Precision Dosing of Meropenem in a Neonate on CARPEDIEM Dialysis: A Grand Round

Optimal antibiotic dosing is challenging in critically ill neonates because of the substantial pharmacokinetic variability, which is influenced by factors such as immature renal function, body composition, and critical illness. The use of extracorporeal therapies adds complexity, making predictions difficult in many cases. Meropenem, a broad-spectrum antibiotic, is commonly used due to resistant gram-negative organisms in neonates; however, dosing guidelines for neonates on CARPEDIEM dialysis are lacking.

This is a case of a neonate with liver failure of unclear etiology, who was on CARPEDIEM dialysis and started on meropenem for sepsis due to extended-spectrum beta-lactamase-producing Escherichia coli and suspected meningitis. Blood samples were sent to an external laboratory for meropenem concentration measurements, and model-informed precision dosing was used to guide the dosing adjustments.

Initially, meropenem was administered at 40 mg/kg every 8 hours with a 30-min infusion, resulting in exposures that exceeded those required to achieve free concentrations above 4 times the minimum inhibitory concentration for the entire dosing interval (100% f T >4xMIC). The dosing interval was adjusted to every 12 hours to avoid unnecessarily high exposure. The regimen was continued without further complications, and the patient underwent successful liver transplantation.

This case highlights the successful application of model-informed precision dosing to individualize meropenem therapy in a critically ill neonate with liver failure on CARPEDIEM dialysis. MIPD is a valuable tool for dose adjustment in patients with unique and unpredictable pharmacokinetics.