Recombinant filgrastim (BK0023) pharmacodynamics and pharmacokinetics after single and multiple escalating doses in an equivalence study in healthy men.

Background And Objectives: The new filgrastim formulation, BK0023, whose synthesis method is patented, was tested in a phase I clinical study that was aimed at investigating the pharmacodynamic and pharmacokinetic equivalence and the safety of BK0023 in healthy male subjects.

Methods: Single and multiple escalating doses were administered to healthy male volunteers according to a double-blind, randomised, two-way crossover design. Thirty-two subjects received subcutaneous filgrastim 2.5 µg/kg/day for 7 consecutive days in each period, 36 subjects received 5 µg/kg/day for 7 days in each period, and 22 subjects received 10 µg/kg/day for 5 days. Absolute neutrophil count (ANC) and CD34+ cell count were measured in whole blood as primary and secondary pharmacodynamic parameters. Filgrastim concentrations were measured in serum to calculate the primary pharmacokinetic parameters.

Results: The maximum ANC and the area under the curve of the ANC after the first dose and to the end of treatment satisfied the equivalence criterion (95 % confidence intervals within 85-115 or 85-117 % in case of log-transformation). At all three dose regimens, BK0023 was also bioequivalent to the reference product in terms of pharmacokinetic profile of serum filgrastim. The frequency of the treatment-emergent adverse events did not differ significantly between treatments, with the most frequent untoward effects being back and bone pain.

Conclusions: Equivalence could be established using both the baseline-adjusted values and the original unadjusted values. The tested formulation at all three dose regimens was also bioequivalent to the reference product in terms of pharmacokinetic profile.