in their CKD patients.

Cilostazol: a pilot study on safety and clinical efficacy in neuropathies of diabetes mellitus type 2 (ASCEND)

BACKGROUND

Diabetic polyneuropathy may have vascular and metabolic components in its pathophysiologic mechanism. Cilostazol, aside from its antiplatelet and vasodilatory properties, may increase nerve blood flow and potentially improve neuropathy.

OBJECTIVE

To assess the efficacy and safety of cilostazol in diabetic polyneuropathy.

METHODS

Forty-seven diabetic patients were randomized into placebo, low-dose (100 mg/d), and high-dose (200 mg/d) cilostazol groups. Primary efficacy parameter was a change in neuropathy symptom scores and secondary efficacy parameter was a change in walking speed from baseline to week 12. Safety parameters were changes in nerve conduction studies as well as reporting of adverse events.

RESULTS/CONCLUSION

Despite significant improvement in the neuropathy symptom scores in the overall motor and sensory categories of the 3 arms of the study from baseline to week 12, no significant differences were found among the groups, indicating nonsuperiority of cilostazol in regard to improvement of neuropathy symptoms over the short study span. However, cilostazol, at low dose, was effective in improving walking speed from baseline to week 12, implying an improved blood flow. No significant worsening nor improvement in motor and sensory nerve conduction parameters were observed, comparing the 3 study arms from baseline to weeks 4, 12, and 16, supporting cilostazol's safety. Overall, the adverse events of the 3 study arms did not significantly differ, and neither were there serious adverse events reported, also signifying safety and tolerability in our Filipino cohort of patients with neuropathy in diabetes mellitus treated with cilostazol.

Peripheral artery disease. Part 2: medical and endovascular treatment

The treatment of peripheral artery disease (PAD) focuses on risk factor modification, cardiovascular event reduction, limb viability, and symptom improvement. Hypertension, hyperlipidemia, and diabetes mellitus should all be controlled to recommended target levels, and smoking cessation is vital. Antiplatelet therapies, such as aspirin or clopidogrel, should be administered in all patients unless contraindicated. Whenever possible, patients who present with claudication should be offered a regimen comprised of both medical and exercise therapy, which often results in substantial improvement in symptoms. For patients presenting with more-advanced disease, such as acute limb ischemia, critical limb ischemia, and severely-limiting symptoms of PAD, revascularization is often necessary. As a result of the rapid evolution in endovascular revascularization technology and expertise, many patients with PAD can be treated percutaneously. Therefore, in this Review, we will focus on medical therapy and endovascular revascularization of patients with PAD, with reference to surgical bypass in specific clinical scenarios.

Targeting cancer with phosphodiesterase inhibitors

IMPORTANCE OF THE FIELD

For many cancers, there has been a shift from management with traditional, nonspecific cytotoxic chemotherapies to treatment with molecule-specific targeted therapies that are used either alone or in combination with traditional chemotherapy and radiation therapy. Accumulating data suggest that multi-targeted agents may produce greater benefits than those observed with single-targeted therapies, may have acceptable tolerability profiles, and may be active against a broader range of tumour types. Thus, regulation of cyclic nucleotide signalling is properly regarded as a composite of multiple component pathways involved in diverse aspects of tumour cell function. The impairment of cAMP and/or cGMP generation by overexpression of PDE isoforms that has been described in various cancer pathologies, and the effects of PDE inhibitors in tumour models in vitro and in vivo, may offer promising insight into future cancer treatments because of the numerous advantages of PDE inhibitors.

AREAS COVERED IN THIS REVIEW

In this review, we focus on the expression and regulation of cyclic nucleotide phosphodiesterases (PDEs) in tumour progression and provide evidence that PDE inhibitors may be effective agents for treating cancer; the review covers literature from the past several years.

