Sarpogrelate Hydrochloride, a Selective 5-HT2A Antagonist, Improves Vascular Function in Patients With Peripheral Arterial Disease

Effect of sarpogrelate treatment on 5-HT modulation of vascular sympathetic innervation and platelet activity in diabetic rats

This study aimed to investigate whether the 5-HT₂ receptor blockade alters the 5-HT effect on vascular sympathetic neurotransmission and platelet activation in type 1 diabetes. 28-day diabetes was obtained by alloxan (150 mg/kg; s.c.) in male Wistar rats, administering sarpogrelate (5-HT₂ blocker; 30 mg/kg/day; p.o.) for 14 days. Blood glucose and body weight were monitored for 28 days. After 4 weeks of diabetes induction, food and drink intake, urine, plasma-platelet 5-HT, and platelet activation were determined in normoglycemic, non-treated diabetic and sarpogrelate-treated diabetic rats. Another set of diabetic rats were pithed to run the vascular sympathetic stimulation or exogenous noradrenaline administration, examining the induced vasoconstrictor responses. Sarpogrelate treatment significantly reduced drink intake and urine, whereas BW gain, hyperglycemia, and food intake were not modified in diabetic rats. The platelet activation and plasma 5-HT concentration were decreased (increasing the stored 5-HT platelet) by 5-HT₂ blockade in diabetic animals. The sympathetic-induced vasoconstrictions were higher in non-treated than in sarpogrelate-treated diabetic rats. 5-HT inhibited these vasopressor responses, reproduced exclusively by the 5-HT_1/5/7 receptor agonist, 5-CT. The 5-CT-produced inhibition was partly reversed by 5-HT_1D or 5-HT₇ antagonists (LY310762 or SB-258719, respectively), and totally annulled by the mixture of LY310762+SB-258719. Noradrenaline-caused vasoconstrictions were also decreased by 5-CT. In conclusion, our results reveal that 14-day sarpogrelate treatment improves polydipsia and polyuria, reduces platelet hyperactivation, plasma 5-HT and the vascular sympathetic tone, and changes 5-HT receptors inhibiting noradrenergic drive in diabetic rats: pre and/or postjunctional 5-HT_1D/7 are involved in the sympatho-inhibition.

Inhibiting serotonin signaling through HTR2B in visceral adipose tissue improves obesity-related insulin resistance

Insulin resistance is a cornerstone of obesity-related complications such as type 2 diabetes, metabolic syndrome, and nonalcoholic fatty liver disease. A high rate of lipolysis is known to be associated with insulin resistance, and inhibiting adipose tissue lipolysis improves obesity-related insulin resistance. Here, we demonstrate that inhibition of serotonin (5-hydroxytryptamine [5-HT]) signaling through serotonin receptor 2B (HTR2B) in adipose tissues ameliorates insulin resistance by reducing lipolysis in visceral adipocytes. Chronic high-fat diet (HFD) feeding increased Htr2b expression in epididymal white adipose tissue, resulting in increased HTR2B signaling in visceral white adipose tissue. Moreover, HTR2B expression in white adipose tissue was increased in obese humans and positively correlated with metabolic parameters. We further found that adipocyte-specific Htr2b-knockout mice are resistant to HFD-induced insulin resistance, visceral adipose tissue inflammation, and hepatic steatosis. Enhanced 5-HT signaling through HTR2B directly activated lipolysis through phosphorylation of hormone-sensitive lipase in visceral adipocytes. Moreover, treatment with a selective HTR2B antagonist attenuated HFD-induced insulin resistance, visceral adipose tissue inflammation, and hepatic steatosis. Thus, adipose HTR2B signaling could be a potential therapeutic target for treatment of obesity-related insulin resistance.

Sarpogrelate and rosuvastatin synergistically ameliorate aortic damage induced by hyperlipidemia in apolipoprotein E-deficient mice

The current study aimed to investigate whether sarpogrelate and rosuvastatin possess anti-arterial injury, and attempted to elucidate the mechanism of action underlying this activity. Sarpogrelate, a 5-hydroxytryptamine type 2A antagonist, is extensively used to prevent arterial thrombosis; however, its effects on atherosclerosis remain unknown. In the present study, sarpogrelate combined with rosuvastatin or rosuvastatin alone were administered to male ApoE^-/- mice fed a high-fat diet (HFD) for 8 weeks. Metabolic parameters in the blood samples were analyzed using an automatic analyzer. Aortic tissues were stained with hematoxylin and eosin for morphological analysis. The expression levels of oxidized-low density lipoprotein (LDL) specific scavenging receptors, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and cluster of differentiation 68 were detected via immunostaining. mRNA expression levels of interleukin (IL)-1β, IL-6 and tumor necrosis factor-α were determined via reverse transcription-quantitative PCR analysis, while protein expression levels of LOX-1 and phosphor(p)-ERK were determined via western blot analysis. The results demonstrated that sarpogrelate combined with rosuvastatin treatment significantly decreased total cholesterol and LDL cholesterol levels in the serum, and alleviated intimal hyperplasia and lipid deposition, accompanied by decreased inflammatory cell infiltration and lower expression levels of inflammatory cytokines, compared with rosuvastatin monotherapy or HFD treatment. Furthermore, sarpogrelate combined with rosuvastatin treatment significantly decreased the expression levels of LOX-1 and p-ERK. Taken together, these results suggest that the positive effects of sarpogrelate combined with rosuvastatin treatment on aortic injury may be associated with the regulation of the LOX-1/p-ERK signaling pathway. Sarpogrelate and rosuvastatin synergistically decreased aortic damage in ApoE^-/- HFD mice, and thus provide a basis for the treatment of aortic injury caused by hyperlipidemia with sarpogrelate.

Blockade of 5-HT2 receptors with sarpogrelate uncovers 5-HT7 receptors inhibiting the tachycardic sympathetic drive in pithed rats

Our group has previously shown in pithed rats that the cardiac sympathetic drive, which produces tachycardic responses, is inhibited by 5-HT via the activation of prejunctional 5-HT_1B/1D/5 receptors. Interestingly, when 5-HT₂ receptors are chronically blocked with sarpogrelate, the additional role of cardiac sympatho-inhibitory 5-HT_1F receptors is unmasked. Although 5-HT₂ receptors mediate tachycardia in rats, and the chronic blockade of 5-HT₂ receptors unmasked 5-HT₇ receptors mediating cardiac vagal inhibition, the role of 5-HT₇ receptors in the modulation of the cardiac sympathetic tone remains virtually unexplored. On this basis, male Wistar rats were pretreated during 14 days with sarpogrelate (a 5-HT₂ receptor antagonist) in drinking water (30 mg/kg/day; sarpogrelate-pretreated group) or equivalent volumes of drinking water (control group). Subsequently, the rats were pithed to produce increases in heart rate by either electrical preganglionic spinal (C₇ -T₁ ) stimulation of the cardiac sympathetic drive or iv administration of exogenous noradrenaline. The iv continuous infusion of AS-19 (a 5-HT₇ receptor agonist; 10 µg/kg/min) (i) inhibited the tachycardic responses to sympathetic stimulation, but not those to exogenous noradrenaline only in sarpogrelate-pretreated rats. This inhibition was completely reversed by SB258719 (a selective 5-HT₇ receptor antagonist; 1 mg/kg, iv) or glibenclamide (an ATP-sensitive K⁺ channel blocker; 20 mg/kg, iv). These results suggest that chronic 5-HT₂ receptor blockade uncovers a cardiac sympatho-inhibitory mechanism mediated by 5-HT₇ receptors, involving a hyperpolarization due to the opening of ATP-sensitive K⁺ channels. Thus, these findings support the role of 5-HT₇ receptors in the modulation of the cardiac sympathetic neurotransmission.

Effects of sarpogrelate hydrochloride on peripheral arterial disease: A meta-analysis of randomized controlled trials

OBJECTIVE

The aim of our study was to assess the efficacy and safety of sarpogrelate hydrochloride by comparing the effects of sarpogrelate with conventional treatment on the improvement of symptoms in PAD patients.

