1
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Zhou L, Zhou H, Xiao H, Zhang Z, Xiong Z, Tuo X, Guo H. Elucidation on inhibition and binding mechanism of bovine liver catalase by nifedipine: multi-spectroscopic analysis and computer simulation methods. LUMINESCENCE 2022; 37:1547-1556. [PMID: 35816002 DOI: 10.1002/bio.4330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 06/18/2022] [Accepted: 07/07/2022] [Indexed: 11/10/2022]
Abstract
Nifedipine (NDP), a dihydropyridine calcium antagonist, is widely used for the treatment of hypertension and angina pectoris. Catalase is a key antioxidant enzyme that is closely relevant to the level of reactive oxygen species (ROS) in vivo. Here, the research explored the effects of NDP on the conformation and catalytic function of bovine liver catalase (BLC) through enzymatic reaction kinetic techniques, multi-spectroscopic analysis and computer simulation method. Kinetic studies clarified that the NDP debased the activity of BLC by non-competitive inhibition mechanism. Based on the data of trials, it was a static quenching mechanism that functioned in the quenching of intrinsic fluorescence of BLC. The binding constant value was (4.486 ± 0.008) × 104 M-1 (298 K) and BLC had one binding site for NDP. Tyr was prone to be exposed more to a hydrophilic environment in wake of a shift in fluorescence value. The binding reaction of BLC to NDP caused the conformational alteration of BLC, which in turn led to increase of the α-helix and decline of β-sheet contents. Furthermore, several amino acids residues interacted with NDP by means of van der Waals forces, whereas Gln397, Asn368, Gln371, Asn384 and Pro377 formed several Hydrogen Bonds with NDP.
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Affiliation(s)
- Like Zhou
- School of Chemistry and Chemical Engineering, Nanchang University, Nanchang, Jiangxi, China
| | - Hui Zhou
- School of Chemistry and Chemical Engineering, Nanchang University, Nanchang, Jiangxi, China
| | - Huilong Xiao
- School of Pharmacy, Nanchang University, Nanchang, Jiangxi, China
| | - Zihang Zhang
- School of Chemistry and Chemical Engineering, Nanchang University, Nanchang, Jiangxi, China
| | - Ziyun Xiong
- School of Pharmacy, Nanchang University, Nanchang, Jiangxi, China
| | - Xun Tuo
- School of Chemistry and Chemical Engineering, Nanchang University, Nanchang, Jiangxi, China
| | - Hui Guo
- School of Chemistry and Chemical Engineering, Nanchang University, Nanchang, Jiangxi, China
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2
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Deng H, Wu X, Zhang L, Shen J, Qiao Y, Wang X, Bai C, Zheng T, Okamoto Y. Synthesis and application of chitosan thiourea derivatives as chiral stationary phases in HPLC. Carbohydr Polym 2022; 296:119888. [DOI: 10.1016/j.carbpol.2022.119888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 07/13/2022] [Accepted: 07/15/2022] [Indexed: 11/27/2022]
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3
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Wang X, Wu J, Liu X, Qiu X, Cao L, Ji Y. Enhanced Chiral Recognition Abilities of Cyclodextrin Covalent Organic Frameworks via Chiral/Achiral Functional Modification. ACS APPLIED MATERIALS & INTERFACES 2022; 14:25928-25936. [PMID: 35609238 DOI: 10.1021/acsami.2c05572] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
β-Cyclodextrin covalent organic frameworks (β-CD COFs) show great potential in enantioseparation due to their uniformly distributed chiral recognition sites and good chemical stability. The hydroxyl and amino groups of β-CD COFs enable facile post-modification to introduce the desired functionality into the frameworks. In this study, we perform post-modification of β-CD COFBPDA with 1,4-butane sultone and [(3R,4R)-4-acetyloxy-2,5-dioxooxolan-3-yl] acetate to construct two kinds of novel functional β-CD COFs. The capillary columns prepared with these two functional β-CD COFs separated chiral dihydropyridines and fluoroquinolones with excellent selectivity and repeatability in capillary electrochromatography, while β-CD COFBPDA-modified capillary columns did not present the chiral recognition ability for these drugs. The mechanism of chiral recognition and the enhanced enantioselectivity of functional β-CD COFs were further demonstrated by molecular docking simulation. The divergent chiral separation performances of β-CD COFs suggest that the introduction of functional groups enables the modification of β-CD COF properties and tuning of its chiral recognition abilities for the diversity of enantioseparation.
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Affiliation(s)
- Xuehua Wang
- Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009, China
- Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009, China
| | - Jiaqi Wu
- Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009, China
- Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009, China
| | - Xue Liu
- Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009, China
- Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009, China
| | - Xin Qiu
- Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009, China
- Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009, China
| | - Liqin Cao
- Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009, China
- Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009, China
| | - Yibing Ji
- Department of Analytical Chemistry, China Pharmaceutical University, Nanjing 210009, China
- Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing 210009, China
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4
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Sun J, Ma S, Liu B, Yu J, Guo X. A fully derivatized 4-chlorophenylcarbamate-β-cyclodextrin bonded chiral stationary phase for enhanced enantioseparation in HPLC. Talanta 2019; 204:817-825. [PMID: 31357369 DOI: 10.1016/j.talanta.2019.06.071] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 06/12/2019] [Accepted: 06/18/2019] [Indexed: 10/26/2022]
Abstract
This paper reports an effective approach for the fabrication of a per-4-chlorophenylcarbamate-β-cyclodextrin (β-CD) bonded chiral stationary phase (CPCDP) in high-performance liquid chromatography. The morphology and structure of the ligand and the chiral stationary phase (CSP) were characterized by scanning electron microscopy, transmission electron microscopy, solid state 13C nuclear magnetic resonance spectra, fourier transform infrared spectra, elemental analysis and thermogravimetric analysis. Because CPCDP was a kind of multimode enantioseparation materials, the enantioseparation of chiral compounds including twelve azole antifungal agents, five proton pump inhibitors and five dihydropyridine calcium antagonists were studied in both reversed-phase and normal-phase chromatography. All analytes were obtained enantiomeric separation. Especially, the resolution of azoles was excellent. The selectivity and resolution of voriconazole reached 15.41 and 16.80, which was an exciting achievement for the enantioseparations by β-CD based chiral stationary phases. Compared with the commercial 3,5-dimethylphenyl carbamate-β-CD based chiral stationary phase (DMP), enhanced enantioselectivities for all the above compounds (except ilaprazole) were obtained on CPCDP column, which indicated that the 4-chlorophenylcarbamate group was conducive to the chiral recognition. Chromatographic studies elucidated that enhancement of analyte-chiral substrate interactions were attributed to the inclusion complexation, π-π stacking interaction, hydrogen-bonding, dipole-dipole interaction and steric hindrance. For further study, we also prepared semi-preparative chromatographic columns to obtain a single enantiomer. In addition to excellent chromatographic performance, the prepared CD-based column is stable and much cheaper than commercial columns, which can reduce the cost of test and has a good application prospect in chiral drug analysis.
