Formulation and characterization of voriconazole nanospray dried powders.

Purpose: Voriconazole nanoparticles (API-NPs) were prepared by nanospray drying to improve the solubility of voriconazole and reduce its interindividual variability.Methods: The preparation procedure was optimized by central composite design-response surface methodology. The properties of the nanoparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) analyses. The solubility, dissolution, and stability of the API-NPs were determined experimentally. The pharmacokinetics were assessed based on rat plasma levels of voriconazole. An acute oral toxicity test of the API-NPs was performed in mice.Results: The powers were formulated using cetyltrimethylammonium chloride (CTAC) as the carrier material. SEM and particle size results showed that the API-NPs had a narrow particle size distribution. The XRD, DSC, and FTIR analyses show a decrease in crystallinity and a polymorphic transformation of the nanoparticles after nanospray drying. The solubility in water was approximately 15 times higher than that of voriconazole. The API-NP tablets exhibited significantly higher plasma exposure, namely, longer acting times and lower variability. The acute administration of voriconazole showed no toxic histopathological effects on organ tissue.Conclusion: The solubility of voriconazole was greatly improved, it showed higher bioavailability and safety, and the interindividual variability in voriconazole pharmacokinetics was reduced by nanospray drying.

Photosensitisation by voriconazole-N-oxide results from a sequence of solvent and pH-dependent photochemical and thermal reactions.

The phototoxicity of voriconazole (VN) prescribed in the treatment of severe fungal infections is frequently reported. Its major metabolite, a N-oxide derivative (VNO), was suspected to be the photosensitizer because it shows a maximum absorbance at ~310 nm in aqueous solutions. It was reported that the VNO photoproduct (VNOP) was phototoxic to human keratinocytes. Steady state and laser flash photolyses were performed to shed light on the phototoxic properties of VNO and VNOP. The quantum yield of the VNOP production by UVB-UVA light in buffered or alcoholic solutions is 0.6. VNOP has been identified as (2R,3S)-2-(2,4-difluorophenyl)-3-(5-fluoro-7-oxa-1,3-diazabicyclo[4.1.0]hepta-2,4-dien-4-yl)-1-(1H-1,2,4-triazol-1-yl)butan-2-ol. VNOP undergoes a marked thermal degradation and an efficient UVA photolysis with well differentiated kinetics and end-products. The temperature-dependent VNOP dark degradation produces a single product VNOPD identified as 6-[(2S,3R)-3-(2,4-difluorophenyl)-3-hydroxy-4-(1H-1,2,4-triazol-1-yl)butan-2-yl]-5-fluoropyrimidin-4-ol with absorbance maximum at 308 nm and ε = 2700 M-1 cm-1. Under UVB-UVA irradiation, VNOPD, the stable end-product, is a remarkable photodynamic photosensitizer towards Trp and His. The Trp photo-oxidation (Φox(Trp) = 0.13) mainly involves type I radical reactions whereas His is oxidized by 1O2 (Φox(His) = 0.012). These results force us to question the validity of the in vitro photosensitization of human keratinocytes by VNO and VNOP previously reported.