New oral
anticoagulants (
NOAC) are approved for several indications for prophylaxis and treatment of
venous thromboembolism and for prevention of
embolism in
atrial fibrillation at fixed daily doses without need of laboratory guided dose adjustment. Due to their low molecular weight of about 500 to 600 Dalton and their hydrophilicity free
anticoagulant is excreted immediately through glomerular filtration into the urine. Impairment of renal function may increase the plasma concentration of the
anticoagulants and lowered
creatinine clearance is a declared
contraindication. In contrast to the initial aim of development the
anticoagulant effect is required to be determined in special clinical situations. Several specific and non-specific assays using plasma samples are currently undergoing standardization. As all NOACs are excreted into the urine, specific assays were developed for this matrix to determine them quantitatively of qualitatively. Urine samples can be easily and repetitively obtained avoiding problems and risks associated with blood sampling. The qualitative assay can be performed as a point of care test (POC) also by the patient by judging the different colours for the absence or presence of the drugs with the naked eye. The test is rapid (results available within 15 min), sensitive, specific and accurate and does not require a purified
NOAC as control. The tests may be a tool for clinicians who need to know for treatment decisions if a
NOAC is on board or not. As the tests are specific for oral
direct thrombin inhibitors and for oral
direct factor Xa inhibitors, the indication does not interfere with other qualitative POC test in development using clotting systems. The test may be indicated for patients at acute hospitalization, before surgery or central nervous system
puncture anaesthesia, if
fibrinolytic therapy is indicated, acute deterioration of renal function, and for control of adherence to
therapy.