"4F-PCCs did not appear to have an effect on the inhibition of thrombin generation by apixaban or rivaroxaban unless the Factor Xa inhibitor concentration was less than 75 ng/mL. "
To gage the potential impact this understanding may have on clinical treatment, one needs to know what a typical inhibitor concentration is for an X or E patient presenting with a bleed.
"Rivaroxaban measurements varied from 5 to 358 ng/ml, with a post-intake delay ranging from 9 to 38 h. At trough, estimated plasma concentrations were between 12 and 251 ng/ml (median value 94 ng/ml). Four patients had higher-than-expected rivaroxaban levels. Inadequate dose regimen, excessive alcohol consumption and lack of treatment reassessment were observed in several patients. Half of patients were taking ≥1 drug with potential pharmacokinetics interactions (e.g. amiodarone, diltiazem), while half of patients were taking ≥1 drug increasing the risk of bleeding. All 3 patients with available genotyping data and higher-than-expected rivaroxaban levels were heterozygous or homozygous mutated for the ABCB1 1236C > T, 2677G > T, 3435 C > T and rs4148738 single nucleotide polymorphisms (SNP)."