WHAT THE READER WILL GAIN

PDEs have been studied in a variety of tumours; data have suggested that the levels of PDE activity are elevated and, therefore, the ratio of cGMP to cAMP is affected. In addition, PDE inhibitors may be potential targets for tumour cell growth inhibition and induction of apoptosis. This review explores the prospects of targeting PDEs with therapeutic agents for cancer, as well as the shortcomings of this approach such as dose-limiting side effects, toxicity/efficacy ratio and selectivity towards tumour tissue. In addition, it includes opinions and suggestion for developing PDE inhibition for cancer treatment from initial concept to potential therapeutic application and final relevance in clinical use.

TAKE HOME MESSAGE

Impaired cAMP and/or cGMP generation upon overexpression of PDE isoforms has been described in various cancer pathologies. Inhibition of selective PDE isoforms, which raises the levels of intracellular cAMP and/or cGMP, induces apoptosis and cell cycle arrest in a broad spectrum of tumour cells and regulates the tumour microenvironment. Therefore, the development and clinical application of inhibitors specific for individual PDE isoenzymes may selectively restore normal intracellular signalling, providing antitumour therapy with reduced adverse effects.

Peripheral arterial disease: current perspectives and new trends in management

Peripheral arterial disease (PAD) is defined as an arterial brachial index (ABI) of < or =0.90 in the lower extremities and results from a narrowing of the arteries as a result of progressive atherosclerosis. PAD affects 12-20% of Americans aged 65 years or older; however, most are asymptomatic and many do not seek treatment. Improved awareness and education in both the general population and among health care providers about these modifiable risk factors has the potential to improve general health and decrease morbidity and mortality secondary to atherosclerotic vascular disease.

The vascular and biochemical effects of cilostazol in patients with peripheral arterial disease

OBJECTIVES

Cilostazol improves walking distance and quality of life in patients with peripheral arterial disease (PAD). This study assessed the vascular and biochemical effects of cilostazol therapy in PAD patients.

METHODS

PAD patients were prospectively recruited to a randomized, double-blinded, placebo-controlled trial. Baseline clinical data were recorded. Clinical assessment included measurement of arterial compliance, transcutaneous oxygenation, ankle-brachial index (ABI), and treadmill walking distance. Blood analyses included a full blood panel, coagulation screen, urea and electrolytes, liver function tests, estimated glomerular filtration rate, and lipid profiles. Quality of life indices were recorded using validated generic and walking-specific questionnaires. All tests were performed at baseline, 6, and 24 weeks.

RESULTS

Eighty patients (53 men) were recruited from December 2004 to January 2006. The cilostazol group had a significant reduction in the augmentation index compared with the placebo group at 6 weeks (19.7% vs 26.7%, P = .001) and at 24 weeks (19.7% vs 27.7%, P = .005). A paradoxic reduction in transcutaneous oxygenation levels was identified in the cilostazol group for the left foot at 6 weeks and for the right foot at both 6 and 24 weeks. The ABIs were not significantly different between treatment groups at baseline, 6 weeks, or 24 weeks for the left and right lower limbs. The mean percentage change in walking distance from baseline improved more markedly in the cilostazol compared with the placebo group for absolute claudication distance at 6 (78.6% vs 26.4%, P = .20) and 24 weeks (173.1% vs 92.1%, P = .27); however, these failed to reach significance. Significant improvements in lipid profiles were demonstrated with cilostazol therapy at 6 weeks (triglycerides, high-density lipoprotein [HDL]) and at 24 weeks (cholesterol, triglycerides, HDL, and low-density lipoprotein). The cilostazol treatment group demonstrated significant improvements in the Short Form-36 (physical functioning, physical component score), Walking Impairment (distance and speed), and Vascular Quality of Life (pain) indices at 6 and 24 weeks. Although cilostazol was associated with side effects in approximately one-third of patients, most settled within 6 weeks, facilitating the continuation of therapy in >89%.

CONCLUSION

Cilostazol is a well-tolerated, safe, and efficacious treatment for PAD patients. It not only improves patients' symptomatology and quality of life but also appears to have beneficial effects on arterial compliance, possibly through its lipid-lowering property.

