Medication Dosing for Children With Overweight and Obesity

Approximately 14.7 million US children aged 2 to 19 years are obese. This creates significant challenges to dosing medications that are primarily weight based (mg/kg) and in predicting pharmacokinetics parameters in pediatric patients. Obese individuals generally have a larger volume of distribution (Vd) for lipophilic medications. Conversely, the Vd of hydrophilic medications may be increased or decreased owing to increased lean body mass, blood volume, and decreased percentage of total body water. They may also experience decreased hepatic clearance secondary to fatty infiltrates of the liver. Hence, obesity may affect loading dose, dosage interval, plasma half-life, and time to reach steady-state concentration for various medications. Weight-based dosing is also a cause for potential medication errors. This position statement of the Pediatric Pharmacy Association recommends that weight-based dosing should be used in patients ages <18 years who weigh <40 kg; weight-based dosing should be used in patients ≥40 kg, unless the recommended adult dose for the specific indication is exceeded; clinicians should use pharmacokinetic analysis for adjusting medications in children diagnosed with overweight and obesity; and research efforts continue to evaluate dosing of medications in children diagnosed with overweight and obesity.