Effects of cilostazol on the pharmacokinetics of carvedilol after oral and intravenous administration in rats

This study was designed to investigate the effects of cilostazol on the pharmacokinetics of carvedilol following oral or intravenous administration of carvedilol in rats. Clinically carvedilol and cilostazol can be prescribed for treatment of cardiovascular diseases. Carvedilol and cilostazol are all substrates of CYP2C9 enzymes. Carvedilol was administered orally or intravenously without or with oral administration of cilostazol to rats. The effects of cilostazol on cytochrome P450 (CYP) 2C9 activity and P-gp activity were also evaluated. Cilostazol inhibited CYP2C9 activity in a concentration-dependent manner with 50% inhibitory concentration (IC(50)) of 8.7 μM. Compared with the control group, the area under the plasma concentration-time curve (AUC) of carvedilol was significantly (P < 0.05) increased by 38.0%. The peak concentration (C(max)) was significantly (P < 0.05) increased by 49.2% in the presence of cilostazol after oral administration of carvedilol. Consequently, the relative bioavailability (R.B.) of carvedilol was increased by 1.15 - 1.38-fold, and the absolute bioavailability (A.B.) of carvedilol in the presence of cilostazol was significantly (P < 0.05) higher than that of the control. After intravenous administration, the AUC of carvedilol was significantly (P < 0.05) increased by 19.2% compared to that in the control by cilostazol. These results suggest that cilostazol effectively inhibited the metabolism of carvedilol. The increased oral bioavailability of carvedilol might be due to the inhibition of CYP2C9-mediated metabolism of carvedilol in the liver by cilostazol.

Non-Invasive Therapy of Peripheral Arterial Disease

Peripheral arterial disease (PAD) is a significant cause of morbidity and mortality worldwide. Lifestyle changes, like the cessation of the use of tobacco as well as a modification of dietary and exercise habits, can be the most cost-effective interventions in patients with PAD. Smocking cessation is the most important intervention, since it increases survival in these patients. Antiplatelet therapy is an essential component in the treatment of peripheral arterial disease (PAD) of the lower extremities. In addition to delaying arterial obstructive progression, these agents are most usefull in reducing adverse cardiovascular events such as non-fatal myocardial infarction (MI), stroke and vascular death. Mainstay of treatment continues to be aspirin monotherapy (75-325mg daily). Current treatment for lower extremity PAD is directed towards the relief of symptoms and improvement in QoL. The two agents which have consistently been found to be most efficient in achieving these goals are cilostazol and naftidrofuryl oxalate. Naftidrofuryl oxalate may emerge as the most efficient and cost-effective treatment for symptom relief.

PTEN upregulation may explain the development of insulin resistance and type 2 diabetes with high dose statins

PURPOSE

Statins increase the incidence of new onset diabetes. Prolonged statin therapy upregulates PTEN expression. PTEN levels are also elevated in diabetic animals. Activation of protein kinase A by cAMP decreases PTEN expression. We assessed whether prolonged treatment with rosuvastatin (ROS) induces glucose intolerance by upregulating Phosphatase and Tensin Homologue on Chromosome 10 (PTEN) in mice receiving normal (ND) or Western Diet (WD) and whether concomitant treatment with cilostazol (CIL, a phosphodiesterase-3 inhibitor) attenuates the effects.

METHODS

PTEN(loxp/cre) or PTEN(+/-) mice received ND or WD without or with ROS (10 mg/kg/day). Wild-type mice received ND or WD without or with ROS, CIL (10 mg/kg/day), or ROS+CIL for 30 days. Fasting insulin and glucose tolerance test were measured as well as PTEN and P-AKT levels in skeletal muscle.

RESULTS

Serum glucose after intraperitoneal injection of glucose was higher in PTEN(loxp/cre) mice receiving WD or ROS and especially WD+ROS. Levels were lower in PTEN(+/-) mice compared to PTEN(loxp/cre) in each treatment group. CIL decreased glucose levels in mice receiving WD, ROS and their combination. Insulin levels were higher in the WD+ROS group. CIL decreased insulin in mice receiving WD+ROS. WD, ROS and especially their combination increased PTEN and decreased P-AKT levels. CIL attenuated the effect of WD, ROS and their combination.

CONCLUSIONS

Long-term ROS can induce diabetes by upregulating PTEN. CIL attenuates these changes. Partial knockdown of PTEN also ameliorates ROS-induced insulin resistance. Further studies are needed to assess the effects of increasing cAMP levels to prevent the induction of diabetes by statins.

Cilostazol attenuates ovariectomy-induced bone loss by inhibiting osteoclastogenesis

Background

Cilostazol has been reported to alleviate the metabolic syndrome induced by increased intracellular adenosine 3’,5’-cyclic monophosphate (cAMP) levels, which is also associated with osteoclast (OC) differentiation. We hypothesized that bone loss might be attenuated via an action on OC by cilostazol.

Methodology and Principal Findings

To test this idea, we investigated the effect of cilostazol on ovariectomy (OVX)-induced bone loss in mice and on OC differentiation in vitro, using μCT and tartrate-resistant acid phosphatase staining, respectively. Cilostazol prevented from OVX-induced bone loss and decreased oxidative stress in vivo. It also decreased the number and activity of OC in vitro. The effect of cilostazol on reactive oxygen species (ROS) occurred via protein kinase A (PKA) and cAMP-regulated guanine nucleotide exchange factor 1, two major effectors of cAMP. Knockdown of NADPH oxidase using siRNA of p47^phox attenuated the inhibitory effect of cilostazol on OC formation, suggesting that decreased OC formation by cilostazol was partly due to impaired ROS generation. Cilostazol enhanced phosphorylation of nuclear factor of activated T cells, cytoplasmic 1 (NFAT2) at PKA phosphorylation sites, preventing its nuclear translocation to result in reduced receptor activator of nuclear factor-κB ligand-induced NFAT2 expression and decreased binding of nuclear factor-κB-DNA, finally leading to reduced levels of two transcription factors required for OC differentiation.

Conclusions/Significance

Our data highlight the therapeutic potential of cilostazol for attenuating bone loss and oxidative stress caused by loss of ovarian function.

Disintegration mediated controlled release supersaturating solid dispersion formulation of an insoluble drug: design, development, optimization, and in vitro evaluation

The objective of this study was to develop a solid dispersion based controlled release system for drug substances that are poorly soluble in water. A wax-based disintegration mediated controlled release system was designed based on the fact that an amorphous drug can crystallize out from hydrophilic matrices. For this study, cilostazol (CIL) was selected as the model drug, as it exhibits poor aqueous solubility. An amorphous solid dispersion was prepared to assist the drug to attain a supersaturated state. Povidone was used as carrier for solid dispersion (spray drying technique), hydrogenated vegetable oil (HVO) as wax matrix former, and sodium carboxymethyl cellulose (NaCMC) as a disintegrant. The extreme vertices mixture design (EVMD) was applied to optimize the designed and developed composition. The optimized formulation provided a dissolution pattern which was equivalent to the predicted curve, ascertaining that the optimal formulation could be accomplished with EVMD. The release profile of CIL was described by the Higuchi's model better than zero-order, first-order, and Hixson-Crowell's model, which indicated that the supersaturation state of CIL dominated to allow drug release by diffusion rather than disintegration regulated release as is generally observed by Hixson-Crowell's model. The optimized composition was evaluated for disintegration, dissolution, XRD, and stability studies. It was found that the amorphous state as well as the dissolution profile of CIL was maintained under the accelerated conditions of 40°C/75% RH for 6 months.

Cilostazol for intermittent claudication

BACKGROUND

Peripheral arterial disease (PAD) affects between 4% and 12% of people aged 55 to 70 years, and 20% of people over 70 years. A common complaint is intermittent claudication, characterised by pain in the legs or buttocks that occurs with exercise and which subsides with rest. Compared with age-matched controls, people with intermittent claudication have a three- to six-fold increase in cardiovascular mortality. Symptoms of intermittent claudication, walking distance, and quality of life can be improved by risk factor modification, smoking cessation, and a structured exercise programme. Antiplatelet treatment is beneficial in patients with intermittent claudication for the reduction of vascular events but has not previously been shown to influence claudication distance. This is an update of a review first published in 2007.

OBJECTIVES

To determine the effect of cilostazol (an antiplatelet treatment) on improving initial and absolute claudication distances, and in reducing mortality and vascular events in patients with stable intermittent claudication.

SEARCH METHODS

For this update, the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched October 2013) and CENTRAL (2013, Issue 9).

