Background: Despite how commonly they are prescribed, there are few data specifically evaluating the pharmacokinetics of direct oral anticoagulants (DOACs) after bariatric surgery (BS).
Aims: To evaluate peak DOAC drug levels in patients after BS.
Methods: We performed a retrospective cohort study of patients who had BS in Hamilton, Canada between 2015 and 2021, received a DOAC post-operatively and had at least one DOAC drug level measured using a drug-specific anti-Xa assay. Eligible patients were identified using the Ontario Bariatric Network database and Thrombosis Service records. Demographics, pharmacokinetic data and 30-day clinical outcomes were summarized descriptively.
Results: Forty-five patients had seventy-two DOAC drug levels drawn: apixaban (n=22), rivaroxaban (n=39), dabigatran (n=5) and edoxaban (n=6). The most common procedures were sleeve gastrectomy (n=35, 78%) and Roux-en-Y gastric bypass (n=9, 20%). Mean body mass index (BMI) before BS was 51.8 kg/m2 (SD=8). Drug levels were measured a median of 12.5 days post-operatively. Thirty-six patients (80%) had at least one peak drug level within the expected range seen in phase II-III DOAC clinical trials. All four patients on dabigatran had low drug levels and were switched to apixaban (n=3) or rivaroxaban (n=1). Two patients on rivaroxaban with low drug levels were switched to apixaban. Ten patients had peak drug levels repeated a median of 6.1 months post-operatively and all levels were in the expected range. Mean weight loss at follow-up was 28 kg. One patient had a splenic infarct, and one had a pulmonary embolism within 30-days of surgery.
Conclusion(s): Our study suggests that apixaban, rivaroxaban, and edoxaban are absorbed adequately after BS. Dabigatran should be used with caution. Limitations include a small sample size, brief follow-up period, and use of peak drug levels as a surrogate for total anticoagulant exposure.
To cite this abstract in AMA style:Gunka B, Mackenzie D, Doumouras A, Mithoowani S. Pharmacokinetics of direct oral anticoagulants after bariatric surgery: A retrospective cohort study [abstract]. https://abstracts.isth.org/abstract/pharmacokinetics-of-direct-oral-anticoagulants-after-bariatric-surgery-a-retrospective-cohort-study/. Accessed August 16, 2022.
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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/pharmacokinetics-of-direct-oral-anticoagulants-after-bariatric-surgery-a-retrospective-cohort-study/