Cilostazol inhibits the expression of activation-dependent membrane surface glycoprotein on the surface of platelets stimulated in vitro

Differential inhibition of platelet function by cilostazol in combination with clopidogrel

PURPOSE

To assess the antiplatelet effect of cilostazol clinically, we compared the effects of cilostazol in combination with clopidogrel on various platelet function tests.

METHODS

We recruited patients with ischemic stroke at high risk of recurrence who were treated with clopidogrel alone within 180 days after stroke onset. Subjects underwent baseline platelet function tests, and were then randomly assigned to receive dual antiplatelet therapy (DAPT) comprising clopidogrel and cilostazol or clopidogrel monotherapy (SAPT). After 6 months, platelet function was measured again and compared to that at baseline in each group, and the rate of change was compared between groups.

RESULTS

Thirty-four patients were enrolled, but 4 patients were excluded for various reasons. In total, 30 subjects (13 in DAPT and 17 in SAPT group) were analyzed. Adenosine diphosphate- and collagen-induced aggregation, VerifyNow P2Y12 reaction units, vasodilator-stimulated phosphoprotein (platelet reactivity index: PRI) and plasma p-selectin concentration were significantly lower (P = 0.004, 0.042, 0.049, 0.003 and 0.006 respectively), while VerifyNow % inhibition was significantly higher at 6 months compared to baseline (P = 0.003) in the DAPT group only. Comparison of the rate of change in each parameter from baseline to 6 months showed that while PRI decreased at a greater rate (P = 0.012), VerifyNow % inhibition increased at a greater rate (P = 0.003) in the DAPT group than the SAPT group.

CONCLUSIONS

The inhibitory effects of adjunctive cilostazol added to clopidogrel on platelet function differed by type of platelet function test. VerifyNow % inhibition and PRI were more inhibited than the other platelet function tests.

TRIAL REGISTRATION

CSPS.com substudy in TWMU (UMIN000026672), registered on April 1, 2017. This study was performed as a substudy of CSPS.com (UMIN000012180, registered on October 31, 2013) and was retrospectively registered.

Triple Antiplatelet Therapy with Cilostazol and Favorable Early Clinical Outcomes after Acute Myocardial Infarction Compared to Dual Antiplatelet Therapy with Standard or Potent P2Y12 Inhibitors

Current guidelines for the management of acute myocardial infarction (AMI) recommend potent P2Y12 inhibitors rather than clopidogrel to prevent ischemic events. However, their ischemic benefits are offset by an increased major bleeding risk. We compared the efficacy and safety of triple antiplatelet therapy with cilostazol in the first month after AMI. This study investigated 16,643 AMI patients who received percutaneous coronary intervention (PCI) with drug-eluting stents (DES) in nationwide, real-world, multicenter registries in Korea. Patients were divided into DAPT (aspirin and clopidogrel, n = 11,285), Triple (aspirin, clopidogrel and cilostazol, n = 2547), and Potent (aspirin and ticagrelor/prasugrel, n = 2811) groups. The primary outcomes were net adverse clinical events (NACE), a composite of death from any cause, myocardial infarction (MI), stroke, and TIMI major bleeding one month after AMI. After adjusting for covariates, there were no statistically significant differences in the risk of death from any cause, MI, or stroke between the three groups. However, the risk of TIMI major bleeding was significantly greater in the Potent group than in the DAPT and Triple groups (p < 0.001). Accordingly, NACE was significantly higher in the DAPT (HR 1.265; 95% CI 1.006−1.591, p = 0.044) and Potent groups (HR 1.515; 95% CI 1.142−2.011, p = 0.004) than in the Triple group. Triple antiplatelet therapy with cilostazol was associated with an improved net clinical outcome in the first month after AMI without increasing the risk of bleeding compared to potent or standard P2Y12 inhibitor-based DAPT.

Electrospun poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) nanofibers for the controlled release of cilostazol

Drug delivery devices are attractive alternatives to drugs usually orally administrated. Therefore, this work aimed to produce PLA/PBAT-based nanofibers for the controlled release of cilostazol, evaluating the effect of different drug concentrations (20 and 30%) over the properties of the fibers. The fibers were characterized by scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), x-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric (TG/DTG), and mechanical analysis. SEM results indicated a high concentration of drug crystals on the surface of the fibers that contained 20% of cilostazol. These fibers were also thinner, more crystalline, less thermally stable, and less fragile in comparison to the fibers containing 30% of cilostazol, according to the XRD, DSC, TG/DTG, and mechanical results. The controlled release assays indicated that the fibers containing 20% of cilostazol would be attractive for short-term releases, reaching the equilibrium after approximately 6 h, while the ones containing 30% would ensure a slower release (~ 12 h). Despite the differences, both fibers would improve and enhance the efficiency of the treatment, and they would also prevent possible side effects caused by the drug to the gastric system.

