Table 2 Generalized clinical pearls for crafting medication doses in the setting of extreme obesity

• Seek consistency within and between all healthcare professionals involved in size estimates

• Clearly document instrument (e.g., type of scale) and methods used (e.g., clothes on or off) for weight measurement

• Document when estimates or patient-stated weights are utilized

• When using total body weight, do not change the weight used for calculations (due to weight gain or loss) after therapy has been initiated

• Clinical monitoring of the individual patient’s response to therapy should supersede data from pharmacokinetic studies

• Pharmacokinetic parameters (volume of distribution, clearance) are typically greater and with more variability in critically ill versus non-critically ill patients

• Assess for dose-proportionality using pharmacokinetic studies that report volume of distribution and clearance in obese and non-obese individuals

• The duration of action of a single dose (i.e., a loading dose) is generally a function of volume of distribution rather than clearance

• Always assess the benefits and risks of the dosing regimen especially when using a larger dose or total body weight for calculations (i.e., is there a narrow therapeutic index or dose-related adverse effects)

• Use technology or automated dosing calculators to minimize calculation errors

• Even with medications that can be rapidly titrated to effect, using an inappropriate weight metric for weight-based dosing can lead to adverse effects upon initiation or maximum doses above-recommended values