This study applied physiologically based pharmacokinetic (PBPK) modeling to characterize the disposition of the antibiotic meropenem in preterm and term infants. Meropenem is approved by the US Food and Drug Administration for use in pediatric patients, including treating complicated intra-abdominal infections in infants < 3 months of age. The PBPK model-based simulations were performed to evaluate meropenem dosing in the product label for infants < 3 months of age treated for complicated intra-abdominal infections. The PBPK model used supports the meropenem dosing regimens recommended in the product label for infants <3 months of age.