Cilostazol and peripheral arterial disease

Peripheral arterial disease is both common and disabling. Contemporary management of peripheral arterial disease is multimodal, encompassing both medical and interventional treatments. Cilostazol (Pletal), a 2-oxoquinolone derivative, is currently licensed in the UK for the treatment of patients with intermittent claudication to improve their walking distance in the absence of tissue necrosis or rest pain. The therapeutic effects of cilostazol are thought to be mediated through antiplatelet, antiproliferative and vasodilatory activities. This review aims to provide an overview of the management of peripheral arterial disease focusing upon cilostazol pharmacotherapy.

The Role of Aspirin in Cardiovascular Disease Prevention in Women

Cardiovascular disease is the nation's number one killer of women. Through its actions on platelet inhibition, aspirin is an effective agent for primary and secondary cardiovascular disease prevention and for use with cardiac interventions. However, the evidence for aspirin's effectiveness in women differs by age and indication compared to men. As primary prevention, low dose aspirin is recommended for women over age 65 to reduce the risk of myocardial infarction and stroke while younger women at high risk for stroke may benefit from aspirin. Aspirin has benefits in other selected patient groups, including diabetics and patients presenting with ST segment elevation myocardial infarction (STEMI), non-ST segment elevation myocardial infarction acute coronary syndrome (NSTEMI/ACS), peripheral arterial disease, stroke, coronary artery bypass graft (CABG), and percutaneous coronary intervention (PCI). Alternative platelet therapy using dipyridamole or clopidogrel, alone or with aspirin, provides some improved efficacy for reduction in recurrent events for NSTEMI, ASC and PCI, although bleeding risks may be greater. However, dual antiplatelet therapy is not currently recommended for primary prevention in even high risk subjects. Despite the evidence base and guidelines, the use of aspirin in women remains suboptimal and warrants improved provider and patient awareness.

Inhibition of phosphodiesterase has an additive effect on estrogen's ability to inhibit collagen synthesis in vascular smooth muscle cells

Several studies have shown that estrogen has the ability to decrease collagen synthetic rates in vascular smooth muscle cells (VSMCs) by increasing cellular cyclic AMP (cAMP) levels. Phosphodiesterase inhibitors have also been shown to inhibit collagen synthesis in VSMCs presumably by preventing the degradation of cAMP. Since estrogens and phosphodiesterase inhibitors are used clinically, it is important to determine the potential for phosphodiesterase inhibitors to potentiate estrogen's ability to inhibit collagen synthesis in VSMCs. The results of the present study demonstrate that the phosphodiesterase inhibitors cilostamide and Ro-20-1724 had an additive effect on estrogen's ability to inhibit collagen synthesis in VSMC. Also, the data suggests that phosphodiesterase inhibitors mediated this additive effect by increasing cellular levels of cAMP.

Future innovations in anti-platelet therapies

Platelets have long been recognized to be of central importance in haemostasis, but their participation in pathological conditions such as thrombosis, atherosclerosis and inflammation is now also well established. The platelet has therefore become a key target in therapies to combat cardiovascular disease. Anti-platelet therapies are used widely, but current approaches lack efficacy in a proportion of patients, and are associated with side effects including problem bleeding. In the last decade, substantial progress has been made in understanding the regulation of platelet function, including the characterization of new ligands, platelet-specific receptors and cell signalling pathways. It is anticipated this progress will impact positively on the future innovations towards more effective and safer anti-platelet agents. In this review, the mechanisms of platelet regulation and current anti-platelet therapies are introduced, and strong, and some more speculative, potential candidate target molecules for future anti-platelet drug development are discussed.

