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ABSTRACT: Plasma protein binding of drugs may have significant effect on its pharmacodynamic, toxicological and pharmacokinetic properties, since only the free drug can pass across biological membrane and get to its specific site of action. Many drugs show a high affinity to albumin which is the most abundant plasma protein. In the present study capillary electrophoresis in the frontal analysis mode (CE/FA), as promising technique for assessment of drug-protein interaction was used. The free drug concentration was measured from height of the frontal peak and calculated based on the external drug standard in absence of protein. With a known concentration of total drug, the percentage of protein bound drug was determined. The binding parameters were also estimated based on the equilibrium dialysis experiment which is considered to be a reference method. This study was designed to examine the interaction of dexamethasone sodium phosphate (DXM) with BSA and HSA under simulated physiological conditions (pH 7.4, 67 mM phosphate buffer, I = 0.17). Using fixed, at physiological level, HSA and BSA concentrations and increasing DXM concentrations, the number of binding sites (n) and binding constant (K(a) ) was calculated from both nonlinear regression fitting and Scatchard Plot. Despite some differences, it can be concluded that the CE/FA is comparable with equilibrium dialysis, but since the first one offers advantages such as low sample consumption, short analysis time, and high separation efficiency, it can be used in high-throughput screening of drug protein binding at the early stage of drug discovery. Interspecies differences in binding of a drug to albumins have been observed and it should be taken into account in interpretation of the results.
Electrophoresis 09/2012; · 3.30 Impact Factor
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ABSTRACT: A sensitive and stereospecific liquid chromatography-tandem mass spectrometry method for the quantitative determination of TWo8 enantiomers ((2RS)-1-(7-methoxy-1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)-propan-2-ol) was developed and validated in rat serum and some tissues. Racemic TWo8 is a new chemical entity, and it has been shown to possess pharmacological activity in vivo. The assay involved the diastereomeric derivatization of racemic TWo8 with 2,3,4,6-tetra-O-acetyl-beta-glucopyranosyl isothiocyanate. The TWo8 diastereoisomers quantification was performed on a triple quadrupole mass spectrometer employing an electrospray ionization technique. The precursor to the product ion transition for TWo8 derivatives and for the internal standard (carbamazepine) was m/z 776.4 → 387.2 and 237.4 → 194.4, respectively. The assay was validated with a linear range of 10-2000 ng/ml of racemic TWo8. The inter-day precisions for (-)-(S)-TWo8 and (+)-(R)-TWo8 were 2.1% to 14.9% and 1.3% to 14.8%, respectively. The inter-day accuracy for (-)-(S)-TWo8 and (+)-(R)-TWo8 was within 86% to 114% and 91% to 114%, respectively. A pilot pharmacokinetic study of this new β-adrenolytic compound has shown that (-)-(S)-TWo8 is eliminated faster than its antipode. The terminal half-lives of (-)-(S)-TWo8 and (+)-(R)-TWo8 were 3.2 and 3.9 h, respectively. The compound distribution into different organs, evaluated in tissue homogenate samples following TWo8 intravenous administration, showed an enantioselective penetration of TWo8 enantiomers in the liver (p < 0.03), in the kidney (p < 0.001), and in the lungs (p < 0.05). The developed method using liquid chromatography-tandem mass spectrometry method with electrospray ionization could be employed for quantitative determination of compounds with similar structure.
Chirality 06/2012; 24(8):591-9. · 2.35 Impact Factor
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ABSTRACT: A sensitive and specific liquid chromatography electrospray ionization-mass spectrometry method for determination of 1,4-dimethylpyridinium (1,4-DMP) in rat plasma has been developed and validated. Chromatography was performed on an Aquasil C(18) analytical column (4.6 × 150 mm, 5 µm, Thermo Scientific, Rockford, IL, USA) with isocratic elution using a mobile phase containing acetonitrile and water with an addition of 0.1% of formic acid. Detection was achieved by an Applied Biosystems MDS Sciex (Concord, Ontario, Canada) API 2000 triple quadrupole mass spectrometer. Electrospray ionization was used for ion production. The limit of detection in the single ion monitoring mode was found to be 10 ng/mL. The limit of quantification was 50 ng/mL. The precision and accuracy for both within-day and between-day determination of 1,4-dimethylpyridinium was 2.4-7.56 and 90.93-111.48%. The results of this analytical method validation allow pharmacokinetic studies to be carried out in rats. The method was used for the pilot study of the pharmacokinetic behavior of 1,4-DMP in rats after intravenous administration. Copyright © 2012 John Wiley & Sons, Ltd.
