Personalized Anticoagulation: Guided Apixaban Dose Adjustment to Compensate for Pharmacokinetic Abnormalities Related to Short-Bowel Syndrome

A 45-year-old woman who required lifelong anticoagulation for recurrent thrombosis had her therapeutic choices limited by heparin-induced thrombocytopenia and abnormal pharmacokinetics (greatly reduced absorption) resulting from short gut syndrome from extensive gut resection after mesenteric thrombosis. As an alternative to inconvenient and expensive injections of fondaparinux, personalized dosing of a direct oral anticoagulant was sought using clinical pharmacology techniques. Enteral absorption was ascertained with small test doses of apixaban, and the ability of supraconventional doses to deliver effective concentrations was verified.