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Affiliation(s)
- Jiayi Sun
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning Province, PR China
| | - Siman Ma
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning Province, PR China
| | - Beibei Liu
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning Province, PR China
| | - Jia Yu
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning Province, PR China.
| | - Xingjie Guo
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning Province, PR China.
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5
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Sun J, Gözde Gündüz M, Zhang J, Yu J, Guo X. Direct Enantiomeric Resolution of Seventeen Racemic 1,4-Dihydropyridine-Based Hexahydroquinoline Derivatives by HPLC. Int J Mol Sci 2019; 20:ijms20102513. [PMID: 31121823 PMCID: PMC6566779 DOI: 10.3390/ijms20102513] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/17/2019] [Accepted: 05/19/2019] [Indexed: 11/25/2022] Open
Abstract
1,4-Dihydropyridine (DHP) scaffold holds an outstanding position with its versatile pharmacological properties among all heterocyclic compounds. Although most of the commercially available DHPs are marketed as a racemic mixture, the chiral center at C-4 can lead to even opposite pharmacological activities between the enantiomers. In the present study, enantioseparation of seventeen DHP structural analogues, consisting of either pharmacologically active or newly synthesized derivatives, (M2-4, MD5, HM2, HM10, CE5, N11, N10, N7, M11, MC6-8, MC13, MD23, and 42IIP) by high-performance liquid chromatography was investigated using immobilized polysaccharide-based chiral stationary phase, Chiralpak IC column. Due to the solvent versatility of the covalently immobilized chiral stationary phase in enantiomer separation, multiple elution modes including standard normal phase, nonstandard mobile phase, and reversed phase were used to expand the possibility to find the optimum enantioselective conditions for the tested analytes. Under appropriate separation conditions, complete enantiomeric separation was obtained for nearly all compounds except MC6-8 and MC13 which contained two chiral centers. Additionally, the effects of the polar modifier, the additive, and column temperature on the chiral recognition were evaluated. The thermodynamic parameters calculated according to the linear van’t Hoff equation indicated that the chiral separations in this study were enthalpy-driven or entropy-driven. Some parameters of method validation such as linearity, limit of quantitation, and repeatability were also measured for all studied compounds to prove the reliability of the method.
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Affiliation(s)
- Jiayi Sun
- Shenyang Pharmaceutical University, Shenyang 110016, China.
| | - Miyase Gözde Gündüz
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Hacettepe University, Sıhhiye, Ankara 06100, Turkey.
| | - Junyuan Zhang
- Shenyang Pharmaceutical University, Shenyang 110016, China.
| | - Jia Yu
- Shenyang Pharmaceutical University, Shenyang 110016, China.
| | - Xingjie Guo
- Shenyang Pharmaceutical University, Shenyang 110016, China.
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6
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Conformational and characterization of benidipine hydrochloride polymorphs: Spectroscopic and computational modeling investigations. J Mol Struct 2018. [DOI: 10.1016/j.molstruc.2018.03.103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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7
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Yu J, Tang J, Yuan X, Guo X, Zhao L. Evaluation of the chiral recognition properties and the column performances of three chiral stationary phases based on cellulose for the enantioseparation of six dihydropyridines by high-performance liquid chromatography. Chirality 2017; 29:147-154. [PMID: 28349560 DOI: 10.1002/chir.22690] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Revised: 12/10/2016] [Accepted: 12/23/2016] [Indexed: 11/12/2022]
Abstract
Separations of six dihydropyridine enantiomers on three commercially available cellulose-based chiral stationary phases (Chiralcel OD-RH, Chiralpak IB, and Chiralpak IC) were evaluated with high-performance liquid chromatography (HPLC). The best enantioseparation of the six chiral drugs was obtained with a Chiralpak IC (250 × 4.6 mm i.d., 5 μm) column. Then the influence of the mobile phase including an alcohol-modifying agent and alkaline additive on the enantioseparation were investigated and optimized. The optimal mobile phase conditions and maximum resolution for every analyte were as follows respectively: n-hexane/isopropanol (85:15, v/v) for nimodipine (R = 5.80) and cinildilpine (R = 5.65); n-hexane/isopropanol (92:8, v/v) for nicardipine (R = 1.76) and nisoldipine (R = 1.92); and n-hexane/isopropanol/ethanol (97:2:1, v/v/v) for felodipine (R = 1.84) and lercanidipine (R = 1.47). Relative separation mechanisms are discussed based on the separation results, and indicate that the achiral parts in the analytes' structure showed an important influence on the separation of the chiral column.
