title: Danofloxacin-mesylate is a substrate for ATP-dependent efflux transporters.
abstract: OBJECTIVE
  Next to its broad antimicrobial spectrum, the therapeutic advantages of the fluoroquinolone antimicrobial drug Danofloxacin-Mesylate (DM) are attributed to its rapid distribution to the major target tissues such as lungs, intestines and the mammary gland in animals. Previous analyses revealed that effective drug concentrations are achieved also in luminal compartments of these organs, suggesting that active transport proteins facilitate excretion into the luminal space. Members of the ATP-Binding Cassette (ABC) superfamily, including P-gp, BCRP and MRP2 are known to be expressed in many tissue barriers and in cell-membranes facing luminal compartments. Hence we hypothesized that DM is a substrate for one of these efflux-transporters.
  
  
  METHODS
  Confluent monolayers of Caco-2 cells, grown on microporous membranes in two-chamber devices were used. DM concentrations were measured by fluorimetric assay after HPLC of the culture media.
  
  
  RESULTS
  DM transport across Caco-2 cells was asymmetric, with a rate of secretion exceeding that of absorption. The P-gp inhibitors PSC833 and GF120918 and the MRP-inhibitor MK571 partially decreased the secretion of DM and increased its absorption rate. The BCRP inhibitor, Ko143, decreased secretion only at a concentration of 1 microM. When DM was applied together with ciprofloxacin, secretion as well as absorption of DM decreased.
  
  
  CONCLUSIONS
  DM is a substrate for the efflux transporters P-gp and MRP2, whereas the specific role of BCRP in DM transport needs further evaluation. These findings provide a mechanistic basis for the understanding of the pharmacokinetics of DM in healthy and diseased individuals.
authors.affiliation: Department of Veterinary Pharmacology, Pharmacy and Toxicology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands. j.a.schrickx@vet.uu.nl
authors.forename: J A
authors.initials: JA
authors.lastname: Schrickx
authors.forename: J
authors.initials: J
authors.lastname: Fink-Gremmels
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors; D000166:Acridines / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000502:physiology*; D000900:Anti-Bacterial Agents / Q000378:metabolism*; D018938:Caco-2 Cells; D002352:Carrier Proteins / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media; D003524:Cyclosporins / Q000494:pharmacology; D015194:Diffusion Chambers, Culture; D005470:Fluorometry; D024841:Fluoroquinolones / Q000378:metabolism*; D006801:Humans; D026901:Membrane Transport Proteins / Q000378:metabolism; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors; D011422:Propionates / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D044005:Tetrahydroisoquinolines / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000166:Acridines; D000255:Adenosine Triphosphate; D000900:Anti-Bacterial Agents; D002352:Carrier Proteins; D003470:Culture Media; D003524:Cyclosporins; D024841:Fluoroquinolones; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D011422:Propionates; D011804:Quinolines; D044005:Tetrahydroisoquinolines; C000715087:ABCC2 protein, human; C116614:ABCG2 protein, human; C068581:danofloxacin; C059141:verlukast; C083501:Elacridar; C070272:valspodar