SELECTION CRITERIA

Double-blind, randomised controlled trials (RCTs) of cilostazol versus placebo, or versus other antiplatelet agents in patients with stable intermittent claudication.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trials for selection and independently extracted data. Disagreements were resolved by discussion. We performed the meta-analysis as a fixed-effect model with weighted mean differences (WMDs) and 95% confidence intervals (CIs) for continuous data, and odds ratios (ORs) with 95% CIs for dichotomous data.

MAIN RESULTS

We included fifteen double-blind, RCTs comparing cilostazol with placebo, or medications currently known to increase walking distance e.g. pentoxifylline. There were a total of 3718 randomised participants with treatment durations ranging from six to 26 weeks. All participants had intermittent claudication secondary to PAD. Comparisons included cilostazol twice daily, with dosages of 50 mg, 100 mg and 150 mg compared with placebo, and cilostazol 100 mg, twice daily, compared with pentoxifylline 400 mg, three times daily. The methodological quality of the trials was generally low, with the majority being at an unclear risk for selection bias, performance bias, detection bias and other bias. Attrition bias was generally low, but reporting bias was high or unclear in the majority of the studies. For eight studies data were compatible for comparison by meta-analysis, but data for seven studies were too heterogenous to be pooled. For the studies included in the meta-analysis, for initial claudication distance (ICD - the distance walked on a treadmill before the onset of calf pain) there was an improvement in the cilostazol group for the 100 mg and 50 mg twice daily, compared with placebo (WMD 31.41 metres, 95% CI 22.38 to 40.45 metres; P < 0.00001) and WMD 19.89 metres, 95% CI 9.44 to 30.34 metres; P = 0.0002), respectively. ICD was improved in the cilostazol group for the comparison of cilostazol 150 mg versus placebo and cilostazol 100 mg versus pentoxifylline, but only single studies were used for these analyses. Absolute claudication distance (ACD - the maximum distance walked on a treadmill) was significantly increased in participants taking cilostazol 100 mg and 50 mg twice daily, compared with placebo (WMD 43.12 metres, 95% CI 18.28 to 67.96 metres; P = 0.0007) and WMD 32.00 metres, 95% CI 14.17 to 49.83 metres; P = 0.0004), respectively. As with ICD, ACD was increased in participants taking cilostazol 150 mg versus placebo, but with only one study an association cannot be clearly determined. Two studies comparing cilostazol to pentoxifylline had opposing findings, resulting in an imprecise CI (WMD 13.42 metres (95% CI -43.51 to 70.35 metres; P = 0.64). Ankle brachial index (ABI) was lowered in the cilostazol 100 mg group compared with placebo (WMD 0.06, 95% CI 0.04 to 0.08; P < 0.00001). The single study evaluating ABI for the comparison of cilostazol versus pentoxifylline found no change in ABI.There was no association between treatment type and all-cause mortality for any of the treatment comparisons, but there were very few events, and therefore larger, adequately powered studies will be needed to assess if there is a relationship. Only one study evaluated individual cardiovascular events, and from this study there is no clear evidence of a difference between any of the treatment groups and risk of myocardial infarction or stroke. We evaluated adverse side effects, and in general cilostazol was associated with a higher odds of headache, diarrhoea, abnormal stool, dizziness and palpitations. We only reported quality of life measures descriptively as there was insufficient statistical detail within the studies to combine the results, although there was a possible indication in improvement of quality of life in the cilostazol treatment groups.

AUTHORS' CONCLUSIONS

Cilostazol has been shown to be of benefit in improving walking distance in people with intermittent claudication secondary to PAD. Although there is an increase in adverse side effects, they are generally mild and treatable. There is currently insufficient data on whether taking cilostazol results in a reduction of all-cause mortality and cardiovascular events or an improvement in quality of life. Future research into the effect of cilostazol on intermittent claudication should carefully consider comparability, sample size and homogeneity when designing a study.

Antiplatelet therapy in critical limb ischemia: update on clopidogrel and cilostazol

Antiplatelet therapy is essential for critical limb ischemia (CLI) patients, both as primary prevention for ischemic events and as adjuvant pharmacotherapy in order to avoid acute or late thrombo-occlusive events and maintain patency following peripheral endovascular or open surgical limb-salvage revascularization procedures. According to currently updated international guidelines clopidogrel as monotherapy or as part of dual antiplatelet therapy is recommended in CLI patients, while recent evidence delineated the beneficial effect of cilostazol in patients undergoing peripheral endovascular angioplasty or stenting as its administration resulted in a decrease of restenosis and clinically-driven reinterventions, as well as in the enhancement of platelet inhibition. This review aims in discussing recent evidence on the topic of antiplatelet therapy in CLI patients, with a special focus on the use of clopidogrel and cilostazol.

Role of Ser102 and Ser104 as regulators of cGMP hydrolysis by PDE5A

Background

Phosphodiesterases (PDEs) cleave phosphodiester bonds in cyclic nucleotides and play diverse roles in cell biology. PDE5A is a cytoplasmic phosphodiesterase which specifically degrades cyclic guanosine monophosphate (cGMP), a cell signaling molecule that plays important roles in neuronal signaling and vascular smooth muscle contraction. Inhibition of PDE5A induces headache resembling migraine headaches.

Aim

To test the hypothesis that Ser102 and Ser104 in PDE5A and/or their phosphoserine derivatives 1) regulate the intracellular localization and/or activity of PDE5A, and 2) modulate the interaction between PDE5A and pharmaceutical reagents in clinical or pre-clinical use for migraine headaches and other types of vascular dysfunction.

Methods

Wild type PDE5A or PDE5A with substitution mutations (Ser102Ala, Ser104Ala or Ser102Ala/Ser104Ala) were overexpressed in SK-N-AS neuroblastoma cells as C-terminal fusions with green fluorescent protein. Transfected cells were treated with sildenafil, cilostazol, glyceryl trinitrate, calcitonin gene-related peptide (CGRP) or sumatriptan. PDE5A-GFP fusion proteins were localized in fixed cells by immunofluorescence and PDE activity was quantified in cell extracts by standard in vitro assay using [³H] cGMP.

Results

The intracellular distribution of wild-type, single and double mutant PDE5A was similar and was not altered by exposure to sildenafil, cilostazol, glyceryl trinitrate, calcitonin gene-related peptide (CGRP) or sumatriptan. PDE5 activity was similar for wild type, Ser102Ala and Ser104Ala PDE5A, but activity of the Ser102Ala/Ser104Ala mutant was approximately two-fold higher than wild type. Double mutant Ser102Ala/Ser104Ala migrated as a single band on a native acrylamide gel, while wild-type and single mutant PDE5A migrated as a doublet.

Interpretation

Ser102 and Ser104 may influence the conformational flexibility of PDE5A, which may in turn influence phosphorylation status, allosteric regulation by cGMP or other as yet unknown regulatory mechanisms for PDE5A. PDE5A activation could be important in reversal of migraine-like headache.

Effect of cilostazol on carotid intima-media thickness in type 2 diabetic patients without cardiovascular event

We investigated the efficacy of cilostazol treatment for 2 years on the attenuation of carotid intima-media thickness (IMT) progression in type 2 diabetic patients without cardiovascular disease history, as compared with other antiplatelet agents. We recruited a total of 230 type 2 diabetic patients who had undergone IMT measurement twice within 1.5-2.5 years (mean 2.06 ± 0.32 years) interval. Among these participants, we classified them into three groups according to antiplatelet agent administration at baseline: Group I (n = 66), antiplatelet naïve; Group II (n = 75), other antiplatelet agent administration; and Group III (n = 50), cilostazol administration. We then analyzed the changes in clinical characteristics from baseline to 2 years. The changes in annual mean IMT at 2 years were 0.019 ± 0.045 mm/year, -0.001 ± 0.058 mm/year, and -0.019 ± 0.043 mm/year for Group I, II, and III, respectively (P < 0.001). Mean change in total cholesterol, low-density lipoprotein-cholesterol, and triglyceride compared with baseline decreased the most in Group III even after adjustment for statin use. We also observed that the odds ratio of carotid IMT progression at 2 years was the lowest in patients who were treated with cilostazol even after adjustment for change of metabolic parameters. When we categorized patients according to baseline carotid IMT tertile, the efficacy of cilostazol against carotid IMT progression was significant only when baseline IMT was over 0.662 mm (mean 0.801). Two-year treatment with cilostazol strongly inhibited carotid IMT progression compared to other antiplatelet agents in type 2 diabetic patients. This beneficial effect of cilostazol was significant when baseline IMT was thicker than 0.662 mm (mean 0.801 mm).