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Affiliation(s)
- Jia Yu
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning Province, P. R. China
| | - Jing Tang
- Department of Pharmacy, Beijing Tsinghua Changgung Hospital, Medical Centre, Tsinghua University, Beijing, P. R. China
| | - Xiaowei Yuan
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning Province, P. R. China
| | - Xingjie Guo
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning Province, P. R. China
| | - Longshan Zhao
- School of Pharmacy, Shenyang Pharmaceutical University, Shenyang, Liaoning Province, P. R. China
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8
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Zhang L, Song Z, Dong Y, Wang Y, Li X, Long H, Xu K, Deng C, Meng M, Yin Y, Xi R. Enantiomeric separation of 1,4-dihydropyridines by liquid-phase microextraction with supercritical fluid chromatography. J Supercrit Fluids 2016. [DOI: 10.1016/j.supflu.2015.08.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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9
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H8-BINOL chiral imidodiphosphoric acids catalyzed cyclization reactions of β,γ-unsaturated α-ketoesters, arylamines and 1,3-dicarbonyl compounds: enantioselective synthesis of 1,4-dihydropyridines. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.tetasy.2015.06.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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10
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Paris D, Ait-Ghezala G, Bachmeier C, Laco G, Beaulieu-Abdelahad D, Lin Y, Jin C, Crawford F, Mullan M. The spleen tyrosine kinase (Syk) regulates Alzheimer amyloid-β production and Tau hyperphosphorylation. J Biol Chem 2014; 289:33927-44. [PMID: 25331948 DOI: 10.1074/jbc.m114.608091] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We have previously shown that the L-type calcium channel (LCC) antagonist nilvadipine reduces brain amyloid-β (Aβ) accumulation by affecting both Aβ production and Aβ clearance across the blood-brain barrier (BBB). Nilvadipine consists of a mixture of two enantiomers, (+)-nilvadipine and (-)-nilvadipine, in equal proportion. (+)-Nilvadipine is the active enantiomer responsible for the inhibition of LCC, whereas (-)-nilvadipine is considered inactive. Both nilvadipine enantiomers inhibit Aβ production and improve the clearance of Aβ across the BBB showing that these effects are not related to LCC inhibition. In addition, treatment of P301S mutant human Tau transgenic mice (transgenic Tau P301S) with (-)-nilvadipine reduces Tau hyperphosphorylation at several Alzheimer disease (AD) pertinent epitopes. A search for the mechanism of action of (-)-nilvadipine revealed that this compound inhibits the spleen tyrosine kinase (Syk). We further validated Syk as a target-regulating Aβ by showing that pharmacological inhibition of Syk or down-regulation of Syk expression reduces Aβ production and increases the clearance of Aβ across the BBB mimicking (-)-nilvadipine effects. Moreover, treatment of transgenic mice overexpressing Aβ and transgenic Tau P301S mice with a selective Syk inhibitor respectively decreased brain Aβ accumulation and Tau hyperphosphorylation at multiple AD relevant epitopes. We show that Syk inhibition induces an increased phosphorylation of the inhibitory Ser-9 residue of glycogen synthase kinase-3β, a primary Tau kinase involved in Tau phosphorylation, by activating protein kinase A, providing a mechanism explaining the reduction of Tau phosphorylation at GSK3β-dependent epitopes following Syk inhibition. Altogether our data highlight Syk as a promising target for preventing both Aβ accumulation and Tau hyperphosphorylation in AD.
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Affiliation(s)
- Daniel Paris
- From the Roskamp Institute, Sarasota, Florida 34243
| | | | | | - Gary Laco
- From the Roskamp Institute, Sarasota, Florida 34243
| | | | - Yong Lin
- From the Roskamp Institute, Sarasota, Florida 34243
| | - Chao Jin
- From the Roskamp Institute, Sarasota, Florida 34243
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11
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Synthesis of Novel Unsymmetrically Substituted 1,4-Dihydroisonicotinic Acid and its Derivatives. Chem Heterocycl Compd (N Y) 2013. [DOI: 10.1007/s10593-013-1304-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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12
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Synthesis and antihypertensive activity evaluation in spontaneously hypertensive rats of nitrendipine analogues. Med Chem Res 2010. [DOI: 10.1007/s00044-010-9477-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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13
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Kasprzyk-Hordern B. Pharmacologically active compounds in the environment and their chirality. Chem Soc Rev 2010; 39:4466-503. [PMID: 20852776 DOI: 10.1039/c000408c] [Citation(s) in RCA: 282] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pharmacologically active compounds including both legally used pharmaceuticals and illicit drugs are potent environmental contaminants. Extensive research has been undertaken over the recent years to understand their environmental fate and toxicity. The one very important phenomenon that has been overlooked by environmental researchers studying the fate of pharmacologically active compounds in the environment is their chirality. Chiral drugs can exist in the form of enantiomers, which have similar physicochemical properties but differ in their biological properties such as distribution, metabolism and excretion, as these processes (due to stereospecific interactions of enantiomers with biological systems) usually favour one enantiomer over the other. Additionally, due to different pharmacological activity, enantiomers of chiral drugs can differ in toxicity. Furthermore, degradation of chiral drugs during wastewater treatment and in the environment can be stereoselective and can lead to chiral products of varied toxicity. The distribution of different enantiomers of the same chiral drug in the aquatic environment and biota can also be stereoselective. Biological processes can lead to stereoselective enrichment or depletion of the enantiomeric composition of chiral drugs. As a result the very same drug might reveal different activity and toxicity and this will depend on its origin and exposure to several factors governing its fate in the environment. In this critical review a discussion of the importance of chirality of pharmacologically active compounds in the environmental context is undertaken and suggestions for directions in further research are made. Several groups of chiral drugs of major environmental relevance are discussed and their pharmacological action and disposition in the body is also outlined as it is a key factor in developing a full understanding of their environmental occurrence, fate and toxicity. This review will be of interest to environmental scientists, especially those interested in issues associated with environmental contamination with pharmacologically active compounds and chiral pollutants. As the review will outline current state of knowledge on chiral drugs, it will be of value to anyone interested in the phenomenon of chirality, chiral drugs, their stereoselective disposition in the body and environmental fate (212 references).
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Affiliation(s)
- Barbara Kasprzyk-Hordern
- University of Huddersfield, Department of Chemical and Biological Sciences, School of Applied Sciences, Queensgate, Huddersfield HD1 3DH, UK.
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14
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Lin W, Hayakawa T, Yanaguimoto H, Kuzuba M, Obara T, Ding G, Cui F, Inotsume N. Pharmacokinetic interaction of ibuprofen enantiomers in rabbits. J Pharm Pharmacol 2010; 56:317-21. [PMID: 15025856 DOI: 10.1211/0022357022845] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Abstract
The potential interaction between two ibuprofen enantiomers was studied after intravenous administration of R-(–)-, S-(+)- and racemic ibuprofen to rabbits. The total body clearance values calculated by compartmental model analysis (0.65+0.21 for R-(–)-ibuprofen and 0.63+0.34 for S-(+)-ibuprofen) after intravenous administration of the racemate of ibuprofen were significantly smaller than those of individual enantiomers (0.95+0.23 for R-(–)-ibuprofen and 1.03+0.23 for S-(+)-ibuprofen), indicating that the enantiomer–enantiomer interaction results in a mutual inhibition. The enantiomeric interaction in the pharmacokinetic behaviour of ibuprofen after racemic administration is considered to be a result of an alteration in the metabolic or excretion phase (or both) rather than stereoselective protein binding in the systemic distribution.
