Impact of bariatric surgery on oral anticoagulants pharmacology, and consequences for clinical practice: a narrative review

Abstract

The prevalence of obesity has been steadily increasing in recent years worldwide. At the same time bariatric surgery, the best therapeutic strategy to date in terms of sustainable weight loss and improvement of associated comorbidities has been also increasing. However, these surgeries, whether primarily restrictive or malabsorptive, raise questions about the pharmacology of oral drugs. Among widely used drugs, anticoagulants are the referent therapy to treat some cardiovascular diseases such as atrial fibrillation and venous thromboembolism. How bariatric surgery may impact pharmacological properties of oral anticoagulants, and more specifically, direct oral anticoagulants (DOACs) are difficult to anticipate. In this review, we describe available data concerning the potential impact of bariatric surgery on the pharmacology of oral anticoagulants. The vitamin K antagonists (VKAs) requirements for the same international normalized ratio target are reduced after bariatric surgery. Limited data available for dabigatran 150 mg twice daily indicate a risk of insufficient efficacy in atrial fibrillation after gastric bypass due to probable impaired absorption. Data for rivaroxaban at the prophylactic dose of 10 mg per day suggest no impact of bariatric surgery from 3 days to 8 months post‐surgery. However, no conclusive data are available for other anticoagulants or the use of DOACs at therapeutic doses. To date, DOACs are not recommended in patients who have undergone bariatric surgery, because of limited available data. Pending new studies to confirm the predictable pharmacokinetics and safety of DOACs in this population, especially at therapeutic doses, VKAs remain the first option for chronic anticoagulation.

A review of indications and comorbidities in which warfarin may be the preferred oral anticoagulant

“…The site of warfarin absorption is not fully understood, but case studies point to the stomach and proximal small intestine, while the DOACs vary by agent (Table 3). 53,55 Procedures such as sleeve gastrectomy, Roux‐en‐Y gastric bypass, and biliopancreatic diversion commonly bypass these sites 53,55,56 …”

“…Adapted from: Martin et al, 53 Hakeam et al, 55 and Leven et al 56 …”

“…53,55 Procedures such as sleeve gastrectomy, Roux-en-Y gastric bypass, and biliopancreatic diversion commonly bypass these sites. 53,55,56 With the continued rise in bariatric and other GI surgeries, there is a significant need for large and focused studies on oral anticoagulants in this population. Currently, empirical evidence, small controlled studies, case reports and expert opinions guide practice.…”

“…Currently, empirical evidence, small controlled studies, case reports and expert opinions guide practice. Adapted from: Martin et al, 53 Hakeam et al, 55 and Leven et al 56 a Many P-gp efflux transporters are located in the distal GI tract.…”

“…on DOACs and the ability to monitor warfarin safety and efficacy through INR monitoring. 53,55,56 Even with INR monitoring, warfarin displays unpredictable PK changes after bariatric surgery. This is thought to be driven by alterations in food intake and vitamin K absorption, pH, transit time, reduced first-pass metabolism and drug interactions.…”