METHODS

The search was conducted in PubMed, Embase, Cochrane library database, CNKI, CBM for relevant randomized controlled trials (RCTs) before January 1st, 2019. Inclusion and exclusion of studies, assessment of quality, outcome measures, data extraction and synthesis were completed by two reviewers independently. The meta-analysis was performed with RevMan 5.3.

RESULTS

Totally, 12 eligible RCTs were included in our analysis. Comparing the results of sarpogrelate group and control group, sarpogrelate significantly improved ankle-brachial index (ABI) levels (SMD = 0.05, [95%CI 0.20 to 0.74, P = .0005]), dorsalis pedis artery blood flow (MD = 0.16, [95%CI 0.09 to 0.23, P < .001]) and pain-free walking distance (PFWD) (MD = 201.86, [95%CI 9.34 to 394.38, P = .04]). The pooled analysis showed that a significant decrease in hsCRP (MD = -0.57, [95%CI -1.12 to -0.02, P = .04]) and IL-6 (MD = 1.48,[95%CI 0.39 to 2.56, P = .008]) was observed in the sarpogrelate treatment.

CONCLUSION

Sarpogrelate was effective for improving the symptoms of PAD and showed good tolerability without significant adverse events.

Effect of sarpogrelate and high-dose statin on the reduction of coronary spasm in vasospastic angina: A two by two factorial, pilot randomized study

Background

Vasospastic angina (VSA) is characterized by coronary spasm, which can be aggravated by vasoactive substances such as serotonin. Hypothesis Sarpogrelate, a selective serotonin receptor antagonist, and high‐dose statin have some effects on the reduction of coronary spasm in patients with VSA.

Methods

We recruited 100 patients with angiographically confirmed VSA, and randomly assigned them into four groups: sarpogrelate with high‐dose statin (Group A, n = 25), sarpogrelate with low‐dose or no statin (Group B, n = 25), placebo with high‐dose statin (Group C, n = 25), and placebo with low‐dose or no statin (Group D, n = 25). The primary endpoint was the remission of coronary spasm on 1‐year follow‐up provocation test.

Results

The most common site of coronary spasm was left anterior descending artery (42%). Most patients (96%) took calcium channel blockers, and 46% were treated with vasodilators. Overall, 40% of patients reported no chest pain at 1 year, and 23% showed complete remission of coronary spasm on 1‐year follow‐up provocation test. No difference was observed in symptomatic and angiographically complete remission rate between the sarpogrelate and the placebo group. Although the apolipoprotein B level at the 1‐year follow‐up was significantly lower in the high‐dose statin group, symptomatic and angiographic outcomes were not different according to statin intensity. Distal thrombolysis in myocardial infarction (TIMI) flow on initial provocation test was independently associated with angiographically complete remission.

Conclusions

Sarpogrelate or high‐dose statin did not significantly improve the angiographic remission rate in patients with VSA. Distal TIMI flow on initial provocation test could predict the complete remission of coronary spasm at follow‐up.

The enhancement of serotonin-induced contraction of rat femoral artery is mediated by angiotensin II release from intact endothelium

We have performed an in vitro study on isolated intact or denuded femoral artery (FA) of healthy, diabetic, and/or rats submitted to the FA occlusion. The aim was to determine the contribution of endothelium and endothelial dysfunction (ED) on serotonin-induced action in FA. Further, the contribution of angiotensin II and cyclooxygenase products of arachidonic acid was investigated. A marker of ED, vWF was measured in animal serum. Serotonin induced contraction-dependent contraction of isolated FA, which was increased in preparations with endothelium. Pathological conditions such as endothelial denudation, nicotine-induced ED, diabetes or occlusion of FA reduced serotonin-induced contraction. Comparable reduction of serotonin-induced contraction was achieved after inhibition of AT1 receptors with losartan in isolated FA with intact endothelium. Our results demonstrate that angiotensin II contributes to the enhancement of serotonin-induced contraction of femoral arteries with intact endothelium. This increase is attenuated by endothelium removal, nicotine treatment, vascular occlusion, and/or hyperglycemia.

Serotonin signals through a gut-liver axis to regulate hepatic steatosis

Nonalcoholic fatty liver disease (NAFLD) is increasing in worldwide prevalence, closely tracking the obesity epidemic, but specific pharmaceutical treatments for NAFLD are lacking. Defining the key molecular pathways underlying the pathogenesis of NAFLD is essential for developing new drugs. Here we demonstrate that inhibition of gut-derived serotonin synthesis ameliorates hepatic steatosis through a reduction in liver serotonin receptor 2A (HTR2A) signaling. Local serotonin concentrations in the portal blood, which can directly travel to and affect the liver, are selectively increased by high-fat diet (HFD) feeding in mice. Both gut-specific Tph1 knockout mice and liver-specific Htr2a knockout mice are resistant to HFD-induced hepatic steatosis, without affecting systemic energy homeostasis. Moreover, selective HTR2A antagonist treatment prevents HFD-induced hepatic steatosis. Thus, the gut TPH1-liver HTR2A axis shows promise as a drug target to ameliorate NAFLD with minimal systemic metabolic effects.

No effective pharmacological treatments exist for nonalcoholic fatty liver disease (NAFLD). Here, the authors show that serotonin concentration in the portal blood is increased in nine human subjects and in mice fed a high-fat diet, and that local serotonin signaling ablation, either genetically or with an antagonist, prevents hepatic steatosis in mice.

Saliva Proteomics Analysis Offers Insights on Type 1 Diabetes Pathology in a Pediatric Population

The composition of the salivary proteome is affected by pathological conditions. We analyzed by high resolution mass spectrometry approaches saliva samples collected from children and adolescents with type 1 diabetes and healthy controls. The list of more than 2000 high confidence protein identifications constitutes a comprehensive characterization of the salivary proteome. Patients with good glycemic regulation and healthy individuals have comparable proteomic profiles. In contrast, a significant number of differentially expressed proteins were identified in the saliva of patients with poor glycemic regulation compared to patients with good glycemic control and healthy children. These proteins are involved in biological processes relevant to diabetic pathology such as endothelial damage and inflammation. Moreover, a putative preventive therapeutic approach was identified based on bioinformatic analysis of the deregulated salivary proteins. Thus, thorough characterization of saliva proteins in diabetic pediatric patients established a connection between molecular changes and disease pathology. This proteomic and bioinformatic approach highlights the potential of salivary diagnostics in diabetes pathology and opens the way for preventive treatment of the disease.

Sarpogrelate Based Triple Antiplatelet Therapy Improved Left Ventricular Systolic Function in Acute Myocardial Infarction: Retrospective Study

PURPOSE

The purpose of this study was to assess the potential benefit of a 5-hydroxytryptamine receptor antagonist, sarpogrelate-based triple antiplatelet therapy (TAPT) in comparison with dual antiplatelet therapy (DAPT) in patients undergoing primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI).

MATERIALS AND METHODS

119 patients of STEMI were retrospectively assessed. All patients received aspirin and clopidogrel per standard of care. Among them, 53 patients received an additional loading dose of sarpogrelate and a maintenance dose for 6 months post-PCI (TAPT group), while others did not (DAPT group).

RESULTS

The rates of complete ST-segment resolution at 30 minutes post-PCI and post-procedural thrombolysis in myocardial infarction flow were not significantly different between the two groups (52.8% vs. 48.5%, p=0.200; 92.5% vs. 89.4%, p=0.080). In addition, no significant differences were observed between the two groups with regard to 30-day and 12-month clinical outcomes (cardiac death, myocardial infarction, stent thrombosis, target vessel revascularization, and severe bleeding). Meanwhile, improvement in left ventricular (LV) systolic function was observed in the TAPT group [ΔLV ejection fraction (LVEF)=17.1±9.4%, p<0.001; Δglobal longitudinal strain (GLS)=-9.4±4.2% , p<0.001] at 6 months, whereas it was not in the DAPT group (ΔLVEF= 8.8±6.5%, p=0.090; ΔGLS=-4.6±3.4%, p=0.106). In multivariate analyses, TAPT was an independent predictor for LV functional recovery (odds ratio, 2.61; 95% confidence interval, 1.16-5.87; p=0.003).

