Glycoprotein IIb/IIIa inhibitors: The resurgence of tirofiban

Tirofiban-induced thrombocytopenia

Tirofiban is a small non-peptide ligand-mimetic Glycoprotein (GP) IIb/IIIa inhibitor which can reversibly bind to the arginine-glycine-aspartic acid (RGD) recognition site of GP IIb/IIIa to prevent platelet aggregation. It reduces the incidence of thrombotic cardiovascular events in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS). Although generally considered safe, tirofiban has been reported to be associated with thrombocytopenia in several case reports and clinical trials. The pathogenesis for this adverse reaction is not entirely understood, is thought to be due to immune-mediated reaction. This side effect caused by tirofiban is especially concerning given how frequently it is used in the practice of contemporary cardiovascular care. The present review provides an overview of the pathophysiology, clinical presentation, management, and risk factors associated with tirofiban-induced thrombocytopenia.

Artificial Intelligence and Neurosurgery: Tracking Antiplatelet Response Patterns for Endovascular Intervention

Platelets play a critical role in blood clotting and the development of arterial blockages. Antiplatelet therapy is vital for preventing recurring events in conditions like coronary artery disease and strokes. However, there is a lack of comprehensive guidelines for using antiplatelet agents in elective neurosurgery. Continuing therapy during surgery poses a bleeding risk, while discontinuing it before surgery increases the risk of thrombosis. Discontinuation is recommended in neurosurgical settings but carries an elevated risk of ischemic events. Conversely, maintaining antithrombotic therapy may increase bleeding and the need for transfusions, leading to a poor prognosis. Artificial intelligence (AI) holds promise in making difficult decisions regarding antiplatelet therapy. This paper discusses current clinical guidelines and supported regimens for antiplatelet therapy in neurosurgery. It also explores methodologies like P2Y12 reaction units (PRU) monitoring and thromboelastography (TEG) mapping for monitoring the use of antiplatelet regimens as well as their limitations. The paper explores the potential of AI to overcome such limitations associated with PRU monitoring and TEG mapping. It highlights various studies in the field of cardiovascular and neuroendovascular surgery which use AI prediction models to forecast adverse outcomes such as ischemia and bleeding, offering assistance in decision-making for antiplatelet therapy. In addition, the use of AI to improve patient adherence to antiplatelet regimens is also considered. Overall, this research aims to provide insights into the use of antiplatelet therapy and the role of AI in optimizing treatment plans in neurosurgical settings.

Multicenter comparison of antiplatelet treatment strategies for urgent/emergent neuroendovascular stenting

BACKGROUND

Emergent neuroendovascular stenting presents challenges for the utilization of antiplatelet agents.

METHODS

This was a multicenter, retrospective cohort of patients who underwent emergent neuroendovascular stenting. The primary endpoints were thrombotic and bleeding events in relation to the timing of antiplatelet administration, route of administration, and choice of intravenous (IV) agent and the study investigated practice variability in antiplatelet utilization.

RESULTS

Five-hundred and seventy patients were screened across 12 sites. Of those, 167 were included for data analysis. For patients who presented with ischemic stroke, artery dissection and emergent internal carotid artery (ICA) stenting who received an antiplatelet agent prior to or during the procedure, 57% were given an IV antiplatelet agent; for patients who were given an antiplatelet agent after the procedure, 96% were given an oral agent. For patients who presented for aneurysm repair and received an antiplatelet agent prior to or during the procedure, 74% were given an IV agent; patients who were given an antiplatelet agent after the completion of the procedure were given an oral antiplatelet agent 90% of the time. In patients who presented with ischemic stroke, artery dissection and emergent ICA stenting who received oral antiplatelet agents post-procedure were more likely to have thrombotic events compared to those who received oral antiplatelet agents prior to or during the procedure (29% vs 9%; p  =  0.04). There were no differences in the primary outcomes observed when comparing other antiplatelet treatment strategies.

CONCLUSION

The optimal timing of antiplatelet administration in relation to stent placement and route of administration of antiplatelet agents is unclear. Timing and route of administration of antiplatelet agents may have an effect on thrombosis in emergent neuroendovascular stenting. Significant practice variation exists in antiplatelet agent utilization in emergent neuroendovascular stenting.

Rescue therapy after thrombectomy for large vessel occlusion due to underlying atherosclerosis: review of literature

In this review article, we summarized the current advances in rescue management for reperfusion therapy of acute ischemic stroke from large vessel occlusion due to underlying intracranial atherosclerotic stenosis (ICAS). It is estimated that 24-47% of patients with acute vertebrobasilar artery occlusion have underlying ICAS and superimposed in situ thrombosis. These patients have been found to have longer procedure times, lower recanalization rates, higher rates of reocclusion and lower rates of favorable outcomes than patients with embolic occlusion. Here, we discuss the most recent literature regarding the use of glycoprotein IIb/IIIa inhibitors, angioplasty alone, or angioplasty with stenting for rescue therapy in the setting of failed recanalization or instant/imminent reocclusion during thrombectomy. We also present a case of rescue therapy post intravenous tPA and thrombectomy with intra-arterial tirofiban and balloon angioplasty followed by oral dual antiplatelet therapy in a patient with dominant vertebral artery occlusion due to ICAS. Based on the available literature data, we conclude that glycoprotein IIb/IIIa is a reasonably safe and effective rescue therapy for patients who have had a failed thrombectomy or have residual severe intracranial stenosis. Balloon angioplasty and/or stenting may be helpful as a rescue treatment for patients who have had a failed thrombectomy or are at risk of reocclusion. The effectiveness of immediate stenting for residual stenosis after successful thrombectomy is still uncertain. Rescue therapy does not appear to increase the risk of sICH. Randomized controlled trials are warranted to prove the efficacy of rescue therapy.

Antiplatelet Therapy in Neurointervention

The aim of this review is to provide an overview of the use of antiplatelet medication in neurointervention, with a focus on the clinical indications for antiplatelet use in both preventing and reducing platelet aggregation. This review will cover current antiplatelet medications, pharmacokinetics, and pharmacodynamics. We will provide an overview of different endovascular devices and discuss the antiplatelet regimes in neurointervention, highlighting gaps in evidence and scope for future studies.Two randomized controlled trials have evaluated antiplatelet use in the setting of acute large vessel occlusion stroke, with neither demonstrating benefit in their overall cohorts. Evidence on antiplatelet medication for both acute and elective stenting for acute stroke and treatment of cerebral aneurysms is currently based on large case series, and practice in neurointervention has increasingly utilized dual antiplatelet regimes with clopidogrel and second-line agents like prasugrel and ticagrelor. Clopidogrel function testing has an increasing role in neurointerventional procedures, particularly for high metal surface area stents such as the braided flow diverter type stents. Intravenous glycoprotein IIB/IIIA inhibitors have been utilized for both acute bridging and rescue therapy.Antiplatelet decision making is complex, and there are few randomized control trials to guide clinical practice. Comparative trials to guide decision making remain important in both the acute and elective settings. Standardised protocols incorporating platelet function testing may play a role in assisting decision making until more robust clinical evidence is available, particularly in the context of acute neurointerventional stenting for stroke and ruptured cerebral aneurysms.

Predicting the Likelihood of Molecules to Act as Modulators of Protein-Protein Interactions

Targeting protein-protein interactions (PPIs) by small molecule modulators (iPPIs) is an attractive strategy for drug therapy, and some iPPIs have already been introduced into the clinic. Blocking PPIs is however considered to be a more difficult task than inhibiting enzymes or antagonizing receptor activity. In this paper, we examine whether it is possible to predict the likelihood of molecules to act as iPPIs. Using our in-house iterative stochastic elimination (ISE) algorithm, we constructed two classification models that successfully distinguish between iPPIs from the iPPI-DB database and decoy molecules from either the Enamine HTS collection (ISE 1) or the ZINC database (ISE 2). External test sets of iPPIs taken from the TIMBAL database and decoys from Enamine HTS or ZINC were screened by the models: the area under the curve for the receiver operating characteristic curve was 0.85-0.89, and the Enrichment Factor increased from an initial 1 to as much as 66 for ISE 1 and 57 for ISE 2. Screening of the Enamine HTS and ZINC data sets through both models results in a library of ∼1.3 million molecules that pass either one of the models. This library is enriched with iPPI candidates that are structurally different from known iPPIs, and thus, it is useful for target-specific screenings and should accelerate the discovery of iPPI drug candidates. The entire library is available in Table S6.

