A comparison of the exponential decay slope between PEG-IFN alfa-2b/ribavirin and IFN alfa-2b/ribavirin combination therapy in patients with chronic hepatitis C genotype 1b infection and a high viral load.

Objectives: A high virological response rate can often be shown to be obtained with PEG-IFN alpha-2b and ribavirin combination therapy in chronic hepatitis C patients. Viral dynamics have been utilized for the evaluation of antiviral effects, especially the exponential second decay slope, which represents the elimination of infected cells.

Methods: Forty-nine patients were randomly assigned to the IFN alpha-2b group (n = 26) or the PEG-IFN alpha-2b group (n = 23). Ribavirin was administered equally to both groups. Measuring the serum concentration of HCVRNA, the exponential viral decay during phase 1 and 2 was calculated.

Results: The exponential decay slope in phase 2 during the first 2 weeks was greater in the IFN alpha-2b group than in the PEG-IFN alpha-2b group; however, from weeks 3 to 4, it was greater in the PEG-IFN alpha-2b group than in the IFN alpha-2b group. Interestingly, in the PEG-IFN alpha-2b group, the exponential decay slope was greater from weeks 3 to 4 after initiating combination therapy than during the weeks 1-2 (p < 0.01), despite administration of the same PEG-IFN alpha-2b dose (1.5 microg/kg once weekly).

Conclusions: In PEG-IFN alpha-2b and ribavirin combination therapy, elimination of infected cells may be pronounced following an increase in serum ribavirin concentration in chronic hepatitis C patients with genotype 1b infection and a high viral load.