title: Characterization of the inhibitory effect of voriconazole on the fungicidal activity of amphotericin B against Candida albicans in an in vitro kinetic model.
abstract: OBJECTIVE
  The aim of the present investigation was to study and characterize the effect of voriconazole on the fungicidal activity of amphotericin B.
  
  
  METHODS
  Four strains of Candida albicans susceptible to voriconazole were exposed to voriconazole and amphotericin B, either alone, simultaneously or sequentially in an in vitro kinetic model. Bolus doses resulting in voriconazole and amphotericin B concentrations of 0.005-5 and 2.5 mg/L, respectively, were administered. Antifungal-containing RPMI 1640 was eliminated and replaced by a fresh medium using a peristaltic pump, with a flow rate adjusted to obtain the desired half-lives. With two drugs tested, a computer-controlled dosing pump compensated for differences in the elimination rates. Using static time-kill methodology, one C. albicans strain was exposed to 5 mg/L voriconazole for varying durations followed by 2.5 mg/L amphotericin B after three repeated washes of voriconazole.
  
  
  RESULTS
  Voriconazole and amphotericin B treatment alone resulted in fungistatic and fungicidal activities, respectively. Simultaneous administration of voriconazole and amphotericin B resulted in fungicidal activity, whereas only fungistatic activity was observed when repeated doses of amphotericin B were administered sequentially after voriconazole at 24-96 h. The inhibition of the fungicidal activity of amphotericin B was voriconazole dose-dependent, but seemed to be recovered once the voriconazole concentration fell below the MIC. The fungicidal activity was quickly regained after the removal of voriconazole, irrespective of the duration of voriconazole pre-exposure.
  
  
  CONCLUSIONS
  Voriconazole inhibited the fungicidal effect of sequentially administered amphotericin B in a concentration- and time-dependent manner; the clinical significance of this needs further investigation.
authors.affiliation: Section of Infectious Diseases, Department of Medical Sciences, Uppsala University Hospital, Uppsala, Sweden. anders.lignell@akademiska.se
authors.forename: Anders
authors.initials: A
authors.lastname: Lignell
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Löwdin
authors.forename: Otto
authors.initials: O
authors.lastname: Cars
authors.forename: Jan
authors.initials: J
authors.lastname: Sjölin
mesh_terms: D000666:Amphotericin B / Q000493:pharmacokinetics / Q000494:pharmacology*; D000935:Antifungal Agents / Q000493:pharmacokinetics / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004336:Drug Antagonism; D006801:Humans; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects*; D008954:Models, Biological; D011743:Pyrimidines / Q000493:pharmacokinetics / Q000494:pharmacology*; D013997:Time Factors; D014230:Triazoles / Q000493:pharmacokinetics / Q000494:pharmacology*; D065819:Voriconazole
chemical_list: D000935:Antifungal Agents; D011743:Pyrimidines; D014230:Triazoles; D000666:Amphotericin B; D065819:Voriconazole