The Effects of Cilostazol on Peripheral Neuropathy in Diabetic Patients With Peripheral Arterial Disease

Background Evidence from diabetic animal models suggests that cilostazol, a cyclic AMP phosphodiesterase inhibitor used in the treatment of claudication, is efficacious in the treatment of peripheral neuropathy, although this is unproven in humans. The main aim of this study was to assess the effects of cilostazol on neuropathic symptomatology in diabetic patients with peripheral arterial disease (PAD). Methods Diabetic patients with PAD were prospectively recruited to a randomized double-blinded placebo-controlled trial. Baseline clinical data were recorded prior to trial commencement following medical optimization. Neurological assessment included the Toronto Clinical Neuropathy Scoring system (TCNS) and vibration perception thresholds (VPT) with a neurothesiometer at baseline, 6 weeks, and 24 weeks. Results Twenty-six patients were recruited from December 2004 to January 2006, which included 20 males. Baseline patient allocation to treatment arms was matched for age, sex, and medical comorbidities. There was no significant difference in neurological assessment between the treatment groups using the TCNS and VPT at 6 and 24 weeks. Conclusions Despite extensive animal-based evidence that cilostazol attenuates neuropathic symptomatology, our results do not support this effect in human diabetic PAD patients.

Management of peripheral arterial disease in the elderly: focus on cilostazol

Symptomatic and asymptomatic peripheral arterial disease (PAD) is a common problem in the elderly. The management of PAD includes the prevention of cardiovascular events and relief of symptoms--most commonly intermittent claudication (IC). Both require treatment of the causes and consequences of atherothrombosis, but some strategies are more effective for prevention of cardiovascular events and others are more effective for the relief of symptoms. Priorities for the prevention of cardiovascular events include smoking cessation, exercise, antiplatelet therapy, and the treatment of dyslipidemia, hypertension, and diabetes. Walking time and ability are improved by exercise. The benefit of numerous drugs in the treatment of IC has been assessed. The results have generally been disappointing, but there is some evidence that statins and cilostazol (an inhibitor of phosphodiesterase 3) are of benefit. Meta-analyses suggest that cilostazol increases maximum walking distance by 40%-50% and improves other objective measures of walking. The safety profile of cilostazol in patients with PAD appears to be acceptable although the mechanism for its effect on IC is unclear. In addition to risk factor management, treatment with cilostazol should be considered in patients with disabling IC.

Peripheral Arterial Disease: A Guide for Nephrologists

Cardiovascular disease is a major source of morbidity and mortality for patients with chronic kidney disease (CKD). Peripheral arterial disease (PAD) is a strong predictor of coronary artery disease and a risk factor for mortality in the general population. This is of particular interest to nephrologists because the risk for PAD is increased in CKD. Often, PAD is overlooked as a source of morbidity and as a cardiovascular risk factor in this population. This review serves as an overview of the epidemiology, screening, diagnosis, and treatment of PAD with an emphasis on CKD.

Therapy Insight: peripheral arterial disease and diabetes—from pathogenesis to treatment guidelines

The increased risk of atherothrombotic events present in all patients with peripheral arterial disease (PAD) is amplified with concomitant diabetes. Moreover, diabetes is associated with increased PAD severity. This Review summarizes atherothrombosis and PAD in patients with diabetes, and American College of Cardiology and American Heart Association guidelines for management of patients with PAD. Patients with PAD and diabetes require optimal limb care and aggressive cardiovascular risk reduction. An LDL cholesterol level of less than 1.8 mmol/l (<70 mg/dl) is the therapeutic goal in these patients, and this target should be pursued using an aggressive statin regimen. Fibrate therapy can also be indicated. beta-blockers and angiotensin-converting-enzyme inhibitors reduce cardiovascular events in high-risk patient populations, and these agents are recommended for use in patients with both diabetes and PAD. Blood pressure of less than 130/80 mmHg should be achieved, and glycated hemoglobin should be reduced to below 7%. Patients should also receive indefinite antiplatelet therapy with aspirin or clopidogrel. For patients with claudication, a supervised exercise program and cilostazol therapy to improve PAD symptoms and walking distance form the main noninvasive components of therapy. Revascularization can also be indicated in carefully selected patients with claudication. For patients with critical limb ischemia, diagnostic testing by a vascular specialist will determine whether revascularization or amputation is feasible.