Biomedical Chromatography 04/2012; · 1.97 Impact Factor
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ABSTRACT: Photostability of moxifloxacin (MOXI) after UVA irradiation in solutions and solid phase, with and without participation of Cu(II), Zn(II), Al(III), and Fe(III) was tested. The studies were carried out by the TLC-densitometric method and LC-MS/MS method. Elaborated and validated chromatography-densitometric method was used for assaying. It was shown that the number and type of photoproducts depend on the environment and type of the metal ion. The studied ions enhanced the degradation of MOXI in solutions, and the influence of Cu(II) and Fe(III) ions was higher than that of Zn(II) and Al(III) ions. In solid phase, in contrast to solutions, all metal ions decreased the photodegradation, however the influence of ions, Al(III) and Zn(II), was weaker than that of Cu(II) and Fe(III) ions. Identification of the degradation products performed with LC-MS/MS and (1)H NMR identified them as: 1-cyclopropyl-6-fluoro-7-amino-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid, 1-cyclopropyl-6-fluoro-8-methoxy-4-oxo-7-(2-oxo-octahydro-6H-pyrrolo[3,4-b]pyridine-6-yl)-1,4-dihydroquinoline-3-carboxylic acid, 7-[3-hydroxyamino-4-(2-carboxyethyl)pyrrolidin-1-yl]-1-cyclopropyl-6-fluoro-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid.
Photochemical and Photobiological Sciences 12/2011; 11(2):351-7. · 2.58 Impact Factor
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ABSTRACT: A group of trans- and cis-2-(2,6-dimethylphenoxy)-N-(2-hydroxycyclohexyl)acetamides (1-7) and -ethylamines (8-9) have been synthesized and investigated for their anticonvulsant activity. One of them, racemic trans-2-(2,6-dimethylphenoxy)-N-(2-hydroxycyclohexyl)acetamide proved to be the most effective in MES (mice, ip), exhibiting ED(50)=42.97 mg/kg b.w. and TD(50)=105.67 mg/kg b.w. It also proved protection in focal seizures (electric kindling, rats, ip) and it raises seizure threshold. The mechanism of action is inhibition of voltage-gated sodium currents and enhancement of GABA effect. Safety pharmacology assay on threshold tonic extension revealed no lowering of the seizure threshold.
Bioorganic & medicinal chemistry 11/2011; 19(22):6927-34. · 2.82 Impact Factor
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ABSTRACT: A sensitive and selective liquid chromatographic-electrospray ionization mass spectrometric method for the simultaneous determination of propentofylline and enantiomers of its active metabolite M1 in rat serum, cortex and hippocampus was developed and validated according to GLP procedures. Sample preparations were carried out by liquid-liquid extraction using diethyl ether after the addition of the internal standard (pentoxifylline). The dried residue was reconstituted in mobile phase and injected onto a Chiralpak AD column (10 µm, 250 × 4.6 mm i.d.). The limit of quantification for propentofylline in serum, cortex and hippocampus was set at 0.25 ng/mL and for enantiomers of its metabolite M1 at 1.25 ng/mL. The established LC/ESI-MS/MS method has been successfully applied to an initial pharmacokinetic study of propentofylline and also to assessment of distribution of parent drug and enantiomers of its pharmacologically active metabolite M1 to cortex and hippocampus after intravenous administration of propentofylline to rats at a dose of 5 mg/kg.