Three types of ependymal cells with intracellular calcium oscillation are characterized by distinct cilia beating properties

Ependymal cells are multiciliated epithelial cells that line the ventricles in the adult brain. Abnormal function or structure of ependymal cilia has been associated with various neurological deficits. For the first time, we report three distinct ependymal cell types, I, II, and III, based on their unique ciliary beating frequency and beating angle. These ependymal cells have specific localizations within the third ventricle of the mouse brain. Furthermore, neither ependymal cell types nor their localizations are altered by aging. Our high-speed fluorescence imaging analysis reveals that these ependymal cells have an intracellular pacing calcium oscillation property. Our study further shows that alcohol can significantly repress the amplitude of calcium oscillation and the frequency of ciliary beating, resulting in an overall decrease in volume replacement by the cilia. Furthermore, the pharmacological agent cilostazol could differentially increase cilia beating frequency in type II, but not in type I or type III, ependymal cells. In summary, we provide the first evidence of three distinct types of ependymal cells with calcium oscillation properties.

Cilostazol prevents the degradation of collagen type II in human chondrocytes

The alteration of extracellular matrix (ECM) in cartilage during the pathological development of Osteoarthritis (OA) changes the biomechanical environment of chondrocytes, which further drives the progression of the disease in the presence of inflammation. Healthy cartilage matrix mainly contains collagen type II, which is degraded by matrix metalloproteinase13 (MMP13), an important molecules responsible for joint damage in OA. Cilostazol (6-[4-(1-cyclohexyl-1H-tetrazol-5-yl)butoxy]-3,4-dihydro-2-(1H)-quinolinone) is a medication approved by the US Food and Drug Administration and used in the alleviation of the symptom of intermittent claudication in individuals with peripheral vascular disease. In this study, we reported that cilostazol is able to suppress the degradation of type II collagen in human chondrocytes induced by IL-1β. Mechanistically, cilostazol treatment leads to inhibiting the expression of IRF-1, thereby prevents the induction of MMP-13. Signal transducers and activator of transcription 1 (STAT1) has been reported to play an essential role in regulating the activation of IRF-1. Our results indicated that cilostazol suppresses the activation of STAT1 by mitigating the phosphorylation of STAT1 at Ser727 and tyrosine phosphorylation of STAT1 at position 701 (Tyr701).

Inhibition of HMGB1-induced angiogenesis by cilostazol via SIRT1 activation in synovial fibroblasts from rheumatoid arthritis

High mobility group box chromosomal protein 1 (HMGB-1) released from injured cells plays an important role in the development of arthritis. This study investigated the anti-angiogenic effects of cilostazol in collagen-induced arthritis (CIA) of mice, and the underlying mechanisms involved. The expressions of HIF-1α, VEGF, NF-κB p65 and SIRT1 in synovial fibroblasts obtained from rheumatoid arthritis (RA) patients were assessed by Western blotting, and in vitro and in vivo angiogenesis were analyzed. Tube formations by human microvascular endothelial cells (HMVECs) were significantly increased by direct exposure to HMGB1 or to conditioned medium derived from HMGB1-stimulated RA fibroblasts, and these increases were attenuated by cilostazol, the latter of which was blocked by sirtinol. HMGB1 increased the expression of HIF-1α and VEGF and concomitantly increased nuclear NF-κB p65 and DNA binding activity, but these effects of HMGB1 were inhibited by cilostazol. SIRT1 protein expression was time-dependently decreased (3–24 hr) by HMGB1, which was recovered by pretreatment with cilostazol (1–30 µM) or resveratrol, accompanying with increased SIRT1 deacetylase activity. In the tibiotarsal joint tissues of CIA mice treated with vehicle, HIF-1α- and VEGF-positive spots and CD31 staining were markedly exaggerated, whereas SIRT1 immunofluorescence was diminished. These variables were wholly reversed in cilostazol (30 mg/kg/day)-treated mice. Furthermore, number of blood vessels stained by von Willebrand factor antibody was significantly lower in cilostazol-treated CIA mice. Summarizing, cilostazol activated SIRT1 and inhibited NF-κB-mediated transcription, thereby suppressing the expression of HIF-1α and VEGF. In addition, cilostazol caused HIF-1α deacetylation by enhancing SIRT1 activity and reduced VEGF production, thereby had an anti-angiogenic effect in vitro studies and in CIA murine model.

Cilostazol improves hippocampus-dependent long-term memory in mice

RATIONALE

Phosphodiesterases (PDEs) play an important role in the regulation of intracellular signaling mediated by cyclic adenosine monophosphate (cAMP). Recently, several PDE inhibitors were assessed for their possible cognitive enhancing properties. However, little is known about the effect of PDE3 inhibitors on memory function.

OBJECTIVES

We examined how the PDE3 inhibitor cilostazol affects C57BL/6 J mice as they perform various behavioral tasks. After behavioral assessment, brains of the mice were analyzed immunohistochemically to quantify the phosphorylation of cAMP-responsive element binding protein (CREB), a downstream component of the cAMP pathway.

RESULTS

Oral administration of cilostazol significantly enhanced recollection of the exact platform location in the Morris water maze probe test. Cilostazol also improved context-dependent long-term fear memory, without affecting short-term memory. No apparent effect was observed in cue-dependent fear memory. The results suggest that cilostazol selectively improves hippocampus-dependent long-term memory in these tasks. Cilostazol also significantly increased the number of phosphorylated-CREB-positive cells in hippocampal dentate gyrus.

CONCLUSIONS

These results suggest that cilostazol may exert its beneficial effects on learning and memory by enhancing the cAMP system in hippocampus, where it increases intracellular cAMP activity.

Cilostazol renoprotective effect: modulation of PPAR-γ, NGAL, KIM-1 and IL-18 underlies its novel effect in a model of ischemia-reperfusion

Cilostazol, a phosphodiesterase-III inhibitor, reportedly exhibits positive effects against ischemia/reperfusion (I/R)-induced injury in several models. However, its potential role against the renal I/R insult has not been elucidated. To test whether the PPAR-γ (of peroxisome proliferator activated receptor gamma) pathway is involved in the cilostazol effect, rats were randomized into sham, I/R, cilostazol (50 and 100 mg/kg per day, orally), pioglitazone (3 and 10 mg/kg per day, orally) and their combination at the low dose levels. Drugs regimens were administered for 14 days prior to the I/R induction. Pretreatment with cilostazol or pioglitazone provided significant protection against the I/R-induced renal injury as manifested by the attenuated serum levels of creatinine, blood urea nitrogen and cystatin C. Both drugs have also opposed the I/R-induced elevation in tissue contents/activity of neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (Κim-1), nuclear factor-κB, interleuκin-18, caspase-1, as well as malondialdehyde, iNOS, myeloperoxidase, ICAM-1 and VCAM-1. Nevertheless, the drugs increased both the PPAR-γ transcriptional activity and the content of glutathione. Furthermore, combining the two low doses of both drugs produced effects comparable to that of the high dose level of either drug, advocating the fortification of pioglitazone renoprotective effect when given concomitantly with cilostazol. In conclusion, cilostazol purveyed conceivable novel renoprotective mechanisms and alleviated incidents associated with acute renal injury either alone or in combination with pioglitazone partially via the elevation of PPAR-γ besides the amendment of the aforementioned biomarkers.

Cilostazol induces mitochondrial fatty acid β-oxidation in C2C12 myotubes

Cilostazol is a drug licensed for the treatment of intermittent claudication. Its main action is to elevate intracellular levels of cyclic monophosphate (cAMP) by inhibiting the activity of type III phosphodiesterase, a cAMP-degrading enzyme. The effects of cilostazol on fatty acid oxidation (FAO) are as yet unknown. In this study, we report that cilostazol can elevate complete FAO and decrease both triacylglycerol (TAG) accumulation and TAG secretion. This use of cilostazol treatment increases expression of PGC-1α and, subsequently, its target genes, such as ERRα, NOR1, CD36, CPT1, MCAD, and ACO. Expression of these factors is linked to fatty acid β-oxidation but this effect is inhibited by H-89, a specific inhibitor of the PKA/CREB pathway. Importantly, knockdown of PGC-1α using siRNA abolished the effects of cilostazol in fatty acid oxidation (FAO) and TAG metabolism. These findings suggested that the PKA/CREB/PGC-1α pathway plays a critical role in cilostazol-induced fatty acid oxidation and TAG metabolism.

