Abstract Summary
The currently available pegylated interferon (PEG-IFN) formulations, PEG-IFN alfa-2a (40KD, PEGASYS) and PEG-IFN alfa-2b (12KD, PEG-Intron), have different pharmacokinetic profiles. The aim of this current study, conducted at the University of Pavia, Italy, was to compare the pharmacokinetics of the two PEG-IFNs in patients with chronic hepatitis C (CHC).

30 treatment naive patients with CHC and persistently elevated ALT levels have been randomized to receive 180 mcg PEGASYS once-weekly (n=16) or 1.0 mcg/kg once-weekly of PEG-Intron (n=14). Serum concentrations of both PEG-IFNs were measured at baseline and 24, 48, 120 and 168 hours after administration using a quantitative sandwich ELISA (lower limit of detection 125 pg/ml).

Serum concentration of PEG-Intron achieved maximum levels at 24 hours after injection and decreased rapidly until 120 hours. Drug was undetectable 120 and 168 hours after injection in 7 (50%) and 11 (78%) subjects, respectively. In contrast, PEGASYS concentrations increased continuously overtime, reaching maximum levels from 48 to 168 hours.

Conclusions: The investigators conclude, “Our data demonstrate substantial differences in plasma concentration profiles between PEGASYS and PEG-Intron. Five days after injection concentrations of PEG-Intron are marginal or undetectable, while those of PEGASYS remain stable overtime.

“These findings suggest that PEG-Intron administration should be intensified to twice weekly to avoid "blips" in viral replication. Differences in pharmacokinetics could explain the differences observed in HCV decay.”

03/24/03

Reference
R Bruno and others. PHARMACOKINETICS OF PEGINTERFERON ALFA-2A (40KD, PEGASYS) COMPARED TO PEGINTERFERON ALFA-2B (12KD, PEGINTRON) IN NAIVE PATIENTS WITH CHRONIC HEPATITIS C (CHC). Abstract 4203.00. Abstracts of the 38th Annual Meeting of the European Association of the Study of the Liver (EASL).