title: Concentration of antifungal agents within host cell membranes: a new paradigm governing the efficacy of prophylaxis.
abstract: Posaconazole prophylaxis has proven highly effective in preventing invasive fungal infections, despite relatively low serum concentrations. However, high tissue levels of this agent have been reported in treated patients. We therefore hypothesized that the intracellular levels of antifungal agents are an important factor in determining the success of fungal prophylaxis. To examine the effect of host cell-associated antifungals on the growth of medically important molds, we exposed cells to antifungal agents and removed the extracellular drug prior to infection. Epithelial cells loaded with posaconazole and its parent molecule itraconazole, but not other antifungals, were able to inhibit fungal growth for at least 48 h and were protected from damage caused by infection. Cell-associated posaconazole levels were 40- to 50-fold higher than extracellular levels, and the drug was predominantly detected in cellular membranes. Fungistatic levels of posaconazole persisted within epithelial cells for up to 48 h. Therefore, the concentration of posaconazole in mammalian host cell membranes mediates its efficacy in prophylactic regimens and likely explains the observed discrepancy between serum antifungal levels and efficacy.
authors.affiliation: Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Campoli
authors.forename: Q
authors.initials: Q
authors.lastname: Al Abdallah
authors.forename: R
authors.initials: R
authors.lastname: Robitaille
authors.forename: N V
authors.initials: NV
authors.lastname: Solis
authors.forename: J A
authors.initials: JA
authors.lastname: Fielhaber
authors.forename: A S
authors.initials: AS
authors.lastname: Kristof
authors.forename: M
authors.initials: M
authors.lastname: Laverdiere
authors.forename: S G
authors.initials: SG
authors.lastname: Filler
authors.forename: D C
authors.initials: DC
authors.lastname: Sheppard
mesh_terms: D000935:Antifungal Agents / Q000493:pharmacokinetics* / Q000494:pharmacology; D001232:Aspergillus fumigatus / Q000187:drug effects* / Q000254:growth & development; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D018890:Chemoprevention; D004847:Epithelial Cells / Q000378:metabolism* / Q000382:microbiology; D006801:Humans; D017964:Itraconazole / Q000493:pharmacokinetics / Q000494:pharmacology; D008168:Lung / Q000166:cytology; D008264:Macrophages / Q000378:metabolism* / Q000382:microbiology; D009181:Mycoses / Q000517:prevention & control*; D014230:Triazoles / Q000493:pharmacokinetics* / Q000494:pharmacology
chemical_list: D000935:Antifungal Agents; D014230:Triazoles; D017964:Itraconazole; C101425:posaconazole