Triple versus dual antiplatelet therapy after percutaneous coronary intervention for coronary bifurcation lesions: results from the COBIS (COronary BIfurcation Stent) II Registry

The efficacy and safety of adding cilostazol to aspirin plus clopidogrel (triple antiplatelet therapy, TAPT) have not been fully evaluated in complex percutaneous coronary intervention (PCI). We sought to investigate whether TAPT after PCI for bifurcation lesions improves long-term clinical outcomes. Consecutive patients undergoing PCI for bifurcation lesions were enrolled from 18 centers in Korea between 2003 and 2009. We compared target vessel failure (TVF), defined as a composite of cardiac death, myocardial infarction (MI), and target vessel revascularization (TVR), among 675 patients who received TAPT and 2081 who received dual antiplatelet therapy (DAPT: aspirin plus clopidogrel). Patients who received TAPT had more cardiovascular co-morbidities with regard to clinical, angiographic, and procedural characteristics. During the follow-up (median 36 months), 346 (12.6%) TVFs occurred. The incidence of TVF was significantly higher in the TAPT group, mainly driven by a higher TVR rate. In the TAPT group, however, the risk of TVF was not significantly different from the DAPT group after adjusting for the confounders of TVFs (adjusted hazard ratio [HR] 0.86, 95% confidence interval [CI] 0.53-1.39, p = 0.53). And also, there were no significant differences between the 2 groups in terms of the risks for death, cardiac death, MI, TVR, stent thrombosis, or cerebrovascular accident. These results were consistent after propensity score-matched analysis, and were also constant among the high-risk subgroups. TAPT after bifurcation PCI had no beneficial effect on the risk of long-term clinical outcomes in real-world clinical practice. Further studies are needed to confirm these findings.

Cilostazol effectively attenuates deterioration of albuminuria in patients with type 2 diabetes: a randomized, placebo-controlled trial

Cilostazol is an antiplatelet, antithrombotic agent with anti-inflammatory properties. To date, no clinical study has specifically evaluated the efficacy of cilostazol in patients with diabetic nephropathy (DN). We hypothesized that cilostazol might delay renal deterioration in DN patients at high risk of progression. Between April 2008 and April 2010, we screened 156 consecutive patients aged 35-80 years who were first diagnosed with type 2 diabetes after the age of 30 years. Of these, 90 patients with DN, as defined by morning spot urine microalbuminuria (MAU) >20 mg/L or an albumin-to-creatinine ratio (ACR) >30 μg/mg on at least two consecutive occasions within the prior 3 months, were enrolled into a 52-week randomized, single-blinded, placebo-controlled trial of oral cilostazol 100 mg twice daily or placebo (45 subjects in each group). Morning spot urine samples were collected to determine MAU and ACR. Fasting plasma levels of metabolic, endothelial variables, and inflammatory markers were examined. Following 52 weeks of treatment, urinary MAU and ACR were significantly reduced in the cilostazol group compared with the placebo group (P = 0.024 and P = 0.02, respectively). In regression analyses, changes in monocyte chemotactic protein-1, E-selectin, and soluble vascular cell adhesion molecule-1 (sVCAM-1) were significantly associated with changes in MAU and ACR. Net changes of E-selectin (P < 0.001) and sVCAM-1 (P < 0.05) were independent predictors of change in MAU and ACR, respectively. Our results suggest that cilostazol may effectively attenuate deterioration of albuminuria in patients with type 2 diabetes. This effect is likely mediated by an improvement of adhesion molecules.

Cilostazol add-on therapy in patients with mild dementia receiving donepezil: a retrospective study

Goal

Combinatorial therapy directed at both vascular and neurodegenerative aspects of dementia may offer a promising strategy for treatment of dementia, which often has a multifactorial basis in the elderly. We investigated whether the phosphodiesterase III inhibitor cilostazol, which is often used in the prevention of stroke and peripheral artery disease, may delay cognitive decline in the elderly receiving donepezil.

Methods

Medical records were retrospectively surveyed to identify patients who had received donepezil for more than one year and had undergone Mini-Mental State Examination (MMSE) at least at two time points. Those with an initial MMSE score of less than 27 points were subjected to analysis (n = 156), with a cut-point of 21/22 applied to assign them to mild (n = 70) and moderate/severe (n = 86) dementia. The change of total MMSE score per year was compared between patients who had received donepezil and those given both donepezil and cilostazol.

Findings

In patients with mild dementia who had received donepezil and cilostazol (n = 34; 77.2±6.8 years old), the annual change in MMSE score was −0.5±1.6 during an observational period of 28.6±11.7 months, with those receiving donepezil only (n = 36; 78.4±6.5 years old) scoring less (−2.2±4.1) during 30.4±12.8 months with a statistical intergroup difference (p = 0.022). Multivariate analysis showed that absence of cilostazol treatment was the only significant predictor of MMSE decline. A positive effect of cilostazol was found in three subscale scores of MMSE, orientation for time or place and delayed recall. By clear contrast, in patients with moderate/severe dementia, there were no intergroup differences in decrease of total or subscale MMSE scores between the two groups.

Conclusions

These results suggest potential for cilostazol treatment in the suppression of cognitive decline in patients receiving donepezil with mild dementia but not in those with moderate/severe dementia.

Predictors of symptomatic and asymptomatic intracranial atherosclerosis: what is different and why?

AIM

The prognoses of symptomatic and asymptomatic intracranial atherosclerotic stenosis(ICAS) differ. Understanding the underlying pathomechanisms and predictors of progression or regression may help to clarify the differences. We herein attempted to compare the course and predictors of symptomatic ICAS to those of coexisting asymptomatic ICAS.

METHODS

This was a post-hoc analysis of the 'Trials of Cilostazol in Symptomatic intracranial arterial stenosis-2(TOSS-2)' study, which recruited patients with acute symptomatic ICAS receiving intensive medical treatment. Changes in the status of ICAS were classified as being indicative of regression, progression or no changes. Univariate and multivariate ordinal regression analyses were performed to identify predictors of symptomatic and asymptomatic ICAS based on clinical, laboratory and radiologic data.

RESULTS

Of the 409 patients, symptomatic ICAS demonstrated regression in 110(27%) cases and progression in 52(13%) cases. Among these patients, 250(61.1%) had asymptomatic ICAS, which regressed in 38(15%) cases and progressed in 16(6%) cases. Severe baseline stenosis, a high high-density lipoprotein(HDL) cholesterol level and the use of cilostazol were found to be independently associated with a favorable course of symptomatic ICAS(p＜0.001, p=0.005 and p=0.038, respectively). Regarding asymptomatic ICAS, severe stenosis, the use of angiotensin receptor antagonists and a low fasting glucose level were associated with a favorable course(p＜0.001, p=0.011 and p=0.007, respectively).

CONCLUSIONS

Changes in atherosclerosis are more dynamic in patients with symptomatic ICAS, and the predictors of symptomatic and asymptomatic ICAS differ. In this study, changes in the status of symptomatic ICAS were associated with the level of HDL cholesterol, which is known to affect the regression of atherosclerosis and vascular remodeling.

Homocysteine as a predictor of early neurological deterioration in acute ischemic stroke

BACKGROUND AND PURPOSE

Hyperhomocysteinemia is a well-known risk factor for vascular disease. However, its action, mechanism, and role in the acute phase of stroke have not been determined. We tried to determine whether an association existed between elevated serum homocysteine levels and early neurological deterioration (END) in patients with acute ischemic stroke.

METHODS

We performed a secondary analysis from the Cilostazol in Acute Ischemic Stroke Treatment (CAIST) trial, which was a double-blinded, randomized, multicenter trial, assessing the noninferiority of cilostazol over aspirin within 48 hours of an acute ischemic stroke. END was defined as an increase of ≥1 point in motor power or an increase of ≥2 points in the total National Institute of Health Stroke Scale score within 7 days.

RESULTS

The mean (±SD) serum homocysteine level was 11.4±4.7 μmol/L. Of the 396 patients studied, 57 (14.4%) patients worsened during the 7 days after inclusion. Most (68%) of the END cases occurred within the first 24 hours after treatment. High levels (>10.3 μmol/L) of serum homocysteine were independent predictors for END (third quartile odds ratio, 3.45; 95% confidence intervals, 1.25-9.50; P=0.016; fourth quartile odds ratio, 3.36; 95% confidence intervals 1.18-9.52; P=0.023) in multivariate analysis.

CONCLUSIONS

Patients with acute stroke with elevated serum homocysteine levels are at an increased risk for END.