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Affiliation(s)
- Wenhui Lin
- Department of Pharmacology and Therapeutics, Hokkaido College of Pharmacy, Katsuraoka, Otaru 047-0264, Japan
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15
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Kong D, Yang W, Duan K, Cui Y, Xing S, Zhang X, Sheng X, Zhang L. Capillary electrophoretic enantioseparation of m-nisoldipine using two different beta-cyclodextrins. J Sep Sci 2010; 32:3178-83. [PMID: 19746398 DOI: 10.1002/jssc.200900203] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The methods for the enantioseparation of m-nisoldipine, a new 1,4-dihydropyridine calcium ion antagonist, were developed. The elaborated methods of m-nisoldipine enantiomers separation were successfully performed using an anionic CD-sulfobutyl ether-beta-CD (SBE-beta-CD) or carboxymethyl-beta-CD as chiral selector. However, the results indicated that SBE-beta-CD was a better chiral selector for enantioseparation of the neutral m-nisoldipine. Furthermore, comparing the two SBE-beta-CDs, the derivative with a higher degree of substitution (DS) of 7.0 induced better enantioresolution than the one with low DS (4.0). In addition, possible chiral recognition mechanisms of dihydropyridines were discussed.
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Affiliation(s)
- Dezhi Kong
- Department of Pharmaceutical Analysis, School of Pharmacy, Hebei Medical University, Shijiazhuang, PR China
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16
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Höcht C, Bertera FM, Mayer MA, Taira CA. Issues in drug metabolism of major antihypertensive drugs: β-blockers, calcium channel antagonists and angiotensin receptor blockers. Expert Opin Drug Metab Toxicol 2010; 6:199-211. [DOI: 10.1517/17425250903397381] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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17
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Sobolev A, Franssen M, Duburs G, Groot AD. Chemoenzymatic synthesis of enantiopure 1,4-dihydropyridine derivatives. BIOCATAL BIOTRANSFOR 2009. [DOI: 10.1080/10242420400009939] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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18
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Yoon YJ, Kim KB, Kim H, Seo KA, Kim HS, Cha IJ, Kim EY, Liu KH, Shin JG. Characterization of benidipine and its enantiomers' metabolism by human liver cytochrome P450 enzymes. Drug Metab Dispos 2007; 35:1518-24. [PMID: 17537876 DOI: 10.1124/dmd.106.013607] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Benidipine is a dihydropyridine calcium antagonist that has been used clinically as an antihypertensive and antianginal agent. It is used clinically as a racemate, containing the (-)-alpha and (+)-alpha isomers of benidipine. This study was performed to elucidate the metabolism of benidipine and its enantiomers in human liver microsomes (HLMs) and to characterize the cytochrome P450 (P450) enzymes that are involved in the metabolism of benidipine. Human liver microsomal incubation of benidipine in the presence of NADPH resulted in the formation of two metabolites, N-desbenzylbenidipine and dehydrobenidipine. The intrinsic clearance (CL(int)) of the formation of N-desbenzylbenidipine and dehydrobenidipine metabolites from (-)-alpha isomer was similar to those from the (+)-alpha isomer (1.9 +/- 0.1 versus 2.3 +/- 2.3 microl/min/pmol P450 and 0.5 +/- 0.2 versus 0.6 +/- 0.6 microl/min/pmol P450, respectively). Correlation analysis between the known P450 enzyme activities and the rate of the formation of benidipine metabolites in the 15 HLMs showed that benidipine metabolism is correlated with CYP3A activity. The P450 isoform-selective inhibition study in liver microsomes and the incubation study of cDNA-expressed enzymes also showed that theN-debenzylation and dehydrogenation of benidipine are mainly mediated by CYP3A4 and CYP3A5. The total CL(int) values of CYP3A4-mediated metabolite formation from (-)-alpha isomer were similar to those from (+)-alpha isomer (17.7 versus 14.4 microl/min/pmol P450, respectively). The total CL(int) values of CYP3A5-mediated metabolite formation from (-)-alpha isomer were also similar to those from (+)-alpha isomer (8.3 versus 11.0 microl/min/pmol P450, respectively). These findings suggest that CYP3A4 and CYP3A5 isoforms are major enzymes contributing to the disposition of benidipine, but stereoselective disposition of benidipine in vivo may be influenced not by stereoselective metabolism but by other factors.
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Affiliation(s)
- Yune-Jung Yoon
- Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine, 633-165, Gaegum-Dong, Busanjin-Gu, Busan 614-735, South Korea
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19
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Niwa T, Shiraga T, Hashimoto T, Kagayama A. Effect of nilvadipine, a dihydropyridine calcium antagonist, on cytochrome P450 activities in human hepatic microsomes. Biol Pharm Bull 2005; 27:415-7. [PMID: 14993813 DOI: 10.1248/bpb.27.415] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effects of nilvadipine, a dihydropyridine calcium antagonist, on cytochrome P450 (CYP) activities in human hepatic microsomes were investigated. Nilvadipine competitively inhibited CYP1A2-mediated 7-ethoxyresorufin O-deethylase, CYP2A6-mediated coumarin 7-hydroxylase, CYP2C8/9-mediated tolbutamide methylhydroxylase, CYP2C19-mediated S-mephenytoin 4'-hydroxylase, and CYP3A4-mediated nifedipine oxidase activities, and the inhibition constant (Ki) values were 13.0, 35.8, 5.02, 24.5 and 44.3 microM, respectively. On the other hand, no inhibition of CYP2B6-mediated 7-benzyloxyresorufin O-debenzylation, CYP2D6-mediated bufuralol 1'-hydroxylation, or CYP2E1-mediated chlorzoxazone 6-hydroxylation by nilvadipine at 40 microM concentration was observed. The free fractions of nilvadipine in the incubation mixture estimated by ultracentrifugation were 18.9-27.4%. These results suggest that nilvadipine would not cause clinically significant interactions with other drugs, which are metabolized by CYPs, via the inhibition of metabolism.
