A population pharmacokinetic model for pegylated-asparaginase in children.

We analysed 1221 serum activity measurements in 168 children from the Berlin-Frankfürt-Münster acute lymphoblastic leukaemia studies, ALL-BFM (Berlin-Frankfürt-Münster) 95 and ALL-BFM REZ, in order to develop a pharmacokinetic model describing the activity-time course of pegylated (PEG)-asparaginase for all dose levels. Patients received 500, 750, 1000 or 2500 U/m(2) PEG-asparaginase on up to nine occasions. Serum samples were analysed for asparaginase activity and data analysis was done using nonlinear mixed effects modelling (NONMEM Vers.

Serum cystatin C is a better marker of topotecan clearance than serum creatinine.

Purpose: To evaluate plasma cystatin level as a covariate to predict topotecan pharmacokinetics. Cystatin C, a member of the cystatin superfamily of cysteine proteinase inhibitors, has been recently proposed as an alternative endogenous marker of glomerular filtration. Renal function is known as a key factor of topotecan clearance.