Body mass – a crucial consideration when prescribing antithrombotic therapy

Appropriate selection of a drug regimen is a crucial to the efficacy and safety of cardiovascular pharmacotherapy. In particular, when prescribing antithrombotic therapy, it is vital to avoid under-dosing, which can contribute to potentially catastrophic thrombotic events, but also over-dosing, which can increase bleeding risk.

A number of patient factors influence the pharmacokinetics of antithrombotic drugs, including body mass. Body mass not only affects the volume of distribution, but also drug absorption, metabolism and elimination. This leads to complex, often non-linear relationships between body mass and drug exposure.1

The issue of body mass in antithrombotic drug regimen selection has become particularly significant given the prevalence of obesity has increased rapidly in recent years, but there has been poor representation of patients with extremes of body weight in randomised controlled trials.2

In 2018, an expert position paper of the ESC Working Group on Thrombosis on antithrombotic therapy and body mass was published.3 This included a comprehensive review and recommendations to guide decision making in clinical practice. 

To ensure appraisal of the very latest evidence, the ESC Working Groups on Cardiovascular Pharmacotherapy and Thrombosis have collaborated to produce an updated clinical consensus statement, now published in the European Heart Journal – Cardiovascular Pharmacotherapy.4 Using the World Health Organisation classification of body mass, evidence-based consensus statements are provided for each class of antithrombotic drug in each class of obesity, as well as for underweight individuals. The updated statement includes particular consideration of patients undergoing bariatric surgery, which sets up a complex pharmacokinetic state, and also in silico pharmacokinetic models that can help to gain insights where gaps in the literature exist.

Importantly, clear consensus statements are made to guide prescribers, with grading of these bu the expert group of authors based on the evidence available. These also serve to highlight areas of uncertainty as a priority for further investigation.

Overall, the updated scientific document provides a considered, comprehensive and state-of-the-art summary of the available evidence, with clear consensus statements forming an invaluable guide for prescribers and key areas for future study identified.