Cilostazol: improving walking distance in patients with intermittent claudication

Intermittent claudication is a common, disabling symptom of peripheral arterial disease that limits walking distance and is associated with an increased cardiovascular risk of acute limb- or life-threatening complications. Very few patients with intermittent claudication (<7%) are suitable candidates for surgical revascularization, yet in contrast to the treatment of stable angina, few effective medical therapies (apart from exercise) are available for the symptomatic relief of intermittent claudication. The phosphodiesterase-3 inhibitor, cilostazol (Pletal, Otsuka Pharmaceuticals Ltd), is the first symptom-relieving treatment for intermittent claudication that has been evaluated successfully in large multicenter placebo-controlled, double-blind clinical trials (involving >2000 patients). A meta-analysis of the eight major efficacy studies with cilostazol has shown significant improvements in pain-free and maximum walking distance, and a good overall safety and tolerability profile. Thus, in the UK, USA and Japan, cilostazol administered at 100 mg twice daily is licensed for symptom relief in patients with stable, moderate-to-severe intermittent claudication, as an adjunct to nonpharmacological approaches such as exercise.

The blood glucose level increased in parallel with the heart rate following cilostazol administration in three diabetic patients

Cilostazol, a phosphodiesterase III inhibitor, is known to increase the heart rate; however, its effects on glucose metabolism remain unclear. We observed that the blood glucose level varied in parallel with the heart rate immediately after starting or stopping cilostazol therapy in three patients with type 2 diabetes. This finding indicates that cilostazol induces hyperglycemia and tachycardia in a portion of diabetic patients, presumably via similar pharmacological effects on different organs. Much more attention should be paid to the possible effects of cilostazol on glycemic control, including taking into consideration the risk-benefit ratio of cilostazol use and individual circumstances.

The hypolipidemic effect of cilostazol can be mediated by regulation of hepatic low-density lipoprotein receptor-related protein 1 (LRP1) expression

OBJECTIVES

Cilostazol, a selective phosphodiesterase 3 (PDE3) inhibitor, is a vasodilator and an anti-thrombotic agent. The mechanism whereby cilostazol reduces plasma triglyceride is not completely understood. Here we investigated the effect of cilostazol on a remnant lipoprotein receptor, low-density lipoprotein receptor-related protein 1 (LRP1), which has been reported to play an essential role in clearance of circulating triglyceride in the liver.

MATERIALS/METHODS

Total cellular expression, and functional and transcriptional regulation of LRP1 were analyzed in human hepatocarcinoma cell lines incubated with cilostazol. Also, C57BL/6 mice were subjected to high-fat diet (60% kcal) and cilostazol (30 mg/kg) treatment for 10 weeks.

RESULTS

Cilostazol increased both mRNA and protein expression of LRP1 in HepG2 and Hep3B cells. In addition, enhanced transcriptional activity of the LRP1 promoter containing a peroxisome proliferator response element (PPRE) was observed after cilostazol exposure. Cilostazol treatment enhanced the uptake of lipidated apoE3, and this effect was abolished when LRP1 was silenced by siRNA knockdown. High-fat diet induced hyperglycemia with high level of plasma triglycerides, and reduced hepatic LRP1 expression in mice. Treatment with cilostazol for the same period of time, however, successfully prevented this down-regulation of LRP1 expression and reduced plasma triglycerides.

CONCLUSION

Taken together, our results demonstrated that cilostazol enhances LRP1 expression in liver by activating PPARγ through the PPRE in the LRP1 promoter. Increased hepatic LRP1 may be essential for the reduction of circulating triglycerides brought about by cilostazol.

Long-term pharmacological therapy of Brugada syndrome: is J-wave attenuation a marker of drug efficacy?

We herein describe two patients with Brugada syndrome in whom J-waves were successfully modified by drugs. Case 1 was a 54-year-old man who presented with repeated ventricular fibrillations (VF) and J-point elevation in the right precordial and lateral leads. After administration of cilostazol (200 mg/d), J-waves disappeared and coved-type ST-segment elevation changed to a saddleback-type for 25 months. Case 2 was a 31-year-old man who presented with a VF storm and J-point elevation in the lateral leads. After administration of quinidine (300 mg/d), J-waves and coved-type ST-segment elevation disappeared for 20 months. J-wave disappearance and coved-type ST-segment elevation were followed by VF suppression, probably due to transient outward potassium current (Ito) suppression.

Combined therapeutic effect of probucol and cilostazol on endothelial function in patients with silent cerebral lacunar infarcts and hypercholesterolemia: a preliminary study

OBJECTIVE

This study evaluated the efficacy of combined therapy with probucol and cilostazol on endothelial function in silent lacunar cerebral infarcts (SLCI) and mild hypercholesterolemia.

SUBJECTS AND METHODS

Flow-mediated vasodilatation (FMD) and nitroglycerin-induced vasodilatation (NMD) were measured before and after 4 weeks of combined therapy with probucol (500 mg/day) and cilostazol (200 mg/day) in 34 patients with a mean age of 72 ± 7 years (range 57-80 years) with SLCI, mild hypercholesterolemia (low-density lipoprotein cholesterol >100 mg/dl) and impaired endothelial function (FMD <6%). Patients were randomly allocated to one of the following two treatment groups: (1) aspirin (100 mg/day) with behavioral modifications, such as diet and/or exercise therapy (A group or control group, n = 17), and (2) probucol and cilostazol treatment (PC group, n = 17), also with behavioral modifications.

RESULTS

Although the baseline FMD was not different between the two treatment arms (2.7 ± 1.5 vs. 2.6 ± 1.5%, n.s.), the posttreatment FMD was significantly improved in the PC group (from 2.7 ± 1.5 to 3.5 ± 1.7%, p < 0.05) but not in the A group (from 2.6 ± 1.5 to 2.9 ± 1.4%, n.s.). No differences were observed between baseline and posttreatment NMD in either group. The effects of treatments on lipid profiles were more profound in the PC group.

CONCLUSION

Combined treatment with probucol and cilostazol resulted in subacute improvement in FMD/endothelial function in patients with SLCI with mild hypercholesterolemia. This combination therapy has the potential to reduce the risk of cardiovascular events via improvements in endothelial function and lipid profiles.

Long-term clinical efficacy and safety of adding cilostazol to dual antiplatelet therapy for patients undergoing PCI: a meta-analysis of randomized trials with adjusted indirect comparisons

OBJECTIVE

To assess the long-term clinical efficacy and safety of adding cilostazol to aspirin plus clopidogrel (triple antiplatelet therapy, TAT) in patients undergoing percutaneous coronary intervention (PCI) and explore its role in the era of new generation adenosine diphosphate (ADP)-receptor antagonists.

METHODS

PUBMED, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for randomized controlled trials (RCTs) comparing TAT versus dual antiplatelet therapy (DAT), followed by a manual search. Then, a meta-analysis of RCTs comparing TAT versus standard DAT in patients undergoing PCI was performed. Furthermore, indirect comparisons of TAT versus new generation ADP-receptor antagonist based DAT (prasugrel or ticagrelor based DAT) were undertaken, with standard DAT as a common comparator. The included end-points were major adverse cardiovascular event (MACE), target lesion revascularization (TLR), target vessel revascularization (TVR), death, myocardial infarction (MI), stent thrombosis, bleeding and other drug adverse events.

RESULTS

Twelve RCTs with a total of 31,789 patients were included. Compared with standard DAT (n = 2551), TAT (n = 2545) significantly reduced the incidence of MACE (OR: 0.56, 95% CI: 0.47-0.68, P < 0.00001), TLR (OR: 0.51, 95% CI: 0.34-0.75, P = 0.0006) and TVR (OR: 0.59, 95% CI: 0.46-0.75, P < 0.0001), and did not change significantly in death (OR: 0.68, 95% CI: 0.44-1.05, P = 0.08), MI (OR: 0.80, 95% CI: 0.45-1.44, P = 0.46), stent thrombosis (OR: 0.61, 95% CI: 0.27-1.36, P = 0.23), major bleeding (OR: 1.42, 95% CI: 0.52-3.85, P = 0.49) and overall bleeding (OR: 1.16, 95% CI: 0.79-1.69, P = 0.45). Compared with prasugrel (n = 6813) or ticagrelor based DAT (n = 6732), TAT (n = 2545) further reduced the incidence of MACE (OR: 0.80, 95% CI: 0.72-0.90, P = 0.0012; OR: 0.83, 95% CI: 0.75-0.92, P = 0.0003, respectively).

CONCLUSIONS

Compared with standard DAT, the long-term use of TAT in patients with PCI gives more benefits in reducing the incidence of MACE, TLR and TVR without increasing bleeding. Furthermore, it might be superior to prasugrel or ticagrelor based DAT in term of MACE, which needs to be confirmed by future studies with direct comparisons.

