CFTR and cystic fibrosis: We aim to develop a population pharmacokinetic (popPK) model of tobramycin in children with CF and determine the: (i) effect of cystic fibrosis transmembrane conductance regulator (CFTR) modulators on tobramycin pharmacokinetics (PK); (ii) attainment of the commonly used serum steady state area under the concentration-time curve target (AUC24,ss) of 80–110 mg/L⋅h with standard dosing; and (iii) generate an optimized fully individualized dosing strategy to improve target attainment.