Sida chlorotic leaf virus: a new recombinant begomovirus found in non-cultivated plants and Cucumis sativus L

Background

Begomoviruses are circular single-stranded DNA plant viruses that cause economic losses worldwide. Weeds have been pointed out as reservoirs for many begomoviruses species, especially from members of the Sida and Malvastrum genera. These weeds have the ability to host multiple begomoviruses species simultaneously, which can lead to the emergence of new viral species that can spread to commercial crops. Additionally, begomoviruses have a natural tendency to recombine, resulting in the emergence of new variants and species.

Methods

To explore the begomoviruses biodiversity in weeds from genera Sida and Malvastrum in Colima, México, we collected symptomatic plants from these genera throughout the state. To identify BGVs infecting weeds, we performed circular DNA genomics (circomics) using the Illumina platform. Contig annotation was conducted with the BLASTn tool using the GenBank nucleotide "nr" database. We corroborated by PCR the presence of begomoviruses in weeds samples and isolated and sequenced the complete genome of a probable new species of begomovirus using the Sanger method. The demarcation process for new species determination followed the International Committee on Taxonomy of Viruses criteria. Phylogenetic and recombination analyses were implemented to infer the evolutionary relationship of the new virus.

Results

We identified a new begomovirus species from sida and malvastrum plants that has the ability to infect Cucumis sativus L. According to our findings, the novel species Sida chlorotic leaf virus is the result of a recombination event between one member of the group known as the Squash leaf curl virus (SLCV) clade and another from the Abutilon mosaic virus (AbMV) clade. Additionally, we isolated three previously identified begomoviruses species, two of which infected commercial crops: okra (Okra yellow mosaic Mexico virus) and cucumber (Cucumber chlorotic leaf virus).

Conclusion

These findings support the idea that weeds act as begomovirus reservoirs and play essential roles in begomovirus biodiversity. Therefore, controlling their populations near commercial crops must be considered in order to avoid the harmful effects of these phytopathogens and thus increase agricultural efficiency, ensuring food and nutritional security.

Long-Term Outcomes of Local Tirofiban Infusion for Intracranial Atherosclerosis-Related Occlusion

Local tirofiban infusion has been reported as a rescue strategy for intracranial atherosclerotic stenosis (ICAS)-related stroke. However, the long-term outcomes of local tirofiban infusion during endovascular reperfusion therapy (ERT) for ICAS-related stroke are still uncertain. This study aimed to investigate the long-term outcomes of local tirofiban infusion during ERT. We retrospectively analyzed acute patients with ICAS-related stroke who were treated with local tirofiban as a rescue strategy during ERT. The primary outcomes were ischemic stroke, transient ischemic stroke (TIA), and stroke-related death within 30 days. Secondary outcomes included ischemic stroke and TIA beyond 30 days and up to 2 years after ERT in the corresponding treated vessel, symptomatic brain hemorrhage, any stroke, and non-stroke-related death. During a median follow-up of 24.0 months, 12 patients developed an ischemic stroke and TIA (4 within 30 days and 8 afterward). The 1-year risk of stroke and TIA was 9.2% (95% confidence interval, 8.0–18.6%). This study demonstrates that 1-year outcomes of local tirofiban infusion were comparable to the results of intracranial stenting in patients with symptomatic ICAS. Local tirofiban infusion for ICAS-related stroke may be a feasible rescue strategy that can have a bridging role until the maximum effect of antiplatelet agents is achieved.

Safety and efficacy of different tirofiban administration routes on acute ischemic stroke patients with successful recanalization: A propensity score matching analysis

OBJECTIVE

This study aimed to explore the effect of different administration routes of a low dose of tirofiban on acute ischemic stroke (AIS) patients with successful recanalization after endovascular treatment (EVT).

METHODS

This is a cohort study that retrospectively analyzed data of patients with AIS who underwent EVT and achieved successful recanalization from a prospective registry. Eligible patients were divided into three groups according to their use of tirofiban. Propensity score matching (PSM) was used to balance baseline bias. Safety outcomes included any intracranial hemorrhage (ICH) and symptomatic ICH (sICH). Efficacy outcomes included arterial reocclusion, in-hospital mortality, 3-month mortality, and 3-month functional outcomes.

RESULTS

We included 821 patients with 306 in the no tirofiban group, 202 in the IA + IV tirofiban group, and 313 in the IV tirofiban group. After PSM, each group included 101 patients with balanced baseline characteristics. There was no difference between the IV tirofiban group and the no tirofiban group in terms of safety and efficacy outcomes (all p > 0.05). Compared with no tirofiban, IA + IV tirofiban group did not increase ICH (30.7% vs. 37.6%, p > 0.05) and sICH (6.9% vs. 17.8%, p > 0.05) whereas reduced 3-month mortality (14.3% vs. 28.7%, p < 0.05) and improved 3-month modified Rankin Scale (median 3 vs. 4, p < 0.05).

CONCLUSIONS

A low dose of tirofiban, regardless of their administration routes, was safe for AIS patients who achieved successful recanalization with EVT, whereas only IA + IV tirofiban improved clinical outcomes.

Comparison of Ischemic and Bleeding Events Between Short-Duration Versus Long-Duration Tirofiban Regimens in Patients With ST-Segment Elevation Myocardial Infarction Undergoing Percutaneous Coronary Intervention

ABSTRACT

Tirofiban has been used historically as a bridge to platelet inhibition with clopidogrel in ST-segment myocardial infarction (STEMI) during percutaneous coronary intervention (PCI) to prevent stent thrombosis. However, ticagrelor and prasugrel reach similar levels of platelet inhibition at 30 minutes to that of clopidogrel at 6 hours, challenging the need for long-duration tirofiban. This 1-year, retrospective cohort study compared ischemic and bleeding outcomes of short-duration versus long-duration tirofiban regimens in patients with STEMI who received ticagrelor or prasugrel at the time of PCI. The primary outcome was major adverse cardiovascular events (MACEs) including cardiovascular mortality, recurrent myocardial infarction, urgent target vessel revascularization, or stroke. Secondary outcomes included individual MACE, all-cause mortality, bleeding events defined by the International Society on Thrombosis and Hemostasis, thirty-day readmissions for MACE and bleeding, and tirofiban pharmacy cost. A total of 283 charts were reviewed and 177 included (short duration n = 57; long duration n = 120). MACE rates were similar between short-duration and long-duration groups (0 [0%] vs. 5 [4.2%]; P = 0.18), including 4 cardiovascular deaths and 1 recurrent myocardial infarction. Bleeding event rates were also similar in short-duration versus long-duration groups including major bleeds (2 [3.5%] vs. 2 [1.7%]; P = 0.60) and clinically relevant nonmajor bleeds (3 [5.3%] vs. 9 [7.5%]; P = 0.75). Cost analysis indicated lower pharmacy cost with the short-duration group. In this cohort of patients with STEMI receiving a fast-acting P2Y12 inhibitor, the length of tirofiban infusion did not affect ischemic or bleeding outcomes, yet short-duration regimens were lower cost.

Efficacy and Safety of Tirofiban in Clinical Patients With Acute Ischemic Stroke

BACKGROUND

Intravenous thrombolysis and endovascular thrombectomy have been approved for acute ischemic stroke (AIS). However, only a minority of patients received these treatments in China. We aimed to evaluate the efficacy and safety of tirofiban in patients with AIS who were not undergoing early recanalization treatments.