Cilostazol improves the response to ischemia in diabetic mice by a mechanism dependent on PPARγ

Cilostazol is effective for the treatment of peripheral ischemia. This compound has several beneficial effects on platelet aggregation, serum lipids and endothelial cells, and we recently found that it enhances collateral blood flow in the ischemic hind limbs of mice. Peroxisome proliferator-activated receptor (PPAR)γ, a receptor for thiazolidinediones, plays a role in angiogenesis. The aim of this work was to investigate the underlying molecular mechanisms and effects of cilostazol in a model of peripheral ischemia in diabetic mice. We induced diabetes in mice by streptozotocin (STZ) administration and studied ischemia-induced angiogenesis in the ischemic hind limbs of cilostazol-treated and untreated control mice. We found that perfusion recovery was significantly improved in treated compared with control diabetic mice. Interestingly, we found that the expression of PPARγ is reduced in ischemic tissues of diabetic mice. Furthermore, we discovered that local inhibition of the activity of this nuclear receptor decreased the angiogenic response to cilostazol treatment. Finally, we noted that this phenomenon is dependent on VEGF and modulated by PPARγ. Cilostazol administration enhances collateral blood flow in the ischemic hind limbs of STZ-induced diabetic mice through a PPARγ-dependent mechanism.

Cilostazol-induced relaxation of calf cardiac vein and coronary artery during cooling

OBJECTIVE

At present very little is known about the role of endothelial nitric oxide (NO) in the effects of temperature on vascular reactivity. The aim of the present study is to evaluate the influence of cooling (to 28 °C) on the vasodilatation induced by cilostazol(10-9-3x10-4M) on carbachol (10-6)-precontracted calf cardiac vein and coronary artery and the role of NO in these effects.

MATERIALS AND METHODS

Ring preparations of great cardiac vein and the anterior interventricular branch of left coronary artery were used.

RESULTS

Cilostazol produced concentration-dependent relaxation of calf cardiac vein and coronary artery rings precontracted with carbachol. During cooling, the pIC50 values, but not the maximal responses to cilostazol were significantly lower than at 37 °C in both preparations. Cooling to 28 °C in the presence of NG-nitro-L-arginine methyl ester (L-NAME, 10-4 M) did not modify the effect of temperature both in cardiac vein and coronary artery. These results demonstrate for the first time that cooling-induced changes of cilostazol in calf cardiac vein and coronary artery are independent of NO (Tab. 2, Fig. 3, Ref. 32).

Comparison of peri-procedural platelet inhibition with prasugrel versus adjunctive cilostazol to dual anti-platelet therapy in patients with ST segment elevation myocardial infarction

BACKGROUND

It has been well known that the inhibition of platelet aggregation (IPA) by anti-platelet agents was important to reduce the thrombo-embolic events in patients with ST segment elevation myocardial infarction (STEMI). However, the peri-procedural IPA by anti-platelet agents was not well known.

METHODS

We compared the peri-procedural IPA between prasugrel and adjunctive cilostazol to dual anti-platelet therapy (triple anti-platelet therapy; TAP) in patients with STEMI undergoing primary percutaneous coronary intervention (PCI). We prospectively randomized 70 consecutive clopidogrel-naive patients with STEMI planned PCI to either prasugrel [loading dose (LD) 60 mg; 37 patients] or TAP (LD aspirin 300 mg, clopidogrel 600 mg, and cilostazol 200mg; 33 patients). Primary end points of the study were the platelet reactivity unit (PRU) or % inhibition by the VerifyNow P2Y12 assay at pre-PCI and pre-discharge.

RESULTS

The drug loading to pre-PCI time was similar between prasugrel and TAP groups (25.4 ± 10.42 min vs. 25.5 ± 10.56 min, p=0.957). PRU at pre-PCI was significantly lower in prasugrel than in TAP (269.1 ± 71.69 vs. 306.5 ± 48.67, p=0.012). The lower PRU and greater % inhibition also observed in prasugrel than in TAP at pre-discharge (108.2 ± 60.51 vs. 238.1 ± 73.40; 63.6 ± 18.51% vs. 16.8 ± 17.91%, p<0.001 respectively). No differences in in-hospital bleeding complications between the two groups were observed.

CONCLUSION

Our study demonstrates that prasugrel could produce a significantly greater peri-procedural as well as in-hospital IPA compared with TAP in patients with STEMI undergoing primary PCI.

Cilostazol Reduces Angiographic Restenosis After Endovascular Therapy for Femoropopliteal Lesions in the Sufficient Treatment of Peripheral Intervention by Cilostazol Study

Background—

It remains unclear whether cilostazol, which has been shown to improve the clinical outcomes of endovascular therapy for femoropopliteal lesions, also reduces angiographic restenosis.

Methods and Results—

The Sufficient Treatment of Peripheral Intervention by Cilostazol (STOP-IC) study investigated whether cilostazol reduces the 12-month angiographic restenosis rate after percutaneous transluminal angioplasty with provisional nitinol stenting for femoropopliteal lesions. Two hundred patients with femoropopliteal lesions treated from March 2009 to April 2011 at 13 cardiovascular centers were randomly assigned 1:1 to receive oral aspirin with or without cilostazol. The primary end point was 12-month angiographic restenosis rate. Secondary end points were the restenosis rate on duplex ultrasound, the rate of major adverse cardiac events, and target lesion event-free survival. Researchers evaluated all follow-up data and assessed the end points in a blinded fashion. The mean lesion length and reference vessel diameter at the treated segment were 128±86 mm and 5.4±1.4 mm, respectively. The frequency of stent used was similar between groups (88% versus 90% in the cilostazol and noncilostazol group, respectively, P =0.82). During the 12-month follow-up period, 11 patients died and 152 patients (80%) had evaluable angiographic data at 12 months. The angiographic restenosis rate at 12 months was 20% (15/75) in the cilostazol group versus 49% (38/77) in the noncilostazol group ( P =0.0001) by intention-to-treat analysis. The cilostazol group also had a significantly higher event-free survival at 12 months (83% versus 71%, P =0.02), although cardiovascular event rates were similar in both groups.

Conclusions—

Cilostazol reduced angiographic restenosis after percutaneous transluminal angioplasty with provisional nitinol stenting for femoropopliteal lesions.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00912756; and URL: https://www.umin.ac.jp . Unique identifier: UMIN000002091.

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.

[The efficiency of cilostazol for cerebral vasospasm following subarachnoid hemorrhage]

Delayed ischemic deficit following subarachnoid hemorrhage(SAH)is a major source of morbidity and mortality after rupture of an intracranial aneurysm. Once symptomatic cerebral vasospasm has occured, available treatments do not provide good outcomes for all patients. Symptomatic vasospasm results in serious sequelae for 10-15% of patients and the etiology and pathogenesis remain unclear. Cilostazol is a specific inhibitor of cAMP(cyclic adenosine monophosphate)phosphodiesterase, and is used for treating ischemic symptoms of peripheral vascular disease. Cilostazol has various actions, such as inhibiting vascular smooth muscle proliferation, and increasing nitric oxide(NO)levels derived from endothelial cells. The present study included 81 patients with SAH caused by ruptured cerebral aneurysms treated in two hospitals between June, 2008 and September, 2009. All patients were treated with clipping surgery, and were classified into two groups: 25 patients who received cilostazol from postoperative day 1 to 14 or 28; and 56 control patients. Clinical symptoms due to cerebral vasospasm and frequency of severe spasm were compared between each of the groups. The frequencies of severe spasm appearing on angiography(age>65)and symptomatic cerebral vasospasm were lower in the cilostazol group than in controls. These findings suggest that cilostazol may prevent symptomatic cerebral vasospasm after subarachnoid hemorrhage.

Adjunctive cilostazol versus high maintenance dose of clopidogrel in patients with hyporesponsiveness to chronic clopidogrel therapy

PURPOSE

Whether addition of cilostazol is superior to increasing dose of clopidogrel in patients with hyporesponsiveness to chronic clopidogrel therapy is unknown.

MATERIALS AND METHODS

We studied 73 patients with hyporesponsiveness to clopidogrel on standard dual antiplatelet therapy for more than 2 weeks. Clopidogrel hyporesponsiveness was defined as percent inhibition of P2Y12 reaction units (PRU) <30% on VerifyNow P2Y12 assay. Patients were randomly assigned to increased dose of clopidogrel (aspirin 100 mg+clopidogrel 150 mg daily: group A, n=38) or to receiving additional cilostazol (aspirin 100 mg+clopidogrel 75 mg+cilostazol 100 mg bid daily: group B, n=35).

