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Keywords:

  • genotype 1;
  • hepatitis C virus;
  • high viral load;
  • peginterferon alpha-2a;
  • peginterferon alpha-2b;
  • ribavirin;
  • virologic response

Abstract  Patients infected with hepatitis C virus (HCV) genotype 1 and with serum HCV RNA concentrations over 800 000 IU/mL have relatively low rates of virologic response to pegylated interferons. The 2 forms of pegylated interferon have different pharmacokinetic profiles, and pilot studies comparing them have yielded varying results. We compared the virologic response to 12 weeks of treatment with peginterferon alpha-2a plus ribavirin vs peginterferon alpha-2b plus ribavirin in 380 patients who were infected with HCV genotype 1 and had high viral loads.

We observed no between-group differences in viral load reduction over time and no differences in the percentage of patients treated with peginterferon alpha-2a or peginterferon alpha-2b plus ribavirin who achieved early virologic response (EVR), defined as ≥2-log reduction in HCV RNA concentration or undetectable HCV RNA at 12 weeks (66%vs 63%). Serum levels of interferon were more frequently below the level of quantitation in patients treated with peginterferon alpha-2b plus ribavirin (58–68%) than in those treated with peginterferon alpha-2a plus ribavirin (1–2%). Patients treated with peginterferon alpha-2b plus ribavirin had higher rates of discontinuation for safety reasons (6%vs 1%).

In conclusion, a substantial percentage of patients infected with HCV genotype 1 and high viral load can achieve EVR when treated with peginterferon and ribavirin. The 2 pegylated interferons showed comparable anti-HCV activity during the first 12 weeks of treatment when combined with the same doses of ribavirin (1000–1200 mg/day), but discontinuations for safety reasons were higher in the patients treated with peginterferon alpha-2b plus ribavirin.