Delayd Cmax following infusion of a monoclonal antibody

Dear NMUsers, Some pharmacokinetic data of a monoclonal antibody (IGG1 like) administered as 2-h infusion (single dose and repeated administration every two weeks) show a peak concentration observed (generally 1 to 6 hours) after the end of infusion. At the current stage, we are aiming to develop as quickly as possible a pragmatic PK model that can be further used to simulate alternative administration regimens under discussion for future studies. What could be the physiological explanation for observing a peak concentration after the end of the infusion? Maybe can target drug-mediated disposition, a common observation in mAbs pharmacokinetics, be - at least part of - the answer? Assuming a plausible explanation can be found, what would be your advice on the more efficient modeling strategy, keeping in mind that the modeling interest at this stage is only for simulation purpose? Thanks in advance for any suggestion! Fabrice Fabrice Nollevaux, Arlenda SA http://www.arlenda.com www.arlenda.com