RESULTS

Baseline percent inhibition of PRU and PRU was similar between 2 groups (13.0 ± 10.2% versus 11.8 ± 9.7%, p = 0.61, and 286.3 ± 54.7 versus 295.7 ± 53.7, p=0.44, respectively). At follow-up, percent inhibition of PRU was higher and PRU was lower significantly in group B than in group A (38.5 ± 17.9% versus 28.3 ± 16.6%, p=0.02, and 207.3 ± 68.2 versus 241.3 ± 76.7, p=0.050, respectively). Among those still showing hyporesponsiveness to clopidogrel at follow-up (21 patients in group A, 10 patients in group B), 12 patients completed further crossover study. Compared to the baseline, magnitude of change in percent inhibition of PRU and PRU showed an improved tendency after the crossover (from 2.7 ± 8.7% to 15.8 ± 18.4%, p=0.08, and from -18.6 ± 58.0 to -61.9 ± 84.3, p=0.08).

CONCLUSION

Adjunctive cilostazol improved clopidogrel responsiveness better than the higher maintenance dose of clopidogrel in hyporesponsive patients with chronic clopidogrel therapy.

[Cilostazol inhibits proliferation and induces apoptosis in rat vascular smooth muscle cells through Rb-p53-p21 pathways]

OBJECTIVE

To explore the effects and related mechanisms of cilostazol on rat vascular smooth muscle cells (VSMCs)proliferation.

METHODS

VSMCs were treated with DMEM (control) and various doses of cilostazol (1.0×10(-7), 2.5×10(-7), 5.0×10(-7), 7.5×10(-7) and 1.0×10(-6) mol/L) for 13 d (cell counting) or 72 h. Proliferation of VSMCs was investigated by cell-counting, MTT and flow cytometry analysis. Cell apoptosis was determined by TUNEL staining. mRNA and protein expressions of cell cycle regulatory proteins, such as Rb, p53 and p21 were detected by RT-PCR and Western blot, respectively.

RESULTS

Cilostazol inhibited VSMCs proliferation and induced VSMCs arrest at G1 phase in a dose-dependent manner. High dose of cilostazol (7.5×10(-7) and 1.0×10(-6) mol/L) induced VSMCs apoptosis. p53 mRNA expression in 2.5×10(-7) mol/L to 7.5×10(-7) mol/L groups as well as 1.0×10(-6) mol/L group (3.22 ± 0.45 vs. 1.75 ± 0.32) and p53 protein expression in 7.5×10(-7) mol/L group and 1.0×10(-6) mol/L group (0.53 ± 0.11 vs. 0.18 ± 0.06) were significantly upregulated after 72 h culture (all P < 0.05 vs. control). Low dose of cilostazol (1.0×10(-7), 2.5×10(-7) and 5.0×10(-7) mol/L) significantly upregulated p21 mRNA expression compared to control group (1.86 ± 0.19, 2.20 ± 0.24 and 2.10 ± 0.18 vs. 1.210 ± 0.18, all P < 0.05). Similarly, Rb mRNA expression was significantly upregulated in 1.0×10(-7), 2.5×10(-7) and 5.0×10(-7) mol/L groups (0.89 ± 0.07 vs. 0.38 ± 0.04)compared with control group (all P < 0.05). However, high dose cilostazol (7.5×10(-7) and 1.0×10(-6) mol/L) significantly downregulated p21 mRNA expression (0.81 ± 0.09 vs. 1.21 ± 0.18, 0.36 ± 0.10 vs. 1.21 ± 0.18, all P < 0.05 vs. control) and Rb mRNA expression (0.12 ± 0.02 and 0.11 ± 0.02 vs. 0.38 ± 0.04, all P < 0.05 vs. control). p21 and Rb protein expressions also upregulated at low concentrations of cilostazol and downregulated at high concentrations of cilostazol.

CONCLUSION

Cilostazol could inhibit the proliferation of rat VSMCs through modulating Rb-p53-p21 pathway and induce VSMCs apoptosis through upregulating p53.

Dual antiplatelet therapy clopidogrel with low-dose cilostazol intensifies platelet inhibition in patients with ischemic stroke

OBJECTIVE

We previously reported that the antiplatelet action is intensified with combined use of clopidogrel and cilostazol in ischemic stroke patients using the VerifyNow P2Y12 Assay. In this study, the relationship between the cilostazol dose and the platelet function achieved with combination therapy was investigated.

METHODS

The subjects included 231 patients with noncardiogenic ischemic stroke treated at our hospital (18 patients treated with a combination of clopidogrel (75 mg) and cilostazol (100 mg), 52 patients treated with a combination of clopidogrel (75 mg) and cilostazol (200 mg), 126 patients treated with clopidogrel (75 mg) alone and 35 patients treated with cilostazol (200 mg) alone). The platelet function achieved with 20 μM of adenosine diphosphate was measured using the VerifyNow P2Y12 Assay. Clopidogrel resistance was defined as P2Y12 Reaction Units (PRU) >230 and/or % inhibition <20%. Results The PRU was >230 in 32 patients (25.4%) receiving clopidogrel alone, one patient (5.6%) receiving combination therapy with cilostazol (100 mg) and one patient (1.9%) receiving combination therapy with cilostazol (200 mg). The rate of PRU >230 was significantly lower in both of the cilostazol combination groups than in the clopidogrel alone group. The percent inhibition was <20% in 41 patients (32.5%) receiving clopidogrel alone, one patient (5.6%) receiving a combination with cilostazol (100 mg) and one patient (1.9%) receiving a combination with cilostazol (200 mg). The rate of % inhibition <20% was significantly lower in both of the cilostazol combination groups than in the clopidogrel alone group.

CONCLUSION

Clopidogrel resistance was clearly decreased with combination clopidogrel (75 mg) and low-dose (100 mg) cilostazol therapy. The use of combination therapy with clopidogrel and low-dose cilostazol may be one means of overcoming clopidogrel resistance.

Efficacy and safety of triple-antiplatelet therapy after percutaneous coronary intervention: a meta-analysis

BACKGROUND

The combination of cilostazol, aspirin and clopidogrel (triple antiplatelet therapy, TAT) after a percutaneous coronary intervention has been used as an alternative therapy. We performed a meta-analysis to evaluate the efficacy and safety of TAT for patients after percutaneous coronary intervention (PCI).

METHODS

We systematically searched Pubmed, Embase and Web of Science databases to identify all randomized controlled trials (RCTs) that compared dual antiplatelet therapy (DAT) with and without cilostazol after PCI. All analyses were conducted using Review Manager 5.0.

RESULTS

The final analysis consisted of 4474 patients from ten studies. The combined results suggested that there was a lower risk of cardiac death (relative risk (RR) = 0.55, 95% confidence interval (CI): 0.31 - 0.98, P < 0.05) and major adverse cardiac events (MACEs) (RR = 0.63, 95% CI: 0.54 - 0.74, P < 0.05) in patients treated with TAT as compared to those with DAT follow-ups after six months to one year; no significant difference was observed in bleeding and non-fatal myocardial infarction (MI) (RR = 1.14, 95% CI: 0.80 - 1.64, P > 0.05; RR = 0.87, 95% CI: 0.42 - 1.83, P > 0.05). However, the rate of adverse drug reaction was higher in patients receiving TAT than in patients receiving DAT (RR = 2.21, 95% CI: 1.84 - 2.66, P < 0.05). Moreover, there was a lower risk of stent thrombosis in patients treated with TAT as compared to those treated with DAT (RR = 0.44, 95% CI: 0.21 - 0.94, P < 0.05). The TAT group had a reduced risk of target lesion revascularization (TLR) (RR = 0.60, 95% CI: 0.43 - 0.82, P = 0.001) and target vessel revascularization (TVR) than the DAT group (RR = 0.56, 95% CI: 0.45 - 0.71, P < 0.05). The number of MACEs was lower for patients in the TAT group than in the DAT group with diabetes mellitus sub-analysis (RR = 0.41, 95% CI: 0.28 - 0.61, P < 0.05). But no significant difference was observed between the two groups regarding MACEs in patients with drug-eluting stent implantations (RR = 0.82, 95% CI: 0.65 - 1.03, P > 0.05).

CONCLUSION

TAT could significantly reduce the rates of MACEs and cardiac death in comparison to DAT, but more attention should be paid to adverse side effects of the drugs.