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Affiliation(s)
- Toshiro Niwa
- Biopharmaceutical and Pharmacokinetic Research Laboratories, Fujisawa Pharmaceutical Co., Ltd., Kashima, Osaka, Japan.
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20
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Van Eeckhaut A, Detaevernier MR, Michotte Y. Separation of neutral dihydropyridines and their enantiomers using electrokinetic chromatography. J Pharm Biomed Anal 2004; 36:799-805. [PMID: 15533673 DOI: 10.1016/j.jpba.2004.08.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Accepted: 08/28/2004] [Indexed: 11/16/2022]
Abstract
The separation and simultaneous enantiomeric separation of three neutral 1,4-dihydropyridine (DHP) derivatives (nimodipine, nisoldipine and nitrendipine) was studied using electrokinetic chromatography. Bile salts allowed the non-chiral separation of these DHP derivatives. With the taurine-conjugated bile salts a beginning of enantiomeric separation was observed for nimodipine and nisoldipine. Achiral micelles of sodium dodecyl sulphate mixed with neutral cyclodextrins did not allow enantioseparation. Baseline chiral separation of nisoldipine and nimodipine was obtained with carboxymethyl-beta-cyclodextrin at pH 5.0. The buffer type affected the chiral separation, especially in the case of nisoldipine. The addition of organic solvent decreased the enantioresolution of nimodipine. However, the resolution between the nisoldipine enantiomers was increased when methanol or ethanol were added to the background electrolyte. Varying the temperature had almost no effect on the enantioresolution of nisoldipine, whereas with nimodipine a clear improvement at lower temperatures was observed. Using the optimised method, the selectivity of this method was investigated for three possible impurities of nisoldipine.
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Affiliation(s)
- Ann Van Eeckhaut
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Pharmaceutical Institute, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium.
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21
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Lämmerhofer M, Gyllenhaal O, Lindner W. HPLC enantiomer separation of a chiral 1,4-dihydropyridine monocarboxylic acid. J Pharm Biomed Anal 2004; 35:259-66. [PMID: 15063460 DOI: 10.1016/s0731-7085(03)00644-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2003] [Revised: 09/08/2003] [Accepted: 09/20/2003] [Indexed: 11/20/2022]
Abstract
An enantioselective anion exchanger based on tert-butylcarbamoylquinine as chiral selector and thiol-modified silica as chromatographic support was applied for the enantiomer separation of the shortacting calcium antagonist clevidipine after its hydrolysis to methyl 4-(2',3'-dichlorophenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate. This hydrolyzed derivative of clevidipine is the primary metabolite and precursor of the parent drug. Method development included the steps of optimization of the composition of the mobile phase (pH, type and content of organic modifier, polar organic mode), screening of various structural analogs of above mentioned CSP, and evaluation of the effect of the flow rate. These detailed studies gave insight into the operational mode of the CSP, which is basically an enantioselective anion exchange mechanism. The polar organic mode turned out to be advantageous with regard to enantioselectivity and resolution. The optimized method makes use of an eluent composed of 0.125% acetic acid in acetonitrile with flow rate of 1 ml/min at a constant temperature of 25 degrees C, and allows the separation of the both enantiomers with enantioselectivity alpha of 1.25 and a resolution RS of 3.0 within 10 min. On the above mentioned quinine carbamate phase the (R)-enantiomer is stronger retained, while a change to the corresponding quinidine carbamate CSP allows the reversal of the elution order.
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Affiliation(s)
- Michael Lämmerhofer
- Christian Doppler Laboratory for Molecular Recognition Materials, Institute of Analytical Chemistry, University of Vienna, Währingerstrasse 38, A-1090 Vienna, Austria
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22
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Fu Q, Sanbe H, Kagawa C, Kunimoto KK, Hagina J. Uniformly sized molecularly imprinted polymer for (S)-nilvadipine. Comparison of chiral recognition ability with HPLC chiral stationary phases based on a protein. Anal Chem 2003; 75:191-8. [PMID: 12553751 DOI: 10.1021/ac026039z] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Uniformly sized molecularly imprinted polymers (MIPs) for (S)-nilvadipine have been prepared by a multistep swelling and polymerization method using methacrylic acid, 2-(trifluoromethyl)acrylic acid, 2-vinylpyridine, or 4-vinylpyridine (4-VPY) as a functional monomer and ethylene glycol dimethacrylate (EDMA) as a cross-linker. The chiral recognition abilities of the MIPs for nilvadipine and other dihydropyridine calcium antagonists were evaluated using a mixture of sodium phosphate buffer (or water) and acetonitrile or only acetonitrile as the mobile phase. The (S)-nilvadipine-imprinted 4-VPY-co-EDMA polymers gave the highest resolution for nilvadipine among the MIPs prepared. In addition, the enantioseparation of nilvadipine was attained using the (S)-nilvadipine-imprinted EDMA polymers, without use of a functional monomer. 1H NMR and molecular modeling studies suggested a one-to-one hydrogen-bonding-based complex formation of (S)-nilvadipine with 4-VPY in chloroform. These results reveal that the (S)-nilvadipine-imprinted EDMA polymers could recognize the template molecule by its molecular shape, and that in addition to this recognition, hydrophobic and hydrogen-bonding interactions seems to play important roles in the retention and chiral recognition of nilvadipine on the 4-VPY-co-EDMA polymers in hydroorganic mobile phases. By optimizing chromatographic conditions such as column temperature and flow rate, the baseline separation of nilvadipine enantiomers was attained with a short analysis time and with a column efficiency comparable to commercially available chiral stationary phases based on a protein, such as ovomucoid or alpha1-acid glycoprotein.
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Affiliation(s)
- Qiang Fu
- Faculty of Pharmaceutical Sciences, Mukogawa Women's University, 11-68, Koshien Kyuban-cho, Nishinomiya 663-8179, Japan
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23
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Inotsume N, Nakano M. Stereoselective determination and pharmacokinetics of dihydropyridines: an updated review. JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 2002; 54:255-74. [PMID: 12543503 DOI: 10.1016/s0165-022x(02)00120-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
All dihydropyridines, except nifedipine, have at least one chiral center, and their pharmacokinetics and clinical effects differ from one enantiomer to another. Chiral separation methods for dihydropyridines using chromatographic techniques are discussed. The stereoselective pharmacokinetics of dihydropyridine calcium antagonists were reviewed in detail in 1995. The present review article updates the methods for the stereoselective determination of dihydropyridines using chromatographic techniques and summarizes the pharmacokinetics of the dihydropyridines, including the newest drugs under development.
