基于聚酰胺6纳米纤维膜的固相萃取-高效液相色谱法测定兔血浆中酮康唑对映体

以基于聚酰胺6纳米纤维膜的固相萃取法,结合高效液相色谱手性流动相添加剂法测定了兔血浆中的酮康唑对映体的浓度。仅用1.5mg聚酰胺6纳米纤维膜、100μL甲醇即可完成目标物的富集和洗脱。酮康唑的2个对映体在50.0～400.0μg/L范围内呈良好的线性;方法的定量限为40.0μg/L;日内和日间精密度分别小于6.3%和8.6%;平均绝对回收率为79.4%～85.6%;平均相对回收率为90.0%～96.5%。本方法灵敏、准确、重现性好,符合生物样本中酮康唑对映体分析测定的要求。     

Preparation and Characterization of Bhant Leaves‐derived Nitrogen‐doped Carbon and its Use as an Electrocatalyst for Detecting Ketoconazole

In this study, the electrocatalytic characteristics of nitrogen‐doped carbon (NDC) prepared from Clerodendrum Infortunatum L leaves on a glassy carbon electrode (GCE) surface was evaluated with regards to its ability to detect the electroactive drug ketoconazole (KCZ). The NDC was prepared by carrying out a simple pyrolysis of dry powder of the leaves at 850 °C. The prepared NDC was characterized using field‐emission scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, X‐ray photoelectron spectroscopy and Brunauer‐Emmett‐Teller analysis, and was then used as an electrode material. The performance of the electrochemical KCZ sensor with the NDC‐modified glassy carbon electrode (NDC/GCE) was found to be optimal when using PBS buffer at pH 3 and a concentration of 0.1 mg/ml of NDC in the conjugate with Nafion polymer. Under these conditions, the NDC/GCE displayed a KCZ detection limit of 3 μM and a linear dependence of its response on KCZ concentration over a wide range of KCZ concentrations from 47 μM to 752 μM (R²=0.9742). These results confirmed the potential of NDC as an electrocatalyst.     

Electrooxidation of Some Antifungal Agents and Their Square-Wave Voltammetric Determination in Cosmetics and Pharmaceutics

Ketoconazole and methylparaben were electrochemically studied using cyclic and square wave voltammetric (SWV) techniques at glassy carbon electrode. The oxidation of methylparaben and ketoconazole—the mechanism under scrutiny in this study—was characterized by irreversibility and the features of a pH-dependent diffusion controlled process. Optimal conditions for the electrochemical behavior of methylparaben and ketoconazole were investigated [e.g., potential window, supporting electrolyte and potential scan rates, the dependence of current intensities and potentials on pH, the linear relationship between the peak current and the concentration, limit of detection (LOD), limit of quantification (LOQ), recovery, and accuracy]. The proposed procedures were used for the determination of studied substances in cosmetic and pharmaceutical samples for methylparaben and ketoconazole, respectively. The current-concentration plot for methylparaben was linear over the range from 1 · 10^?5 to 2.02 · 10^?4 mol L^?1 in 0.1 mol L^?1 HClO₄. The linear response for ketoconazole was obtained in the range of 3.2 · 10^?7–9.58 · 10^?6 mol L^?1 in NH₃-NH₄Cl buffer at pH 9. The repeatability and reproducibility of the methods for the studied substances were also determined. Furthermore, results obtained by the proposed methods have been compared with high-performance liquid chromatographic methods.     