METHODS

Patients with mild-to-moderate stroke [National Institutes of Health Stroke Scale (NIHSS) score, 4-15] were enrolled in this study. Patients due to cardiogenic embolism were excluded. Eligible patients within 12 h from symptom onset were randomly assigned (1:1) to receive tirofiban (a loading dose of 0.4 μg/kg/min over 30 min and a maintenance dose of 0.1 μg/kg/min up to 48 h) followed by regular treatment or to receive regular treatment (aspirin at a dose of 100 mg per day for 90 days) (control). The primary outcome was the proportion of favorable functional outcomes at 90 days [defined as the modified Rankin Scale (mRS) score of 0-2]. The secondary outcomes included a shift in the distribution of the mRS scores at 90 days and the NIHSS score at 24 h and 7 days. The primary safety outcome was symptomatic intracranial hemorrhage (sICH) within 7 days after tirofiban treatment.

RESULTS

A total of 380 eligible patients were randomly assigned to the tirofiban group (n = 190) or the control group (n = 190). The proportion of favorable functional outcomes was higher in the tirofiban group (79.1%) than that in the control group (67.8%) at 90 days [odds ratio (OR), 1.80; 95% CI, 1.12-2.90; p = 0.0155]. An improvement was also observed in the overall distribution of the 90-day mRS scores (adjusted common OR, 2.31; 95% CI, 1.58-3.39; p < 0.0001). Additionally, the median NIHSS score was lower in the tirofiban group than in the control group at 7 days (3 vs. 5, p < 0.0001). Next, we observed that the occurrence of sICH did not differ between the two groups.

CONCLUSION

Our trial supports that tirofiban was safe and effective and might be a remedial treatment for patients with AIS who did not receive recanalization treatments.

CLINICAL TRIAL REGISTRATION

http://www.chictr.org.cn/, identifier: ChiCTR2000031297.

The integrin beta1 modulator Tirofiban prevents adipogenesis and obesity by the overexpression of integrin-linked kinase: a pre-clinical approach in vitro and in vivo

Background

Obesity is caused by the enlargement of the white adipose tissue (WAT) depots, characterized by the hypertrophic enlargement of malfunctioning adipocytes within WAT which increases the storage of triglycerides (TG) in the lipid droplets (LD). Adipogenesis pathways as well as the expression and activity of some extracellular matrix receptors integrins are upregulated. Integrinβ1 (INTB1) is the main isoform involved in WAT remodeling during obesity and insulin resistance-related diseases. We recently described Integrin Linked Kinase (ILK), a scaffold protein recruited by INTB1, as an important mediator of WAT remodeling and insulin resistance. As the few approved drugs to fight obesity have brought long-term cardiovascular side effects and given that the consideration of INTB1 and/or ILK modulation as anti-obesogenic strategies remains unexplored, we aimed to evaluate the anti-obesogenic capacity of the clinically approved anticoagulant Tirofiban (TF), stated in preclinical studies as a cardiovascular protector.

Methods

Fully differentiated adipocytes originating from C3H10T1/2 were exposed to TF and were co-treated with specific INTB1 blockers or with siRNA-based knockdown ILK expression. Lipid-specific dyes were used to determine the TG content in LD. The genetic expression pattern of ILK, pro-inflammatory cytokines (MCP1, IL6), adipogenesis (PPARγ, Leptin), thermogenesis (UCP1), proliferation (PCNA), lipid metabolism (FASN, HSL, ATGL), and metabolite transporters (FABP4, FAT, AQP7) were detected using quantitative PCR. Cytoskeletal actin polymerization was detected by confocal microscopy. Immunoblotting was performed to detect INTB1 phosphorylation at Thr788/9 and ILK activity as phosphorylation levels of protein kinase B (AKT) in Ser473 and glycogen synthase kinase 3β (GSK3β) at Ser9. TF was intraperitoneally administered once per day to wildtype and ILK knockdown mice (cKDILK) challenged with a high-fat diet (HFD) or control diet (STD) for 2 weeks. Body and WAT weight gains were compared. The expression of ILK and other markers was determined in the visceral epididymal (epi) and inguinal subcutaneous (sc) WAT.

Results

TF reduced TG content and the expression of adipogenesis markers and transporters in adipocytes, while UCP-1 expression was increased and the expression of lipases, cytokines or PCNA was not affected. Mechanistically, TF rapidly increased and faded the intracellular phosphorylation of INTB1 but not AKT or GSK3β. F-actin levels were rapidly decreased, and INTB1 blockade avoided the TF effect. After 24 h, ILK expression and phosphorylation rates of AKT and GSK3β were upregulated, while ILK silencing increased TG content. INTB1 blockade and ILK silencing avoided TF effects on the TG content and the transcriptional expression of PPARγ and UCP1. In HFD-challenged mice, the systemic administration of TF for several days reduced the weight gain on WAT depots. TF reduced adipogenesis and pro-inflammatory biomarkers and increased lipolysis markers HSL and FAT in epiWAT from HFD, while increased UCP1 in scWAT. In both WATs, TF upregulated ILK expression and activity, while no changes were observed in other tissues. In HFD-fed cKDILK, the blunted ILK in epiWAT worsened weight gain and avoided the anti-obesogenic effect of in vivo TF administration.

Conclusions

ILK downregulation in WAT can be considered a biomarker of obesity establishment. Via an INTB1-ILK axis, TF restores malfunctioning hypertrophied WAT by changing the expression of adipocyte-related genes, increasing ILK expression and activity, and reducing TG storage. TF prevents obesity, a property to be added to its anticoagulant and cardiovascular protective advantages.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00746-1.

Safety, pharmacokinetics and pharmacodynamics of an original glycoprotein IIb/IIIa inhibitor in healthy volunteers: results of the clinical trial

Aim. To study the tolerability, safety, pharmacokinetics (PK) and pharmacodynamics of single intravenous infusions of Angipur in healthy male volunteers.

Material and methods. The Phase I trial included 20 healthy male volunteers (mean age, 30,8±7,7 years; mean body weight, 77,4±12,1 kg). Angipur (0,02% concentrate for solution for infusion) was administered to every subject in single doses 0,015, 0,05, 0,09 mg/kg for 3 consecutive days. Volunteers were divided in 6 groups (1, 1, 3, 5, 5, 5); every following group was recruited only after the previous one finished the study. The following were assessed: rate and severity of adverse events (AEs), key PK parameters of Angipur and its antiplatelet activity by impedance aggregometry.

Results. No moderate or severe AEs, as well as no serious AEs were reported according to obtained data of clinical and laboratory monitoring of healthy subjects. Totally 6 mild AEs were registered in 4 subjects. Four AEs (mild hematological deviations and episode of nose bleed) were classified as possibly related to study drug and 1 AE (positive fecal occult blood test)  — probably related. Key PK parameters of Angipur in single intravenous doses 0,015, 0,05 и  0,09 mg/kg were determined as follows: Cmax — 12,44±4,689, 46,10±14,295, 92,48±33,896 ng/ml; Vd  — 304,01±55,300, 299,67±64,244, 252,96±47,790 l; T1/2  — 6,72±1,290, 6,84±2,341, 6,06±2,287 h; Cl  — 32,19±6,919, 32,29±8,357, 31,55±10,113 l/h, respectively. Dose proportionality (linear PK) for parameters Cmax, AUC0-t and AUC0-∞ was established. Dose-dependent reduction of ADP-induced platelet aggregation degree and area under curve was revealed at period of 15 min to 2-4 h after Angipur infusion in doses 0,05 and 0,09 mg/kg.

Conclusion. Results of phase I clinical trial demonstrated good tolerability of single intravenous infusions of Angipur (0,015, 0,05 и 0,09 mg/kg) in healthy subjects. We determined key PK parameters and indicated dose-dependent antiplatelet activity of Angipur.

Electrical impedance vs. light transmission aggregometry: Testing platelet reactivity to antiplatelet drugs using the MICELI POC impedance aggregometer as compared to a commercial predecessor

BACKGROUND

Patients' responses to antiplatelet therapy significantly vary, with individuals showing high residual platelet reactivity associated with thrombosis. To personalize thrombosis management, platelet function testing has been suggested as a promising tool able to monitor the antithrombotic effect of antiplatelet agents in real-time. We have prototyped the MICELI, a miniature and easy-to-use electrical impedance aggregometer (EIA), measuring platelet aggregation in whole blood. Here, we tested the capability of the MICELI aggregometer to quantify platelet reactivity on antiplatelet agents, as compared with conventional light-transmission aggregometry (LTA).

