Apixaban Pharmacokinetics in Bariatric Patients (APB)

The Center for Bariatric Surgery is interested in conducting a pharmacokinetic study of apixaban (an oral anticoagulant with FDA approval for use of venous thrombo embolism (VTE) prophylaxis and treatment) in the obese adult population to determine if bariatric surgery influences apixaban exposure. More interesting would be to see how the dose may need to change pre- vs. post-bariatric surgery (this will be important for physicians as more and more patients undergo this procedure worldwide and many may require anticoagulation in their future healthcare). Physicians and surgeons are very interested in oral anticoagulants for this special patient population. To date, there is no approved dosing for the obese patient (especially when considering surgical intervention such as bariatric surgery). Primary outcome variable. To determine the durability or change in pharmacokinetics and pharmacodynamics of apixaban in patients with a body mass index (BMI) of 35 kg/m2 or greater following one of two bariatric surgical procedures (pre-operative versus post-operative vertical sleeve gastrectomy or Roux-en-Y gastric bypass patients). Secondary outcome variables. 1. To compare/contrast the pharmacokinetics and pharmacodynamics of apixaban in bariatric surgical patients who have undergone RYGB vs. VSG. 2. To determine how the pharmacokinetics of the drug may differ when there is significant post-operative surgical weight loss (>40% estimated excess body weight) 12 to 18 months following surgery versus those patients who have suboptimal weight loss following bariatric surgery (< 40% of estimated excess body weight).