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Background: Apixaban is a newly developed direct oral anticoagulant targeting activated factor X (FXa). The degree of interference of apixaban with coagulation parameters has not been thoroughly investigated., Methods: Increasing amounts of apixaban were added to aliquots of a pooled normal plasma (PNP) to mimic a large range of concentrations (n=8) that are observed in treated patients. Upon preparation, samples were stored frozen and tested for a vast array of coagulation parameters (including procoagulant and anticoagulant factors) in three laboratories, using three widely used coagulation platforms (reagent/coagulometer combinations)., Results: Results for each parameter were expressed as ratios of the value corresponding to each apixaban concentration to the value corresponding to the PNP without apixaban. By definition, ratios higher or lower than the unity define overestimation or underestimation, respectively. Prothrombin and activated partial thromboplastin times were barely prolonged by apixaban 200 ng/mL (ratios <1.29 or <1.19, respectively). Conversely, antithrombin was considerably overestimated when the measurement was made with FXa as target enzyme (ratios up to 1.43). Protein C and protein S were overestimated when measured as anticoagulant activities (ratios up to 1.20 or 1.95, respectively), and most measurements for individual coagulation factors (except fibrinogen) were considerably underestimated (ratios from 0.62 to 1.01)., Conclusions: This large multicenter multiplatform study investigating a common set of test plasmas shows that apixaban interferes with the measurement of most coagulation parameters requested for investigation of hemostasis and highlights the need for a careful interpretation of results obtained in patients under treatment.

The acute and chronic effects of a preparation of dried garlic powder (Sapec) in a total daily dose of 900 mg on fibrinolysis and platelet aggregation have been evaluated in a randomized, double-blind, placebo controlled cross-over study of 12 healthy subjects. Total euglobulin fibrinolytic activity and t-PA (tissue plasminogen activator) activity were significantly higher 4 and 6 h after garlic and placebo ingestion, and no differences were recorded between treatments. After 14 days of treatment, t-PA activity was significantly higher after garlic, with inter-treatment significance. No significant changes in PAI (Plasminogen Activator Inhibitor) activity and fibrinogen levels were recorded. Platelet aggregation induced by adenosine diphosphate and collagen, and especially beta-thromboglobulin (beta-TG) release after collagen stimulation were significantly inhibited 2 and 4 h after garlic ingestion; platelet aggregation values were also significantly lower after 7 and 14 days of garlic treatment. No significant changes were found in adenosine triphosphate release and serum TXB2 levels after acute garlic administration.