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Summary
Ezetimibe is the first in a new class of antihypercholesterolemic drugs. Since it has not long been available on the market, many of its properties may still be revealed. Analytical methods for its determination are scarce, especially regarding serum samples. A simple, fast, and effective high-performance liquid chromatography-ultraviolet (HPLC-UV) method for the determination of ezetimibe concentration in human serum has therefore been developed. Three mobile phases were analysed, and original modifications to the concentration and flow parameters were made. Of five potential internal standards (IS), only nitrendipine was found to be suitable. The analytical wavelength was chosen based on the absorption spectrum of ezetimibe in the mobile phase. Finally, an extraction analysis was performed using two different solvents, and the extrahent volume was optimised. The final method developed was as follows. Single extraction of 1 mL serum sample, spiked with IS, was performed using 10 mL of methyl-t-butyl ether. Separation was obtained at ambient temperature on a Waters C18 Symmetry Shield (4.6 mm × 250 mm, 5 μm) column. The isocratic mobile phase was composed of acetonitrile and 0.1 M ammonium acetate aqueous solution 55:45 (v/v), set at flow rate of 0.75 mL min−1. Ezetimibe was detected at a wavelength of 232 nm after 5.49 min, and the IS was detected at 8.05 min. The developed method has been validated according to ICH standards. It was found to be specific, precise, accurate and linear over the range 10–800 ng mL−1 with R 2 > 0.998, and detection and quantification limits of 4.60 ng mL−1 and 13.94 ng mL−1, respectively. The method has been applied to clinical serum samples. The developed technique allowed for successful in vivo assessment of ezetimibe concentrations in samples obtained from hypercholesterolemia patients who are chronically receiving the drug.
proportionality with respect to maximal plasma concentrations and area under the plasma concentration–time curve was demonstrated across a dose range of 300 to 900 mg twice daily, with 600-mg twice daily being recommended for further phase 2 studies on the basis
during the freezing process and it results in the concentration of components, that leads to the accumulation of low-density lipoproteins in plasma ( Zhao et al., 2021 ). Au and his co-authors examined the effect of freezing at –20 °C and frozen storage
mortality in Philadelphia associated with daily air pollution concentrations. Am. Rev. Respir. Dis., 1992, 145 , 600–604. Dockery D. W. Increased mortality in Philadelphia associated with
, leaving room for further biosynthesis of bioactive compounds. Various strategies have been developed to increase the concentration of bioactive compounds during post-harvest storage. Among them, artificial lighting treatments using ultraviolet light (UV
[ 1 ]. Lutein is found in a number of human tissues but the highest concentration of these carotenoids (0.1–1 mM) is found in the human retina [ 2 ]. In the human eye, lutein and zeaxanthin are specifically located at the center of the retina
framework of the research procedure for this review paper is presented in Fig. 2 . This information can help the researchers to learn the scope of concentration. Fig. 2. A framework of the search procedure in this review paper The keywords are chosen by two
we found significantly elevated PACAP concentrations in the colostrum samples compared to transitional and mature milk [ 9–11 ]. PACAP is present in the milk whey of small ruminants at concentrations 5–20 times higher than in the plasma, and does not
pathogenic bacteria surviving in the intestine, depending on the sensitivity to glyphosate. Regarding a ruminal setting, these findings could not be confirmed [ 19 ]. Shehata et al. [ 20 ] determined differing minimum inhibitory concentrations (MIC) for
is the most hydrophobic between them [ 6 ]. The determination of drug concentrations in plasma or other biological samples through liquid chromatography coupled with mass spectrometry (LC-MS/MS) methods is now considered a technological
