Serum concentration of interferon-alpha: a comparison between once-a-day and twice-a-day administration

The aim of this study was to determine the possible mechanism of the antiviral activity of twice daily administration of interferon (IFN)-alpha for active hepatitis C and to evaluate serum concentrations of IFN-alpha with enzyme-linked immunosorbent assay (ELISA). Forty-seven patients with active hepatitis C received IFN-alpha intramuscularly for 24 weeks. They were divided into once-a-day and twice-a-day groups. Changes in serum IFN-alpha levels were assessed during the treatment period. Compared with twice-a-day treatment, the once-a-day group showed no increase in serum IFN-alpha at the end of daily treatment (p < 0.03). In contrast, one-third of the twice-a-day group showed increased IFN-alpha at the end of daily treatment (p < 0.02). In conclusion, measured with ELISA, twice-daily administration of IFN-alpha manifested prolonged elevation in serum levels when compared with once daily administration.