Platelet-generated amyloid beta peptides in Alzheimer's disease and glaucoma

Amyloid beta (Aβ) peptides have been implicated in both Alzheimer's disease (AD) and glaucoma and have been shown to be the key etiological factor in these dangerous health complications. On the other hand, it is well known that Aβ peptide can be generated from its precursor protein and massively released from the blood to nearby tissue upon the activation of platelets due to their involvement in innate immunity and inflammation processes. Here we review evidence about the development of AD and glaucoma neuronal damage showing their dependence on platelet count and activation. The correlation between the effect on platelet count and the effectiveness of anti-AD and anti-glaucoma therapies suggest that platelets may be an important player in these diseases.

Mean Platelet Volume Is Associated with Early Neurological Deterioration in Patients with Branch Atheromatous Disease: Involvement of Platelet Activation

BACKGROUND

The most attentive clinical problem in patients with branch atheromatous disease (BAD) is early neurological deterioration (END). Although the platelet activation (PA) is involved in pathogenesis, the relationship between PA and END has remained unclear. We investigated clinical data including mean platelet volume (MPV, fL) as a marker for PA to identify clinically useful biomarkers for END.

METHODS

A total of 64 patients with BAD were investigated retrospectively, and divided into 2 groups based on whether neurologic symptoms deteriorated or not: BAD with and without END (END and non-END). The END was defined as patients with point increase of 1 or greater in the National Institutes of Health Stroke Scale (NIHSS); non-END was defined as those without such increase. Clinical features such as NIHSS, modified Rankin scale (mRS), laboratory data including MPV, lesion size (LS, mm) on admission, and treatments were compared between the 2 groups.

RESULTS

Of 64 patients, 17 cases had an END. The median values of NIHSS, mRS, MPV, and LS on admission were significantly greater in END than in non-END (P < .05, respectively). There was no correlation of MPV with NIHSS, mRS and LS, respectively. The median values of MPV were significantly higher in END than in non-END and control (P < .05, respectively). A receiver operating characteristic curve indicated a value of 10.1 as cutoff level for MPV to discriminate between END and non-END.

CONCLUSIONS

High MPV values on admission may be an independent biomarker for END. Physicians should pay more careful attention to END in BAD showing MPV values higher than 10.1 on admission.

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 versus aspirin for secondary prevention of vascular events after stroke of arterial origin

BACKGROUND

Aspirin is widely used for secondary prevention after stroke. Cilostazol has shown promise as an alternative to aspirin in Asian people with stroke.

OBJECTIVES

To determine the relative effectiveness and safety of cilostazol compared directly with aspirin in the prevention of stroke and other serious vascular events in patients at high vascular risk for subsequent stroke, those with previous transient ischaemic attack (TIA) or ischaemic stroke of arterial origin.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched September 2010), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, Issue 4), MEDLINE (1950 to May 2010) and EMBASE (1980 to May 2010). In an effort to identify further published, ongoing and unpublished studies we searched journals, conference proceedings and ongoing trial registers, scanned reference lists from relevant studies and contacted trialists and Otsuka Pharmaceutical Co Ltd.

SELECTION CRITERIA

We selected all randomised controlled trials (RCTs) comparing cilostazol with aspirin where participants were treated for at least one month and followed systematically for development of vascular events.

DATA COLLECTION AND ANALYSIS

Data extracted from eligible studies included: (1) a composite outcome of vascular events (stroke, myocardial infarction or vascular death) during follow up (primary outcome); (2) separate outcomes of stroke (ischaemic or haemorrhagic, fatal or non-fatal), myocardial infarction (MI) (fatal or non-fatal), vascular death and death from all causes; and (3) main outcomes of safety including any intracranial, extracranial or gastrointestinal (GI) haemorrhage and other outcomes during treatment follow up (secondary outcomes). We computed an estimate of treatment effect and performed a test for heterogeneity between trials. We analysed data on an intention-to-treat basis and assessed bias for all included studies.

