Wyniki wyszukiwania - BazTech

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Development of a rapid LC-MS/MS assay to determine letrozole in human plasma and its application in a pharmacokinetic study after oral administration

Li Pengfei, Zhang Xi, Wang Shumin, Wang Jing, Liu Ziqi, Wang Chen, Tong Weihang, Liu Lihong

Acta Chromatographica

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2022

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Vol. 34, no. 2

179--184

EN

Letrozole is one of the third generation aromatase inhibitors. It is suitable for the treatment of postmenopausal patients with advanced breast cancer and early treatment of breast cancer. It is necessary to develop a rapid, reliable, selective and sensitive LC–MS/MS assay to determine letrozole in human plasma to evaluate the clinical efficacy and adverse reactions with clinical pharmacokinetic and therapeutic drug monitoring. Separation was carried out on a Kromasil-C18 column using acetonitrile-water (55: 45, v/v) as mobile phase. Detection was carried out by multiple reaction monitoring on a 3200Qtrap mass spectrometry. The method needed one-step protein precipitation procedure only, and the cycle time was 2.5 min allowing 500–550 samples per day. It was linear within 0.30–50.00 ng/mL for plasma with the limit of detection (LOD) of 0.030 ng/mL. The intra- and inter-day RSD were 5.51–8.63%, 2.28–9.95% and the RE was 0.18–1.65%. The recovery rates of letrozole and internal standard for plasma were 89.30–98.55%. Letrozole was stable under all the conditions in the study. The method was sensitive enough to quantitate letrozole over a period of 288 h after giving a single oral dose of 2.5 mg–24 Chinese healthy volunteers. The absorption of letrozole was rapid with small individual difference, the tissue distribution of letrozole was more than that in blood, and the clearance was slow. Letrozole was similar to three-compartment model in vivo. Due to metabolism and excretion, the AUCs of letrozole varied greatly among individuals.

2

RP-HPLC–UV method for the quantification of propranolol in rat's serum and krebs buffer using one-step protein precipitation

Al Shaker H., Qinna Nidal A., Hroub H., Omari M. M. H., Adnan A.

Acta Chromatographica

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2018

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Vol. 30, no. 3

147--152

EN

Krebs buffer is considered one of the most used physiological buffers in biomedical research. In the current work, a rapid reversed-phase high-performance liquid chromatographic (RP-HPLC) method with ultraviolet (UV) detection at 214 nm was developed and validated according to European Medicines Evaluation Agency (EMEA) guidelines for the determination and quantification of propranolol in Sprague–Dawley rat's serum and in Krebs buffer. This method can be applied for both in vivo and in vitro studies with short run time of 7.0 min . Isocratic elution with a flow rate of 1.0 mL/min was employed. BDS Hypersil C-18 column (150 mm × 4.6 mm and 5 μm) was used to obtain satisfactory resolution. The mobile phase used contained a mixture of acetonitrile, methanol, and triethylammonium phosphate solution (15.0:32.5:52.5, v/v). Best separation between propranolol and the internal standard (I. S.) sildenafil was obtained at 4.2 and 5.5 min, respectively. Propranolol was linear over a concentration range of 50.00–3000 ng/mL with acceptable accuracy, and intra- and inter-day precision. Dilution integrity was assessed and was found to be within the acceptable range for both serum and Krebs buffer. Sample stability tests were studied at different storage conditions, and all the analytes were found to be stable. The mean percentage of recovery of propranolol was found to be 97.06% and 98.57% for serum and Krebs buffer, respective.

3

A Simple Liquid Chromatographic Method for the Determination of Tenofovir in Rat Plasma and Its Application to Pharmacokinetic Studies

Ravi P. R., Joseph S., Avula U. S. R., Anthireddy S.

Acta Chromatographica

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2015

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Vol. 27, no. 4

597--612

EN

The objective of this study was to develop and validate a novel, simple, and selective high-performance liquid chromatographic (HPLC) method with photodiode array detector for the estimation of tenofovir in rat plasma, which can be utilized in analyzing the pharmacokinetic samples from rats. Prior to analysis, an optimized protein precipitation technique was used to extract tenofovir from plasma. The mobile phase for this method comprised of 10 mM ammonium acetate buffer (pH 4) and methanol in the ratio of 97:3 υ/υ. Chromatographic separation of tenofovir was achieved using Spincotech C-18G enabled column (250 × 4.6 mm, 5 μm). Tenofovir was monitored at a wavelength of 260 nm, and the calibration curve was linear in the range of 250–4000 ng mL−1 (R2 = 0.999). High recovery obtained after extraction (97%–101%) of plasma samples precluded the use of an internal standard. Validation studies were performed as per the standard guidelines, and the developed method was accurate, precise, and selective for the determination of tenofovir in the rat plasma. The stability studies performed during the sample pretreatment process and sample storage conditions did not show a quantifiable degradation of tenofovir. Further, this method was able to estimate tenofovir and determine its pharmacokinetic parameters, post IV bolus administration in male Wistar rats. The pharmacokinetic profile of tenofovir followed one compartmental open model.

4

Techniki chromatograficzne stosowane w oczyszczaniu białek. Cz. 1, Izolacja i wstępne frakcjonowanie białek

Błaszczyk U.

Laboratorium - Przegląd Ogólnopolski

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2009

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nr 7-8

42--45

PL

Izolacja i oczyszczanie są niezbędnymi etapami na drodze do poznania struktury, sposobu działania czy funkcji biologicznej badanego białka. Rozwój technik chromatograficznych wykorzystywanych w separacji biocząsteczek przyczynił się do postępu w biochemii i biotechnologii. W celu uzyskania pożądanego poziomu czystości produktu końcowego, większość procedur oczyszczania składa się kilku etapów.

EN

Protein isolation and purification are essential steps to the characteristics of the structure, mode of action and biological function of the protein of interest. The development of chromatographic techniques used in biomolecule separation has contributed to the advances made in biochemistry and biotechnology. Most purification procedures require more than one step to achieve the desired level of the final product purity.