From Linda Stang, Alberta Health Services: As apixaban (Eliquis) is sure to start wreaking havoc in some of our special coag assays (read: tests will be ordered while patients are on this drug, but they WON’T tell us…), I did a search for publications about apixaban interference, and found nothing. Does anyone have any experience with interference in lupus anticoagulant panels (DRVVT– or SCT-based) or any other tests such as clot-based protein C or S assays, activated protein C resistance clot based assays, etc.?
Rivaroxaban (Xarelto) seems to be fairly obvious in our lupus anticoagulant panel as the DRVVT 1:1 mix samples are usually 75 seconds or above. They stand out like a sore thumb compared to the other patients, but I am not sure if any samples containing apixaban have come in, and just ‘slid under the radar.’
Thanks for your question, Linda. I’ll take a chance and suggest that apixaban will have the same effects on our clot-based assays as rivaroxaban, considering that both are direct anti-Xa anticoagulants, but I’ll ask for comments from those who have actually encountered apixaban in practice. Geo.
From Linda Stang, Alberta Health Services,
From Linda Stang, Alberta Health Services, My theory about apixaban vs rivaroxaban: if you happen to run a sample from a patient on rivaroxaban on an anti-Xa assay with a hybrid curve more often than not you will get a very high value (i. e. >2.0), whereas apixaban reads about where LMWH/UNFH would read. Also, if you take a patient sample that reads 0.75 U/mL on an anti-Xa result read off a hybrid curve, and then try to run that sample on the Aniara rivaroxaban assay, it is hardly a blip on the radar. The Aniara assay does a very large dilution of patient sample–1/50 or close to it. To put it another way, I think rivaroxaban needs a whole pile of little anti-Xa soldiers to do its job, while the apixaban army seems to need a whole lot less of its soldiers to do the job. In other words, I don’t think the assay interference from apixaban is going to be quite as obvious as the Rivaroxaban–but I have been wrong before 😉