Pharmacokinetics of apixaban in patients undergoing pancreaticoduodenectomy (PAP-UP).

OBJECTIVE The impact of pancreaticoduodenectomy on absorption of drugs in the duodenum remains largely unknown. We aim to characterize the pharmacokinetics of apixaban in patients who had previously undergone pancreaticoduodenectomy. MATERIALS AND METHODS A single 10-mg dose of apixaban was administered to 4 volunteers who underwent pancreaticoduodenectomy at least 6 months prior. The maximum plasma apixaban concentration (Cmax) and area under the plasma concentration time-curve (AUC0-24, AUC0-inf) were compared against healthy historical control subjects (N = 12). Geometric mean ratios (GMR) with 90% confidence interval (CI) were calculated for determination of comparative bioequivalence. RESULTS In pancreaticoduodenectomy patients, AUC0-24 and AUC0-inf were 1,861 and 2,080 ng×h/mL, respectively. The GMRs of AUC0-24 and AUC0-inf between study subjects and healthy controls were 1.27 (90% CI 0.88 - 1.83) and 1.18 (90% CI 0.82 - 1.72). The mean Cmax of apixaban was 201 ng/mL (SD 15.6) occurring at a median tmax of 3.25 hours (range 2.5 - 4 hours). The GMR of Cmax between study subjects and healthy controls was 1.12 (90% CI 0.77 - 1.63). CONCLUSION The pharmacokinetic characteristics of apixaban in subjects who had undergone pancreaticoduodenectomy are not significantly different from those of healthy controls. Though the sample size of this study is small, results suggest that no change to apixaban dose regimen is needed in patients who have had a pancreaticoduodenectomy.