Pharmacokinetics and Antiviral Activity of Pegasys vs Peg-Intron

A combination of pegylated interferon plus ribavirin is standard therapy for the treatment of chronic hepatitis C, but there is little research comparing the two approved brands of pegylated interferon.

As reported in the August 2006 Journal of Hepatology, researchers from Argentina compared the pharmacokinetics, pharmacodynamics, and antiviral activity of 180 mcg/week pegylated interferon alfa-2a (Pegasys) vs 1.5mcg/kg/week pegylated interferon alfa-2b (Peg-Intron) in 36 patients with genotype 1 chronic hepatitis C. Patients were randomly assigned to receive one of the two types of pegylated interferon as monotherapy for four weeks, then 13 mg/kg/day ribavirin was added for an additional four weeks.

Results

Patients receiving Peg-Intron had significantly greater up-regulation of interferon-alfa response genes compared with those receiving Pegasys.

Patients treated with Peg-Intron also had a significantly greater log maximum and log time-weighted average decrease in serum HCV RNA.

A greater proportion of patients receiving Peg-Intron achieved a 2-log reduction in serum HCV RNA by week 8, compared with those taking Pegasys (72% vs 44%; P = 0.09).

There was an approximately 16-fold greater exposure to pegylated interferon in the serum of patients treated with Pegasys.

Conclusion

The authors concluded that, "These findings suggest that the biological activity, measured by early interferon-induced gene transcripts and early antiviral responsiveness, may have been greater in patients treated with [Peg-Intron], despite their lower exposure to the drug compared with patients treated with [Pegasys]."

7/25/06

Reference
M Silva, J Poo, F Wagner, and others. A randomised trial to compare the pharmacokinetic, pharmacodynamic, and antiviral effects of peginterferon alfa-2b and peginterferon alfa-2a in patients with chronic hepatitis C (COMPARE). Journal of Hepatology 45(2): 204-213. August 2006.