Current endovascular treatment of peripheral arterial disease

Atherosclerotic peripheral arterial disease is a common medical problem worldwide and portends a poor prognosis because of increased cardiovascular morbidity and mortality. Regular exercise, weight loss, and aggressive risk factor modification, including treatment of dyslipidemia and complete cessation of smoking, is extremely important in this high-risk cohort. Vascular surgery in these patients, who often have concomitant coronary or cerebrovascular atherosclerosis, is associated with significant risk. Steady improvements in endovascular revascularization techniques have made this a safe and effective alternate revascularization modality. Percutaneous peripheral vascular interventions have increased dramatically in recent years, from 90,000 in 1994 to more than 200,000 in 1997, and endovascular techniques may soon replace up to 50% of traditional vascular operations. In this article, the authors review the current state of interventional treatment for peripheral arterial disease.

Reduced 6-month resource use and costs associated with cilostazol in patients after successful coronary stent implantation: results from the Cilostazol for RESTenosis (CREST) trial

BACKGROUND

The CREST trial demonstrated that after successful coronary stent implantation, the 6-month rate of target vessel revascularization (TVR) was similar (15.4% vs 16%, P = .90) for the 2 treatment groups, but restenosis rate was lower (22.0% vs 34.5%, P = .002) in cilostazol-treated patients. We sought to evaluate resource use, cost, and cost-effectiveness of cilostazol in CREST.

METHODS

A total of 705 patients were randomized to cilostazol 100 mg twice daily (n = 354) versus placebo (n = 351) for 6 months. Resources included rehospitalizations, medications, and outpatient services. Costs were determined from the Medicare fee schedule. Cilostazol was priced at 1.64 dollars a day. Base-case cost and cost-effectiveness analysis was performed for the entire population using TVR as a measure of effectiveness. Sensitivity analysis was conducted among 526 patients because restenosis data were available only for this patient population. A bootstrap resample approach (5000 samples) was used to obtain confidence intervals for cost differences.

RESULTS

For the entire population, costs of rehospitalizations, concomitant medications, outpatient tests, and physician or emergency department visits were lower during follow-up for cilostazol-treated patients. Overall, total 6-month follow-up costs remained 447 dollars lower for cilostazol (4178 dollars vs 4625 dollars), although this difference did not reach significance (95% CI -1458 dollars to 515 dollars). Cilostazol is likely a cost-saving strategy (similar rate of TVR and lower costs). Sensitivity analysis showed that cilostazol is likely a dominant strategy (lower restenosis rate and costs, 85% dominant, 88.9% <1000 dollars per restenosis averted).

CONCLUSIONS

Treatment with cilostazol is likely a cost-saving or dominant strategy in patients with successful coronary bare metal stent implantation. Cilostazol may offer a low-cost alternative to restenosis prevention in patients who do not receive drug-eluting stents.

Pharmacodynamic interaction studies of Ginkgo biloba with cilostazol and clopidogrel in healthy human subjects

AIMS

Ginkgo biloba is available as an over-the-counter drug and reported to cause haemorrhage when coadministered with other antiplatelet agents. We set out to study the interactions of G. biloba with cilostazol and clopidogrel.

METHODS

A randomized, open-label, crossover study of 10 healthy male volunteers. The dosage schedules were 120 mg G. biloba, 240 mg G. biloba, 100 mg cilostazol, 200 mg cilostazol, 75 mg clopidogrel, 150 mg clopidogrel, 120 mg G. biloba+ 100 mg cilostazol and 120 mg G. biloba+ 75 mg clopidogrel. Platelet aggregation, platelet count, bleeding time and clotting time were measured 0 and 6 h after drug administration. Platelet aggregation was performed using a dual channel aggregometer, by the turbimetric technique using adenosine diphosphate 5 micromol and 10 micromol, and collagen 1 microg ml(-1).

RESULTS

Platelet inhibition with the combination of G. biloba and clopidogrel or cilostazol was not statistically significant compared with individual doses of drugs, with all the three aggregants. There was significant (P < 0.05) potentiation of prolongation of bleeding time with the combination of cilostazol and G. biloba compared with individual doses of both the drugs. There was no significant change in clotting time and platelet count.