MAIN RESULTS

We included two RCTs with 3477 Asian participants. Compared with aspirin, cilostazol was associated with a significantly lower risk of composite outcome of vascular events (6.77% versus 9.39%, risk ratio (RR) 0.72, 95% confidence interval (CI) 0.57 to 0.91), and lower risk of haemorrhagic stroke (0.53% versus 2.01%, RR 0.26, 95% CI 0.13 to 0.55). In terms of outcome of safety compared with aspirin, cilostazol was significantly associated with minor adverse effects (8.22% versus 4.95%, RR 1.66, 95% CI 1.51 to 1.83).

AUTHORS' CONCLUSIONS

Cilostazol is more effective than aspirin in the prevention of vascular events secondary to stroke. Cilostazol has more minor adverse effects, although there is evidence of fewer bleeds.

Study design and rationale of 'Influence of Cilostazol-based triple anti-platelet therapy on ischemic complication after drug-eluting stent implantation (CILON-T)' study: A multicenter randomized trial evaluating the efficacy of Cilostazol on ischemic vascular complications after drug-eluting stent implantation for coronary heart disease

Background

Current guidelines recommend dual anti-platelet therapy, aspirin and clopidogrel, for patients treated with drug-eluting stent for coronary heart disease. In a few small trials, addition of cilostazol on dual anti-platelet therapy (triple anti-platelet therapy) showed better late luminal loss. In the real-world unselected patients with coronary heart disease, however, the effect of cilostazol on platelet reactivity and ischemic vascular events after drug-eluting stent implantation has not been tested. It is also controversial whether there is a significant interaction between lipophilic statin and clopidogrel.

Methods/Design

CILON-T trial was a prospective, randomized, open-label, multi-center, near-all-comer trial to demonstrate the superiority of triple anti-platelet therapy to dual anti-platelet therapy in reducing 6 months' major adverse cardiovascular/cerebrovascular events, composite of cardiac death, nonfatal myocardial infarction, target lesion revascularization and ischemic stroke. It also tested whether triple anti-platelet therapy is superior to dual anti-platelet therapy in inhibiting platelet reactivity in patients receiving percutaneous coronary intervention with drug-eluting stent. Total 960 patients were randomized to receive either dual anti-platelet therapy or triple anti-platelet therapy for 6 months and also, randomly stratified to either lipophilic statin (atorvastatin) or non-lipophilic statin (rosuvastatin) indefinitely. Secondary endpoints included all components of major adverse cardiovascular/cerebrovascular events, platelet reactivity as assessed by VerifyNow P2Y12 assay, effect of statin on major adverse cardiovascular/cerebrovascular events, bleeding complications, and albumin-to-creatinine ratio to test the nephroprotective effect of cilostazol. Major adverse cardiovascular/cerebrovascular events will also be checked at 1, 2, and 3 years to test the 'legacy' effect of triple anti-platelet therapy that was prescribed for only 6 months after percutaneous coronary intervention.

Discussion

CILON-T trial will give powerful insight into whether triple anti-platelet therapy is superior to dual anti-platelet therapy in reducing ischemic events and platelet reactivity in the real-world unselected patients treated with drug-eluting stent for coronary heart disease. Also, it will verify the laboratory and clinical significance of drug interaction between lipophilic statin and clopidogrel.

Trial Registration

National Institutes of Health Clinical Trials Registry (ClinicalTrials.gov identifier# NCT00776828).

Combined aspirin and cilostazol treatment is associated with reduced platelet aggregation and prevention of exercise-induced platelet activation

BACKGROUND

Cilostazol has proven efficacy in increasing walking distance in claudicants, but it has not been demonstrated to be more effective than placebo in secondary cardiovascular prevention. The direct effect of exercise on platelet function remains less well defined. We have investigated the effect of combination treatment with aspirin and cilostazol on platelet activity in claudicants subjected to repeated treadmill exercise.

METHODS

Nineteen claudicants completed a double-blind, randomised, controlled, cross-over trial. Each subject received a 2-week course of aspirin (75mg) and placebo and aspirin and cilostazol (100mg twice daily). Following each 2-week treatment period, patients participated in a standardised treadmill test (3.2kmh(-1), 10 degrees incline) walking to maximal claudication distance. The exercise was repeated thrice in total, and blood was sampled before and after exercise. Platelet activation was measured using free platelet counting aggregation, flow cytometry for surface markers of platelet activation and soluble P-selectin assay.