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Affiliation(s)
- Nobuo Inotsume
- Department of Pharmacology and Therapeutics, Hokkaido College of Pharmacy, 7-1 Katsuraoka-cho, Otaru 047-0264, Japan
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24
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Bojarski J. Stereoselective chromatography of cardiovascular drugs: an update. JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 2002; 54:197-220. [PMID: 12543499 DOI: 10.1016/s0165-022x(02)00143-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This review reports the latest achievements in chromatographic enantioseparations of various classes of cardiovascular drugs and selected applications of these methods in pharmaceutical and clinical analysis. The use of these drugs as test compounds for new chiral stationary phases and different parameters of chromatographic processes is also presented.
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Affiliation(s)
- Jacek Bojarski
- Department of Organic Chemistry, Medical College, Faculty of Pharmacy, Jagiellonian University, Medyczna 9, 30-688 Cracow, Poland.
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25
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Streel B, Lainé C, Zimmer C, Sibenaler R, Ceccato A. Enantiomeric determination of amlodipine in human plasma by liquid chromatography coupled to tandem mass spectrometry. JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 2002; 54:357-68. [PMID: 12543511 DOI: 10.1016/s0165-022x(02)00133-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A sensitive method for the separation and determination of amlodipine enantiomers in plasma has been developed based on solid-phase extraction (SPE) with disposable extraction cartridges (DECs) in combination with chiral liquid chromatography (LC). The SPE technique is used to isolate the drug from the biological matrix and to prepare a cleaner sample before injection and analysis by HPLC coupled to mass spectrometry. The DEC is filled with ethyl silica (50 mg) and is first conditioned with a 2.5% ammonia in methanol solution and then with ammonium acetate buffer. A 1.0-ml volume of plasma is then applied on the DEC. The washing step is first performed with ammonium acetate buffer and secondly with a mixture of water and methanol (65:35, v/v), while the final elution step is obtained by dispensing methanol containing 2.5% of ammonia. The eluate is then collected and evaporated to dryness before being dissolved in the LC mobile phase and injected into the LC system. The stereoselective analysis of amlodipine is achieved on a Chiral AGP column containing alpha(1)-acid glycoprotein as chiral selector by using a mobile phase consisting of a 10-mM acetate buffer (pH 4.5) and 1-propanol (99:1, v/v). The LC system is coupled to tandem mass spectrometry with an APCI interface in the positive-ion mode. The chromatographed analytes are detected in the selected reaction monitoring mode (SRM). The MS/MS ion transitions monitored are 409 to 238 for amlodipine, and 260 to 116 for S-(-)-propranolol used as internal standard (IS). The method was validated considering different parameters, such as linearity, precision and accuracy. The limit of quantitation was found to be 0.1 ng/ml for each amlodipine enantiomer.
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Affiliation(s)
- B Streel
- Galephar MF, 39 rue du Parc Industriel, B-6900 Marche-en-Famenne, Belgium
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26
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Sobolev A, Franssen MC, Poikans J, Duburs G, de Groot A. Enantioselective lipase-catalysed kinetic resolution of acyloxymethyl and ethoxycarbonylmethyl esters of 1,4-dihydroisonicotinic acid derivatives. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s0957-4166(02)00655-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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27
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Lindmark B, Ahnoff M, Persson BA. Enantioselective determination of felodipine in human plasma by chiral normal-phase liquid chromatography and electrospray ionisation mass spectrometry. J Pharm Biomed Anal 2002; 27:489-95. [PMID: 11755750 DOI: 10.1016/s0731-7085(01)00582-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An analytical method was developed for the determination of the enantiomers of felodipine, a dihydropyridine-type calcium antagonist, in human blood plasma. Felodipine was extracted from plasma using toluene as extraction solvent. The enantiomers were separated on a cellulose tris(4-methyl benzoate) stationary phase (Chiralcel OJ-R) using 2-propanol-iso-hexane (11:89) as mobile phase. Post-column addition of ammonium acetate in ethanol-water (95:5) allowed sensitive detection of the ammonium adduct by electrospray ionisation and selected reaction monitoring. Deuterated felodipine racemate was used as internal standard. Within-run repeatability was determined and a coefficient of variation below 2% was achieved at 22 nmol/l and below 10% at 0.27 nmol/l. Between-day precision was evaluated and a coefficient of variation of 3.6% at 4 nmol/l plasma was obtained. Limit of quantification (LOQ) was set at 0.25 nmol/l (0.10 microg/l). The method proved adequate for pharmacokinetic studies of R- and S-felodipine after oral administration of therapeutic doses of felodipine.
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Affiliation(s)
- Bo Lindmark
- DMPK & Bioanalytical Chemistry, AstraZeneca R&D Mölndal, SE-431 83 Mölndal, Sweden
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28
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Sobolev A, Franssen MC, Vigante B, Cekavicus B, Makarova N, Duburs G, de Groot A. An efficient chemoenzymatic approach to enantiomerically pure 4-[2-(difluoromethoxy)phenyl] substituted 1,4-dihydropyridine-3,5-dicarboxylates. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s0957-4166(02)00022-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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29
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Marques MP, Santos NA, Coelho EB, Bonato PS, Lanchote VL. Enantioselective assay of nisoldipine in human plasma by chiral high-performance liquid chromatography combined with gas chromatographic-mass spectrometry: applications to pharmacokinetics. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 2001; 762:87-95. [PMID: 11589462 DOI: 10.1016/s0378-4347(01)00352-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Nisoldipine, a second-generation dihydropyridine calcium antagonist, is a racemate compound used in the treatment of hypertension and coronary heart disease. This study presents an enantioselective HPLC-GC-MS method for the analysis of nisoldipine in human plasma and establishes confidence limits for its application to pharmacokinetic studies. Plasma samples were basified and extracted with toluene. The enantiomers were resolved on a Chiralcel OD-H column using hexane-ethanol (97.5:2.5, v/v) and the (+)- and (-)-fractions were collected separately with the diode array detector switched off. For the quantification of the nisoldipine enantiomers a GC-MS with an Ultra 1 Hewlett-Packard column was used with the detector operated in the single-ion monitoring mode with electron-impact ionization (m/z 371.35 and 270.20 for nisoldipine and m/z 360.00 for the internal standard, nitrendipine). The method proved to be suitable for pharmacokinetic studies based on the low quantification limit (0.05 ng/ml for each enantiomer) and the broad linear range (0.05-50.0 ng/ml for each enantiomer). Low coefficients of variation (<15%) were demonstrated for both within-day and between-day assays. No interference from drugs associated with nisoldipine treatment was observed. The enantioselective pilot study on the kinetic disposition of nisoldipine administered in the racemic form to a hypertensive patient using a multiple dose regimen revealed the accumulation of the (+)-enantiomer with an AUC(0-24) (+)/(-) ratio of approximately 8. Both enantiomers were quantified in plasma at a time interval of 24 h. This HPLC-GC-MS method is reliable, selective and sensitive enough to be used in clinical pharmacokinetic studies on the enantioselective disposition of nisoldipine in humans.