CONCLUSIONS

Coadministration of G. biloba either with cilostazol or clopidogrel did not enhance antiplatelet activity compared with individual agents. Ginkgo biloba potentiated the bleeding time prolongation effect of cilostazol. There was no significant correlation between prolongation of bleeding time and inhibition of platelet aggregation.

Simultaneous quantification of cilostazol and its primary metabolite 3,4-dehydrocilostazol in human plasma by rapid liquid chromatography/tandem mass spectrometry

A simple, rapid, sensitive and selective liquid chromatography/electrospray tandem mass spectrometry method was developed and validated for the simultaneous quantification of cilostazol and its primary metabolite 3,4-dehydrocilostazol in human plasma using mosapride as an internal standard. The method involves a simple one-step liquid-liquid extraction with a diethyl ether and dichloromethane mixture (7:3). The analytes were chromatographed using an isocratic mobile phase on a reversed-phase C18 column and analyzed by mass spectrometry in the multiple reaction monitoring mode using the respective [M+H]+ ions, m/z 370/288 for cilostazol, m/z 368/286 for 3,4-dehydrocilostazol and m/z 422/198 for the internal standard. The assay exhibited a linear dynamic range of 5-2,000 ng/mL for cilostazol and 5-400 ng/mL for 3,4-dehydrocilostazol in human plasma. The lower limit of quantitation was 5 ng/mL for both cilostazol and its metabolite. Acceptable precision and accuracy were obtained for concentrations over the standard curve ranges. A run time of 2.5 min for each sample made it possible to analyze more than 400 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetics, bioavailability or bioequivalence studies.

The crystal structure of AMP-bound PDE4 suggests a mechanism for phosphodiesterase catalysis

Cyclic nucleotide phosphodiesterases (PDEs) regulate the intracellular concentrations of cyclic 3',5'-adenosine and guanosine monophosphates (cAMP and cGMP, respectively) by hydrolyzing them to AMP and GMP, respectively. Family-selective inhibitors of PDEs have been studied for treatment of various human diseases. However, the catalytic mechanism of cyclic nucleotide hydrolysis by PDEs has remained unclear. We determined the crystal structure of the human PDE4D2 catalytic domain in complex with AMP at 2.4 A resolution. In this structure, two divalent metal ions simultaneously interact with the phosphate group of AMP, implying a binuclear catalysis. In addition, the structure suggested that a hydroxide ion or a water bridging two metal ions may serve as the nucleophile for the hydrolysis of the cAMP phosphodiester bond.

Effects of cilostazol in patients with Raynaud's syndrome

Raynaud's syndrome (RS), which is characterized by recurrent episodes of vasospasm with exposure to cold, may occur alone (primary RS) or in association with connective tissue diseases or other underlying conditions (secondary RS). We investigated the effect of cilostazol on vessel wall responses in RS. Patients were diagnosed (primary or secondary RS associated with connective tissue diseases) and randomized to placebo or cilostazol 100 mg twice daily for 6 weeks in a double-blind manner. Brachial artery vasoreactivity, laser Doppler fluxmetry, and cold pressor testing (CPT) were performed at study initiation and completion. Symptoms were assessed using standardized questionnaires. Forty subjects completed the study (19 with primary RS and 21 with secondary RS). Cilostazol significantly increased the mean brachial artery diameter at 6 weeks (primary RS, p = 0.006; secondary RS, p = 0.06). There was no change in median flow-mediated dilation (FMD) with cilostazol in primary RS (25th, 75th percentiles) (4.06% [2.5, 6.1] to -0.77% [-2.4, 3.4] or secondary RS (2.2% [0.05, 6.3] to 2.95% [1.7, 7.4]). There were no changes in nitroglycerin-mediated dilation or microvascular flow indexes in either cohort. In patients with primary RS, cilostazol treatment yielded a positive change in the slope of brachial responsiveness to CPT (increase of 0.32 mm/min; p = 0.002 vs placebo). Cilostazol treatment remained significantly associated with increased brachial artery diameter when controlling for baseline values (p = 0.018). Cilostazol increased conduit vessel diameter in patients with primary and secondary RS, with a favorable impact on conduit vessel responsiveness to cold in patients with primary RS without affecting microvascular flow or symptoms.

