Gas chromatographic method for the determination of nomifensine in human plasma.

An analytical method based on solvent extraction, formation of a fluorinated derivative and quantitation by gas-liquid chromatography using an electron capture detector has been developed for the determination of nomifensine in biological fluids. The specificity (controlled by mass spectrometry) and the sensitivity appear to be satisfactory for drug level measurements in human body fluids. Its relative simplicity in fact permits its use in serial analysis.     

Gas chromatographic determination of xanthinol in plasma

The determination of xanthinol in plasma is described. After extraction of the drug, together with the internal standard (papaverine hydrochloride), the extract is evaporated to dryness and the drug is derivatized with acetic anhydride for chromatography. The method is linear for 2–100μg ml^-1 ; the coefficient of variation is 3% and the recovery 80%. The resulting stable solution allows large numbers of samples to be processed with an automatic injector.     

Gas chromatographic determination of propyphenazone in plasma

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Combined immunological and thin-layer chromatographic method of the determination of morphine

     

High-performance liquid chromatographic method for the determination of mangiferin in rat plasma and urine

A reversed-phase high-performance liquid chromatography assay for mangiferin in rat plasma and urine was developed. Rutin was employed as an internal standard. The mobile phase consisted of acetonitrile-water (16:84, v/v) containing 3% acetic acid at a flow rate of 1 mL/min. Detection was at 257 and 365 nm for mangiferin in plasma and urine, respectively. The limit of quantitation (LOQ) of mangiferin was 0.6 microg/mL in plasma, and 0.48 microg/mL in urine. The standard curve was linear from 0.6 to 24 microg/mL in plasma, and 0.48 to 24 microg/mL in urine, both intra- and inter-day precision of the mangiferin were determined and their RSD did not exceed 10%. The method provides a technique for rapid analysis of mangiferin in rat plasma and urine, which can be used in pharmacokinetic studies.     

Determination of a platelet activating factor antagonist (CV-3988): methodology and clinical application

A high-performance liquid chromatographic method was developed for determination of the platelet activating factor antagonist CV-3988 in human plasma and urine. After development of a column extraction procedure without an internal standard, a more satisfactory organic extraction procedure was set up with amiodarone as internal standard. Linearity of the calibration curves was found in the range 0.0625-10 micrograms/ml CV-3988. Reproducibility was higher than 10% for the column extraction and lower than 10% for the organic extraction procedure. Recovery of CV-3988 from plasma averaged 81.7% for the column procedure and 40% for the organic extraction. Urine samples could be extracted only by the organic extraction procedure. The organic extraction procedure was applied to the determination of CV-3988 in plasma and urine samples after intravenous administration to normal volunteers.     

Gas chromatographic method for determination of a piperazine derivative (Trelibet) and its metabolites in human plasma and urine

A sensitive gas chromatographic method was developed for the determination of Trelibet, 1-benzyl-4-(2'-pyridinecarbonyl)piperazine, and of its major metabolites in biological fluids. The compounds were extracted as bases into dichloromethane, and the extracts were analysed by a dimethylsilicone capillary column with a nitrogen-phosphorus flame-ionization detector. The lower limit of detection was 1 ng/ml for Trelibet and 5 ng/ml for the metabolites. Peak-area ratios of the compounds and internal standard were linearly correlated to their plasma concentrations between 1 and 1000 ng/ml. The method was used for quantification of Trelibet and two of its metabolites in depressed patients after oral administration of a single dose of 200 mg of Trelibet. Concentration data measured in plasma and urine showed that the method is sensitive enough to monitor concentrations both for pharmacokinetic studies and for plasma steady-state levels daily.     

High-performance liquid chromatographic method for the simultaneous determination of R-(-)- and S-(+)-hexobarbital in rat plasma

The enantiospecific determination of R- and S-hexobarbital in rat plasma is described. The method involves liquid-liquid extraction of racemic hexobarbital from plasma, separation of the underivatized enantiomers by high-performance liquid chromatography on an alpha 1-acid glycoprotein column and ultraviolet detection. The mobile phase consists of a phosphate buffer (pH 5.4) containing 0.4% 2-propanol as organic modifier. An alpha 1-acid glycoprotein guard column is used to increase the lifetime of the analytical column. Heptabarbital is the achiral internal standard. With detection limits of ca. 0.05 microgram/ml for both R- and S-hexobarbital, the assay is suitable for pharmacokinetic studies of the enantiomers in rats.     

High-performance liquid chromatographic method for simultaneous determination of honokiol and magnolol in rat plasma

A high-performance liquid chromatographic (HPLC) method is described for the simultaneous determination of honokiol and magnolol in rat plasma. The plasma was deproteinized with acetonitrile which contained an internal standard (diphenyl) and was separated from the aqueous layer by adding sodium chloride. Honokiol and magnolol are extracted into the acetonitrile layer with high yield, and determined by reversed-phase HPLC and ultraviolet detection. The limits of quantitation for honokiol and magnolol were 13 and 25 ng ml⁻¹ in plasma, respectively, and recovery of both analytes was greater than 93%. The assay was linear from 20 to 200 ng ml⁻¹ for honokiol and from 40 to 400 ng ml⁻¹ for magnolol. Variation over the range of the standard curve was less than 15%. The method was used to determine the concentration-time profiles of honokiol and magnolol in the plasma following rectal administration of Houpo extract at a dose of 245 mg kg⁻¹, equivalent to 13.5, 24.4 mg kg⁻¹ of honokiol and magnolol, respectively.     

