Pharmacodynamics of peginterferon alpha-2a and peginterferon alpha-2b in interferon-naïve patients with chronic hepatitis C: a randomized, controlled study.

Background Peginterferon alfa-2a and alfa-2b, the two commercially available pegylated interferons, have different pharmacokinetic properties that produce differing abilities to suppress replication of the hepatitis C virus. Aim To compare the pharmacodynamics of peginterferon alfa-2a and peginterferon alfa-2b in interferon-naive patients with chronic hepatitis C. Methods Patients were randomized to receive peginterferon alfa-2a, 180 mu g (n = 10) or peginterferon alfa-2b 1.0 mu g/kg (n = 12) once weekly. The enzymatic activity of 2'5'-oligoadenylate synthetase and levels of neopterin and beta(2)-microglobulin were measured at baseline and at 24, 48, 120 and 168 h. Results Oligoadenylate synthetase activity and serum neopterin and beta(2)-microglobulin concentrations did not differ significantly between the two patient groups at any time point, nor was there a significant correlation between the serum area under the concentration-time curve of either peginterferon and the area under the concentration-time curve for 2',5'-oligoadenylate synthetase, neopterin and beta(2)-microglobulin. The area under the concentration-time curves calculated for these three markers did not correlate with body mass index stratified at < 25 and >= 25 kg/m(2) for either peginterferon. Conclusions Despite pharmacokinetic differences between peginterferon alfa-2a and peginterferon alfa-2b, the pharmacodynamic profiles of the two formulations appear to be comparable.