CONCLUSION

Sarpogrelate-based TAPT improved LV systolic function at 6 months in STEMI patients undergoing primary PCI.

Clarification of serotonin-induced effects in peripheral artery disease observed through the femoral artery response in models of diabetes and vascular occlusion: The role of calcium ions

Recent findings have demonstrated that serotonin is an important participant in the development and progression of peripheral artery diseases. Taking this into consideration, the goals of this study were to investigate the effects of serotonin on isolated Wistar rat femoral arteries in both healthy and diabetic animals, with and without artery occlusion, with a particular focus on determining the role of calcium in this process. Contraction experiments with serotonin on intact and denuded femoral artery rings, in the presence or absence of nifedipine and ouabain (both separately, or in combination), as well as Ca²⁺ -free Krebs-Ringer bicarbonate solution were performed. The serotonin-induced results were concentration dependent, but only in healthy animals. The endothelium-dependent contraction of the femoral artery was assessed. In healthy animals, the endothelium-reliant part of contraction was dependent on the extracellular calcium, while the smooth muscle-related part was instead dependent on the intracellular calcium. In diabetic animals, both nifedipine and ouabain influenced serotonin-induced vascular effects by blocking intracellular calcium pathways. However, this was diminished after the simultaneous administration of both blockers.

Effect of sarpogrelate, a selective 5-HT2A receptor antagonist, on characteristics of coronary artery disease in patients with type 2 diabetes

BACKGROUND AND AIMS

Sarpogrelate, a 5-hydroxytryptamine type 2A antagonist, is a potential antiplatelet agent. We performed a randomized study to evaluate the effect of sarpogrelate on vascular health in Korean patients with diabetes.

METHODS

Forty diabetic patients aged 58.6 ± 6.8 years with 10-75% coronary artery stenosis, as assessed by coronary computed tomography angiography, were randomly assigned to sarpogrelate 300 mg/day plus aspirin 100 mg/day (SPG + ASA group) or aspirin 100 mg/day alone (ASA group) for 6 months. The primary endpoint of this study was the change in coronary artery disease including the calcium score (CACS), maximal stenosis, and plaque volume (calcified vs. noncalcified). The secondary endpoints were changes in biochemical parameters related to glucose and lipid metabolism, and in subclinical atherosclerosis assessed by ankle-brachial index and pulse wave velocity.

RESULTS

After 6-month treatment, there was no significant difference in the changes in CACS, coronary stenosis, ankle-brachial index, and pulse wave velocity, between groups. The total plaque volume decreased from 82.4 ± 14.5 mm³ to 74.6 ± 14.4 mm³ in the SPG + ASA group, but increased from 64.9 ± 16.0 mm³ to 68.6 ± 16.3 mm³ in the ASA group (p < 0.05), mainly driven by changes in the noncalcified component (SPG + ASA group 15.6 ± 4.6 mm³ to 11.2 ± 3.7 mm³vs. ASA group 21.2 ± 6.2 mm³ to 22.8 ± 6.6 mm³, p < 0.01). Serum C-reactive protein levels and homeostasis model assessment of insulin resistance tended to decrease in the SPG + ASA group, but they were not altered in the ASA group.

CONCLUSIONS

The present study demonstrated that sarpogrelate treatment may decrease coronary artery plaque volume, particularly the noncalcified portion, in patients with diabetes.

Application of physiologically based pharmacokinetic modeling in predicting drug-drug interactions for sarpogrelate hydrochloride in humans

Background

Evaluating the potential risk of metabolic drug–drug interactions (DDIs) is clinically important.

Objective

To develop a physiologically based pharmacokinetic (PBPK) model for sarpogrelate hydrochloride and its active metabolite, (R,S)-1-{2-[2-(3-methoxyphenyl)ethyl]-phenoxy}-3-(dimethylamino)-2-propanol (M-1), in order to predict DDIs between sarpogrelate and the clinically relevant cytochrome P450 (CYP) 2D6 substrates, metoprolol, desipramine, dextromethorphan, imipramine, and tolterodine.

Methods

The PBPK model was developed, incorporating the physicochemical and pharmacokinetic properties of sarpogrelate hydrochloride, and M-1 based on the findings from in vitro and in vivo studies. Subsequently, the model was verified by comparing the predicted concentration-time profiles and pharmacokinetic parameters of sarpogrelate and M-1 to the observed clinical data. Finally, the verified model was used to simulate clinical DDIs between sarpogrelate hydrochloride and sensitive CYP2D6 substrates. The predictive performance of the model was assessed by comparing predicted results to observed data after coadministering sarpogrelate hydrochloride and metoprolol.

Results

The developed PBPK model accurately predicted sarpogrelate and M-1 plasma concentration profiles after single or multiple doses of sarpogrelate hydrochloride. The simulated ratios of area under the curve and maximum plasma concentration of metoprolol in the presence of sarpogrelate hydrochloride to baseline were in good agreement with the observed ratios. The predicted fold-increases in the area under the curve ratios of metoprolol, desipramine, imipramine, dextromethorphan, and tolterodine following single and multiple sarpogrelate hydrochloride oral doses were within the range of ≥1.25, but <2-fold, indicating that sarpogrelate hydrochloride is a weak inhibitor of CYP2D6 in vivo. Collectively, the predicted low DDIs suggest that sarpogrelate hydrochloride has limited potential for causing significant DDIs associated with CYP2D6 inhibition.

Conclusion

This study demonstrated the feasibility of applying the PBPK approach to predicting the DDI potential between sarpogrelate hydrochloride and drugs metabolized by CYP2D6. Therefore, it would be beneficial in designing and optimizing clinical DDI studies using sarpogrelate as an in vivo CYP2D6 inhibitor.

Comprehensive Proteome Profiling of Platelet Identified a Protein Profile Predictive of Responses to An Antiplatelet Agent Sarpogrelate

Sarpogrelate is an antiplatelet agent widely used to treat arterial occlusive diseases. Evaluation of platelet aggregation is essential to monitor therapeutic effects of sarpogrelate. Currently, no molecular signatures are available to evaluate platelet aggregation. Here, we performed comprehensive proteome profiling of platelets collected from 18 subjects before and after sarpogrelate administration using LC-MS/MS analysis coupled with extensive fractionation. Of 5423 proteins detected, we identified 499 proteins affected by sarpogrelate and found that they strongly represented cellular processes related to platelet activation and aggregation, including cell activation, coagulation, and vesicle-mediated transports. Based on the network model of the proteins involved in these processes, we selected three proteins (cut-like homeobox 1; coagulation factor XIII, B polypeptide; and peptidylprolyl isomerase D) that reflect the platelet aggregation-related processes after confirming their alterations by sarpogrelate in independent samples using Western blotting. Our proteomic approach provided a protein profile predictive of therapeutic effects of sarpogrelate.

Antiplatelet Therapy of Cilostazol or Sarpogrelate with Aspirin and Clopidogrel after Percutaneous Coronary Intervention: A Retrospective Cohort Study Using the Korean National Health Insurance Claim Database

Background/Objectives

Addition of cilostazol or sarpogrelate to the standard dual antiplatelet therapy of aspirin and clopidogrel has been implemented in patients that underwent percutaneous coronary intervention (PCI) with stents in Korea. This study aimed to evaluate the efficacy and safety of triple antiplatelet therapies.

