title: Improvement of sensitivity and selectivity of high-performance liquid chromatography for anti-retroviral drugs (non-reverse transcriptase inhibitors) by diamond-electrode electrochemical and fluorescence detection.
abstract: The new non-reversed transcriptase inhibitor (NRTI) drugs for treatment of acquired immunodeficiency syndrome (AIDS) are reported. An improvement in the sensitivity and selectivity of high-performance liquid chromatography was obtained by diamond electrode-electrochemical detector and fluorescence detector owing to different structural information. The four anti-retroviral NRTI drugs (abacavir, didanosine, lamivudine and zidovudine) were separated on a CapcellPak C18 UG120 column (250 mm x 4.6 mm I.D., 5 microm) with an acetonitrile-25 mM potassium dihydrogenphosphate buffer (pH 8.0; 1:9, v/v) as the mobile phase. We applied dual detection (electrochemical detection and florescence detection) for improving the peak identification and also for improved selectivity, which assisted monitoring by trace-volume samples (e.g., plasma). The electrochemical detector, equipped with a diamond electrode, was set at 2000 mV (applied voltage) and the fluorescence detector was set at excitation wavelength 275 nm and emission wavelength 315 nm. The detection limits of the four NRTIs in spiked plasma were 1-100 ng/ml by electrochemical detection and 5-10 pg/ml by fluorescence detection. The calibration graphs were linear up to 20 microg/ml by electrochemical detection and 10 microg/ml by fluorescence detection. This is the first report of LC analysis of NRTIs by electrochemical detection, also combined with fluorescence detection. The detection limits of didanosine, lamivudine and zidovudine were improved 20-fold by electrochemical detection and 500-fold by fluorescence detection compared to previous reports on UV detection. The selectivity was also improved by dual detection. The proposed method was applied to the preliminary monitoring of NRTIs in plasma.
authors.affiliation: Department of Drug Metabolism Research Laboratories, Drug Discovery Research, Astellas Pharma Inc, Tokyo, Japan.
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Suzuki
authors.forename: Masatoki
authors.initials: M
authors.lastname: Katayama
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Takamatsu
authors.forename: Satoru
authors.initials: S
authors.lastname: Kaneko
authors.forename: Keisuke
authors.initials: K
authors.lastname: Miyaji
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Ishikawa
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Matsuda
mesh_terms: D044966:Anti-Retroviral Agents / Q000032:analysis / Q000097:blood; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D016049:Didanosine / Q000032:analysis / Q000097:blood; D015224:Dideoxynucleosides / Q000032:analysis / Q000097:blood; D055664:Electrochemical Techniques / Q000379:methods*; D005453:Fluorescence; D006801:Humans; D019259:Lamivudine / Q000032:analysis / Q000097:blood; D016014:Linear Models; D015203:Reproducibility of Results; D018894:Reverse Transcriptase Inhibitors / Q000032:analysis / Q000097:blood; D012680:Sensitivity and Specificity; D014867:Water / Q000737:chemistry; D015215:Zidovudine / Q000032:analysis / Q000097:blood; D000099227:Abacavir
chemical_list: D044966:Anti-Retroviral Agents; D016049:Didanosine; D015224:Dideoxynucleosides; D019259:Lamivudine; D018894:Reverse Transcriptase Inhibitors; D014867:Water; D015215:Zidovudine; D000099227:Abacavir