Performance and reliability of splitless microliter gradient pumps in a metabolic stability study using cytochrome P450/3A4 and capillary liquid chromatography-mass spectrometry

The performance of two commercially available capillary LC pumps (MicroPro (Eldex, USA), Evolution 200 (ProLab, Switzerland)) generating really splitless gradients in the microliter per minute range was tested in detail concerning their applicability for routine drug discovery. A standard method to study metabolic stability against CYP450 isoform 3A4 was selected. This method was transformed into a fast splitless capillary LC-MS method. Both pumps generated reproducible gradients at flows of 5-10 microl/min within 10-15 min. Although gradient formation of the MicroPro system was very reproducible, its equilibration time was too long for fast gradients around 5 microl/min. The Evolution 200 pump offered a good performance with 180 microm i.d. columns at a flow rate of 6 microl/min. The precision of the retention time of the internal standard (ISTD) varied between 1.4 and 3.4% (n = 131-152, three different columns tested). Up to 800 injections of sufficient performance on one column and a stable enough response of the ISTD for 16 h sequence duration were obtained. Accuracy between 95 and 105% and precision < or = 8.4% for 1'-hydroxylated midozolam were reached. The IC50 values of the miniaturized assay (drug candidate BAL4815 1.7 +/- 0.5, itraconazole 0.46 +/- 0.06, and ketoconazole 0.12 +/- 0.01 microM) agreed well with those of the conventional approach. Details concerning method optimization and limitations in operation are discussed in detail. Still, the overall performance of the capillary LC pumps cannot cope completely with that of conventional HPLC pumps in terms of user-friendliness.     

D1-Differential Potentiometric and 1H-NMR Spectrometric Determinations of Ketoconazole and its Formulations

Abstract

Two rapid and direct quantitative assays have been investigated for ketoconazole alone and in tablet form. the first one is a non-aqueous potentiometric titration in which the equivalence point has been located graphically using its distinct and sharp D₁differential (peak-shape) potentiograph. the second is based on ₁H-NMR spectrometry and involves the integration of the methyl protons-signal of ketoconazole (at 2.07 δ) relative to that of benzocaine (at 1.30 δ) which is used as internal standard. the obtained results were in good agreement with regard to accuracy, precision as well as sensitivity and reproducibility. However, by comparison with the official USP procedure, the two methods were significantly more accurate and more sensitive. the validity of the two methods were confirmed using the authentic addition technique.     

Enantiomeric separation of ketoconazole and terconazole antifungals by electrokinetic chromatography: Rapid quantitative analysis of ketoconazole in pharmaceutical formulations

EKC using a neutral CD as chiral selector was applied in this work to the development of a method enabling the enantiomeric separation of ketoconazole and terconazole antifungals. The influence of different experimental conditions such as temperature, CD concentration, pH, and nature and concentration of the buffer on the enantiomeric resolution of the compounds studied was investigated. The use of 10 mM heptakis-(2,3,6-tri-O-methyl)-beta-CD in a 100 mM phosphate buffer (pH 3.5) with a temperature of 15 degrees C allowed the separation of the enantiomers of ketoconazole and terconazole with high resolution (R(s) > 2.0). The rapid separation of ketoconazole enantiomers with an analysis time less than 3 min was carried out after fitting some experimental parameters. The developed method was applied to the determination of ketoconazole in different pharmaceutical formulations.     

Griseofulvin and ketoconazole solubilization by bile salts studied using fluorescence spectroscopy

The capacity of solubilization of the five physiological bile salts: cholate, deoxicholate, hiocholate, quenodeoxicholate and taurocholate were assayed on two low aqueous soluble antimicotic agents: griseofulvin and ketoconazole. The fluorescence emission of these antimicotic agents was used as tool to study their solubilization in bile salts micelle. Griseofulvin enhanced its fluorescence and shifted to the blue in the presence of bile salts micelles. The shift was dependent of the polarizability of the micelle zone where the antimicotic is located. Cholate and deoxicholate showed a good solubilization capacity for griseofulvin: 321 mol and 394 mol surfactant per mol of antimicotic, respectively. These values decreased in the presence of NaCl in agreement with a compactness of the micelle due to an electrostatic repulsion decreasing between the bile salts monomer negatively charged. The imidazole and piperazine rings present in the ketoconazole molecule give to this the capacity of fluorescence emission with two vibronic bands at 364 nm and 382 nm, respectively. The solubilization in cholate micelle induced an increase in the band at 382 nm, while deoxicholate induced the opposite effect, suggesting a strong intercation between the polar groups of ketoconazole molecule (imidazole and piperazine rings) and the OH of these bile salts. The solubilization capacities were 47 mol and 117 mol surfactant per ketoconazole mol for cholate and deoxicholate, respectively. The other bile salts assayed did not show any appreciable solubilization capacity. Ketoconazole and griseofulvin solubilized in micelles of cholate and deoxicholate were stable during the thermal recycling treatment for over 100 days.     