Methods

This retrospective cohort study was performed using the Korean National Insurance Claim Data of the Health Insurance Review and Assessment Service from January 1, 2009 to December 31, 2014. The study cohort population consisted of patients with ischemic heart diseases and a history of PCI. They were treated with antiplatelet therapy of aspirin, clopidogrel (AC); aspirin, clopidogrel, cilostazol (ACCi); or aspirin, clopidogrel, sarpogrelate (ACSa) during the index period from January 1, 2010 to December 31, 2011. During the follow-up period up to December 31, 2014, the major adverse cardiac or cerebral events (MACCE) including death, myocardial infarction, target lesion revascularization, and ischemic stroke were assessed. Bleeding complications were also evaluated as adverse drug events.

Results

Out of 93,876 patients with PCI during the index period, 69,491 patients started dual (AC) or triple therapy (ACSa or ACCi). The clinical outcomes of comparing ACSa and ACCi therapy showed beneficial effects in the ACSa group in the prevention of subsequent cardiac or cerebral events. After Propensity score-matching between ACSa and ACCi groups, there were significant differences in MI and revascularization, with corresponding HR of 0.38 (95% CI, 0.20–0.73) and 0.66 (95% CI, 0.53–0.82) in ACSa vs. ACCi at 12 months, respectively. At the 24-month follow-up, the triple therapy groups (ACS or ACC) had a higher incidence of MACCE compared to the dual therapy (AC) group; ACSa vs. AC HR of 1.69 (95% CI, 1.62–1.77); ACC vs. AC HR of 1.22 (95% CI, 1.06–1.41). There was no significant difference in severe or life-threatening bleeding risk among three groups; ACSa vs. AC, HR of 0.68 (95% CI, 0.37–1.24), ACCi vs. AC, HR of 0.91 (95% CI, 0.77–1.09).

Conclusion

Sarpogrelate-containing triple antiplatelet therapy demonstrated comparable rates of MACCE prevention to the conventional dual antiplatelet therapy after PCI without significantly increasing bleeding risk during the two-year follow-up period.

Efficacy and Safety of DP-R202 in Patients with Chronic Artery Occlusive Disease: Multicenter Randomized Double-blind Active-controlled Parallel Group Phase III Clinical Study

PURPOSE

Sarpogrelate hydrochloride, a selective 5-hydroxytryptamine 2A antagonist, is a widely used antiplatelet agent for the treatment of peripheral arterial disease (PAD). DP-R202 is a new sarpogrelate hydrochloride product with an improved dosage regimen compared with the agent in current use. The aim of this study was to compare the efficacy and safety profile of DP-R202 and Anplag(⁎) Tab in patients with PAD.

METHODS

This study was a 12-week, multicenter, randomized, double-blinded, active-controlled, parallel group comparative Phase III clinical trial. One hundred fifty-one volunteer patients with PAD were randomized to receive DP-R202 300 mg once daily or Anplag Table 100 mg TID for 12 weeks. The primary end point was a change in patient assessment of lower leg pain intensity with the use of a visual analog scale (VAS) after 12 weeks of treatment. Results after 4, 8, and 12 weeks of treatment were compared with baseline and between treatment groups, and all patients were assessed for adverse events (AEs), clinical laboratory data, and vital signs.

FINDINGS

Two hundred thirty-one patients from 25 medical centers were assessed, and 151 were enrolled and randomly assigned to 1 of 2 treatment groups. Seventy-five patients received DP-R202 300 mg once daily and 76 patients received Anplag Table 100 mg TID for 12 weeks. Analysis of the change in lower leg pain intensity as determined by VAS score between baseline and week 12 (mean [SD], 20.72 [20.06] mm vs 15.55 [21.44] mm) suggested that DP-R202 was not inferior to Anplag Tab, and no significant differences were found in the secondary end points. No significant between-group differences were observed in the prevalence of drug-related clinical- or laboratory-determined AEs. For tolerability, no specific issue was found during the treatment period.

IMPLICATION

The results of this study suggest that DP-R202 was not inferior to Anplag Tab for efficacy in patients with PAD and indicated a good safety profile.

Increased plasma serotonin metabolite 5-hydroxyindole acetic acid concentrations are associated with impaired systolic and late diastolic forward flows during cardiac cycle and elevated resistive index at popliteal artery and renal insufficiency in type 2 diabetic patients with microalbuminuria

Although lower extremity arterial disease is frequently accompanied by diabetes mellitus, the association of circulating biomarkers with flow components during the cardiac cycle in lower-leg arteries has yet to be fully elucidated. We enrolled 165 type 2 diabetic patients with normal ankle-brachial index (ABI 1.0-1.4), comprising 106 normoalbuminuric and 59 microalbuminuric patients, and 40 age-matched nondiabetic subjects consecutively admitted to our hospital. Serum high sensitivity C-reactive protein (hsCRP) level and plasma von Willebrand factor ristocetin cofactor activity (VWF) and vasoconstrictor serotonin metabolite 5-hydroxyindole acetic acid (5-HIAA) concentrations were measured. An automatic device was used to measure ABI and brachial-ankle pulse wave velocity (baPWV). Flow components during the cardiac cycle, total flow volume, and resistive index at popliteal artery were evaluated using gated magnetic resonance imaging. Although estimated glomerular filtration rate (eGFR), early diastolic flow reversal, heart rate, and ABI were similar between the groups, diabetic patients had higher log hsCRP (p<0.001), VWF (p<0.001), 5-HIAA (p=0.002), resistive index (p<0.001) and baPWV (p<0.001) and lower systolic (p=0.026) and late diastolic (p<0.001) forward flows and total flow volume (p<0.001) than nondiabetic subjects. Multivariate analyses demonstrated that 5-HIAA in microalbuminuric patients showed higher associations with systolic and late diastolic forward flows during the cardiac cycle, total flow volume and resistive index at popliteal artery, and eGFR compared to normoalbuminuric patients. In microalbuminuric patients, 5-HIAA was a significant independent determinant among these factors. Thus, increased plasma 5-HIAA levels are involved in the pathogenesis of impaired blood flow in lower extremities and renal insufficiency in diabetic patients with microalbuminuria.

5-HT2 receptor blockade exhibits 5-HT vasodilator effects via nitric oxide, prostacyclin and ATP-sensitive potassium channels in rat renal vasculature

The aim of this study was to determine whether orally sarpogrelate (selective 5-HT2 antagonist) treatment (30 mg/kg/day; 14 days) could modify 5-HT renal vasoconstrictor responses, characterizing 5-HT receptors and mediator mechanisms involved in serotonergic responses in the in situ autoperfused rat kidney. Intra-arterial (i.a.) injections of 5-HT (0.00000125 to 0.1 μg/kg) decreased renal perfusion pressure (RPP) but did not affect the mean blood pressure (MBP). i.a. agonists 5-CT (5-HT1/7), CGS-12066B (5-HT1B), L-694,247 (5-HT1D) or AS-19 (5-HT7) mimicked renal 5-HT vasodilator effect. However, neither 8-OH-DPAT (5-HT1A) nor 1-phenylbiguanide (5-HT3) modified RPP. Moreover: (i) GR-55562 (5-HT1B antagonist) and L-NAME (nitric oxide synthase [NOS] inhibitor) blocked CGS-12066B-induced vasodilator response, (ii) LY310762 (5-HT1D antagonist) and indomethacin (non-selective cyclooxygenase inhibitor) blocked L-694,247-induced vasodilator response; (iii) SB-258719 (5-HT7 antagonist) and glibenclamide (ATP-sensitive K+ channel blocker) blocked AS-19-induced vasodilator response; and (iv) 5-HT- or 5-CT-elicited renal vasodilation was significantly blocked by the mixture of GR-55562 + LY310762 + SB-258719. Furthermore, eNOS and iNOS proteins and prostacyclin levels are overexpressed in sarpogrelate-treated rats. Our data suggest that 5-HT exerts renal vasodilator effect in the in situ autoperfused sarpogrelate-treated rat kidney, mediated by 5-HT1D, 5-HT1B and 5-HT7 receptors, involving cyclooxygenase-derived prostacyclin, nitric oxide synthesis/release and ATP-sensitive K+ channels, respectively.