RESULTS

Compared to aspirin and placebo, combination treatment with aspirin and cilostazol was associated with reduced arachidonic-acid-induced platelet aggregation (p<0.01, Wilcoxon signed-rank test). Aspirin and placebo treatment were associated with elevated P-selectin expression, platelet-monocyte aggregation and reduced CD42b expression (p<0.05, Wilcoxon signed-rank test) post-exercise. No difference was seen in spontaneous platelet aggregation whilst soluble P-selectin was reduced post-exercise with combination treatment with aspirin and cilostazol (p<0.05, Wilcoxon signed-rank test).

CONCLUSIONS

Combination treatment with aspirin and cilostazol results in suppression of platelet activation and reduces the effect of exercise on platelets. The benefit seen may be a result of cilostazol enhancing the inhibitory effect of aspirin on the cyclo-oxygenase pathway.

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.

Cilostazol could ameliorate platelet responsiveness to clopidogrel in patients undergoing primary percutaneous coronary intervention

BACKGROUND

Cilostazol increases the cyclic adenosine monophosphate levels in platelets and might ameliorate the antiplatelet activity of clopidogrel. This study investigated the additional effect of cilostazol on platelet aggregation measured by a VerifyNow analyzer and soluble CD40 ligand (sCD40L) as a marker of activated platelet in patients undergoing primary percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Sixty cases of primary PCI were randomly assigned to dual (aspirin and clopidogrel) or triple (dual plus cilostazol) therapy. The antiplatelet effects of aspirin and clopidogrel were evaluated by VerifyNow tests. The plasma sCD40L levels at admission, 24 h and 21 days were measured by the ELISA method. The arachidonic acid induced platelet aggregation was similar in both groups. However, the triple group had a significantly lower P2Y12 reaction unit (dual 208.8+/-69.0 vs triple 168.2+/-79.2, p=0.041) and higher % inhibition of adenosine diphosphate (ADP)-induced platelet aggregation (dual 23.8+/-21.4% vs triple 40.5+/-21.0%, p=0.004). In the multivariate analysis, cilostazol was a negative predictor for low responders to clopidogrel (95% confidence interval 0.067-0.711). The plasma sCD40L levels were not significantly different between the 2 groups at the same point of time.

CONCLUSIONS

The addition of cilostazol to the combination of aspirin plus clopidogrel significantly increases the inhibition of ADP-induced platelet aggregation. However, there was no additive effect on aspirin-induced antiplatelet activity or lowering of sCD40L.

Comparison of changes in circulating platelet-derived microparticles and platelet surface P-selectin expression after coronary stent implantation

Platelet-derived microparticles (PDMPs) are released from activated platelets and may participate in the inflammatory process in response to vessel wall injury. This study was designed to compare the clinical significance of circulating PDMPs with that of P-selectin on the platelet membrane surface. In 20 patients with stable angina undergoing coronary stent implantation, circulating PDMPs were serially measured by enzyme-linked immunosorbent assay, and P-selectin expression on the surface of platelets was simultaneously analyzed by flow cytometry. PDMPs increased 24-48 h after coronary stenting in the coronary sinus (8.7 +/- 8.9 to 31.8 +/- 19.8 U/ml, P < 0.001) with a maximum at 48 h. In contrast, the mean channel fluorescence intensity for P-selectin increased 15 min after coronary stenting in the coronary sinus (19.5 +/- 5.6 to 25.2 +/- 7.5, P < 0.01) and remained elevated for 48 h; the changes were less striking in peripheral blood. The relative increase in PDMPs was not correlated with the increase in P-selectin expression at 15 min or 24 h after coronary stenting, but was correlated at 48 h (R = 0.48, P < 0.05). Both circulating PDMPs and P-selectin expression were enhanced in association with stent-induced platelet activation; however, the time course of changes in these two platelet activation markers was different. Therefore, the clinical relevance of circulating PDMPs may differ from that of P-selectin expression on the platelet membrane surface.

New Modalities and Aspects of Antiplatelet Therapy for Stroke Prevention

Antiplatelet therapy is indicated for secondary prevention of ischaemic stroke. The first-line antiplatelet agent is aspirin. The effect of aspirin is, however, very limited, and this limited effect of aspirin is argued with termed 'aspirin resistance'. Strategies against aspirin resistance may include alternative use of other antiplatelet agents, combination of aspirin with other antiplatelet agents and investigation into molecular targets to develop novel antiplatelet agents. Progress in antiplatelet therapy should be directed at further reducing the risk of ischaemic events including ischaemic stroke without increasing the risk of haemorrhagic events including haemorrhagic stroke.