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Affiliation(s)
- M P Marques
- Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Brazil
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30
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Ericsson H, Schwieler J, Lindmark BO, Löfdahl P, Thulin T, Regårdh CG. Enantioselective pharmacokinetics of the enantiomers of clevidipine following intravenous infusion of the racemate in essential hypertensive patients. Chirality 2001; 13:130-4. [PMID: 11270321 DOI: 10.1002/1520-636x(2001)13:3<130::aid-chir1009>3.0.co;2-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The aim of the study was to characterize the individual pharmacokinetics of (-)-R- and (+)-S-clevidipine following intravenous constant rate infusion of rac-clevidipine to essential hypertensive patients. Twenty patients received three out of five randomized treatments with clevidipine. The pharmacokinetics of the separate enantiomers were evaluated by compartmental analysis of blood concentrations vs. time curves using the population approach. The derived pharmacokinetic parameters were used to simulate the time for 50 and 90% postinfusion decline following various infusion times of rac-clevidipine. A two-compartment model was used to describe the dispositions of the enantiomers; there were only minor differences between the estimated pharmacokinetic parameters of the separate enantiomers. The mean blood clearance values of (-)-R- and (+)-S-clevidipine were 0.103 and 0.096 l/min/kg, and the corresponding volumes of distribution at steady state were 0.39 and 0.54 l/kg, respectively. The context-sensitive half-time was approximately 2 min regardless of stereochemical configuration, and a 90% decline in concentration was achieved approximately 8 min postinfusion for (-)-R-clevidipine and 11 min for (+)-S-clevidipine, following clinically relevant infusion times with clevidipine. In conclusion, both enantiomers are high-clearance compounds with similar blood clearance values. The volume of distribution for the enantiomers is slightly different, presumably due to differences in the protein binding. From a pharmacokinetic point of view, the use of a single enantiomer as an alternative to the racemic clevidipine will not offer any clinical advantages.
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Affiliation(s)
- H Ericsson
- AstraZeneca, R&D Mölndal, Mölndal, Sweden.
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31
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Marinkovic V, Agbaba D, Vladimirov S, Stankovic S. Simultaneous HPLC determination of nitrendipine and impurities of the process of synthesis. J Pharm Biomed Anal 2001; 24:993-8. [PMID: 11248493 DOI: 10.1016/s0731-7085(00)00531-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A method has been developed for separation of nitrendipine and its impurities of reaction partners and side reaction products by high-performance liquid chromatographic method on a RP-18 column and detection at 238 nm. The mobile phase composition that provided an acceptable nitrendipine resolution, in large excess and possible impurities, in a short elution time, is methanol:water (70:30) and pH 3. Linearity (r> or =0.999), reproducibility (RSD=0.8--1.4%), determination limit (0.5--2%) and recovery (99.8--102.3) were validated and found to be satisfactory. This method enables monitoring of the process of synthesis, as well as the choice of the synthetic design.
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Affiliation(s)
- V Marinkovic
- A.D. Zdravlje, Pharmaceutical and Chemical Industry, 16000 Leskovac, Serbia, Yugoslavia
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Vincent J, Harris SI, Foulds G, Dogolo LC, Willavize S, Friedman HL. Lack of effect of grapefruit juice on the pharmacokinetics and pharmacodynamics of amlodipine. Br J Clin Pharmacol 2000; 50:455-63. [PMID: 11069440 PMCID: PMC2014412 DOI: 10.1046/j.1365-2125.2000.00283.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AIMS To determine whether repeated once daily administration of grapefruit juice altered the pharmacokinetics or pharmacodynamics of the calcium antagonist amlodipine. METHOD S The effects of grapefruit juice on the pharmacokinetics and pharmacodynamics of oral and intravenous amlodipine were assessed in 20 healthy men in a placebo-controlled, open, randomized, four-way crossover study using single doses of amlodipine 10 mg. For 9 days beginning with the day of administration of amlodipine, grapefruit juice (or water control) was given once daily, and blood samples, blood pressure and heart rate measures were obtained. Plasma concentrations of amlodipine and its enantiomers were determined in separate assays by GC-ECD. RESULTS Oral amlodipine had high systemic availability (grapefruit juice: 88%; water: 81%). Pharmacokinetic parameters of racemic amlodipine (AUC, Cmax, tmax, and kel) were not markedly changed with grapefruit juice coadministration. Total plasma clearance and volume of distribution, calculated after intravenous amlodipine, were essentially unchanged by grapefruit juice (CL 6.65 ml min-1 kg-1, juice vs 6.93 ml min-1 kg-1, water; Vdss 22.7 l kg-1, juice vs 21.0 l kg-1, water). Grapefruit juice coadministration did not greatly alter the stereoselectivity in amlodipine oral or intravenous kinetics. The sum of S(-) and R(+) enantiomer concentrations correlated well with total racemic amlodipine concentration (r2 = 0. 957; P = 0.0001). Coadministration of grapefruit juice with either route of amlodipine administration did not significantly alter blood pressure changes vs control. CONCLUSIONS Grapefruit juice has no appreciable effect on amlodipine pharmacodynamics or pharmacokinetics, including its stereoselective kinetics. Bioavailability enhancement by grapefruit juice, noted with other dihydropyridine calcium antagonists, does not occur with amlodipine. Once daily grapefruit juice administration with usual oral doses of amlodipine is unlikely to alter the profile of response in clinical practice.