Sarpogrelate hydrochloride, a serotonin 5HT2A receptor antagonist, ameliorates the development of chronic hypoxic pulmonary hypertension in rats

PURPOSE

The purpose of the present study was to determine if sarpogrelate hydrochloride (SPG), a serotonin 5HT2A receptor antagonist, prevented the development of chronic hypoxia-induced pulmonary hypertension (PH) and hypertensive pulmonary vascular remodeling.

METHODS

Forty-one male Sprague-Dawley rats were exposed to hypobaric hypoxia (380 mmHg, 10 % oxygen) or room air and administered 50 mg/kg SPG or vehicle by gavage once daily from day -2 to day 14. The mean pulmonary artery pressure (PAP) and right ventricular hypertrophy (RVH) were measured. Hypertensive pulmonary vascular remodelings were assessed morphometrically by light microscopy. Serotonin-induced contraction was determined in isolated pulmonary artery rings from 24 rats. In another set of rats, Western blotting, real-time polymerase chain reaction and immunofluorescent staining (n = 9) for lung tissue were performed.

RESULTS

Chronic hypoxia induced a rise in mean PAP and RVH, increased the percentage of muscularized arteries in peripheral pulmonary arteries and medial wall thickness in small muscular arteries, and potentiated serotonin-induced contraction, each of which was significantly (p < 0.05) ameliorated by SPG. Chronic hypoxia significantly increased the expression of endothelial nitric oxide synthase (eNOS) and phosphorylated eNOS (peNOS) protein levels, cyclic guanosine monophosphate, and matrix metalloproteinase-13 (MMP-13) mRNA levels in whole lung tissues. SPG increased peNOS expression in the immunofluorescent staining of peripheral pulmonary arteries from chronic hypoxic rats and decreased the MMP-13 mRNA in lung tissue in chronic hypoxic rats.

CONCLUSIONS

The administration of SPG ameliorated the development of chronic hypoxic PH and hypertensive pulmonary vascular changes.

Effect of food on the pharmacokinetic properties of the oral sarpogrelate hydrochloride controlled-release tablet in healthy male Korean subjects

BACKGROUND

A new controlled-release formulation of sarpogrelate, a 5-hydroxytryptamine receptor subtype 2 antagonist that blocks serotonin-induced platelet aggregation, has been developed for once-daily administration.

OBJECTIVE

This study evaluated the effect of food on the pharmacokinetic properties of controlled-release sarpogrelate (sarpogrelate CR) in healthy volunteers.

METHODS

A randomized, open-label, two-period, two-treatment crossover study was performed in healthy male Korean subjects. Following an overnight fast, a single dose of sarpogrelate CR 300 mg was administered either in the fasted condition or immediately after a high-fat breakfast. Pharmacokinetic parameters were calculated using a noncompartmental analysis. Tolerability was determined using clinical laboratory testing and physical examination, including vital sign measurements, electrocardiography, and interviews with the volunteers regarding adverse events (AEs).

RESULTS

A total of 24 healthy subjects were enrolled, 23 of whom completed the study (mean [range] age, 26 years [21-45]; weight, 68.1 kg [56.0-79.9]; body mass index, 22.1 kg/m(2) [18.8-25.0]). Sarpogrelate C(max) and AUC(last) were decreased In the fed condition compared with those in the fasted condition, with geometric mean ratios (90% CI) of 0.4868 (0.4041-0.5864) and 0.7394 (0.6809-0.8028), respectively. T(max) was delayed from 0.75 to 4.0 hours after a high-fat meal, but the fed condition exhibited a similar elimination profile to that of the fasted condition. The most commonly reported AE was headache (n = 2), and other AEs were reported in 1 subject each. All of the AEs were considered mild in intensity, and the participants recovered without treatment.

CONCLUSIONS

Compared with the administration of sarpogrelate CR 300 mg in the fasted condition, administration with food was associated with a decreased rate and extent of absorption, as assessed by C(max) and AUC(last), respectively. The drug was well-tolerated by the healthy subjects in this study.

Effect of sarpogrelate hydrochloride, a 5-hydroxytryptamine2 receptor antagonist, on allograft arteriosclerosis after aortic transplantation in rats

BACKGROUND

Sarpogrelate hydrochloride, a 5-hydroxytryptamine2 receptor antagonist, is known to prevent serotonin-induced neointimal hyperplasia. We examined the effect of this agent on allograft arteriosclerosis in a rat model of aortic transplantation.

METHODS

Rats were given an aortic isograft or allograft and oral administration of either saline vehicle alone or 20mg/kg daily of sarpogrelate for 8 weeks. The grafts were then harvested, and the lumen diameter and the thickness of the intima and media were measured. Comparisons were made between measurement results in isografts and allografts from rats treated and not treated with sarpogrelate. Immunohistochemistry assessments were used to detect expression of serotonin in graft specimens.

RESULTS

For both allografts and isografts, significantly less intimal thickening was observed in specimens from rats given sarpogrelate compared with rats given saline. Sarpogrelate had no effect on medial thickening in either graft type. Serotonin was detected in allografts from rats given saline alone but not in allografts from rats given sarpogrelate or in isografts.

CONCLUSIONS

Sarpogrelate hydrochloride may mitigate arteriosclerosis in allografts. Platelet aggregation and serotonin may be correlated with intimal thickening associated with chronic rejection.

Platelet antiaggregants in stroke prevention

Antiplatelet agents are one of the main interventions for recurrent ischemic stroke prevention. Their time of use, dosage, and combination of therapy have different effects in terms of stroke risk reduction and adverse effects. This review provides an evidence-based update of the latest on antiplatelet therapy for stroke prevention.

Possible roles of 5-HT in vein graft failure due to intimal hyperplasia 5-HT, nitric oxide and vein graft

For vascular occlusive disease, an autologous vein graft is the most suitable conduit for arterial reconstruction. Intimal hyperplasia, resulting from the migration and proliferation of vascular smooth muscle cells, is a major obstacle to patency after vein grafting. The degree to which the function of nitric oxide (NO) in the vein graft is preserved has been reported to be associated with the magnitude of intimal hyperplasia. Serotonin (5-HT) is released from platelets in the vascular system and plays physiological roles in controlling the vascular tone. The subtype receptors contributing to the 5-HT-induced mechanical responses vary by vessel type (artery and vein) and among species (dogs, rabbits, rats, and so on). Recent studies have demonstrated that 5-HT induces vasoconstriction through the activation of 5-HT2A receptors in smooth muscle cells or vasodilatation through the activation of endothelial 5-HT1B receptors in arteries from various animals. However, the effects of 5-HT have not been clarified in grafted veins. We herein demonstrate the responses to 5-HT in un-operated veins and then autogenous vein grafts. Next, we describe the effects of chronic in vivo administration of Rho-kinase inhibitors and 5-HT2A receptor antagonists, both of which reduce the 5-HT-induced contraction and intimal hyperplasia in vein grafts. Further studies targeting 5-HT are required to evaluate its possible benefits for autologous vein grafts with respect to vasospasm, function, and patency.

Effect of sarpogrelate treatment on the prognosis after endovascular therapy for critical limb ischemia

5-Hydroxytryptamine type 2 antagonists are used to treat symptomatic peripheral arterial disease. However, it remains unknown as to whether the administration of sarpogrelate, a 5-hydroxytryptamine type 2 antagonist, improves the prognosis after endovascular therapy for critical limb ischemia (CLI). We performed a retrospective analysis using a database of 386 Japanese patients undergoing endovascular therapy for CLI. Sixty-seven patients were treated with sarpogrelate, and we compared their prognosis with that of an equal number of background-matched controls extracted from the population. The primary end point was the first event of either major amputation or death from any cause, and amputation-free survival was evaluated. The follow-up period was 21 ± 18 months (mean ± standard deviation), and 58 end points were observed. Patients treated with sarpogrelate had a significantly higher amputation-free survival rate than their matched controls (P = 0.036). The hazard ratio for the end point and its 95 % confidence interval was 0.57 (0.34–0.97). These results suggest that sarpogrelate treatment is associated with a favorable prognostic outcome in CLI patients undergoing endovascular therapy. Future prospective studies are required to investigate whether sarpogrelate treatment would improve the prognosis of CLI patients.

