Improving Medication Dosing in the Obese Patient

The purpose of this paper is to provide clinicians with important considerations and caveats when evaluating published literature on medication dosing in obese subjects, since much of this literature involves short-term pharmacokinetic or pharmacodynamic studies that are not designed to look at clinically important outcomes. A secondary objective is to suggest improvements in the reporting of dosing information derived from clinical studies and incorporated into product information labeling that should help clinicians design medication-specific dosing regimens for patients with obesity. Data sources included published studies, review papers, and clinical practice guidelines concerning drug dosing of subjects with obesity. Medication dosing recommendations in product labeling typically are derived from studies of normal healthy volunteers and patients with single-system disease states or patients in a specialized setting (e.g. operating room, intensive care unit). Even in studies with relatively large sample sizes there are often relatively few subjects with extremes of body composition such as patients with a body mass index (BMI) greater than 40 kg/m², so the appropriateness of labeled dosing information for these subjects is particularly ill-defined. Investigations of medication labeling information have demonstrated the inadequacy of this information for dosing patients of more extreme body size. Clinical investigations of drugs should be designed and the results reported in a manner that allows for meaningful recommendations for drug dosing in patients with varying degrees of obesity. Until and when such studies are routinely performed, there are steps that can be taken by the pharmaceutical industry, clinicians, and governmental agencies to help insure optimal drug dosing in obesity.