Biomedical Chromatography 03/2011; 25(3):381-90. · 1.97 Impact Factor
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ABSTRACT: A sensitive and specific liquid chromatography tandem mass spectrometry method with electrospray ionization for the determination of endothelin-1 in rat plasma and lung effluents has been developed and validated. Detection was achieved by an Applied Biosystems MDS Sciex API 2000 triple quadrupole mass spectrometer coupled to an Agilent 1100 LC system. The limit of detection and the limit of the quantification of ET-1 in matrix buffer was estimated at 40 pM and 1 nM, respectively. The precision and accuracy for both intra- and inter-day determination of the analyte ranged from 2.5% to 14.7% and from 104.2% to 113.3%, respectively. No significant relative matrix effect was observed. Stability of ET-1 established in a bench-top, autosampler, long-term storage stability as well as freeze/thaw cycles shown no significant degradation products in the samples. The results of the method validation indicated that this method is applicable for the determination of the ET-1 concentration in an effluent from the isolated lung preparation as well as in vivo in plasma samples to evaluate ET-1 as a potential biomarker of the progression of pulmonary endothelial dysfunction and pulmonary hypertension in rats induced by a monocrotaline injection.
Talanta 07/2010; 82(2):710-8. · 3.79 Impact Factor
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ABSTRACT: A thin-layer chromatographic-densitometric method was used to determine the stability of ciprofloxacin and norfloxacin in the presence and absence of metal ions in acidic solutions at 22 degrees C, 50 degrees C and 90 degrees C. The degradation of ciprofloxacin and norfloxacin followed first order reaction kinetics in presence of metal ions. The extent of this degradation however depended on the type of metal ion and temperature. Product structures of ciprofloxacin (1-cyclopropyl-6-fluoro-7-(piperazin-1-yl)quinolin-4(1H)-one) and norfloxacin (1-ethyl-6-fluoro-7-(piperazin-1-yl)quinolin-4(1H)-one) were determined by analysis of UV spectra and using LC-MS method.
Pharmaceutical Development and Technology 10/2009; 15(5):532-44. · 1.36 Impact Factor
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ABSTRACT: The synthesis of (2RS)-1-(5-methoxy-1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)propan-2-ol and (2RS)-1-(7-methoxy-1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)propan-2-ol and its enantiomers, analogs of 1-(1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)propan-2-ol ((RS)-9) is described. Compounds were tested for electrographic, antiarrhythmic, hypotensive and spasmolytic activities as well as for alpha(1)-, alpha(2)- and beta(1)-adrenoceptors binding affinities. The antagonist potency of the new compounds was compared with carvedilol and (RS)-9.
European journal of medicinal chemistry 08/2009; 44(12):5103-11. · 3.27 Impact Factor
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ABSTRACT: A series of appropriate alkanolamine and amide derivatives of xanthone were prepared and evaluated for anticonvulsant activity using maximal electroshock (MES) and subcutaneous pentylenetetrazole (scMet) induced seizures, and for neurotoxicity (TOX) using the rotorod test on mice and rats. The most promising compounds seem to be the appropriate aminoalkanolic derivatives of 6-chloroxanthone, among which the R-(-) and S-(+)-2amino-1-propanol derivatives of 6-chloro-2-methylxanthone (2(a) and 2(b)) displayed anti-MES activity (in mice) with a protective index (TD(50)/ED(50)) of 6.23<6.85, corresponding to that of phenytoin, carbamazepine and valproate. The most active compound, 2(b), was determined to have an affinity to the benzodiazepine (BDZ) receptor and voltage-dependent Ca(2+) channel (VDCC) by using radioligand binding assays. The enantiomeric purities of 2(a) and 2(b) were determined using an analytical liquid chromatography-mass spectrometry method.
