Development and validation of a liquid chromatography/tandem mass spectrometry method for the simultaneous quantification of serotonin and thromboxane B2 from activated platelets.

INTRODUCTION: Availability of a rapid and reliable platelet activation assay avoiding limitations of current techniques would be valuable to diagnose heparin-induced thrombocytopenia and platelet secretion disorders. OBJECTIVES: The first aim was to develop and validate an ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method to quantify in a single run TxB2 synthesized and serotonin released from platelets. The second aim was to use our method in association with light transmission aggregometry (LTA) to select good platelet responders for the diagnosis of HIT. METHODS: Electrospray ionization and chromatographic separation were optimized for the simultaneous dosage of serotonin and TxB2. The method was validated according to the European Medicines Agency (EMA) guideline for bioanalytical method validation. LTA was performed with monoclonal anti-CD9 (clone ALB6) as platelet activator to select good responders. RESULTS: Detection was performed using a tandem mass spectrometer with alternated positive and negative electrospray ionization. The total run time was 6 minutes. The method was validated for calibration curves, precision, accuracy, lower limit of quantification, carry-over, selectivity, and matrix effect. Platelet response to ALB6 was highly variable among donors. CONCLUSION: We developed and validated a UHPLC-MS/MS method for the simultaneous quantification of TxB2 and serotonin.

Functional Assays in the Diagnosis of Heparin-Induced Thrombocytopenia: A Review.

A rapid and accurate diagnosis in patients with suspected heparin-induced thrombocytopenia (HIT) is essential for patient management but remains challenging. Current HIT diagnosis ideally relies on a combination of clinical information, immunoassay and functional assay results. Platelet activation assays or functional assays detect HIT antibodies that are more clinically significant. Several functional assays have been developed and evaluated in the literature. They differ in the activation endpoint studied; the technique or technology used; the platelet donor selection; the platelet suspension (washed platelets, platelet rich plasma or whole blood); the patient sample (serum or plasma); and the heparin used (type and concentrations). Inconsistencies in controls performed and associated results interpretation are common. Thresholds and performances are determined differently among papers. Functional assays suffer from interlaboratory variability. This lack of standardization limits the evaluation and the accessibility of functional assays in laboratories. In the present article, we review all the current activation endpoints, techniques and methodologies of functional assays developed for HIT diagnosis.

Persistent heparin-induced thrombocytopenia: danaparoid cross-reactivity or delayed-onset heparin-induced thrombocytopenia? A case report.

Clinical suspicion of immune heparin-induced thrombocytopenia (HIT) requires cessation of heparin and initiation of an alternative anticoagulant. The platelet count will subsequently recover. This case report describes the clinical course of a patient after a cardiovascular surgery. HIT was clinically and biologically confirmed. Unexpectedly, the platelet count did not recover despite the arrest of heparin. Danaparoid was initiated, and thrombocytopenia persisted. Danaparoid cross-reactivity was suspected, and laboratory assay was performed. Results were misinterpreted because no comparative buffer control was performed to ensure that the platelet aggregation was caused by danaparoid. Moreover, plasma/serum must be diluted to demonstrate this effect. Danaparoid cross-reactivity was incorrectly concluded, and the patient was switched to bivalirudin. The severe thrombocytopenia persisted. Plasmapheresis was started, and platelet count finally increased. The clinical course suggested a delayed-onset HIT. This case report illustrates the need for appropriate testing to differentiate drug cross-reactivity from delayed-onset HIT.

Non-VKA Oral Anticoagulants: Accurate Measurement of Plasma Drug Concentrations.

Non-VKA oral anticoagulants (NOACs) have now widely reached the lucrative market of anticoagulation. While the marketing authorization holders claimed that no routine monitoring is required and that these compounds can be given at fixed doses, several evidences arisen from the literature tend to demonstrate the opposite. New data suggests that an assessment of the response at the individual level could improve the benefit-risk ratio of at least dabigatran. Information regarding the association of rivaroxaban and apixaban exposure and the bleeding risk is available in the drug approval package on the FDA website. These reviews suggest that accumulation of these compounds increases the risk of experiencing a bleeding complication. Therefore, in certain patient populations such as patients with acute or chronic renal impairment or with multiple drug interactions, measurement of drug exposure may be useful to ensure an optimal treatment response. More specific circumstances such as patients experiencing a haemorrhagic or thromboembolic event during the treatment duration, patients who require urgent surgery or an invasive procedure, or patient with a suspected overdose could benefit from such a measurement. This paper aims at providing guidance on how to best estimate the intensity of anticoagulation using laboratory assays in daily practice.

Dabigatran etexilate and risk of myocardial infarction, other cardiovascular events, major bleeding, and all-cause mortality: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Signals of an increased risk of myocardial infarction (MI) have been identified with dabigatran etexilate in randomized controlled trials (RCTs). METHODS AND RESULES: We conducted searches of the published literature and a clinical trials registry maintained by the drug manufacturer. Criteria for inclusion in our meta-analysis included all RCTs and the availability of outcome data for MI, other cardiovascular events, major bleeding, and all-cause mortality. Among the 501 unique references identified, 14 RCTs fulfilled the inclusion criteria. Stratification analyses by comparators and doses of dabigatran etexilate were conducted. Peto odds ratio (ORPETO) values using the fixed-effect model (FEM) for MI, other cardiovascular events, major bleeding, and all-cause mortality were 1.34 (95% CI 1.08 to 1.65, P=0.007), 0.93 (95%CI 0.83 to 1.06, P=0.270), 0.88 (95% CI 0.79 to 0.99, P=0.029), and 0.89 (95% CI 0.80 to 1.00, P=0.041). When compared with warfarin, ORPETO values using FEM were 1.41 (95% CI 1.11 to 1.80, P=0.005), 0.94 (95%CI 0.83 to 1.06, P=0.293), 0.85 (95% CI 0.76 to 0.96, P=0.007), and 0.90 (95% CI 0.81 to 1.01, P=0.061), respectively. In RCTs using the 150-mg BID dosage, the ORPETO values using FEM were 1.45 (95% CI 1.11 to 1.91, P=0.007), 0.95 (95% CI 0.82 to 1.09, P=0.423), 0.92 (95% CI 0.81 to 1.05, P=0.228), and 0.88 (95% CI 0.78 to 1.00, P=0.045), respectively. The results of the 110-mg BID dosage were mainly driven by the RE-LY trial. CONCLUSIONS: This meta-analysis provides evidence that dabigatran etexilate is associated with a significantly increased risk of MI. This increased risk should be considered taking into account the overall benefit in terms of major bleeding and all-cause mortality.

Impact of Silver Nanoparticles on Haemolysis, Platelet Function and Coagulation.

Silver nanoparticles (Ag NPs) are increasingly used in biomedical applications because of their large antimicrobial spectrum. Data in the literature on the ability of Ag NPs to perform their desired function without eliciting undesirable effects on blood elements are very limited and contradictory. We studied the impact of Ag NPs on erythrocyte integrity, platelet function and blood coagulation. Erythrocyte integrity was assessed by spectrophotometric measurement of haemoglobin release. Platelet adhesion and aggregation was determined by light transmission aggregometry and scanning electron microscopy. The calibrated thrombin generation test was used to study the impact on coagulation cascade. We demonstrated that Ag NPs induced haemolysis. They also increase platelet adhesion without having any impact on platelet aggregation. Finally, they also had procoagulant potential. Bringing all data from these tests together, the no observed effect concentration is 5 µg/mL.