title: Simultaneous high-performance liquid chromatography analysis of azithromycin and two of its metabolites in human tears and plasma.
abstract: This article describes a high-performance liquid chromatographic (HPLC) method for the measurement of azithromycin (AZI) and two of its metabolites, 9a-N-desmethylazithromycin (ADES) and N-desmethylazithromycin (NDES), in human tears and plasma. The drug, metabolites, and internal standard (n-propylazithromycin [IS]) were detected electrochemically after injection of the extracted sample into the HPLC system. The peak height ratio (AZI, ADES, or NDES to IS) varied linearly, with concentrations in the ranges of 0.1 mg/L to 2.0 mg/L (tears) and 0.01 mg/L to 2.0 mg/L (plasma) of AZI, ADES, and NDES; the correlation coefficient (r) was more than 0.994 mg/L for all of the compounds (n=6). The analysis of tear samples collected at different intervals within 12 hours to 144 hours after a dose of 20 mg/kg of AZI from a trachoma patient yielded concentrations ranging from 1.52 mg/L to 0.34 mg/L for AZI, 0.79 mg/L to 0.27 mg/L for ADES, and 1.99 mg/L to less than 0.20 mg/L for NDES. The concentration of AZI in plasma ranged from 0.15 mg/L to 0.01 mg/L, whereas ADES and NDES were undetectable.
authors.affiliation: Department of Biological and Medical Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
authors.forename: D A
authors.initials: DA
authors.lastname: Raines
authors.forename: A
authors.initials: A
authors.lastname: Yusuf
authors.forename: M H
authors.initials: MH
authors.lastname: Jabak
authors.forename: W S
authors.initials: WS
authors.lastname: Ahmed
authors.forename: Z A
authors.initials: ZA
authors.lastname: Karcioglu
authors.forename: A
authors.initials: A
authors.lastname: El-Yazigi
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis* / Q000097:blood; D017963:Azithromycin / Q000031:analogs & derivatives* / Q000032:analysis* / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D004563:Electrochemistry; D006801:Humans; D008565:Membrane Proteins / Q000032:analysis*; D010949:Plasma / Q000737:chemistry; D015800:Protozoan Proteins; D015203:Reproducibility of Results; D013666:Tears / Q000737:chemistry*
chemical_list: C118491:9a-N-desmethylazithromycin; D000900:Anti-Bacterial Agents; D008565:Membrane Proteins; D015800:Protozoan Proteins; C117490:pypag-1 protein, Plasmodium yoelii; D017963:Azithromycin