Cholesterol reduction with atorvastatin improves walking distance in patients with peripheral arterial disease

BACKGROUND

Cholesterol modification reduces cardiovascular events in patients with atherosclerosis, including those with peripheral arterial disease. The purpose of this study was to determine whether cholesterol lowering with atorvastatin improves walking performance in patients with intermittent claudication.

METHODS AND RESULTS

This randomized, double-blind, parallel-design study included 354 persons with claudication attributable to peripheral arterial disease. Patients were treated with placebo, atorvastatin (10 mg per day), or atorvastatin (80 mg per day) for 12 months. The outcome measures included change in treadmill exercise time and patient-reported measures of physical activity and quality of life based on questionnaires. Maximal walking time after 12 months of treatment with atorvastatin did not change significantly. However, there was improvement in pain-free walking time after 12 months of treatment for the 80-mg (P=0.025) group compared with placebo. A physical activity questionnaire demonstrated improvement in ambulatory ability for the 10- and 80-mg groups (P=0.011), whereas 2 quality of life instruments, the Walking Impairment Questionnaire and Short Form 36 Questionnaire, did not show significant change.

CONCLUSIONS

Atorvastatin improves pain-free walking distance and community-based physical activity in patients with intermittent claudication. When treated with atorvastatin, patients with peripheral arterial disease may experience improvement in symptoms to complement the anticipated reduction in cardiovascular events reported in other studies of statins.

Three-dimensional structures of PDE4D in complex with roliprams and implication on inhibitor selectivity

Selective inhibitors against the 11 families of cyclic nucleotide phosphodiesterases (PDEs) are used to treat various human diseases. How the inhibitors selectively bind the conserved PDE catalytic domains is unknown. The crystal structures of the PDE4D2 catalytic domain in complex with (R)- or (R,S)-rolipram suggest that inhibitor selectivity is determined by the chemical nature of amino acids and subtle conformational changes of the binding pockets. The conformational states of Gln369 in PDE4D2 may play a key role in inhibitor recognition. The corresponding Y329S mutation in PDE7 may lead to loss of the hydrogen bonds between rolipram and Gln369 and is thus a possible reason explaining PDE7's insensitivity to rolipram inhibition. Docking of the PDE5 inhibitor sildenafil into the PDE4 catalytic pocket further helps understand inhibitor selectivity.

Treatment of intermittent claudication with beraprost sodium, an orally active prostaglandin I2 analogue: a double-blinded, randomized, controlled trial

OBJECTIVES

In the current study, we hypothesized that beraprost would: 1) improve treadmill exercise performance and quality of life; and 2) decrease rates of ischemic events in patients with intermittent claudication.

BACKGROUND

Previous trials with beraprost sodium, an orally active prostaglandin I(2) analogue, in the treatment of claudication in patients with peripheral arterial disease (PAD) have been inconsistent.

METHODS

Patients with intermittent claudication (n = 897) were randomized to receive either 40 microg three times a day of beraprost with meals (n = 385) or placebo (n = 377) in a double-blinded manner for one year. The primary efficacy parameter was treadmill-measured maximum walking distance, as assessed at three and six months after randomization. Secondary efficacy parameters included treadmill-measured pain-free walking distance and change in quality of life.

RESULTS

There was no significant improvement in maximum walking distance in the beraprost group (16.7%) as compared with the placebo group (14.6%, p = NS). Administration of beraprost did not improve the pain-free walking distance (p = NS between treatment groups), and there was no improvement in the quality-of-life measures between the treatment groups. The incidence of critical cardiovascular events was 7.3% in the beraprost group and 11.4% in the placebo group (p = NS). There was a significant reduction in the combination of cardiovascular death and myocardial infarction in the beraprost group (p = 0.01).

CONCLUSIONS

Despite previous investigations suggesting efficacy, these results indicate that beraprost is not an effective treatment to improve symptoms of intermittent claudication in patients with PAD. The potential benefit of beraprost on critical cardiovascular events would require confirmation in a larger prospective investigation.