Safety and Efficacy of Oral Anticoagulants for Atrial Fibrillation in Patients After Bariatric Surgery

Full-dose rivaroxaban in patients with a history of bariatric surgery: bridging the knowledge gap through a phase 1 study

BACKGROUND

Bariatric surgery (BS) induces significant changes in gastrointestinal anatomy, potentially influencing the pharmacokinetics of orally administered drugs such as rivaroxaban.

OBJECTIVES

This phase 1 study aimed to assess the pharmacokinetics and safety of full-dose rivaroxaban in post-BS patients.

METHODS

The ABSORB (Rivaroxaban Pharmacokinetics and Pharmacodynamics After Bariatric Surgery and in Morbid Obesity) study was a single-center, nonrandomized, multiple-dose, parallel-design bioequivalence trial. Adult patients with stable weight after Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) were compared with subjects with class III obesity and healthy controls. Participants received 20 mg of rivaroxaban daily for 8 days.

RESULTS

Post-BS patients exhibited altered rivaroxaban pharmacokinetics, suggesting reduced absorption. Mean area under the concentration-time curve from time 0 to 24 hours after the first dose (RYGB, 1806.8 ng.h/mL; SG, 1648.9 ng.h/mL) was lower compared with that in controls (1893.5 ng.h/mL). At steady state, the area under the concentration-time curve values remained lower in BS groups (RYGB, 2129.9 ng.h/mL; SG, 1946.4 ng.h/mL) than in controls (2224.8 ng.h/mL). The maximum concentration after the first dose was lower in post-RYGB subjects (214.9 ng/mL) than in controls (264.1 ng/mL). This difference was less pronounced at steady state (RYGB, 256.9 ng/mL vs controls, 288.8 ng/mL). Neither BS group met bioequivalence criteria compared with controls, whereas the group with class III obesity met bioequivalence criteria compared with controls at steady state.

CONCLUSION

Rivaroxaban displayed minor pharmacokinetic variations in post-BS patients. Given reported interindividual variability in the general population, these variations are unlikely to be of clinical significance. Our findings support rivaroxaban use in BS patients, emphasizing the need for further research in this area.

Dilemmas Related to Direct-Acting Oral Anticoagulant Administration in Patients With Extreme Obesity

OBJECTIVE

The objective of the study was to discuss the controversies surrounding the use and dosing of direct-acting oral anticoagulants (DOACs) in obese patients recognizing the limitations of the existing evidence base that preclude strong recommendations.

DATA SOURCES

A literature search of MEDLINE was performed (2020 to end August 2022) subsequent to recent guidelines using the following search terms: direct acting anticoagulants, obesity, rivaroxaban, apixaban, edoxaban, dabigatran, dabigatran etexilate, and clinical practice guidelines.

STUDY SELECTION AND DATA ABSTRACTION

English-language studies and those conducted in adults were selected.

DATA SYNTHESIS

The available randomized studies evaluating DOACs had relatively small numbers of patients with more extreme forms of obesity (body mass index [BMI] > 40 kg/m²) and none of the larger studies had a specific focus on dosing DOACs in obese patients. Recent guidelines by the International Society on Thrombosis and Haemostasis (ISTH) have specific recommendations for dosing DOACs in obesity. There are pharmacokinetic/pharmacodynamic and observational studies published before and after the ISTH guidelines with a focus on DOAC dosing in obese patients that generally support the recommendations in the guidelines, but most involved small numbers of patients usually with BMIs <45 kg/m².

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review discusses DOAC dosing in obesity with important considerations for clinicians related to DOAC choice and dosing.

CONCLUSIONS

Dosing alterations of DOACs do not appear to be necessary when used for either prophylaxis or treatment in patients with BMIs up to approximately 45 to 50 kg/m², but research is needed for BMIs >50 kg/m².

Direct oral anticoagulants after bariatric surgery-What is the evidence?