Cilostazol prevents endothelin-induced smooth muscle constriction and proliferation

Cilostazol is a phosphodiesterase inhibitor that has been shown to inhibit platelet activation. Endothelin is known to be the most potent endogenous growth promoting and vasoactive peptide. In patients and animal models with stroke, the level of circulating endothelin increases and complicates the recovery progress contributed by vascular constriction (an immediate pathology) and vascular proliferation (a long-term pathology). However, the effects of cilostazol on endothelin have not been explored. To demonstrate the dual-antagonizing effects of cilostazol on vasoconstriction and cell proliferation induced by endothelin, we used primary culture of mouse vascular smooth muscle cells in vitro, mouse femoral artery ex vivo, and intracranial basilar artery ex vivo. We show that the dual-inhibition effects of cilostazol are mediated by blocking endothelin-induced extracellular calcium influx. Although cilostazol does not inhibit endothelin-induced intraorganellar calcium release, blockade of extracellular calcium influx is sufficient to blunt endothelin-induced vasoconstriction. We also show that cilostazol inhibits endothelin-induced cellular proliferation by blocking extracellular calcium influx. Inhibition of cAMP-dependent protein kinase (PKA) can block anti-proliferation activity of cilostazol, confirming the downstream role of PKA in cellular proliferation. To further demonstrate the selectivity of the dual-antagonizing effects of cilostazol, we used a different phosphodiesterase inhibitor. Interestingly, sildenafil inhibits endothelin-induced vasoconstriction but not cellular proliferation in smooth muscle cells. For the first time, we show selective dual-antagonizing effects of cilostazol on endothelin. We propose that cilostazol is an excellent candidate to treat endothelin-associated diseases, such as stroke.

Repeated episodes of ischemic stroke over a short period in a patient with essential thrombocythemia on anticoagulant therapy

A 69-year-old man who had essential thrombocythemia, for which he was taking no medications, suddenly developed aphasia and right hemiplegia and was admitted to the hospital. He was thought to have had an embolic stroke and was initially treated with warfarin. Although the international normalized ratio was in the therapeutic range, he had 3 additional ischemic stroke episodes with the same symptoms after the index stroke. Magnetic resonance angiographic examinations revealed serial changes in middle cerebral artery stenosis. After administration of an antiplatelet agent and hydroxyurea, he had no additional strokes.

Cilostazol prevents progression of asymptomatic carotid artery stenosis in patients with contralateral carotid artery stenting

BACKGROUND AND PURPOSE

The progression of atherosclerosis is related to various factors. Although antiplatelet therapy is used for the management of acute ischemic stroke and for the prevention of recurrent stroke, the antiplatelet agent cilostazol may also reduce restenosis after stent implantation in any vessel. This study was performed to assess the impact of cilostazol on plaque progression in the carotid artery contralateral to a stented artery.

MATERIALS AND METHODS

Ninety-five patients who underwent contralateral CAS who also had ipsilateral 0%-79% ICS were enrolled. ICS was assessed by duplex sonography every 6 months and by MR imaging/angiography, and digital subtraction angiography if necessary, every 12 months according to the NASCET method. Patient age, sex, past history, and perioperative medical conditions were recorded.

RESULTS

While 22.1% of patients experienced disease progression, symptomatic ipsilateral stroke occurred in only 1.1% of patients over 36.2 ± 18.8 months. On multivariate analysis, precarotid stenosis (HR per 10% increase, 2.08; 95% CI, 1.43-3.05; P < .001) and cilostazol use (HR 0.16; 95% CI, 0.03-0.85; P = .03) were independent predictors for the progression of ICS.

CONCLUSIONS

A higher degree of initial stenosis is associated with progression of asymptomatic ICS. Cilostazol may reduce the rate of disease progression in patients with asymptomatic ICS.

Ginkgo biloba extract (GbE) enhances the anti-atherogenic effect of cilostazol by inhibiting ROS generation

In this study, the synergistic effect of 6-[4-(1-cyclohexyl- 1H-tetrazol-5-yl) butoxy]-3,4-dihydro-2(1H )-quinolinone (cilostazol) and Ginkgo biloba extract (GbE) was examined in apolipoprotein E (ApoE) null mice. Co-treatment with GbE and cilostazol synergistically decreased reactive oxygen species (ROS) production in ApoE null mice fed a high-fat diet. Co-treatment resulted in a significantly decreased atherosclerotic lesion area compared to untreated ApoE mice. The inflammatory cytokines and adhesion molecules such as monocyte chemoattractant-1 (MCP-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), and VCAM-1 which can initiate atherosclerosis were significantly reduced by the co-treatment of cilostazol with GbE. Further, the infiltration of macrophages into the intima was decreased by co-treatment. These results suggest that co-treatment of GbE with cilostazol has a more potent anti-atherosclerotic effect than treatment with cilostazol alone in hyperlipidemic ApoE null mice and could be a valuable therapeutic strategy for the treatment of atherosclerosis.

[Resistance to antiplatelet agents assessed by a point-of-care platelet function test and thromboembolic adverse events in neurointervention]

OBJECTIVE

To clarify the frequency of Japanese patients who are resistant to antiplatelet agents, and then clarify correlations between resistance and thromboembolic adverse events in neurointervention.

METHODS

Blood samples were collected from 163 patients who were taking antiplatelet agents and received neurointervention, with 128 samples collected just before neurointervention. Residual platelet function was measured using a point-of-care platelet function test, VerifyNow®, and then the frequency of patients resistant to drugs (low-responders), correlations between resistance and thromboembolic events, and effects of adding cilostazol to clopidogrel administration were analyzed. Cut-off values were defined as 550 Aspirin Reaction Units (ARU), 230 P2Y12 Reaction Units (PRU), and 50%inhibition of P2Y12, respectively.

RESULTS

Three of 105 patients (2.9%) taking aspirin at 100 mg/day were low-responders, whereas 48 (41.0%, as measured by PRU) or 80 (68.4%, as measured by %inhibition) of 117 patients taking clopidogrel at 75 mg/day were low-responders. Among the 19 patients taking cilostazol 200 mg/day in addition to clopidogrel 75 mg/day, platelet functions were significantly more strongly inhibited compared to patients taking clopidogrel alone (p=0.02 by PRU, p=0.005 by %inhibition). Thromboembolic adverse events occurred in 7 patients. Among these 7 patients, 6 who were taking aspirin were all responders to aspirin, while 4 of the 6 patients taking clopidogrel were low-responders to clopidogrel. In 69 patients who received aneurysmal transarterial embolization, 2 thromboembolic complications occurred among low-responders (p=0.09).

CONCLUSION

Aspirin resistance is rare in Japanese individuals. With aneurysmal transarterial embolization, thromboembolic events tended to occur among clopidogrel low-responders. Addition of cilostazol may offer one method of overcoming clopidogrel resistance.

Two-wavelength near-infrared fluorescence for the quantitation of drug antiplatelet effects in large animal model systems

OBJECTIVE

Intraoperative imaging of intravascular thrombi is limited by the inability of visible light to penetrate thick-walled vessels. Near-infrared (NIR) light has relatively high tissue penetration and low autofluorescence and scatter, offering significant advantages. We hypothesized that the development of 700-nm NIR fluorophores for platelet labeling, in conjunction with existing 800-nm NIR fluorophores, would permit simultaneous and separable quantitation of intravascular thrombi and measurement of the antiplatelet effect of drugs.

METHODS

We synthesized a series of lipophilic, cationic, polymethine indocyanine dyes (MHI-86, 94, 106, and 114) that emit at approximately 700 nm. Platelet uptake was optimized in vitro and the bioactivity and blood half-life of labeled platelets was characterized in vitro and in vivo. FeCl(3)-induced injury of the femoral arteries and intravascular thrombus formation was performed in 35-kg Yorkshire pigs. A combination of 700-nm and 800-nm NIR fluorophore-labeled platelets was used in conjunction with the fluorescence-assisted resection and exploration imaging system to image and quantify the antiplatelet effect of cilostazol and acetylsalicylic acid.

RESULTS

MHI-114 was incorporated at nearly 4.1 × 10(6) molecules per platelet without affecting platelet function. When infused into pigs, the signal-to-background ratio of MHI-114-labeled platelets exhibited a blood half-life of 16.4 ± 2.2 (mean ± SEM; n = 3) minute and generated a signal-to-background ratio of 2.5 ± 0.5 (mean ± SEM; n = 3) at the site of thrombi. Using dual-NIR-labeled platelet populations, cilostazol and acetylsalicylic acid were found to cause a reduction in platelet incorporation into thrombi of 51 ± 2% and 10 ± 1% (mean ± SEM; n = 3), respectively, relative to vehicle-only treated control thrombi.

CONCLUSIONS

New platelet-avid 700-nm NIR fluorophores permit simultaneous two-wavelength NIR fluorescence imaging and quantitation of intravascular thrombi in intact vessels approaching the size of humans and can be used to study the antiplatelet effect of drugs.