Low direct oral anticoagulant (DOAC) plasma concentrations can lead to treatment failure, but factors causing low DOAC concentrations are not yet fully established.

In a cohort of 131 patients treated with DOACs, including apixaban (85%), rivaroxaban, and dabigatran, we analyzed the association between DOAC concentration and the use of enzyme-inducing antiseizure medications (EI-ASMs).

The proportion of patients with lower than expected DOAC peak concentrations was significantly higher in patients co-treated with EI-ASMs. These results were consistent among all DOACs.

Concomitant treatment with EI-ASMs was associated with statistically significantly decreased apixaban levels.

In multivariable analysis, EI-ASM use was associated with more than 6-fold increased odds for apixaban concentrations below the expected range.