Prospective study of sarpogrelate hydrochloride on patients with arteriosclerosis obliterans

OBJECTIVE

To evaluate the effect of sarpogrelate for patients with atherosclerotic obliterans (ASO).

PATIENTS AND METHODS

Patients with ASO were randomly divided into sarpogrelate group (n = 92) and control group (n = 84). The patients in sarpogrelate group received sarpogrelate (100 mg, tid), whereas in control group aspirin (100 mg, qd) was administered orally. The patients were followed up monthly to observe any side effect of medication. Clinical manifestation, painless walking distance, Rutherford type and ankle brachial Index (ABI) were studied.

RESULTS

In comparison with control group, the severity of pain, Rutherford type 0 and 1 were improved with statistic significance. Incidence of patients with intermittent claudication decreased from 56.6% before treatment to 28.3% after treatment; the painless walking distance was prolonged (116.3 ± 72.3m vs. 243.5 ± 175.3m, P <0.001); ABI values were increased (0.74 ± 0.17 vs. 0.86 ± 0.18; p <0.001). No side effect of medication was observed.

CONCLUSION

Sarpogrelate has a therapeutic effect on patients with atherosclerotic obliterans.

Sarpogrelate hydrochloride, a selective 5-HT(2A) receptor antagonist, improves skin perfusion pressure of the lower extremities in hemodialysis patients with peripheral arterial disease

BACKGROUND

Peripheral arterial disease (PAD) frequently occurs in patients on hemodialysis (HD); however, little is known about the effectiveness of drugs. We compare the effects of sarpogrelate and cilostazol in HD patients with PAD.

METHODS

We conducted a prospective, randomized, open-label, and multicenter trial for 24 weeks in HD patients with PAD. Thirty-five patients were divided into two groups: sarpogrelate (n = 17) and cilostazol (n = 18). We analyzed changes in skin perfusion pressure (SPP), levels of oxidative stress biomarkers, and adverse events.

RESULTS

At 24 weeks, SPP was increased in both groups (sarpogrelate, 43 ± 17 to 55 ± 15 mmHg; cilostazol, 49 ± 21 to 66 ± 29 mmHg; p < 0.05), and no difference was observed between the groups. Plasma pentosidine levels decreased in both groups (sarpogrelate, 0.65 ± 0.24 to 0.48 ± 0.12 mg/mL; cilostazol, 0.58 ± 0.22 to 0.47 ± 0.17 mg/mL; p < 0.05), and there were no differences between the groups. Serum malondialdehyde-modified low-density lipoprotein (MDA-LDL) levels significantly increased only in cilostazol group (p < 0.05). There were no clinically significant safety concerns linked to the both drugs. Although blood pressure did not differ in both groups, heart rate increased only in cilostazol group from 77 ± 13 to 83 ± 16 beats per minute (p < 0.05).

CONCLUSION

Sarpogrelate improves SPP in HD patients with PAD without increasing heart rate and serum MDA-LDL levels. We demonstrated that sarpogrelate is an effective and safe drug for the treatment of HD patients with PAD.

Effects of sarpogrelate hydrochloride on skin ulcers and quality of life in patients with systemic sclerosis

5-Hydroxytryptamine 2A serotonin receptor (5-HT(2A) ) is associated with the contraction of vascular smooth muscle, platelet aggregation and thrombus formation and coronary artery spasms. Sarpogrelate hydrochloride (sarpogrelate) is a selective 5-HT(2A) antagonist and was supposed to be effective for Raynaud's phenomenon with collagen disease. Sarpogrelate has not been investigated regarding the effects, safety and quality of life (QOL) in patient with skin ulcers of collagen disease. Eleven patients with skin ulcers and systemic sclerosis (SSc) were administrated sarpogrelate p.o. three times a day for 3-6 months. The area (mean ± standard error) of skin ulcer at the pretreatment, and after 3 and 6 months of sarpogrelate intake was 2.1 ± 0.8, 0.2 ± 0.1 and 0.1 ± 0.1 mm(2), respectively. The reduction of skin ulcer area was significant after 3 months of sarpogrelate intake. In assessment of QOL, scores of symptoms and emotions but not of functioning were significantly improved after sarpogrelate intake. The global score (mean ± SE) of Skindex-16 at pretreatment, and after 3 and 6 months of sarpogrelate intake was 31.8 ± 8.7, 23.7 ± 8.3 and 10.9 ± 4.6, respectively. The score was significantly improved after 6 months of sarpogrelate intake. There were no obvious side-effects during this study. Sarpogrelate was considered to be a useful drug to improve skin ulcers and QOL in patients with SSc.

Role of serotonin in angiogenesis: induction of angiogenesis by sarpogrelate via endothelial 5-HT1B/Akt/eNOS pathway in diabetic mice

Serotonin (5-hydroxytryptamine, 5-HT) plays a crucial role in peripheral artery disease (PAD) and diabetes mellitus (DM). In these conditions, the balance between the 5-HT2A receptor in smooth muscle cells and the 5-HT1B receptor in endothelial cells (ECs) regulates vascular tonus. In the present study, we focused on the role of 5-HT in endothelial dysfunction using a selective 5-HT2A receptor blocker, sarpogrelate. In human EC, 5-HT markedly stimulated eNOS expression and the phosphorylation of eNOS, Akt and ERK1/2. In addition, a dose-dependent increase in tubule-formation on Matrigel was observed after 5-HT treatment. In contrast, high glucose significantly inhibited tubule formation and eNOS expression through inactivation of Akt, while 5-HT significantly attenuated these actions of high glucose (P<0.01). These results indicate that 5-HT stimulated angiogenesis through activation of Akt in ECs. However, in clinical situations, 5-HT seems to act as the "devil". To examine the role of 5-HT in diabetic PAD, a hindlimb ischemia model was created in diabetic mice. The blood flow ratio of the ischemic to non-ischemic limb was significantly lower in DM mice than in normal mice, while sarpogrelate significantly attenuated the decrease in the blood flow ratio compared to control (P<0.01). Consistently, the decrease in eNOS expression and Akt activity in DM mice was significantly attenuated by sarpogrelate. Overall, the present study demonstrated that selective inhibition of 5-HT2A by sarpogrelate significantly restored ischemic limb blood perfusion in a severe diabetic mouse model through stimulation of the eNOS/Akt pathway via the endothelial 5-HT1B receptor. Enhancement of vasodilation and angiogenesis by sarpogrelate might provide a unique treatment for PAD and DM patients.

Antiplatelet agents for intermittent claudication

BACKGROUND

Peripheral arterial disease (PAD) is common and is a marker of systemic atherosclerosis. Patients with symptoms of intermittent claudication (IC) are at increased risk of cardiovascular events (myocardial infarction (MI) and stroke) and of both cardiovascular and all cause mortality.

OBJECTIVES

To determine the effectiveness of antiplatelet agents in reducing mortality (all cause and cardiovascular) and cardiovascular events in patients with intermittent claudication.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases group searched their Specialised Register (last searched April 2011) and CENTRAL (2011, Issue 2) for publications on antiplatelet agents and IC. In addition reference lists of relevant articles were also searched.

SELECTION CRITERIA

Double-blind randomised controlled trials comparing oral antiplatelet agents versus placebo, or versus other antiplatelet agents in patients with stable intermittent claudication were included. Patients with asymptomatic PAD (stage I Fontaine), stage III and IV Fontaine PAD, and those undergoing or awaiting endovascular or surgical intervention were excluded.

