Time-of-flight mass spectrometry assessment of fluconazole and climbazole UV and UV/H2O2 degradability: Kinetics study and transformation products elucidation.

The efficiency of UV irradiation for the removal of the antimycotic drugs fluconazole (FCZ) and climbazole (CBZ) from water samples is evaluated. Degradation experiments, at laboratory scale, were carried out with spiked aliquots of ultrapure water solutions and treated wastewater samples using low-pressure mercury lamps emitting at 254 nm. Time course of precursor pollutants and identification of arising transformation products (TPs) was performed by injection of different reaction time aliquots in a liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) system. Chemical structures of identified TPs were proposed from their full-product ion spectra, acquired using different collision energies. During UV irradiation experiments, the half-lives (t1/2) of FCZ and CBZ were similar in ultrapure water solutions and wastewater samples; however, the first species was more recalcitrant than the second one. Four TPs were identified in case of FCZ resulting from substitution of fluorine atoms by hydroxyl moieties and intramolecular cyclization with fluorine removal. CBZ interacted with UV radiation through reductive dechlorination, hydroxylation and cleavage of the ether bond; moreover, five additional primary TPs, with the same empirical formula as CBZ, were also noticed. Given the relatively long t1/2 of FCZ under direct photolysis (ca. 42 min), UV irradiation was combined with H2O2 addition to promote formation of reactive hydroxyl radicals. Under such conditions, the degradation rate of FCZ was enhanced significantly and no TPs were detected. These latter conditions allowed also the effective removal of CBZ TPs.

Radiochemical stability of fluconazole in the solid state.

The effect of ionizing radiation in doses between 20 and 200 kGy on physicochemical properties of fluconazole (alpha-(2,4-diflurophenyl)-alpha-(1H-triazol-1-methyl)-1H-1,2,4-triazole-1-ethanol) in the solid state was examined. A number of qualitative and quantitative methods such as scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), ultraviolet (UV) and infrared (IR) spectroscopy, thin layer chromatography (TLC) and high pressure liquid chromatography (HPLC) and organoleptic analysis were used to determine and analyse any changes resulting from irradiation. A change in colour from white to cream was observed at even smallest dose (20 kGy) and as the dose increased the colour deepened from salmon pink to orange at the highest dose of 200 kGy. The UV method showed an increase in absorbance at lambda(max) and an appearance of an additional band in the range 280-310 nm for irradiated samples. These changes were associated with the appearance of one to two decomposition products observed by TLC. Depending on the dose of radiation, the HPLC method detected between 2 and 3 radiolysis products and the decreasing fluconazole content from 0.48 to 7.12%. The remaining analytical methods (SEM, IR and NMR) did not provide any conclusive information in respect of radiological stability of fluconazole. The results indicate that fluconazole is a compound of low radiological stability and should not be sterilized using gamma, beta or E-beam radiation.

[The effect of fluorine substituent on radiochemical stability of some steroid and azole derivatives]. / Wplyw podstawnika fluorowego na trwalosc radiochemiczna niektórych leków pochodnych steroidów i azoli.

Radiochemical stability of three fluorine containing therapeutic substances: dexamethasone, fludrocortisone acetate (steroid derivatives) and fluconazole (azole derivative) has been studied. The compounds in the solid phase were exposed to ionising radiation in the form of electron beam using doses of 20-400 kGy. The inital and irradiated compounds were subjected to comparative analyses by organoleptic, spectrophotometric (UV and IR) and chromatographic (TLC and HPLC) methods. For all compounds studied the irradiation was found to lead to a decrease in the active substance content (HPLC), appearance of radiolysis products (TLC), changes in the physical and chemical properties such as colour (fluconazole), formation of agglomerates (dexamethasone), decrease (dexamethasone, fludrocortisone acetate) or increase in UV absorption (fluconazole). The two steroid derivatives were found resistant to ionising radiation at doses of 25-50 kGy and can be sterilised by radiation, whereas fluconazole was too sensitive to electron beam irradiation and should be sterilised by other methods. The results were compared with those of earlier studies on radiation sterilisation of other steroid derivatives. An interesting conclusion is that the presence of the fluorine atom in the molecule of fludrocortisone acetate has no significant effect on its radiochemical stability when compared with that of hydrocortisone acetate--the analogue without fluorine.