Voriconazole-Based Salts Are Active against Multidrug-Resistant Human Pathogenic Yeasts.

Voriconazole (VOR) hydrochloride is unequivocally converted into VOR lactates and valinates upon reaction with silver salts of organic acids. This study found that the anticandidal in vitro activity of these compounds was comparable or slightly better than that of VOR. The Candida albicans clinical isolate overexpressing CaCDR1/CaCDR2 genes, highly resistant to VOR, was apparently more susceptible to VOR salts. On the other hand, the susceptibility of another C. albicans clinical isolate (demonstrating multidrug resistance due to the overexpression of CaMDR1) to VOR salts was comparable to that to VOR. Comparative studies on the influence of VOR and its salts on Rhodamine 6G efflux from susceptible and multidrug-resistant C. albicans cells revealed that VOR salts are poorer substrates for the CaCdr1p drug efflux pump than VOR.