METHODS

Platelet aggregation in ACD-anticoagulated whole blood and platelet-rich plasma of healthy donors (n = 30) was evaluated. The effect of clopidogrel, ticagrelor, cangrelor, cilostazol, and tirofiban on ADP-induced aggregation was tested, while aspirin was evaluated with arachidonic acid and collagen. Platelet aggregation was recorded using the MICELI or BioData PAP-8E (Bio/Data Corp.) aggregometers.

RESULTS

The MICELI aggregometer detected an adequate and comparable dose-dependent decrease of platelet aggregation in response to increments of drugs' concentrations, as compared to LTA (the inter-device R2 = 0.79-0.93). Platelet aggregation in platelet-rich plasma recorded by LTA showed higher sensitivity to antiplatelet agents, but it couldn't distinguish between different drug doses as indicated by saturation of the aggregatory response.

CONCLUSION

Platelet aggregation in whole blood as recorded by EIA represents a better model system for evaluation of platelet reactivity as compared with platelet aggregation in platelet-rich plasma as recorded by LTA, since EIA takes into consideration the modulatory effect of other blood cells on platelet hemostatic function and pharmacodynamics of antiplatelet drugs in vivo. As such, the MICELI impedance aggregometer could be potentially employed for the point-of-care monitoring of platelet function in patients on-treatment for personalized tailoring of their antiplatelet regimen.

Cell adhesion molecule-mediated therapeutic strategies in atherosclerosis: From a biological basis and molecular mechanism to drug delivery nanosystems

Atherosclerosis (AS), characterized by pathological constriction of blood vessels due to chronic low-grade inflammation and lipid deposition, is a leading cause of human morbidity and mortality worldwide. Cell adhesion molecules (CAMs) have the ability to regulate the inflammatory response and endothelial function, as well as potentially driving plaque rupture, which all contribute to the progression of AS. Moreover, recent advances in the development of clinical agents in the cardiovascular field are based on CAMs, which show promising results in the fight against AS. Here, we review the current literature on mechanisms by which CAMs regulate atherosclerotic progression from the earliest induction of inflammation to plaques formation. In particular, we focused on therapeutic strategies based on CAMs inhibitors that prevent leukocyte from migrating to endothelium, including high-affinity antibodies and antagonists, nonspecific traditional medicinal formulas and lipid lowering drugs. The CAMs-based drug delivery nanosystem and the available data on the more reasonable and effective clinical application of CAMs inhibitors have been emphasized, raising hope for further progress in the field of AS therapy.

Surface modification of polyurethane with eptifibatide-loaded degradable nanoparticles reducing risk of blood coagulation

The main purpose of the work was to develop a drug releasing coatings on the surface of medical devices exposed to blood flow, what should enable effective inhibition of blood coagulation process. As a part of the work, the process of encapsulating the anticoagulant drug eptifibatide (EPT) in poly(DL-lactic-co-glycolic acid) (PLGA) nanoparticles was developed. EPT encapsulation efficiency was 29.1 ± 2.1%, while the EPT loading percentage in the nanoparticles was 4.2 ± 0.3%. The PLGA nanoparticles were suspended in a polyanion solution (hyaluronic acid (HA)) and deposited on the surface-treated thermoplastic polyurethane (TPU) by a layer-by-layer method. As a polycation poly-L-lysine (PLL) was used. The influence of released EPT on the activation of the coagulation system was analyzed using dynamic blood tester. Performed experiments show an effective delivery of the drug to the bloodstream and low risk of platelets (membrane receptor) activation. The dynamic blood test process, including its physical phenomenon, was described using numerical methods, i.e. a finite volume cone-and-plate test model as well as non-Newtonian blood models. The values of shear stress and blood flow velocity under the fast-rotating cone were computed applying boundary conditions of cylinder wall imitating blood-nanomaterial interaction. Implementing boundary conditions as initial shear stress values of bottom cylinder wall resulted in the increase of shear stress in blood under rotating cone. The developed system combining drug eluting polymeric nanoparticles with the polyelectrolyte "layer-by-layer" coating can be easily introduced to medical implants of various shape, with the advantages of resorbable drug carriers allowing for local and controllable delivery of anti-thrombogenic drugs.

Safety and Efficacy of Tirofiban for Acute Ischemic Stroke Patients With Large Artery Atherosclerosis Stroke Etiology Undergoing Endovascular Therapy

Objective: To investigate the safety and efficacy of tirofiban in acute ischemic stroke (AIS) patients with large artery atherosclerosis (LAA) stroke etiology receiving endovascular therapy (EVT).

Methods: In this multi-center prospective study, patients who were considered to have an indication received a low dose intra-arterial bolus (0.25–1 mg) of tirofiban. The safety and efficacy outcomes at 90-day follow-ups included symptomatic intracranial hemorrhage (sICH), recanalization rate, functional outcome, and mortality.

Results: Among the 649 AIS patients with LAA, those in the tirofiban group (n = 244) showed higher systolic blood pressure (BP) and NIHSS score on admission, puncture-to-recanalization time, lower frequency of intravenous thrombolysis and intra-arterial thrombolysis, higher frequency of antiplatelet, heparinization, mechanical stent retrieval, aspiration, balloon angioplasty, and more retrieval times compared with those in the non-tirofiban group (n = 405) (all P < 0.05). Tirofiban was found to be associated with superior clinical outcomes in anterior circulation stroke and major stroke patients [adjusted odds ratio (OR) = 2.163, 95% confidence interval (CI) = 1.130–4.140, P = 0.02 and adjusted OR = 2.361, 95% CI = 1.326–4.202, P = 0.004, respectively] and a lower risk of mortality at 90-day follow-ups (adjusted OR = 0.159, 95% CI = 0.042–0.599, P = 0.007 and adjusted OR = 0.252, 95% CI = 0.103–0.621, P = 0.003, respectively). There was no significant difference in sICH between the two groups.

Conclusions: Tirofiban in AIS patients with LAA undergoing EVT is safe and may benefit the functional outcomes in anterior circulation and major stroke patients and showed a trend for reduced mortality.

Efficacy and safety of abciximab versus tirofiban in addition to ticagrelor in STEMI patients undergoing primary percutaneous intervention

Platelet glycoprotein IIb/IIIa inhibitors (GPIs) have been part of the adjuvant treatment of acute coronary syndrome for years. However, real-life data regarding the efficacy and safety of GPIs under the current indications are lacking in the setting of potent platelet inhibition. The objectives were to assess the efficacy and safety of abciximab versus tirofiban in patients with ST-elevation acute myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI) and pretreated with ticagrelor, and to identify independent predictor factors of efficacy, bleeding and platelet drop. Three hundred sixty-two patients were divided by GPI administered. Clinical, laboratory, angiographic and outcome characteristics were compared. The primary objective was a composite efficacy endpoint (death from any cause, nonfatal myocardial infarction and nonfatal stroke) at 30 days. The secondary objectives were its individual components, safety (bleeding) and the impact on platelet count during hospital stay. The composite efficacy endpoint was similar in the abciximab and tirofiban groups (6.1% vs 7.3%; p = .632). There were also no differences in cardiovascular death (2.5% vs 2.4%; p = .958), nonfatal myocardial infarction (3% vs 4.3%; p = .521) and nonfatal stroke (0.5% vs 1.8%; p = .332). Tirofiban administration was associated with a higher incidence of bleeding (11.6% vs 22%; p = .008) with no differences in BARC ≥ 3b bleeding (3.6 vs 2.5%; p = .760). In STEMI patients undergoing PPCI with ticagrelor, abciximab and tirofiban had similar rates in the composite efficacy endpoint at 30 days. The 30-day bleeding rate was significantly higher in the tirofiban group. Tirofiban administration was an independent predictor of both bleeding and platelet count drop.

Prospective study of the effect of sulfotanshinone sodium combined with tirofiban on vascular endothelial function and indicators of plaque stability in elderly patients with acute coronary syndrome

WHAT IS KNOWN AND OBJECTIVE

This study aimed to explore the effect of sulfotanshinone sodium injection combined with tirofiban on vascular endothelial function and indicators of plaque stability in elderly patients with acute coronary syndrome (ACS).