BACKGROUND

Obesity is a global epidemic and bariatric surgery is used with increasing frequency to treat its complications. The extent to which bariatric surgery alters the efficacy, safety, and pharmacokinetics of direct oral anticoagulants (DOACs) is unknown.

AIMS

In this review, we summarize the evidence supporting the use of DOACs after bariatric surgery and apply our findings to resolve several clinical cases.

MATERIALS & METHODS

We systematically searched MEDLINE, EMBASE, Cochrane Library, CINAHL and ClinicalTrials.gov from January 1, 2000, to June 15, 2021 for randomized and non-randomized studies evaluating the use of DOACs for any indication after bariatric surgery. Two reviewers independently screened titles, abstracts, and full-text articles. Clinical and pharmacokinetic outcomes were pooled by random-effects meta-analysis with inverse variance weighting. We used the Newcastle-Ottawa scale to assess risk of bias in non-randomized studies and assessed the certainty of evidence with GRADE.

RESULTS

From 2519 records, we included 28 studies (n = 3229 patients): no randomized trials, 7 cohort studies, 6 case series, and 15 case reports. Incidence rates for arterial thromboembolism, venous thromboembolism and major bleeding were: 0.73 (95% confidence interval [CI]: 0.01-5.10), 2.45 (95% CI: 0.40-7.94), and 3.40 (95% CI: 0.80-9.36) events per 100 patient-years, respectively. The pooled proportion of peak direct oral anticoagulant drug levels within the expected range was 58% (95% CI: 39%-74%).

CONCLUSION

There appears be substantial risk of DOAC malabsorption after bariatric surgery that could affect clinical outcomes, however the certainty of evidence was very low.

PROSPERO

CRD42020202636.

Psychotropic Medications in Metabolic and Bariatric Surgery: Research Updates and Clinical Considerations

PURPOSE OF REVIEW

We review evidence for assessing and monitoring psychotropic medications in metabolic and bariatric surgery (MBS) patients. We describe weight gain side effects, potential perioperative risks, pharmacokinetic changes that occur after MBS, and conclude with clinical recommendations.

RECENT FINDINGS

Research on psychiatric medication use and post-MBS weight outcomes is lacking and inconsistent; however, there is consistent evidence that, though variable, psychiatric medication use is associated with weight gain. Several meta-analyses and reviews provide guidance on lowering risk when appropriate. Perioperative lithium toxicity and SSRI discontinuation syndrome also warrant consideration, as do potential post-operative pharmacokinetic changes. In the absence of data for each psychiatric drug classification, close symptom monitoring and, where appropriate, serum concentration monitoring are recommended. MBS patients are a psychiatrically vulnerable population, and many are on psychiatric medications. Given potential weight/metabolic side effects, perioperative complications, and post-operative pharmacokinetic changes that occur with psychotropic medication use, providers should stay well informed on psychiatric medication management considerations.

Oral Anticoagulant Use in Morbid Obesity and Post Bariatric Surgery: A Review

Bariatric surgery has emerged as a therapy for obesity and the associated comorbidities. Obesity has been shown to be a risk factor for atrial fibrillation as well as venous thromboembolism, both of which are conditions that warrant anticoagulation. There is significant underrepresentation of the morbidly obese population in prospective trials that evaluated direct oral anticoagulants and vitamin K antagonists in atrial fibrillation and venous thromboembolism. We aim to review all the available data that assessed these oral anticoagulants in the morbidly obese population (body mass index >40 kg/m² and weight >120 kg) and in the post-bariatric surgery population. Our findings suggest that direct oral anticoagulants may be safe and effective for anticoagulation in morbidly obese patients for both atrial fibrillation and venous thromboembolism. However, warfarin is the preferred agent in the post-bariatric surgery population, given the limited number of studies on direct oral anticoagulants in this population. Further adequately powered randomized control trials are needed to confirm the safety and efficacy of these oral anticoagulants in the morbidly obese and post-bariatric surgery population.