DATA COLLECTION AND ANALYSIS

Data on methodological quality, participants, interventions and outcomes including all cause mortality, cardiovascular mortality, cardiovascular events, adverse events, pain free walking distance, need for revascularisation, limb amputation and ankle brachial pressure indices were collected. For each outcome, the pooled risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI) was calculated.

MAIN RESULTS

A total of 12 studies with a combined total of 12,168 patients were included in this review. Antiplatelet agents reduced all cause (RR 0.76, 95% CI 0.60 to 0.98) and cardiovascular mortality (RR 0.54, 95% CI 0.32 to 0.93) in patients with IC compared with placebo. A reduction in total cardiovascular events was not statistically significant (RR 0.80, 95% CI 0.63 to 1.01). Data from two trials (which tested clopidogrel and picotamide respectively against aspirin) showed a significantly lower risk of all cause mortality (RR 0.73, 95% CI 0.58 to 0.93) and cardiovascular events (RR 0.81, 95% CI 0.67 to 0.98) with antiplatelets other than aspirin compared with aspirin. Antiplatelet therapy was associated with a higher risk of adverse events, including gastrointestinal symptoms (dyspepsia) (RR 2.11, 95% CI 1.23 to 3.61) and adverse events leading to cessation of therapy (RR 2.05, 95% CI 1.53 to 2.75) compared with placebo; data on major bleeding (RR 1.73, 95% CI 0.51, 5.83) and on adverse events in trials of aspirin versus alternative antiplatelet were limited. Risk of limb deterioration leading to revascularisation was significantly reduced by antiplatelet treatment compared with placebo (RR 0.65, 95% CI 0.43 to 0.97).

AUTHORS' CONCLUSIONS

Antiplatelet agents have a beneficial effect in reducing all cause mortality and fatal cardiovascular events in patients with IC. Treatment with antiplatelet agents in this patient group however is associated with an increase in adverse effects, including GI symptoms, and healthcare professionals and patients need to be aware of the potential harm as well as the benefit of therapy; more data are required on the effect of antiplatelets on major bleeding. Evidence on the effectiveness of aspirin versus either placebo or an alternative antiplatelet agent is lacking. Evidence for thienopyridine antiplatelet agents was particularly compelling and there is an urgent need for multicentre trials to compare the effects of aspirin against thienopyridines.

Study design of SEASON registry: prospective Surveillance of cardiovascular Events in an Antiplatelet-treated arterioSclerosis Obliterans patients in JapaN )SEASON)

Antiplatelet therapy is widely performed for arteriosclerosis obliterans (ASO) to relieve ischemic symptoms and prevent cardiovascular events. However, the overall rate of cardiovascular events in patients with ASO under treatment with antiplatelet agents has not been fully investigated in Japan. The SEASON registry is a nationwide observational prospective cohort study designed to compile data from over 2,000 institutions across Japan, whose aims are to (1) understand the current status for the management of ASO and clarify the incidence of cardiovascular events in patients with ASO undergoing antiplatelet therapy, and (2) compare the effectiveness of sarpogrelate, a 5-HT(2A) receptor antagonist, in decreasing the event rate with those of other antiplatelet agents [UMIN ID: UMIN000003385]. The registry will recruit approximately 10,000 patients receiving antiplatelet therapy (8,000 patients for sarpogrelate and 2,000 for other antiplatelet agents), and the patients will be followed every 6 months during a two-year follow-up period. The investigators plan to report all cardiovascular events and exacerbations of ASO. Analysis focusing on the sarpogrelate-treated subgroup will also be performed. Exploratory analysis will be performed to determine the clinical characteristics of the patients and to elucidate the relationships between risk factors and cardiovascular events. The SEASON registry is the first attempt to create a nationwide database regarding the incidence of cardiovascular events in 10,000 ASO patients in Japan. In addition, it ultimately may enable us to conclude that sarpogrelate prevents cardiovascular events. Information on the severity and risk factors in ASO patients in the clinical settings will be applicable to epidemiological analysis.

Effects of oral single-dose administration of sarpogrelate hydrochloride on saturation O(2) of calf muscle during plantar flexion exercise

To investigate the effects of a 100-mg oral single-dose administration of sarpogrelate hydrochloride (SH) on saturation O(2) (StO(2)) of calf muscle in healthy subjects experiencing simulated peripheral arterial disease (0.6 ankle brachial pressure index). Ten subjects performed three kinds of plantar flexion exercises at a work rate of 50% of maximal volunteer contraction for 4 min by using cuff occlusion ischemia,. Subjects performed a control test (C) without ischemia and SH, an ischemia test (I) without SH, and an I + SH test with ischemia. StO(2), blood pressures (BP), and heart rate (HR) were measured through all experiments. At the end of the exercise, the decrease in StO(2) from baseline in the C and I + SH tests was significantly less than that in the I test (p < 0.05, respectively). However, there were no significant differences in mean BP or HR in any of the exercise conditions. These results indicated that an oral single-dose administration of SH might improve peripheral circulation independent of any changes in BP and HR.

Overview on 5-HT receptors and their role in physiology and pathology of the central nervous system

The present review gives an overview on the serotonin (5-hydroxytryptamine; 5-HT) system, its receptors and their relationship to central nervous system physiology and disorders. Additionally, we also introduce the recent knowledge about the 5-HT receptor ligands in preclinical research, clinical trials and as approved drugs.

New antiplatelet agents

PURPOSE OF REVIEW

Cardiovascular events are still a major concern despite dual antiplatelet treatment with aspirin and clopidogrel. Moreover, recent developments that improved platelet inhibition were associated with increased bleeding complications, suggesting that personal dose adjustment might be needed. This review is dedicated to new developments in antiplatelet agents other than ADP P2Y12 receptor blockers, which are discussed in a separate article of this issue.

RECENT FINDINGS

The thrombin receptor protease activable receptor-1 antagonist SCH530348 and the thromboxane receptor antagonist terutroban are two promising agents that are now undergoing phase III clinical trials. Cilostazol, a phosphodiesterase III inhibitor, is currently tested in phase IV trials for several new indications. Despite previous disappointing results with oral GPIIbIIIa antagonists, new compounds with unique features are under development. In addition, targeting intracellular signaling pathways is a new area of research, with several attractive targets.

SUMMARY

Recent development of new antiplatelet agents, including inhibitors of thrombin receptor, thromboxane receptor, phosphodiesterase, glycoprotein VI, GPIIbIIIa and signaling pathways, may lead to a more effective and yet safe antiplatelet therapy with an improved clinical outcome.

Assessment of binding affinity to 5-hydroxytryptamine 2A (5-HT2A) receptor and inverse agonist activity of naftidrofuryl: comparison with those of sarpogrelate

Naftidrofuryl is a peripheral vasodilator that has been clinically used in the treatment of intermittent claudication and dementia. It has 5-hydroxytryptamine 2 (5-HT(2)) antiserotonergic activity and selectively binds with the 5-HT(2) receptor. The purpose of the present study is to assess the binding affinity and functional potency of naftidrofuryl to the 5-HT(2A) receptor, to find out the inverse agonist activity of this compound at a constitutively active mutant of 5-HT(2A) receptor, and finally to compare the findings with those of sarpogrelate. The investigation showed that the binding affinity (pK(i)) of naftidrofuryl was decreased 25- or 50-fold compared to sarpogrelate in the wild-type 5-HT(2A) receptor or Cys322Lys mutant receptor, respectively. Moreover, the functional potency (pK(b)) of naftidrofuryl was much lower compared to sarpogrelate at the 5-HT(2A) receptor. In addition, inverse agonist activity of naftidrofuryl was lower compared with sarpogrelate at the constitutively active mutant receptor. Thus, the data of the present study would be very important for the clarification of interaction sites of naftidrofuryl to 5-HT(2A) receptors and also may help to understand the mechanism of inverse agonist activity at the constitutively active mutant receptor.