METHODS

We designed a prospective study and enrolled 169 patients with ACS who were admitted to our hospital as subjects. Patients treated with sulfotanshinone sodium injection combined with tirofiban (n = 99) were allocated to the research group (RG), and the remaining patients treated with tirofiban alone were allocated to the control group (n = 70; CG). The two groups were compared in terms of treatment efficacy, adverse reactions, vascular endothelial function, changes in plaque stability indicator levels, prognosis, recurrence rate, and quality of life after the treatment.

RESULTS AND DISCUSSION

Treatment response rate, SOD and ET-1 levels, and quality-of-life score were markedly lower in RG than in CG (all P < .05). The incidence of adverse reactions; levels of CD63p, CD62p and GP IIb/IIIa; changes in plaque stability indicator levels; and recurrence rate were markedly higher in RG than in CG (all P < .05). There was no significant difference in 3-year survival rate between the two groups (P > .05).

WHAT IS NEW AND CONCLUSION

Compared with tirofiban alone, sulfotanshinone sodium injection combined with tirofiban had superior efficacy and safety in the treatment of ACS. It can effectively reduce recurrence rate and improve quality of life in ACS, making it a strong candidate for popular clinical application.

Safety of Glycoprotein IIb-IIIa Inhibitors Used in Stroke-Related Treatment: A Systematic Review and Meta-Analysis

Background:

Endovascular therapy and intravenous thrombolysis with recombinant tissue plasminogen activator are the 2 most recommended treatments for acute ischemic stroke (AIS). Glycoprotein (GP) IIb-IIIa inhibitors are short-acting selective reversible antiplatelet agents that emerged as promising therapeutic agents for AIS about 10 years ago. Given the unclear safety profile and application coverage of GP inhibitors, we conducted this meta-analysis to explore the same.

Methods:

We used GP IIb-IIIa inhibitors, intracranial hemorrhage, and mortality as the key words on Medline, Web of Science, and the Embase databases. Randomized controlled trials, prospective literatures, and retrospective studies in English published between 1990 and 2020 were screened. The outcomes were relative risk (RR) of death and 90-day intracerebral hemorrhage (ICH). We pooled the results in 2 categories and conducted a subgroup analysis stratified by different drugs. The choice of the effects model depended on the value of I².

Results:

In all, 3700 patients from 20 studies were included. No GP IIb-IIIa inhibitors were found to have a remarkable influence on the ICH rate. The RR values of symptomatic ICH for abciximab and eptifibatide were 4.26 (1.89, 9.59) and 0.17 (0.04, 0.69), respectively. Both tirofiban and abciximab could decrease the mortality rate within 90 days. Age > 70 years, National Institutes of Health Stroke Scale > 15, and overall dose > 10 mg are risk factors for ICH events with tirofiban usage. Thrombectomy combined with tirofiban was safe for arterial reocclusion prevention.

Conclusions:

In stroke-related treatment, administration of GP IIb-IIIa inhibitors could be safe, but care should be taken regarding drug species and doses. Abciximab can increase the risk of symptomatic intracranial hemorrhage. Tirofiban and eptifibatide can be considered safe in low doses. Suitable patients should be selected using strict criteria.

Local tirofiban infusion for remnant stenosis in large vessel occlusion: tirofiban ASSIST study

BACKGROUND

Compared with embolic occlusions, intracranial atherosclerotic stenosis (ICAS)-related large vessel occlusions (LVOs) often require rescue treatment following mechanical thrombectomy (MT). Herein, we hypothesized that local tirofiban infusion can be effective and safe for remnant stenosis in LVO during endovascular treatment and can improve clinical outcomes.

METHODS

This observational multicenter registry study (January 2011 to February 2016) included patients with ICAS who underwent endovascular treatment for LVO within 24 h after stroke onset. An underlying fixed focal stenosis at the occlusion site observed on cerebral angiography during and after MT was retrospectively determined as a surrogate marker of ICAS. Procedural and clinical outcomes were compared between the tirofiban and non-tirofiban groups.

RESULTS

Of 118 patients, 59 received local tirofiban infusion. Compared to the non-tirofiban group, patients were older (non-tirofiban group versus tirofiban group; median, 63 years vs. 71 years, p = 0.015) and the onset-to-puncture time was longer (median, 275 min vs. 395 min, p = 0.036) in the tirofiban group. The median percent of residual stenosis prior to rescue treatment tended to be higher in the tirofiban group (80 [71-86] vs. 83 [79-90], p = 0.056). Final reperfusion success (modified Treatment In Cerebral Ischemic 2b-3) was more frequent (42.4%vs. 86.4%, p = 0.016) and post-procedure parenchymal hematoma type 2 and/or thick subarachnoid hemorrhages were less frequent (15.3%vs. 5.1%, p = 0.068) in the tirofiban group. The frequency of favorable outcomes 3 months after endovascular treatment (modified Rankin Scale 0-2) was significantly higher in the tirofiban group (32.2% vs. 52.5%, p = 0.025), and tirofiban administration was an independent predictor of favorable outcomes (odds ratio, 2.991; 95% confidence interval, 1.011-8.848; p = 0.048).

CONCLUSIONS

Local tirofiban infusion can be a feasible adjuvant treatment option for patients with ICAS-LVO.

Early administration of tirofiban after urokinase-mediated intravenous thrombolysis reduces early neurological deterioration in patients with branch atheromatous disease

Objectives

To investigate the effects of early administration of tirofiban after intravenous thrombolysis on early neurological deterioration in patients with branch atheromatous disease.

Methods

We analyzed clinical data from patients with branch atheromatous disease. We enrolled seven cases into the urokinase-only (UO) control group and 10 cases into the urokinase + tirofiban (UT) treatment group. National Institutes of Health Stroke Scale (NIHSS) scores were obtained at admission and on days 3 and 5 after admission. Modified Rankin Scale (mRS) scores were obtained 3 months after admission.

Results

Significant differences between the UO and UT groups were evident on days 3 and 5 after admission. In the UT group, there was a significant difference between NIHSS scores at admission and on day 5, while there were no significant differences in scores in the UO group. The early neurological deterioration rates were not significantly different between the two groups. However, there were significant differences in these rates at 72 and 120 hours. Both the mRS scores and the prognoses at 3 months differed between the two groups.

Conclusion

Early administration of tirofiban after urokinase-mediated intravenous thrombolysis reduces early neurological deterioration and improves the long-term prognosis of patients with branch atheromatous disease.

Tirofiban Promotes the Proliferation of Human Umbilical Vein Endothelial Cells In Vitro Via Enhanced Vascular Endothelial Growth Factor Expression

BACKGROUND

In the design and development of small-caliber artificial blood vessels, endothelialization is a key issue, but it is not well understood at present. Some studies have used vascular endothelial growth factor (VEGF) sustained-release methods to promote endothelial cell proliferation. However, this method is not ideal. This study has used drugs to induce endothelial cells to produce VEGF. This method in turn functions to promote cell proliferation and promote the endothelialization of artificial blood vessels. This study aimed to investigate the effect of the antiplatelet drug tirofiban on endothelial cell proliferation in vitro.

METHODS

In this study, human umbilical vein endothelial cells (HUVECs) were used to determine the effect of tirofiban-stimulated cell proliferation. Analysis of cell proliferation, assayed by the Cell Counting Kit-8 assay, showed that the number of cells was increasingly higher than in the absence of tirofiban. It was also observed that heparin enhanced the tirofiban effect. The cell VEGF expression at different time points after tirofiban addition was detected by western blot analysis.

RESULTS

The absorbance values of the experimental (1 μg/mL tirofiban) and the control groups (0 tirofiban) were 1.74 (SD, 0.03) and 1.51 (SD, 0.07) (P < .001), respectively, after 4 days of culture under the same conditions. The amount of VEGF produced by HUVECs gradually increased after treatment with tirofiban, reached a peak at 2 hours, and was 1.3-fold greater than the control group (P = .034). Compared with the tirofiban-only group, the absorbance value of the tirofiban and 10 μg/mL of heparin group was significantly increased (P < .001).

