A New, Rapid, Fully Automated Method for Determination of Fluconazole in Serum by Column-Switching Liquid Chromatography

Dispersive liquid-liquid microextraction followed by green high-performance liquid chromatography for fluconazole determination in cerebrospinal fluid with the aid of chemometric tools

A new method, simple and fast, for fluconazole (FLU) quantification in cerebrospinal fluid (CSF) samples using dispersive liquid-liquid microextraction (DLLME) and an eco-friendly mobile phase for HPLC-PDA was developed. The study of DLLME extraction condition covered the investigation of 12 combinations of extraction and disperser solvents followed by a fractional factorial design 2(7-3) to determine the influence of seven factors. After this stage, a central composite design was performed for three factors and a response surface was obtained. Aiming a compromise between a good recovery and a low organic solvent use it was established an extraction condition that consists of: 100 μL of chloroform, 100 μL of isopropyl alcohol, 200 μL of CSF, 200 μL of 50 mM phosphate buffer pH 7.3 and centrifugation for 5 min at 2200g and 4 °C. The HPLC analysis used an Ascentis® Express C18 column (100 mm × 4.6 mm, 2.7 μm) and an Ascentis® Express C18 guard column (3 mm × 4.6 mm, 2.7 μm), ethanol : water (15 : 85, v/v) as mobile phase, temperature of 45 °C, flow rate of 0.8 mL min-1 and phenacetin as internal standard. The method validation was performed according to European Agency's Guideline on Bioanalytical Validation Methodology and a linear range was obtained from 0.25 to 62.5 μg mL-1, with precision and accuracy within the recommended limits and recovery of 70% for FLU and 81% for phenacetin. Samples were stable in the studies performed and the method showed to be selective and with no carryover effect. The feasibility of the obtained method was confirmed by FLU determination at a CSF from a patient who was treated for neuromycosis. Therefore, here is described a method that meets many principles of green analytical chemistry and is useful for FLU therapeutic monitoring.

A rapid and sensitive LC-MS/MS method for determination of fluconazole in human plasma and its application in infants with Candida infections

A rapid and sensitive LC-MS/MS method was developed to quantify fluconazole in human plasma. Seventy microliters of plasma were treated with protein precipitation procedures. Chromatographic separation was achieved on a C18 column using a gradient mobile phase of acetonitrile and water in 0.1% formic acid. Fluconazole and its deuterium-labeled internal standard were monitored in positive mode using electrospray ionization source. The method was fully validated over the range of 0.01 to 10 microg/mL. Intraday and interday precision ranged from 2.84% to 10.8% and 5.27% to 11.5%, respectively. The process recovery efficiency for fluconazole ranged from 98.6% to 104.4%. No carryover and minimal matrix effects were observed. Acceptable stability of fluconazole in blood at room temperature for up to 72 hours guaranteed that fluconazole concentrations in scavenged blood specimens were usable for infant PK analysis and model development. This method has been utilized for a fluconazole pharmacokinetic trial with 55 preterm and term infants younger than 90 days of age. The fast sample preparation cycle and lower limit of quantitation make this method a potential tool for therapeutic drug monitoring of fluconazole to optimize pediatric antifungal therapy. Optimal dose regimen of fluconazole in neonates and young infants might be achieved with application of TDM and pharmacometric approach designed to achieve AUC/MIC >50 for most Candida species with a MIC90 less than 8 microg/mL.

Use of trifluoroacetic acid to quantify small, polar compounds in rat plasma during discovery-phase pharmacokinetic evaluation

Although it is accepted that trifluoroacetic acid (TFA) can cause suppression of an analyte during LC/MS analysis, this paper presents a relatively sensitive gradient method that uses a TFA mobile phase for the improved quantification of small, polar drug-like compounds. The described method was developed in a discovery drug metabolism and pharmacokinetics (DMPK) laboratory for the screening measurement of compound concentrations to calculate PK parameters and CNS exposure of compounds from a chemical series that had poor chromatography under generic methods using formic acid mobile phase. The samples were collected by a Culex automated sampling unit, and the plasma proteins were precipitated by a Tecan robot in 96-well plates. After centrifugation, the supernatant was removed, dried down using a SPE-Dry unit, and the samples were reconstituted in aqueous buffer on the robot. The samples were analyzed on an Agilent LC/MSD using a 5-min gradient on a 5 cm phenyl column. No additional steps, such as the "TFA-fix", were necessary. Although sample batches were analyzed over 6h, no drift or degradation of signal was observed. The improved chromatography resulted in a method that was selective, rugged, and had a dynamic range from 5 to 20,000 nM, which was sufficient to quantitate low volume, serial plasma samples collected out to 8 h postdose.

An optimized analytical method of fluconazole in human plasma by high-performance liquid chromatography with ultraviolet detection and its application to a bioequivalence study

A sensitive and accurate HPLC-UV method for the quantification of fluconazole (FLA) level in human plasma has been developed. The sample was prepared by one-step liquid-liquid extraction (LLE) of FLA from plasma using dichloromethane. Phenacetin was used as the internal standard. The chromatographic retention times of FLA and phenacetin were 4.6 and 8.3 min, respectively. The lower limit of quantitation (LLOQ) was 0.05 microg/mL, and no interferences were detected in the chromatograms. The devised HPLC-UV method was validated by evaluating its intra- and inter-day precisions and accuracies in a linear concentration range between 0.05 and 10.00 microg/mL. The devised method was successfully applied to a bioequivalence studies involving the oral administration of a single 150 mg FLA tablet and 3 x 50 mg FLA capsules in healthy Korean male volunteers.

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.