Bioorganic & medicinal chemistry 08/2008; 16(15):7234-44. · 2.82 Impact Factor
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ABSTRACT: A sensitive and specific liquid chromatography electrospray ionization-tandem mass spectrometry method for the enantioselective determination of the novel beta-adrenolytic compound, 1-(1-H-indol-4-yloxy)-3-{[2-(2-methoxyphenoxy)ethylo]amino} propan-2-ol, in rat plasma has been developed and validated. Chromatography was performed on a reversed-phase Chiralcel OD-RH analytical column (150x4.6 mm, 5 microm, Daicel Chemical Industries, Tokyo, Japan) with isocratic elution using a mobile phase containing acetonitrile and water with 0.01% formic acid. Detection was achieved by an Applied Biosystems MDS Sciex (Concord, Ontario, Canada) API 2000 triple quadrupole mass spectrometer. Electrospray ionization (ESI) was used for ion production. The limit of detection in the MRM mode was found to be 1.25 ng/ml. The limit of quantification of both enantiomers was 2.5 ng/ml. The precision and accuracy for both intra- and inter-day determination of 2F109 enantiomers ranged from 2.6 to 12% and from 89.1 to 107.1%. This analytical method allowed us to carry out pharmacokinetic studies in rats. Our findings demonstrate that 2F109 shows stereoselective disposition in rat plasma after i.v. administration. The terminal half-lives of (+)-(R)-2F109 and (-)-(S)-2F109 were 33.5 and 42.6 min, respectively. The AUC0-inf of (+)-(R)-2F109 exceeded that of (-)-(S)-2F109.
Chirality 08/2007; 19(7):536-41. · 2.35 Impact Factor
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ABSTRACT: The purpose of this work was to develop a sensitive stability-indicating TLC-densitometric method for determination of azithromycin (AZ) in the presence of its impurities E, I, and L, and to study the stability of AZ under different stress conditions. The method was developed on TLC aluminum plates precoated with silica gel F254 using the mobile phase methanol-acetone-ammonia 25% (2+13+0.1, v/v/v), which gives compact zones for AZ (Rf= 0.39) and impurities E, I, and L (Rf = 0.54, 0.20, and 0.05, respectively). Densitometric analysis of AZ and its impurities was carried out at 483 nm after spraying with sulfuric acid-ethanol (1 + 4, v/v) and heating at 100 degrees C for 5 min. The linear regression analysis data for the calibration plots showed good linear relationships with r = 0.9941 for AZ, 0.9987 for impurity E, 0.9989 for impurity I, and 0.9984 for impurity L. AZ was subjected to acidic and alkaline hydrolysis, oxidation, and reduction stress. The drug underwent degradation under these conditions. The degradation products were well-resolved from the pure drug, with significantly different Rf values. A plausible degradation pathway of AZ was established by HPLC/electrospray ionization-MS analysis of the products.
Journal of AOAC International 95(5):1418-24. · 1.20 Impact Factor
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ABSTRACT: Stability of clonazepam, diazepam, haloperidol, and doxepin was determined in acidic solutions. In addition, determination of the kinetic and thermodynamic properties of this stability was carried out. Reaction rate constants (k), half-life times (t(0.1) and t(0.5)), and activation energy (Ea) were estimated for the drugs, which differed in polarity expressed with log P values. It was observed that estimated Ea values increased from 42.13 to 125.03 kJ/mol with an increase of lipophilicity (log P) beginning from the most hydrophilic drug (clonazepam, 2.70 log P) to the most lipophilic drug (doxepin, 4.10 log P). All degradation products were studied using an HPLC/electrospray ionization-MS technique in the positive ionization mode.
Journal of AOAC International 94(6):1791-9. · 1.20 Impact Factor
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ABSTRACT: Preterm infants are at increased risk for DHA deficiency because from 26th weeks of pregnancy until term, 80% of the brain this acid accrues in the fetus. Moreover, the main sources of lipids for preterm newborns are fat emulsions which do not contain DHA.
1) to investigate the plasma DHA concentration in prematurely delivered newborns who are receiving a fish-oil emulsion in amount equal to one third of total daily intravenous lipid intake or soybean/olive oil fat emulsion from the first day of life. 2) to compare plasma DHA concentration, evaluated immediately after birth in prematurely born infants, with the respective data obtained in full term newborns.
