title: Quantitative determination of the macrolide antibiotic tulathromycin in plasma and broncho-alveolar cells of foals using tandem mass spectrometry.
abstract: The long-acting antibiotic tulathromycin is on the marked for treatment of pulmonary infection of cattle, swine and horses. To measure disposition and distribution of tulathromycin in foals, a high throughput method was developed for horse plasma (calibration range: 0.006-0.8 microg/mL) and broncho-alveolar cells (calibration range: 0.1-4.0 microg/10(9)cells) using tandem mass spectrometry. Tulathromycin was extracted from plasma and broncho-alveolar fluid using cation exchange cartridges with acetonitrile/ammonia (95:5, v/v). The chromatography was performed isocratically with a mobile phase consisting of 5 mM ammonium formiate buffer/acetonitrile (30:70, v/v). The mass spectrometer operated in selected ion mode with atmospheric pressure chemical ionization to monitor the respective MH+ ions m/z 577.3 for tulathromycin and m/z 679.3 for the internal standard roxithromycin. All quality parameters fulfilled the international criteria for bioanalytical method validation and were successfully applied to the determination of tulathromycin in plasma of foals and broncho-alveolar cells. In foals, tulathromycin after intramuscular administration was rapidly absorbed, widely distributed and slowly eliminated. It cumulated manifold in broncho-alveolar cells.
authors.affiliation: Department of Clinical Pharmacology, Research Center of Pharmacology and Experimental Therapeutics, University of Greifswald, Germany. scheuch@uni-greifswald.de
authors.forename: Eberhard
authors.initials: E
authors.lastname: Scheuch
authors.forename: Janina
authors.initials: J
authors.lastname: Spieker
authors.forename: Monica
authors.initials: M
authors.lastname: Venner
authors.forename: Werner
authors.initials: W
authors.lastname: Siegmund
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000032:analysis* / Q000097:blood / Q000493:pharmacokinetics; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry*; D004187:Disaccharides / Q000032:analysis* / Q000097:blood / Q000493:pharmacokinetics; D006571:Heterocyclic Compounds / Q000032:analysis* / Q000097:blood / Q000493:pharmacokinetics; D006736:Horses; D012015:Reference Standards; D053719:Tandem Mass Spectrometry / Q000379:methods*; D018942:Macrolides
chemical_list: D000900:Anti-Bacterial Agents; D004187:Disaccharides; D006571:Heterocyclic Compounds; C485204:tulathromycin; D018942:Macrolides