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جستجوی مقالات مرتبط با کلیدواژه "chiral separation" در نشریات گروه "پزشکی"

جستجوی chiral separation در مقالات مجلات علمی
  • Anita Sarkany, Gabriel Hancu*, Claudiu Drăguț, Adriana Modroiu, Enikő Barabás Hajdu

    Tramadol is a widely used opioid analgesic frequently prescribed for treatment of moderate to severe, acute and chronic pain. It has a complex mechanism of action, acting both as a central opiate agonist and as a norepinephrine and serotonin reuptake inhibitor. It is a chiral substance, having two chiral centers in its structure and it is used in therapy as a racemic mixture of two of its enantiomers, (S,S)-tramadol and (R,R)-tramadol. In the last 25 years, several analytical procedures have been published in the literature for the achiral and chiral determination of tramadol from pharmaceutical formulations and biological matrices. Among these methods, capillary electrophoresis techniques have proved to be an efficient, reliable and cost-effective solution. The purpose of the present review is to provide a systematic survey to present and discuss the electrodriven methods available in the literature for the achiral and chiral analysis of tramadol.

    Keywords: Tramadol, Capillary electrophoresis, Chiral separation, Pharmaceutical analysis
  • Alireza Shafaati *, Afshin Zarghi, Farrin Sattary Javid
    A common approach in resolving enantiomers of chiral basic drugs by capillary electrophoresis (CE) is to use cyclodextrins (especially their anionic derivatives) as chiral selector in the acidic buffer (pH ≤ 3) in normal or reversed (carrier) mode. Then, some organic modifiers are added to the buffer solution if the resolution is not satisfactory. In case of cetirizine (CTN), applying the same approach, i.e. a reversed mode capillary zone electrophoresis (CZE) method with an acidic buffer and sulfated-b-cyclodextrine (S-bCD) as chiral selector, was failed and no complete enantioseparation was achieved. Different organic modifiers, like urea and triethylamine HCl, were used to improve chiral resolution which led to partial resolution of the two peaks. Then, guanidine HCl at a concnetration of 100 mM was added to the running buffer and an acceptable resolution of the enantiomers of the drug was obtained. The method was successfully applied to determine optical purity of a levo-cetirizine (l-CTN) sample.
    Keywords: Cetirizine, Chiral separation, Capillary electrophoresis, Guanidine HCl, Sulfated ?, Cyclodextrin
  • Taher Alizadeh *
    A new chromatographic procedure was proposed for the separation of propranolol (PRN) enantiomers based upon enantioselective chiral ligand-exchange chromatography. The separation was carried out on a short C8 column leading to considerably short separation time. L-alanine and Cu2 were applied as chiral selector and central bivalent complexing ion, respectively. It was found that the kind of copper salt could influence the enantioseparation efficiency. The separation on the C8 stationary phase was more efficient than that on the C18 column. It was shown that the pH of mobile phase, organic modifier content of mobile phase, mole ratio of chiral ligand to bivalent ion and Cu(L-alanine)2 concentration in the mobile phase were important in enantioseparation efficiency. Water/methanol (70:30) mixture containing L-alanine-Cu2 (7:1) was found to be the best mobile phase condition for PRN enantioseparation. All effective parameters were optimized in order to improve the separation efficiency. The optimized HPLC method was utilized for analysis of propranolol enantiomers in spiked human blood plasma samples.
    Keywords: L-alanine, Chiral separation, Propranolol, C8 column, Ligand exchange
  • Gabriel Hancu*, Monica Budau, Lajos Kristof Kantor, Anca Carje
    Purpose
    Amlodipine is a long acting, dihydropyridine type calcium channel blocker frequently used in the treatment of hypertension and coronary insufficiency. The calcium channel blocking activity resides primarily in the S-amlodipine enantiomer, while R-amlodipine is a potent inhibitor of smooth muscle cell migration.
    Methods
    In this study capillary electrophoresis was applied for the enantiomeric separation of amlodipine using different native and derivatized; neutral and charged cyclodextrines as chiral selectors. The effects of pH and composition of the background electrolyte, concentration and type of chiral selector, capillary temperature, running voltage and injection parameters have been investigated.