Formation of spherical micelles by the novel platelet activating factor receptor antagonist, E5880

E5880, a novel platelet activating factor receptor antagonist, was dispersed in water for the preparation of injectable formulation and the physicochemical properties of the micelles were characterized. The critical concentration for formation of micelles was 0.12 mM. Using the area per molecule results, the critical packing parameter was calculated and showed that the structure was composed of spherical micelles and the number of the molecules per micelle was 88. The diameter of a micelle was 8.1 nm. The fluidity and micropolarity around the hydrocarbon region of the micelles were evaluated and compared to the surfactants, stearyltrimethylammmonium chloride and cetyltrimethylammonium chloride.     

High-performance liquid chromatographic method for simultaneous determination of sophoridine and matrine in rat plasma

A high-performance liquid chromatographic (HPLC) method is described for the simultaneous determination of sophoridine and matrine in rat plasma. Sophoridine and matrine in the resulting supernatant of the plasma deproteinized with acetonitrile containing an internal standard (acetanilide) were directly determined by reversed-phase HPLC and ultraviolet detection. The result of limits of quantitation for matrine and sophoridine were 200 and 350 ng/mL in plasma, respectively, and recovery of both analytes was greater than 98%. The assay was linear from 250 to 4000 ng/mL for matrine and from 500 to 8000 ng/mL for sophoridine. Variation over the range of the standard curve was less than 15%. The method was used to determine the concentration-time profiles of matrine and sophoridine in the plasma following oral administration of Kexieling tablets, which is one of the preparations of Kudouzi at a dose equivalent to 30 and 60 mg/kg of matrine and sophoridine, respectively.     

Development and validation of GC/MS method for determination of pramipexole in rat plasma

A simple, rapid and sensitive method has been developed and validated for the determination of pramipexole in rat plasma by using gas chromatography mass spectrometry. The lower limit of quantification (LLOQ) is superior to the other reported LC‐MS/MS methods. After being made alkaline with NaOH, plasma samples (0.1 mL) were subjected to liquid–liquid exteraction using methyl‐t‐butyl ether. Analytes were determined using electron impact ionization in a single quadrupole mass spectrometer. GC/MS was performed in the selected ion monitoring mode using target ions at m/z 211, 212 and 152 for pramipexole and m/z 194 and 165 for caffeine as internal standard. A linear calibration curve was plotted over the range of 20–1000 pg/mL for pramipexole (r² > 0.996). The LLOQ was 20.0 pg/mL, respectively, which offered high sensitivity and selectivity enough for bioanalytical investigation. Inter‐ and intraday precisions ranged from 0.3 to 8.8% and from 0.9 to 11.33%, respectively. The recovery of pramipexole from plasma ranged from 82.4 ± 7.1 to 87.8 ± 5.7%. The method fulfills all standards required for bioanalytical methods and can be successfully applied to a pharmacokinetic study of pramipexole in rats. Copyright © 2010 John Wiley & Sons, Ltd.     

Gas chromatographic determination of guanadrel in plasma and urine

To evaluate the pharmacokinetics and drug availability from various dosage formulations, a method for the determination of guanadrel, (1,4-dioxaspiro[4,5]dec-2-ylmethyl)guanidine, in plasma and urine was required. A gas chromatographic procedure, based on formation of a hexafluoroacetylacetone derivative in a two-phase system of water and toluene, was developed. The limit of determination of the method is 5 ng/ml guanadrel in plasma and 15 ng/ml guanadrel in urine. Statistical analyses indicate average recoveries of 98.1 +/- 18.0 and 104.4 +/- 15.6% from plasma and urine, respectively. Mass spectrometric analyses, in conjunction with gas chromatography, confirmed the specificity of the method for intact drug. The procedure was applied successfully to drug absorption studies in humans.     

Gas chromatographic determination of two isosorbide mononitrates in plasma

A GC/EC method has been developed for the determination of 2-isosorbide mononitrate (2-ISMN) and 5-isosorbide mononitrate (5-ISMN) in blood plasma. The procedure is based on extraction of ammonium sulfate-treated plasma with ether followed by a cleanup via n-heptane/methanol partitioning. After conversion to t-butyldimethylsilyl ethers, the ISMNs are chromatographed on a 3% OV-17 column. Absolute recoveries of 76.7 and 84.8% were achieved for 2-ISMN and 5-ISMN, respectively. Using o-nitrobenzyl alcohol as an internal standard, relative standard deviations of 4.8 to 6.1% were observed over the concentration ranges of 10 to 100 ng/ml for 2-ISMN and 250 to 1500 ng/ml for 5-ISMN.