Principles of drug dosing for obese patients in the intensive care unit

The increasing prevalence of severe obesity in intensive care unit (ICU) patients has led to several challenges with medication dosing. Doses listed in product labels or tertiary references typically do not account for the pharmacokinetic or pharmacodynamic variability encountered with obesity, leading to the potential for treatment failure or an adverse effect. The purpose of this review is to provide guidance for ICU clinicians when crafting pharmacotherapy regimens in critically ill patients with extreme obesity.

A literature search was performed to identify relevant articles pertaining to the pharmacokinetics or pharmacodynamics of medications in obese patients. Articles describing both general treatment principles and medication specific assessments were retrieved. Bibliographies were searched for additional publications.

Evidence guiding medication use in critically ill obese patients is limited by the small number of patients with more extreme forms of obesity, the lack of clinical outcome measurements, and the few studies that are specific to the ICU. Obesity-related alterations in pharmacokinetic parameters, such as apparent volume of distribution and drug clearance, may hinder attainment of pharmacodynamic targets. Individualized dosing strategies are essential to optimize therapeutic outcomes. This review provides dosing recommendations for selected ICU medications and proposes a practical framework to guide medication dosing decisions in this patient population.

Drug dosing in critically ill obese patients should be individualized by assessing pharmacokinetic variability and whether pharmacodynamic goals can be achieved. Selecting the correct weight for weight-based calculations or dose for fixed regimens is paramount for achieving these goals. Consultation with a clinical pharmacist may be beneficial.