Cilostazol inhibits platelet-leukocyte interaction by suppression of platelet activation

The influence of three anti-platelet drugs, cilostazol, aspirin, and tirofiban, was investigated on platelet-leukocyte interaction by flow cytometry. When platelets and leukocytes were pre-incubated with anti-platelet drugs and stimulated by thrombin or collagen, cilostazol was found to inhibit platelet adhesion to monocytes and polymorphonuclear cells (PMNs). Similar effects were observed with anti-CD62P antibody, while aspirin and tirofiban did not appear to interfere with interaction between platelets and leukocytes. In the platelets pre-incubated with anti-platelet drugs, cilostazol significantly reduced CD62P expression and GPIIb/IIIa activation on platelet surface stimulated by thrombin or collagen. Aspirin inhibited CD62P expression and GPIIb/IIIa activation induced by collagen, but not thrombin. Tirofiban significantly blocked GPIIb/IIIa activation induced with both, and weakly inhibited CD62P expression induced by collagen. When added after stimulation of platelets, cilostazol again significantly inhibited CD62P expression and GPIIb/IIIa activation, although to a lesser extent than in the pre-incubation study. Aspirin hardly inhibited CD62P expression or GPIIb/IIIa activation, while tirofiban strongly blocked GPIIb/IIIa activation induced by thrombin or collagen, but had little effects on CD62P expression. In conclusion, our results suggest that cilostazol inhibits platelet-leukocyte interaction by reducing CD62P expression on the platelet surface.

Cilostazol inhibits leukocyte integrin Mac-1, leading to a potential reduction in restenosis after coronary stent implantation

OBJECTIVES

The aim of this study was to confirm clinically a hypothesis that cilostazol inhibits leukocyte Mac-1, leading to prevention of post-stent restenosis.

BACKGROUND

The platelet phosphodiesterase III inhibitor called cilostazol also inhibits alpha-granule release of P-selectin in platelets. The P-selectin-mediated platelet-leukocyte interaction promotes activation and upregulation of leukocyte Mac-1 after coronary stenting, which plays a key role on the mechanism of restenosis. Thus, cilostazol's potential inhibition of this process may lead to prevention of restenosis.

METHODS

Using flow cytometric analysis of whole blood obtained from the coronary sinus, the expression of platelet membrane glycoproteins and neutrophil adhesion molecules was observed in 70 consecutive patients undergoing coronary stenting. The patients were randomly assigned to either a cilostazol or ticlopidine group before stent placement.

RESULTS

The restenosis rate was lower (15% vs. 31%, p < 0.05) in the cilostazol group (n = 34) than in the ticlopidine group (n = 32). A stent-induced increase in platelet P-selectin (CD62P) expression and an increase in neutrophil Mac-1 (CD11b) expression were suppressed in the cilostazol group compared with the ticlopidine group. Angiographic late lumen loss was correlated with the relative changes in platelet P-selectin and neutrophil Mac-1 at 48 h after coronary stenting.

CONCLUSIONS

Cilostazol may have effects on suppression of P-selectin-mediated platelet activation, platelet-leukocyte interaction, and subsequent Mac-1-mediated leukocyte activation, which might lead to a reduced restenosis rate after coronary stent implantation.

Cilostazol inhibits high glucose-mediated endothelial-neutrophil adhesion by decreasing adhesion molecule expression via NO production

OBJECTIVE

Endothelial-neutrophil adhesion is crucial for vascular injury, the major cause of diabetic vascular complications. On the other hand, platelet aggregation inhibitors, frequently used for diabetic patients with intermittent claudication, have been shown to decrease the incidence of atherosclerosis-mediated diseases (acute myocardial infarction and stroke). However, whether these agents act directly on the endothelial reactions to hyperglycemia remains unclear. Therefore, we examined their direct effects on endothelial-neutrophil adhesion and expression of endothelial adhesion molecules induced by high glucose.

METHODS AND RESULTS

After human endothelial cells were cultured in high glucose medium, neutrophils from healthy volunteers were added and allowed to adhere for 30 min. Adhered neutrophils were quantified by measuring their myeloperoxidase (MPO) activities, and surface expression of endothelial adhesion molecules was determined with an enzyme immunoassay. Of the platelet aggregation inhibitors tested, only cilostazol significantly attenuated the adhesion through decreasing expression of intercellular adhesion molecule-1 (ICAM-1) and P-selectin. In addition, nitric oxide (NO) synthase inhibitors reduced the inhibitory effects of cilostazol, but a protein kinase C (PKC) activator did not.