CONCLUSIONS

Tirofiban promoted the proliferation of HUVECs by promoting the synthesis of VEGF in HUVECs. Heparin enhanced tirofiban activity in promoting HUVEC proliferation.

Intra-arterial Tirofiban in a Male Nonagenarian with Acute Ischemic Stroke: A Case Report

Nonagenarians with acute ischemic stroke tend to have a higher mortality and morbidity than younger patients. Tirofiban is a glycoprotein IIb/IIIa antagonist that has a therapeutic potential for ischemic stroke. Here, we provide a case report of a 93-year-old male patient with acute ischemic stroke. He presented with right-sided hemiparesis for 2 hours (National Institute of Health Stroke Scale, NIHSS = 23). Immediate treatment with endovascular tirofiban infusion achieved an improvement of intracranial blood flow and a progressively decreased NIHSS one day after admission (NIHSS = 16) and then seven days after admission (NIHSS = 7). After a follow-up of 90 days, the modified ranking score was 2. This case report suggests that endovascular application with tirofiban may be a favorable option for treating nonagenarians presenting with acute ischemic stroke and warrants further study.

Platelet activation in diabetic mice models: the role of vascular endothelial cell-derived protein disulfide isomerase-mediated GP IIb/IIIa receptor activation

GP IIb/IIIa receptor activation plays an important role in thrombosis. The mechanism of early activation of GP IIb/IIIa receptors in diabetic conditions remains unknown. The purpose of this study was to investigate the release of Endothelial microparticle (EMP)-associated protein disulfide isomerase (PDI) after endothelial cell injury induced in diabetes and the changes in platelet activation. We produced an animal model of type 2 diabetes mellitus using ApoE^-/- mice. Normal ApoE^-/- and diabetic mice were allocated to four groups (n = 15): normal diet, normal diet plus rutin, diabetic, and diabetes plus rutin. The EMP-PDI content and GP IIb/IIIa expression of mice platelets were determined. In addition, EMPs obtained from the four groups were pretreated with the PDI inhibitor rutin; then, their effects on the platelets of normal C57 mice were characterized. Compared with the normal diet group, the diabetic group had significantly increased plasma EMP-PDI content and accelerated platelet activation by increased GP IIb/IIIa expression. In conclusion, EMP-PDI promotes early platelet activation through glycoprotein (GP) IIb/IIIa receptors present on platelet surface in the diabetic state. However, this process could be partially suppressed by the administration of rutin.

Comparison of the effect of recombinant human pro-urokinase and tirofiban on myocardial blood flow perfusion in ST elevation myocardial infarction patients receiving primary percutaneous coronary intervention: A one-center retrospective observational study

Ischemia/reperfusion (I/R) injury is associated with primary percutaneous coronary intervention (PPCI). The current study was performed to compare the effect of tirofiban and recombinant human pro-urokinase (rh-proUK) on the improvement of coronary slow blood after PPCI.Sixty-five ST elevation myocardial infarction (STEMI) patients treated with rh-proUK and an equal number treated with tirofiban after PPCI were employed in the current study. The clinicopathological information regarding the biochemical parameters, thrombolysis in myocardial infarction (TIMI) grade, hemodynamics parameters, thrombus core (TS), sum-STR, left ventricular ejection fraction (LVEF), blood routine parameters, high-sensitivity C-reactive protein (CRP) level, uric acid, hepatorenal function, electrocardiogram (ECG), and echocardiography before and after the interventions were collected. The differences in those parameters between the 2 groups then compared with assess the treatment effect and side effects associated with the both therapies.The results showed that the TIMI level post-intervention (P = .03), the proportion of TIMI myocardial perfusion grade level III (P = .04), the changes in thrombus score (P < .001) in rh-proUK group were significantly higher than those in tirofiban group while the corrected TIMI Frame Count (CTFC) (P = .02), the incidence of slow flow (P = .02), the thrombus score post-intervention (P < .001), the stent length (P = .02), and the number of receiving administration of sodium nitroprusside (P = .01) were significantly lower than those in tirofiban group. Moreover, the levels of CK (P < .001), CK-MB (P = .01), and NT-proBNP 24-hour post-intervention (P < .02) were significantly lower in rh-proUK group than those in tirofiban group and the sum-STR right after the intervention (P < .03) of rh-proUK group was significantly higher than that of tirofiban group. No significant difference was detected between the 2 therapies regarding major adverse cardiac events (MACE).The findings outlined in the current study showed that the improvement effect of rh-proUK on blood flow condition was stronger right after the intervention and the therapy had a similar safety when compared with tirofiban during a 30-day follow-up.

Thrombus resolution with tirofiban in the conservative management of patients presenting with plaque erosion

OBJECTIVE

Recent studies suggest that conservative management with antithrombotic therapy without stenting may be an option in selected patients with acute coronary syndrome (ACS). We evaluated whether a glycoprotein IIb/IIIa inhibitor, tirofiban, would offer additional benefit in patients with plaque erosion presenting with ACS who were treated with antiplatelet therapy without stenting.

PATIENTS AND METHODS

Forty-nine patients who completed 1-year follow-up optical coherence tomography imaging in the EROSION study were divided into two groups: tirofiban (n=32) versus no tirofiban (n=17). Thrombus volume, thrombus burden, and the incidence of major adverse cardiovascular events were evaluated.

RESULTS

At baseline, the tirofiban group had similar thrombus volume [3.73 (1.27-12.49) vs. 3.51 (1.70-8.65) mm, P=0.983] and marginally greater thrombus burden [17.9 (10.1-26.1) vs. 10.6 (6.8-19.0)%, P=0.097]. At 1 month, the tirofiban group had smaller residual thrombus volume [0.00 (0.00-1.78) vs. 0.94 (0.07-4.20) mm, P=0.054], thrombus burden [0.0 (0.0-6.4) vs. 7.0 (1.8-14.8)%, P=0.024], and greater reduction of thrombus volume (85.4±24.6 vs. 67.1±27.1%, P=0.021). These differences were maintained up to 1 year. Complete resolution of thrombus at 1 month was more frequent in the tirofiban group (53.1 vs. 17.6%, P=0.031). None of the patients experienced major bleeding during the initial hospitalization. The 1-year major adverse cardiovascular events rate was not different (5.6 vs. 15.0%, P=0.336).

CONCLUSION

In patients with ACS caused by plaque erosion who were managed conservatively without stenting, tirofiban provided additional benefit in reducing residual thrombus without an increased risk for bleeding.

Breaking the Fourth Wall: Modulating Quaternary Associations for Protein Regulation and Drug Discovery

Protein-protein interactions (PPIs) are an effective means to orchestrate intricate biological processes required to sustain life. Approximately 650 000 PPIs underlie the human interactome; thus underscoring its complexity and the manifold signaling outputs altered in response to changes in specific PPIs. This minireview illustrates the growing arsenal of PPI assemblies and offers insights into how these varied PPI regulatory modalities are relevant to customized drug discovery, with a focus on cancer. First, known and emerging PPIs and PPI-targeted drugs of both natural and synthetic origin are categorized. Building on these discussions, the merits of PPI-guided therapeutics over traditional drug design are discussed. Finally, a compare-and-contrast section for different PPI blockers, with gain-of-function PPI interventions, such as PROTACS, is provided.

Safety and efficacy of tirofiban combined with endovascular treatment in acute ischaemic stroke

BACKGROUND AND PURPOSE

Tirofiban is used off-label in clinical practice for acute ischaemic stroke (AIS). However, it is unknown whether tirofiban increases the bleeding risk or improves the outcome of endovascular treatment (EVT) in AIS. This study evaluated the efficacy and safety of tirofiban in combination with EVT for AIS.

METHODS

Consecutive patients with AIS receiving EVT were included in the prospective stroke registry from 2015 to 2018. The efficacy outcomes were modified Rankin Scale (mRS) score at 3 months and National Institutes of Health Stroke Scale (NIHSS) score at 24 h. The safety outcomes were symptomatic intracerebral hemorrhage (sICH), any in-hospital intracerebral hemorrhage, in-hospital death and 3-month death.