    Results
    Stereoselective interactions were observed when using α-CD, β-CD, HP-β-CD, RAMEB, CM-β-CD and SBE-β-CD. Optimized separation conditions consisted on a 50 mM phosphate buffer, pH – 3.0, 20 mM RAMEB as chiral selector, + 25 kV applied voltage, 15°C temperature and UV detection at 238 nm. Using the optimized electrophoretic conditions we succeeded the chiral separation of amlodipine enantiomers in approximately 6 minute, the order of migration being R-amlodipine followed by S-amlodipine. The method was successfully applied for the determination of amlodipine enantiomers from commercially available pharmaceuticals. The linearity range, limits of detection and quantification, precision and accuracy were determined and the results obtained confirmed that the method was suitable for this purpose.
    Conclusion
    It can be concluded that the proposed capillary electrophoresis methods can be useful for routine pharmaceutical applications with benefits of its effectivity, simplicity, short analysis time and low consumption of analytes, solvents and chiral selectors.
    Keywords: Amlodipine, Capillary electrophoresis, Chiral Separation, Cyclodextrines
  • Amelia Tero, Vescan, Gabriel Hancu*, Mihaela Oroian, Anca CÂrje
    Purpose
    Indapamide is probably the most frequently prescribed diuretic drug, generally being used for the treatment of hypertension. It contains a chiral center in its molecule; is marketed as a racemic mixture; but there are rather few studies regarding the pharmacokinetic and the pharmacological effect differences of the two enantiomers. Our aim was the development of a simple, rapid and precise analytical procedure for the chiral separation of indapamide enantiomers.
    Methods
    In this study capillary zone electrophoresis was used for the enantiomeric separation of indapamide using a systematic screening approach involving different native and derivatized; neutral and charged cyclodextrines as chiral selectors. The effects of pH value and composition of the background electrolyte, capillary temperature, running voltage and injection parameters have been investigated.
    Results
    After preliminary analysis a charged derivatized CD, sulfobuthyl ether- β-CD, proved to be the optimum chiral selector for the enantioseparation. Using a buffer solution containing 25 mM disodium hydrogenophosphate – 25 mM sodium didydrogenophosphate and 5 mM sulfobuthyl ether- β-CD as chiral selector at a pH - 7, a voltage of + 25 kV, temperature 15°C and UV detection at 242 nm, we succeeded in the separation of the two enantiomers in approximately 6 minutes, with a resolution of 4.30 and a separation factor of 1.08.
    Conclusion
    Capillary zone electrophoresis using cyclodextrines as chiral selectors proved to be a suitable method for the enantioseparation of indapamide. Our method is rapid, specific, reliable, and cost-effective and can be proposed for laboratories performing indapamide routine analysis.
    Keywords: Indapamide, Capillary electrophoresis, Chiral separation, Cyclodextrines
  • Farrin Sattary Javid, Alireza Shafaati, Afshin Zarghi
    One of the problems encountered in CE separations of basic compounds is the adsorption of analytes onto the negatively charged capillary wall which could lead to poor repeatability of migration time and peak area. Additionally, separation of enantiomers of chiral of basic drugs is commonly carried out in low pH buffer which contributes to strong ionic interaction of the cationic drug ions with negatively charged chiral selectors. The two phenomena results in poor enantioseparations. To overcome the problems associated with chiral separations of basic drugs by CE, the effect of guanidine (GU) on the improvement of chiral separation of a model basic drug, fluoxetine (FLX), was investigated. In the present study, GU was used as a cationic additive to the running buffer containing a chiral selector, sulfated beta cyclodextrine. Better results obtained with GU as the buffer additive in enantioseparation of FLX.
    Keywords: Capillary electrophoresis, Chiral separation, Fluoxetine, Guanidine
نکته
  • نتایج بر اساس تاریخ انتشار مرتب شده‌اند.
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