Separation and Kinetic‐Spectrophotometric Determination of Ketoconazole from Formulations Using SDS‐Coated Al2O3and KMnO4 in Alkaline‐SDS Micellar Medium

A kinetic method for the accurate and sensitive determination of Ketoconazole (KC) has been described. The method is based on the alkaline oxidation of KC with KMnO₄ in micellar SDS medium. At a fixed time of 8 min, the formed manganate ion is spectrophotometrically measured at 610 nm. The determination of KC by the fixed‐concentration and rate constant methods is feasible with the calibration equation obtained, but the fixed time method proves to be more applicable. The proposed method was successfully used for the quantitative determination of KC in formulations after the complete separation of KC using SDS‐coated Al₂O₃ as a suitable solid‐phase extraction system in comparison to liquid‐liquid extraction using poisonous organic solvents. Beer's law was obeyed from 0.4 to 28 μg mL^?1 and the RSD% values for tablet, cream and shampoo samples were 1.8, 1.4 and 2.3, respectively. The results obtained agreed with those obtained by the USP method.     

Determination of Ketoconazole in Plasma and Dosage Forms by High-Performance Liquid Chromatography and a Microbiological Method

Abstract

A simple and rapid high-performance liquid chromatographic (HPLC) method for the determination of ketoconazole in plasma and in tablets was developed. the method employs benzafibrate as internal standard and is sufficiently rapid and sensitive for use in pharmacokinetic studies. Separation of the drug from plasma was achieved by extraction with acetonitrile followed by a reversed phase chromatography on a μ Bondapak column using the isocratic mobile phase of methanol-water-glacial acetic acid (67.5:32:0.5). With this eluting solvent ketoconazole and the internal standard. were well separated from the components of plasma. A linear relationship was obtained between the ratio of the area under the peak of drug to that of the internal standard versus the concentration of the drug. Data comparing the microbiological assay with the HPLC procedure, which was developed, are shown. In the microbiological assay, Candida albicans, was the test organism, using the agar diffusion technique. Both methods were applied to the assay of ketoconazole in plasma and in tablets. Excellent agreement was observed between the results from the two methods.     

Induction of drought stress tolerance by ketoconazole in Catharanthus roseus is mediated by enhanced antioxidant potentials and secondary metabolite accumulation

A pot culture experiment was conducted to estimate the drought stress mitigating effect of ketoconazole (KCZ), a fungicide cum plant growth regulator, in Catharanthus roseus plants. The plants under pot culture were subjected to drought stress and drought stress with KCZ from 30 days after sowing (DAS) and regular irrigation was kept as control. Antioxidant contents and activities of antioxidant enzymes were estimated from root, stem and leaf of both control and treated plants. The alkaloid ajmalicine was extracted and estimated from the roots of control, drought stressed and KCZ treated plants. Individual and combined drought stress and KCZ treatments increased ascorbic acid, -tocopherol contents, superoxide dismutase, ascorbate peroxidase, catalase and polyphenol oxidase activities when compared to control. There was a significant enhancement in ajmalicine production under KCZ treated plants under drought stress when compared to well watered control as well as drought stressed plants. The KCZ treatment resulted in partial mitigation of drought stress by increasing the antioxidant potentials in C. roseus plants.