RESULTS

Of 211 patients, 82 (38.9%) received tirofiban. A total of 39 (48.1%) with tirofiban and 44 (36.1%) without tirofiban had mRS score 0-2 [adjusted odds ratio (OR), 2.41; 95% confidence interval (CI), 1.11-5.23, P = 0.026]. NIHSS score at 24 h was lower in the tirofiban group (9.5 vs. 12.0, adjusted P = 0.032). Five (6.1%) patients with tirofiban and 16 (12.4%) without tirofiban had sICH (adjusted OR, 0.54; 95% CI, 0.16-1.83, P = 0.32). In-hospital intracerebral hemorrhage occurred in 10 (12.2%) patients with tirofiban and 41 (31.8%) without tirofiban (adjusted OR, 0.32; 95% CI, 0.13-0.76, P = 0.01). In-hospital death occurred in 7 (8.5%) patients with tirofiban and 16 (12.4%) without tirofiban (adjusted OR, 0.69; 95% CI, 0.22-2.13, P = 0.52). A total of 13 (15.9%) patients with tirofiban and 22 (17.1%) without tirofiban were dead at 3 months (adjusted OR, 0.98; 95% CI, 0.40-2.40, P = 0.96).

CONCLUSIONS

Tirofiban in combination with EVT was associated with a lower mRS score at 3 months and NIHSS score at 24 h. It was not associated with a higher rate of sICH, in-hospital death and death at 3 months.

Bridging with Tirofiban During Temporary Withdrawal of Oral Antiplatelets for Two Major Surgical Procedures in High Ischaemic Risk Patients

Background:

Recent coronary stent implantation requires Dual Antiplatelet Therapy (DAPT) for at least 6 months. Serious issues are raised when non-cardiac surgery is required during this period, because of the balance between ischemic and haemorrhagic complications.

Case Reports:

We report 2 high ischemic risk cases requiring intermediate bleeding risk non-cardiac surgery, during the first month of DAPT initiation. Perioperative management with discontinuation of the P2Y12 inhibitor and bridging with tirofiban, while aspirin was uninterrupted, was uneventful.

Conclusion:

Bridging with intravenous glycoprotein IIb/IIIa receptor inhibitors may be a safe and effective alternative to P2Y12 inhibitor discontinuation in non-deferrable non-cardiac surgery.

Evolution of In Silico Strategies for Protein-Protein Interaction Drug Discovery

The advent of advanced molecular modeling software, big data analytics, and high-speed processing units has led to the exponential evolution of modern drug discovery and better insights into complex biological processes and disease networks. This has progressively steered current research interests to understanding protein-protein interaction (PPI) systems that are related to a number of relevant diseases, such as cancer, neurological illnesses, metabolic disorders, etc. However, targeting PPIs are challenging due to their "undruggable" binding interfaces. In this review, we focus on the current obstacles that impede PPI drug discovery, and how recent discoveries and advances in in silico approaches can alleviate these barriers to expedite the search for potential leads, as shown in several exemplary studies. We will also discuss about currently available information on PPI compounds and systems, along with their usefulness in molecular modeling. Finally, we conclude by presenting the limits of in silico application in drug discovery and offer a perspective in the field of computer-aided PPI drug discovery.

Platelet Signaling and Disease: Targeted Therapy for Thrombosis and Other Related Diseases

Platelets are essential for clotting in the blood and maintenance of normal hemostasis. Under pathologic conditions such as atherosclerosis, vascular injury often results in hyperactive platelet activation, resulting in occlusive thrombus formation, myocardial infarction, and stroke. Recent work in the field has elucidated a number of platelet functions unique from that of maintaining hemostasis, including regulation of tumor growth and metastasis, inflammation, infection, and immune response. Traditional therapeutic targets for inhibiting platelet activation have primarily been limited to cyclooxygenase-1, integrin αIIbβ3, and the P2Y12 receptor. Recently identified signaling pathways regulating platelet function have made it possible to develop novel approaches for pharmacological intervention in the blood to limit platelet reactivity. In this review, we cover the newly discovered roles for platelets as well as their role in hemostasis and thrombosis. These new roles for platelets lend importance to the development of new therapies targeted to the platelet. Additionally, we highlight the promising receptor and enzymatic targets that may further decrease platelet activation and help to address the myriad of pathologic conditions now known to involve platelets without significant effects on hemostasis.

Adsorbed hollow fiber-based biological fingerprinting for the discovery of platelet aggregation inhibitors from Danshen-Honghua decoction

For lead compound discovery from natural products, hollow fiber cell fishing with chromatographic analysis is a newly developed method. In this study, an adsorbed hollow fiber-based biological fingerprinting method was firstly developed to discover potential platelet aggregation inhibitors from Danshen-Honghua decoction. Platelets were seeded on the fiber and their survival rate was tested. Results indicated that more than 92% platelets survived during the whole operation process. Ranitidine and tirofiban were used as positive and negative control respectively to verify the reliability of the presented approach. The main variables such as amount of extract and stirring time that affect the adsorbed hollow fiber-based biological fingerprinting process were optimized, and the repeatability of this method was also investigated. Finally, 12 potential active compounds in Danshen-Honghua decoction were successfully detected using the established approach and structures for nine of them were tentatively identified by liquid chromatography with mass spectrometry analysis. In addition, the in vitro platelet aggregation inhibition test was carried out for five of the nine hit compounds, and three active components, namely, lithospermic acid, salvianolic acid A, and salvianolic acid B were confirmed. These results proved that the proposed method could be an effective approach for screening platelet inhibitors from plant extracts.

rLj-RGD3, a novel recombinant toxin protein from Lampetra japonica, prevents coronary thrombosis-induced acute myocardial infarction by inhibiting platelet functions in rats

Recombinant Lampetra japonica RGD-peptide (rLj-RGD3), a soluble protein containing three RGD sequences, was acquired from the oral salivary glands of Lampetra japonica using recombinant DNA technology. The aim of this study was to investigate the protective effects of rLj-RGD3 against acute myocardial infarction (AMI) induced by coronary artery thrombosis, as well as the underlying mechanisms. A rat model of AMI caused by ferric chloride-induced thrombosis on the surface of the left anterior descending (LAD) coronary artery was successfully established. Rats were given various doses of rLj-RGD3 (12 μg/kg, 24 μg/kg and 48 μg/kg) via sublingual intravenous delivery 10 min before AMI. ST segment elevation was recorded by electrocardiogram (ECG) until the end of the model. Left ventricular Evans blue content and histopathological changes were examined. Blood samples were collected to determine 5-hydroxytryptamine (5-HT), β-thromboglobulin (β-TG), platelet factor 4 (PF4) and cAMP levels. The effects of rLj-RGD3 on platelet aggregation, adhesion and intracellular calcium concentrations were also measured. rLj-RGD3 significantly reduced ST segment elevation, prevented thrombus formation in the coronary artery and decreased Evans blue content in the left ventricular myocardium. Meanwhile, rLj-RGD3 exerted an inhibitory effect on adenosine diphosphate (ADP)-induced platelet aggregation and blocked platelet adhesion to collagen. Treatment with rLj-RGD3 prevented 5-HT, β-TG and PF4 release and significantly elevated intracellular cAMP levels in a dose-dependent manner but decreased the level of cytosolic-free Ca²⁺, an aggregation-inducing molecule. These results show that rLj-RGD3 can effectively reduce coronary thrombosis in AMI rats by strongly inhibiting platelet function, indicating that the recombinant RGD toxin protein rLj-RGD3 may serve as a potent clinical therapeutic agent for AMI.

Efficacy and safety of quadruple therapy including tirofiban in the treatment of Chinese NSTE-ACS patients failing to receive timely percutaneous coronary intervention

Background

Although it has been shown to be superior to simple antithrombotic drug therapy, most patients are unable to receive timely percutaneous coronary intervention (PCI) and are treated with conventional triple antithrombotic therapy (aspirin, clopidogrel, low-molecular-weight heparin). Here, we evaluate the efficacy and safety of adding low-dose tirofiban to this regimen.

Methods

A total of 1,783 patient records (unable to receive PCI) indicating non-ST-segment elevation acute coronary syndrome (NSTE-ACS) were included. A total of 882 received conventional triple antithrombotic therapy; 901 received quadruple antithrombotic therapy. Efficacy was evaluated in terms of major adverse cardiovascular event (MACE) parameters. Safety was evaluated based on the occurrence of bleeding events. Data were collected over a 6-month period post treatment.