Twenty one preterm infants in the two groups: the study group n=12 (newborns fed parenterally with a partially replaced a soybean/olive oil emulsion with a fish-oil emulsion); the control group n=9 (newborn fed parenterally with a soybean/olive oil emulsion) comparable with regard to demographic and clinical characteristics. Determination of plasma and erythrocytes DHA concentrations in newborns was made using a high-performance liquid chromatography-mass spectrometry (LC-ESI/MS) method. Detection of parent ions with negative ionization mode, m/z 327,5 amu. Method validation was according to the ICH and FDA requirements.
The mean values of plasma DHA level measured on the 7th, 14th, 21st, 28th day of life, were statistically significantly lower in the control group when compared with respective data obtained in the study group (7th day: 7.98 vs 42.4 ěmol/L, p=0.0002; 14th day: 6.8 vs 21.14 ěmol/l, p=0.000001; 21st day: 11.56 vs 19.1 ěmol/L, p=0.035; 28th day: 11.4 vs 25.4 ěmol/L, p=0.0004). The mean value of plasma DHA level in full-term newborns measured in the first hours of life was 164.7 ěmol/L whereas in preterm neonates it reached 15.9 ěmol/L (p=0.000001).
The administration of fish-oil-based fat emulsion as a component of total parenteral nutrition from the first day of life may alleviate a marked decrease in plasma DHA level observed in preterm infants within the first weeks after birth. Established method allows for routine determination of DNA concentrations in plasma erythrocytes of newborns.
Medycyna wieku rozwojowego 15(3):312-7.
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ABSTRACT: Chromatographic and densitometric method for determination of moxifloxacin in the presence of products of acidic hydrolysis was developed. The established method had suitable specificity, precision, good accuracy and high sensitivity. In addition, stability of moxifloxacin in acidic solutions at temperature 90 degrees C and 110 degrees C in the presence and absence of metal ions, such as Cu(II), Fe(III), Zn(II), and Al(III) was studied. It was proved that decomposition of moxifloxacin proceeds according to kinetics of the first-order reaction and is dependent on temperature, incubation time and the type of the metal ion. Based on the calculated kinetic (k, t0.1, and t0.5) and thermodynamic (E(a)) parameters, it was observed that among studied ions the highest effect on decomposition process of moxifloxacin had Cu(II) ions. The liquid chromatography coupled with mass spectrometry detection (LC-MS) and proton nuclear magnetic resonance (1H NMR) techniques have been used to identify degradation products of moxifloxacin.
Acta poloniae pharmaceutica 69(5):821-31. · 0.66 Impact Factor
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ABSTRACT: The aim of this paper was to validate an analytical method for the simultaneous determination of PTX and its active metabolite (-)-(R)-M1 in rat serum and some tissues using a high-performance liquid chromatography method with ultraviolet detection (HPLC-UV). The specificity, linearity, precision, accuracy, recovery, lower limit of detection, lower limit of quantification and stability study were successively conducted according to GLP procedures. HPLC separation of all compounds was carried out on a normal-phase ChiralPak AD column (250 mm x 4.6 mm i.d., 5 mm), using, as a mobile phase, a mixture of hexane and 2-propanol (84:16, v/v) containing 0.01% of diethylamine with a flow rate of 1.5 mL x min(-1). The calibration curves from all studied matrices were linear across the concentration range from 0.01 to 100 mg x mL(-1) with a lower limit of quantification of 0.01 microg x mL(-1) for all analytes. The application of the assay to a pilot pharmacokinetic study and tissue distribution of the compounds in rats after intraperitoneal dosing of 50 mg x kg(-1) of PTX was described. Significant (p<0.05) differences between serum and tissue levels of PTX, (-)-(R)-M1 and (+)-(S)-M1 were observed.
Acta poloniae pharmaceutica 66(3):215-24. · 0.66 Impact Factor
