title: Liquid chromatography assay for routine monitoring of cellular ribavirin levels in blood.
abstract: Ribavirin-induced hemolytic anemia is one cause for cessation of combination therapy with alpha interferon 2b and ribavirin for hepatitis C infection. Determining cellular ribavirin levels in blood, including the levels of its phosphorylated metabolites, might be useful for predicting ribavirin-induced anemia, because the metabolites accumulate in erythrocytes. We simplified an assay method developed previously to make it suitable for routine monitoring of cellular ribavirin. Whole blood diluted with a sixfold volume of ice-cold distilled water was subjected to acid phosphatase digestion to convert phosphorylated ribavirin metabolites to free ribavirin. The resulting mixture, spiked with an internal standard, was treated by phenyl boronic acid column extraction, followed by reverse-phase high-performance liquid chromatography analysis. The calibration curve for ribavirin levels in whole blood was linear at concentrations of 5.3 to 1,024 microM (r(2) = 0.9999). Validation coefficients of variation for intra- and interday assays were 2.9 to 5.8% and 4.3 to 8.3%, respectively. We tested this method by monitoring blood ribavirin concentrations in two hepatitis C patients receiving alpha interferon 2b-plus-ribavirin combination therapy.
authors.affiliation: Department of Pharmaceutical Sciences, Institute of Clinical Medicine, University of Tsukuba, Ten-nodai 1-1-1, Tsukuba, Ibaraki 305-8575, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Inoue
authors.forename: Masato
authors.initials: M
authors.lastname: Homma
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Matsuzaki
authors.forename: Minoru
authors.initials: M
authors.lastname: Shibata
authors.forename: Takuya
authors.initials: T
authors.lastname: Matsumura
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Ito
authors.forename: Keiji
authors.initials: K
authors.lastname: Mitamura
authors.forename: Naomi
authors.initials: N
authors.lastname: Tanaka
authors.forename: Yukinao
authors.initials: Y
authors.lastname: Kohda
mesh_terms: D000998:Antiviral Agents / Q000097:blood* / Q000627:therapeutic use; D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D016903:Drug Monitoring / Q000379:methods*; D006454:Hemoglobins / Q000032:analysis; D006526:Hepatitis C / Q000097:blood / Q000188:drug therapy; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry; D010766:Phosphorylation; D011994:Recombinant Proteins; D015203:Reproducibility of Results; D012254:Ribavirin / Q000097:blood* / Q000627:therapeutic use
chemical_list: D000998:Antiviral Agents; D006454:Hemoglobins; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D011994:Recombinant Proteins; D012254:Ribavirin; D010744:Phosphoric Monoester Hydrolases