CONCLUSIONS

Cilostazol may act directly on endothelial cells to inhibit expression of adhesion molecules and neutrophil adhesion induced by high glucose through increasing NO production.

Cigarette smoking as a risk factor of coronary artery disease and its effects on platelet function

It has been well established that cigarette smoking is a powerful risk factor for coronary artery disease. A number of epidemiologic studies have shown a strong association between cigarette smoking and atherosclerosis, myocardial infarction and death from coronary artery disease. In addition to active smoking, passive smoking can also carry a risk of coronary artery disease. Although the detailed mechanism through which cigarette smoking is associated with cardiovascular disease has not yet been clarified, it is suggested that cigarette smoking is related to thrombogenesis, as well as atherogenesis, and blood platelet behavior is thought to be prominent among the proposed mechanisms involved in atherogenesis and thrombogenesis. The following is a review of evidence that cigarette smoking affects platelet function.

Randomized comparison of cilostazol versus ticlopidine hydrochloride for antiplatelet therapy after coronary stent implantation for prevention of late restenosis

BACKGROUND

Cilostazol is a newly developed antiplatelet drug that has been widely applied for clinical use. Its antiplatelet action appears to be mainly related to inhibition of intracellular phosphodiesterase activity. Recently, cilostazol has been used for antiplatelet therapy after coronary stent implantation. However, its evaluation has not been established yet.

METHODS

This prospective randomized trial was designed to investigate the efficacy of cilostazol for the prevention of late restenosis and acute or subacute stent thrombosis in comparison with ticlopidine hydrochloride. One hundred thirty consecutive patients, scheduled for elective coronary stenting, were randomly assigned to receive oral aspirin (81 mg/day) plus ticlopidine hydrochloride therapy (200 mg/day; group I) or aspirin plus cilostazol therapy (200 mg/day; group II). These medications were started at least 2 days before coronary intervention and continued until follow-up coronary angiography was performed 6 months later.

RESULTS

Subacute stent thrombosis was observed in 2 patients of group I but in no patients of group II. Major cardiac events were similarly present in both groups. Elevated transaminase levels were observed more frequently in group I than in group II (P <.05). Each of the quantitative coronary angiography variables before and immediately after coronary stenting were similar in both groups. At follow-up angiography, however, late lumen loss (0.69 +/- 0.79 mm vs 0.28 +/- 0.40 mm; P <.01) and loss index (0.42 +/- 0.56 vs 0.16 +/- 0.27; P <.01) were smaller in group II than in group I. Restenosis rate (13% vs 31%; P <.05) and target lesion revascularization rate (7% vs 21%; P <.05) were both lower in group II than in group I.

CONCLUSION

Aspirin plus cilostazol therapy may be an effective regimen for prevention of not only stent thrombosis but also restenosis.

The pharmacology of cilostazol

Cilostazol (6-[4-(1-cyclohexyl-1H-tetrazol-5-yl)butoxy]-3,4-dihydro-2(1H)-quinolinone; OPC-13013) is a 2-oxo-quinoline derivative with antithrombotic, vasodilator, antimitogenic and cardiotonic properties. The compound is a potent inhibitor of phosphodiesterase (PDE) 3A, the isoform of PDE 3 in the cardiovascular system (IC50: 0.2 microM). In addition, there is inhibition of adenosine uptake, eventually resulting in changes in cAMP levels, dependent on the type of adenosine receptors (A1 or A2). Cilostazol inhibits platelet aggregation and has considerable antithrombotic effects in vivo. The compound relaxes vascular smooth muscle and inhibits mitogenesis and migration of vascular smooth muscle cells. In the heart, cilostazol causes positive inotropic and chronotropic effects. Most, if not all, of these actions are cAMP-mediated, including the modification of cAMP-controlled gene expression. Cilostazol decreases levels of serum triglycerides and causes some increase in HDL-cholesterol levels. The compound has a number of additional effects which might contribute to its overall clinical efficacy. Cilostazol undergoes intensive and finally complete hepatic metabolism via the cytochrome P450 systems. This might result in some drug interaction, i.e. with erythromycin and omeprazole. The half-life is approximately 10 h, resulting in about 2-fold accumulation of the drug during repeated administration.