title: Complexes of ciprofloxacin with metal ions contained in antacid drugs.
abstract: Simultaneous administration of antacids containing magnesium or aluminium and ciprofloxacin or other quinolones decreases the gastrointestinal absorption of those antibacterial agents. Current speculation about the mechanism of this interaction has focused on drug-cation chelation. The present study was designed to detect the protonation in solutions and the formation of the complex species at the pH levels typical of the gastrointestinal tract. It involves the study of ciprofloxacin in aqueous solutions containing Al3+ and (or) Mg2+ by combining the results of potentiometric and spectroscopic (1H nuclear magnetic resonance) techniques. Calculations were only performed for data in the range 4.5 < pH < 5.5 (pH levels typical of gastrointestinal tract) and the results of both methods are made self-consistent, assuming an equilibrium model including complex species MHL, MLOH (where H2L denotes ciprofloxacin and M is Al3+ or Mg2+); their formation constants are given.
authors.affiliation: Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, Portugal.
authors.forename: M H
authors.initials: MH
authors.lastname: Teixeira
authors.forename: L F
authors.initials: LF
authors.lastname: Vilas-Boas
authors.forename: V M
authors.initials: VM
authors.lastname: Gil
authors.forename: F
authors.initials: F
authors.lastname: Teixeira
mesh_terms: D000535:Aluminum / Q000737:chemistry* / Q000378:metabolism*; D000863:Antacids / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D002412:Cations / Q000737:chemistry; D002939:Ciprofloxacin / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D004347:Drug Interactions; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000737:chemistry* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D011199:Potentiometry
chemical_list: D000863:Antacids; D002412:Cations; D002939:Ciprofloxacin; D000535:Aluminum; D008274:Magnesium