Chronic treatment of hydroxytryptamine type 2a receptor antagonist sarpogrelate hydrochloride modulates the vasoreactivity of serotonin in experimental rabbit vein grafts

OBJECTIVE

It has been suggested that 5-hydroxytryptamine (5-HT) plays a role in the pathogenesis of vein graft spasms. It is suggested that smooth muscle 5-HT(2A) and 5-HT(1B) receptors contribute to 5-HT-induced contraction, while endothelial 5-HT(1B) receptors contribute to the 5-HT-induced endothelium-mediated relaxation. We recently found that chronic administration of the selective 5-HT(2A) receptor antagonist sarpogrelate hydrochloride (SH) enhances the function of endothelium-derived nitric oxide (NO) in rabbit vein grafts. However, it is unknown if such treatment modulates 5-HT-induced vasospasm in vein grafts, and if so, what the underlying mechanisms are.

METHODS

Male rabbits were divided into two groups: a control group and an SH-treated group. The jugular vein was interposed in the carotid artery in reversed fashion. Isometric tension was examined using vein grafts after 4 weeks. 5-HT (10(-8) -10(-6) M)-induced contraction was obtained in each group in the absence or presence of the NO synthase inhibitor l-N(G)-nitroarginine (L-NNA). The expression of 5-HT(2A) and 5-HT(1B) receptors was examined immunohistochemically.

RESULTS

The 5-HT induced a concentration-dependent contractions in both groups. L-NNA did not significantly modify the 5-HT-induced contraction in the control group but enhanced it in the SH group. The 5-HT(1B) receptor antagonist GR55562 inhibited the 5-HT-induced contraction in the control group, while it increased the sensitivity of contraction to 5-HT in the SH-treated group in the absence (but not in the presence) of L-NNA. Positive immunoreactivities against 5-HT(1B) and 5-HT(2A) receptors were identified in endothelial and medial regions of vein grafts in both groups, and the expression of 5-HT(2A) receptors (but not 5-HT(1B) receptors) was significantly less in the SH-treated group than in the control group.

CONCLUSION

Chronically administered SH to rabbits upregulates the autoinhibitory mechanism by 5-HT through a release of NO from endothelium via an activation of endothelial 5-HT(1B) receptors, thus attenuating its own contraction in vein grafts. Furthermore, such SH treatment downregulates the expression of smooth muscle 5-HT(2A) receptors, thus further attenuating the 5-HT-induced contraction. These novel findings further support the clinical usefulness of SH in vein graft spasm after bypass grafting.

Sarpogrelate versus aspirin in secondary prevention of cerebral infarction: differential efficacy in diabetes? Subgroup analysis from S-ACCESS

BACKGROUND AND PURPOSE

The results of the Sarpogrelate-Aspirin Comparative Clinical Study for Efficacy and Safety in Secondary Prevention of Cerebral Infarction (S-ACCESS), a randomized double-blind study of sarpogrelate (selective 5-HT(2A) receptor antagonist) versus aspirin in 1510 Japanese patients, have been reported. But S-ACCESS failed to demonstrate noninferiority of sarpogrelate to aspirin for preventing the recurrence of cerebral infarction. Here we compare the characteristics of sarpogrelate and aspirin in various subgroups.

METHODS

Subgroups were predefined from patients' baseline characteristics. Hazard ratio (HR) and 95% confidence interval (CI) for sarpogrelate versus aspirin were calculated for primary (cerebral infarction) and secondary (serious vascular events) end points. Interactions between treatment effects and subgroup variables were examined by post hoc analysis.

RESULTS

No significant difference in outcome between sarpogrelate and aspirin was found across multiple predefined subgroups. In post hoc analysis, a qualitative treatment interaction with diabetes mellitus was detected (P=0.166 for recurrence of cerebral infarction; P=0.098 for serious vascular events). HR for the recurrence of cerebral infarction with sarpogrelate versus that with aspirin was 0.87 (95% CI: 0.48 to 1.60) in diabetic patients and 1.51 (95% CI: 0.98 to 2.31) in nondiabetic patients. For serious vascular events, the corresponding HRs were 0.73 (95% CI: 0.42 to 1.25) and 1.28 (95% CI: 0.89 to 1.83).

CONCLUSIONS

No specific baseline characteristic resulting in a significant difference between the effects of sarpogrelate and aspirin was identified. Aspirin was superior in most subgroups, except diabetics. Sarpogrelate may be a useful treatment option for Japanese patients with diabetes.

Serotonylation of vascular proteins important to contraction

BACKGROUND

Serotonin (5-hydroxytryptamine, 5-HT) was named for its source (sero-) and ability to modify smooth muscle tone (tonin). The biological effects of 5-HT are believed to be carried out by stimulation of serotonin receptors at the plasma membrane. Serotonin has recently been shown to be synthesized in vascular smooth muscle and taken up from external sources, placing 5-HT inside the cell. The enzyme transglutaminase uses primary amines such as 5-HT to covalently modify proteins on glutamine residues. We tested the hypothesis that 5-HT is a substrate for transglutaminase in arterial vascular smooth muscle, with protein serotonylation having physiological function.

METHODOLOGY/PRINCIPAL FINDINGS

The model was the rat aorta and cultured aortic smooth muscle cells. Western analysis demonstrated that transglutaminase II was present in vascular tissue, and transglutaminase activity was observed as a cystamine-inhibitable incorporation of the free amine pentylamine-biotin into arterial proteins. Serotonin-biotin was incorporated into alpha-actin, beta-actin, gamma-actin, myosin heavy chain and filamin A as shown through tandem mass spectrometry. Using antibodies directed against biotin or 5-HT, immunoprecipitation and immunocytochemistry confirmed serotonylation of smooth muscle alpha-actin. Importantly, the alpha-actin-dependent process of arterial isometric contraction to 5-HT was reduced by cystamine.

CONCLUSIONS

5-HT covalently modifies proteins integral to contractility and the cytoskeleton. These findings suggest new mechanisms of action for 5-HT in vascular smooth muscle and consideration for intracellular effects of primary amines.

Sarpogrelate hydrochloride reduced intimal hyperplasia in experimental rabbit vein graft

OBJECTIVES

The selective 5-HT(2A) receptor antagonist sarpogrelate has been clinically used for treatment in atherosclerotic diseases. However, it remains unknown whether administration of sarpogrelate inhibits intimal hyperplasia seen in autologous vein grafts. Therefore, we sought to clarify this question using an experimental rabbit vein graft model.

METHODS

Male rabbits were divided into two groups: a control group and a sarpogrelate-treated group. The jugular vein was interposed in the carotid artery in reversed fashion for 4 weeks and intimal hyperplasia of the grafted vein was measured (n = 8, in each group). Acetylcholine (ACh)-induced endothelium-dependent relaxation was tested by precontraction with prostaglandin F(2alpha) (PGF(2alpha), 5 muM) (n = 5, in each). endothelial nitric oxide synthase (eNOS) protein expression and superoxide production of these veins were also assessed.

RESULTS

The suppression of intimal hyperplasia was significantly greater in the sarpogrelate-treated group than in the control group. ACh induced an endothelium-dependent relaxation in the sarpogrelate-treated group (but not in the control group). In endothelium-intact strips from the sarpogrelate-treated group, the nitric oxide (NO) synthase inhibitor nitroarginine enhanced the PGF(2alpha)-induced contraction and blocked the ACh-induced relaxation. Immunoreactive eNOS protein expression was similar between the two groups but superoxide production (estimated from ethidium fluorescence) in endothelial cells was significantly smaller in the sarpogrelate-treated group.

CONCLUSION

The present results indicate that in vivo blockade of 5-HT(2A) receptors leads to an inhibition of intimal hyperplasia in rabbit vein graft. It is suggested that an increased function of endothelium-derived NO through a reduction in endothelial superoxide production may be a possible underlying mechanism for this. These novel findings support the clinical usefulness of sarpogrelate for preventing intimal hyperplasia in vein graft after bypass grafting.