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Table 3 Pharmacokinetic parameters of Filgrastim and Pegfilgrastim

From: Pharmacokinetic and -dynamic modelling of G-CSF derivatives in humans

Parameter Meaning Filgrastim Pegfilgrastim
k sc subcutaneous absorption [h−1] 0.161 0.107
k m Michaelis-Menten constant of 34.7 5.5
  subcutaneous elimination [μg]   
v max Maximum of subcutaneous 67.3 16.5
  elimination [h−1]   
k u unspecific elimination [h−1] 0.441 0.087
k m GRA Michaelis-Menten constant of 22.4 30.8
  specific elimination [μg]   
v max GRA Maximum of specific elimination [h−1] 4.77 5.16
k cp transition central to peripheral [h−1] 0.000 0.075
k pc transition peripheral to central [h−1] - 0.548
V D distribution volume [l] 1.156 4.091
C G CSF cent _ ref reference G-CSF serum concentration μ g l 0.02
  1. Compared to Pegfilgrastim, we estimated that Filgrastim is more easily absorbed from the subcutaneous compartment, has a lower bioavailability (see Figure3) and a higher specific and unspecific elimination. Reversible binding is neglectable for Filgrastim but not for Pegfilgrastim. The distribution volume is higher for Pegfilgrastim than for Filgrastim.