Key result
Standard anti-Xa and PT/INR assays correlated with apixaban levels only in the supratherapeutic range (>130 ng/ml), indicating specific anti-Xa tests are best for assessing apixaban levels.
Why the study?
Do standard coagulation assays (PT/INR, anti-Xa) accurately predict apixaban levels in overdose compared to specific chromogenic assays?
Case Report (n=1)
Do standard coagulation assays (PT/INR, anti-Xa) accurately predict apixaban levels in overdose compared to specific chromogenic assays?
Standard anti-Xa tests can serve as a surrogate for apixaban levels when concentrations are high (>130 ng/ml), but specific anti-Xa tests with optimized chromogenic substrates are best for accurate assessment.
Standard assays may miss therapeutic apixaban levels; leaves open whether specific anti-Xa testing improves outcomes.
: Intentional overdose of apixaban is rare and minimal data exist regarding the usefulness of routinely available laboratory tests to predict drug levels. A 50-year-old man was admitted after ingestion of 200-mg apixaban. Serial blood samples were obtained over a 54-h period for assessment of the fall-off in drug levels using the prothrombin time/international normalized ratio and anti-Xa assays and compared with an apixaban-specific chromogenic assay. The prothrombin time/international normalized ratio and anti-Xa assays correlated with the apixaban level when the drug was in the supratherapeutic range (>130 ng/ml) but not in the typical therapeutic trough to peak levels. Apixaban levels are best assessed by a specific anti-Xa test using optimized chromogenic substrates and specific calibrators. A standard anti-Xa test can be a useful surrogate when drug levels are high but use of a specific threshold level for discharge purposes requires caution.
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Guadarrama et al. (2018) conducted a case report in Apixaban overdose (n=1). Apixaban overdose was evaluated on Correlation of prothrombin time/international normalized ratio and anti-Xa assays with apixaban level. Standard anti-Xa and PT/INR assays correlated with apixaban levels only in the supratherapeutic range (>130 ng/ml), indicating specific anti-Xa tests are best for assessing apixaban levels.
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