Results

The rate of occurrence of MACE was significantly lower in the quadruple antithrombotic group (10.5% versus 14.1% at 6 months, P=0.02). The log-rank test showed improved survival in the quadruple antithrombotic group. Total bleeding events were higher in the quadruple antithrombotic group (9.7%) than in the triple antithrombotic group (7.1%) (P=0.04); however, this may be attributed to increased clinically insignificant minor bleeding events.

Conclusion

Quadruple antithrombotic therapy demonstrated a superior alternative for the treatment of high-risk NSTE-ACS patients failing to receive PCI.

Evidence for shear-mediated Ca2+ entry through mechanosensitive cation channels in human platelets and a megakaryocytic cell line

The role of mechanosensitive (MS) Ca²⁺-permeable ion channels in platelets is unclear, despite the importance of shear stress in platelet function and life-threatening thrombus formation. We therefore sought to investigate the expression and functional relevance of MS channels in human platelets. The effect of shear stress on Ca²⁺ entry in human platelets and Meg-01 megakaryocytic cells loaded with Fluo-3 was examined by confocal microscopy. Cells were attached to glass coverslips within flow chambers that allowed applications of physiological and pathological shear stress. Arterial shear (1002.6 s^-1) induced a sustained increase in [Ca²⁺] _i in Meg-01 cells and enhanced the frequency of repetitive Ca²⁺ transients by 80% in platelets. These Ca²⁺ increases were abrogated by the MS channel inhibitor Grammostola spatulata mechanotoxin 4 (GsMTx-4) or by chelation of extracellular Ca²⁺ Thrombus formation was studied on collagen-coated surfaces using DiOC₆-stained platelets. In addition, [Ca²⁺] _i and functional responses of washed platelet suspensions were studied with Fura-2 and light transmission aggregometry, respectively. Thrombus size was reduced 50% by GsMTx-4, independently of P2X1 receptors. In contrast, GsMTx-4 had no effect on collagen-induced aggregation or on Ca²⁺ influx via TRPC6 or Orai1 channels and caused only a minor inhibition of P2X1-dependent Ca²⁺ entry. The Piezo1 agonist, Yoda1, potentiated shear-dependent platelet Ca²⁺ transients by 170%. Piezo1 mRNA transcripts and protein were detected with quantitative RT-PCR and Western blotting, respectively, in both platelets and Meg-01 cells. We conclude that platelets and Meg-01 cells express the MS cation channel Piezo1, which may contribute to Ca²⁺ entry and thrombus formation under arterial shear.

Platelet Integrin αIIbβ3 Inhibitor Rescues Progression of Apoptosis in Human Platelets

BACKGROUND Apoptosis plays an important role in the physiology of platelet function. We aimed to detect the effect of the platelet integrin αIIbβ3 inhibitor, tirofiban, on apoptotic events, including mitochondrial inner-membrane potential (ΔΨm), phosphatidylserine (PS) exposure on platelet surface, and the generation of reactive oxygen species (ROS), when washed platelets were stimulated with thrombin. MATERIAL AND METHODS The study included washed platelets from healthy humans, divided into 4 groups: vehicle, and tirofiban (0.05 μg/ml, 0.25 μg/ml, and 0.5 μg/ml). Platelets were pretreated with vehicle or tirofiban and incubated at 37°C with agitation for 6 h and 24 h. Before thrombin addition, the vehicle group divided into 2 equal groups. Except one vehicle group, the other 4 groups were all stimulated with thrombin (1 U/ml) for 30 min at 37°C. Using flow cytometry, we studied the DYm and PS exposure on platelet surfaces, and the generation of ROS in platelets. RESULTS We observed that at the time of 6 h and 24 h, thrombin-stimulated vehicle platelets induced significant depo-larization of ΔΨm, higher PS exposure, and increased ROS production compared with the vehicle group (P<0.01). However, the tirofiban group had significantly more recovery of DYm, PS exposure, and ROS production compared with the thrombin group (P<0.01). CONCLUSIONS The platelet integrin αIIbβ3 inhibitor, tirofiban, inhibits the depolarization of DYm, PS exposure on platelet surface, and ROS production when stimulated with thrombin. These results suggest that αIIbβ3 inhibitor inhibits the initiation of apoptosis in platelets, showing a potential clinical application of tirofiban as an apoptosis inhibitor.

Radiolabeled tirofiban - a potential radiopharmaceutical for detection of deep venous thrombosis

Aim

The aim of this study was to investigate the possibility of using ^99mtechnetium (^99mTc)-labeled tirofiban (a reversible antagonist of glycoprotein IIb/IIIa) for detection of deep venous thrombosis (DVT) in rats without causing an antiplatelet effect.

Methods

The ability of in vitro tirofiban to inhibit adenosine 5′-diphosphate (ADP)-induced platelet aggregation was evaluated using optical aggregometer. Binding of ^99mTc-tirofiban to platelets was evaluated. Serum levels of unlabeled (a validated high performance liquid chromatography method) and ^99mTc-tirofiban after single intravenous injection were evaluated in male Wistar rats with or without induced DVT (femoral vein ligation model), and the rats were also subjected to whole body scintigraphy.

Results

Tirofiban in vitro inhibits ADP-induced aggregation of human platelets in a dose- and concentration-dependent manner (10 nM to 2 μM), but only if it is added before ADP and not after ADP. ^99mTc labeling did not affect the ability of tirofiban to bind to either human or rat platelets, nor did it affect tirofiban pharmacokinetics in intact rats or in animals with induced DVT. When ^99mTc-tirofiban was injected to rats after induction of DVT, at a molar dose lower than the one showing only a weak antiaggregatory effect in vitro, whole body scintigraphy indicated localization of ^99mTc-tirofiban around the place of the induced DVT.

Conclusion

^99mTc labeling of tirofiban does not affect its ability to bind to glycoprotein IIb/IIIa or its in vivo pharmacokinetics in rats, either intact or with DVT. A low, nonantiaggregatory dose of ^99mTc-tirofiban may be used to visualize DVT at an early stage.

Pre- and in-hospital antithrombotic management patterns and in-hospital outcomes in patients with acute coronary syndrome: data from the Turkish arm of the EPICOR study

Objective:

To evaluate the acute phase (pre- and in-hospital) antithrombotic management patterns (AMPs) and in-hospital outcomes for patients hospitalized with an acute coronary syndrome (ACS).

Methods:

In total, 1034 patients [514 patients with ST-segment elevation myocardial infarction (STEMI) and 520 with unstable angina/non-STEMI (UA/NSTEMI)] hospitalized for ACS within 24 h of symptom onset were included in this multicenter prospective registry study conducted at 34 hospitals across Turkey. Patient characteristics, index event description, pre- and in-hospital AMPs, and clinical outcomes were evaluated.

Results:

Majority (89.1%) of patients did not receive pre-hospital treatment. Overall 87.9% patients with STEMI and 55.6% patients with NSTEMI underwent percutaneous coronary intervention and dual antiplatelet therapy (DAPT) was based mainly on acetylsalicylic acid (ASA) and clopidogrel during hospitalization (99.8% and 98.2%, respectively). DAPT use at discharge was 98.4% and 86.8%, respectively. The percentage of patients with STEMI who received pre-hospital care, in-hospital cardiac catheterization, and pre and/or in-hospital triple antiplatelet therapy was higher than that of patients with UA/NSTEMI. In addition, higher rate of in-hospital hemorrhagic (2.3% vs. 0.8%) and cardiac ischemic (1.2% vs. 0.4% for MI and 1.6% vs. 0.8% for recurrent ischemia) complications and earlier induction of pre and/or in-hospital antiplatelet therapy and cardiac catheterization were also noted in patients with STEMI than in those with UA/NSTEMI.

Conclusion:

Our findings revealed in-hospital and at-discharge management to be mainly based on DAPT in patients with ACS. Interventional strategies were used in the majority of patients with STEMI, while the usage and timing of immediate pre-hospital ECG from symptom onset should be improved in these patients.