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Affiliation(s)
- J Vincent
- Clinical Pharmacology Division, Pfizer Central Research, Groton, CT 06340, USA
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Christians T, Holzgrabe U. Enantioseparation of dihydropyridine derivatives by means of neutral and negatively charged beta-cyclodextrin derivatives using capillary electrophoresis. Electrophoresis 2000; 21:3609-17. [PMID: 11271478 DOI: 10.1002/1522-2683(200011)21:17<3609::aid-elps3609>3.0.co;2-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Employing capillary electrophoresis, the racemates of 29 acidic, neutral and basic dihydropyridines (DHPs) were separated by means of neutral and negatively charged cyclodextrins (CDs). Whereas the enantiomers of the acidic DHPs could be resolved with neutral CDs, mostly alpha- and beta-CD, the enantiomers of the neutral DHPs were only baseline-separated using the sulfobutyl ether-substituted beta-CD. Working in reversed polarity mode (detector at the anode) improved the peak shape and the resolution of the enantiomers. The racemates of the DHP bearing a secondary or tertiary amine function in the side chain at position 3 could be separated by using either the neutral gamma-CD or negatively charged CDs. The poor peak shape found with anionic CDs could be improved by the addition of methanol. The combination of gamma-CD and sulfated beta-CD allowed the detection of the minor enantiomer of lercanidipine (24) at less than 1% w/w.
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Affiliation(s)
- T Christians
- Pharmaceutical Institute, University of Bonn, Germany
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Rask HS, Angelo HR, Christensen HR. Enantioselective determination of isradipine in human serum using chiral stationary phase liquid chromatography and gas chromatography with nitrogen selective detection. Chirality 2000; 10:808-12. [PMID: 9839430 DOI: 10.1002/(sici)1520-636x(1998)10:9<808::aid-chir6>3.0.co;2-h] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
rac-Isradipine is a dihydropyridine type calcium antagonist. Its calcium entry blocking effect is due primarily to the (+)-(S)-enantiomer. This study describes a sensitive enantioselective method for the determination of isradipine in human serum. Following alkaline extraction into hexane, the enantiomers of isradipine are separated quantitatively by high-performance liquid chromatography on a Chiralcel OJ column at 39 degrees C. The collected fractions were evaporated and assayed using capillary gas chromatography on a HP 50+ column with nitrogen selective detection. Using 2.0 ml of serum, 0.7 nmol/1 (0.26 ng/ml) of each enantiomer could be determined with acceptable precision. The method has successfully been used to measure (+)-(S)- and (-)-(R)-isradipine concentrations in samples from volunteers after intravenous and oral administration of isradipine.
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Affiliation(s)
- H S Rask
- Department of Clinical Biochemistry, Bispebjerg Hospital, Copenhagen, Denmark
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35
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Maurer HH. Systematic toxicological analysis procedures for acidic drugs and/or metabolites relevant to clinical and forensic toxicology and/or doping control. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1999; 733:3-25. [PMID: 10572972 DOI: 10.1016/s0378-4347(99)00266-2] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
This paper reviews systematic toxicological analysis (STA) procedures for acidic drugs and/or metabolites relevant to clinical and forensic toxicology or doping control using gas chromatography, gas chromatography-mass spectrometry, liquid chromatography, thin-layer chromatography and capillary electrophoresis. Papers from 1992 to 1998 have been taken into consideration. Screening procedures in biosamples (whole blood, plasma, serum, urine, vitreous humor, brain, liver or hair) of humans or animals (horse, or rat) are included for the following drug classes: angiotensin-converting enzyme (ACE) inhibitors and angiotensin II (AT-II) blockers, anticoagulants of the 4-hydroxy coumarin type, barbiturates, dihydropyridine calcium channel blockers (calcium antagonists), diuretics, hypoglycemic sulfonylureas and non-steroidal anti-inflammatory drugs (NSAIDs). Methods for confirmation of preliminary results obtained by screening procedures using immunoassay or chromatographic techniques are also included. Furthermore, procedures for the simultaneous detection of several drug classes are reviewed. The toxicological question to be answered and the consequences for the choice of an adequate method, the sample preparation and the chromatography itself are discussed. The basic information about the biosample assayed, work-up, separation column, mobile phase or separation buffer, detection mode and validation data of each procedure is summarized in 16 tables. They are arranged according to the drug class and the analytical method. Examples of typical applications are presented. Finally, STA procedures are reviewed and described allowing simultaneous screening for different (acidic) drug classes.
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Affiliation(s)
- H H Maurer
- Department of Toxicology, Institute of Pharmacology and Toxicology, University of Saarland, Homburg (Saar), Germany.
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36
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Visentin S, Amiel P, Gasco A, Bonnet B, Suteu C, Roussel C. Resolution of some 4-benzofurazanyl and 4-benzofuroxanyl 1, 4-dihydropyridine derivatives by chiral HPLC on whelk-o1 and some polysaccharide chiral stationary phases. Chirality 1999; 11:602-8. [PMID: 10423289 DOI: 10.1002/(sici)1520-636x(1999)11:7<602::aid-chir14>3.0.co;2-q] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The chromatographic chiral resolution of racemic methyl 1, 4-dihydro-2,6-dimethyl-5-nitro-4-benzofurazanyl-3-carboxylates 1 and 2 and their benzofuroxanyl analogues 3 and 4 were studied on Whelk-O1, Chiralcel OD-H, Chiralcel OJ, and Chiralpak AD and AS. These CSPs were selected on the basis of the results of structural searches in Chirbase. Examination of the data and cluster analysis pointed out the influence of benzofurazane-benzofuroxane change versus alpha-beta connection change on retention and enantioselectivity, respectively. The major contribution to the retention change arose from the type of heterocycle, whereas the major contribution to the enantioselectivity change came from the mode of connection (alpha or beta) almost irrespective of the nature of the heterocycle. It resulted in a similarity of behaviour between 1 and 2 on one hand and 3 and 4 on the other as far as capacity factors were concerned, and in a similarity of behaviour between 1 and 3 on the one hand and 2 and 4 on the other as far as enantioselectivities were concerned. Chiralpak AS was selected for semipreparative resolution of the enantiomers. The study of several CSPs allowed us to obtain correlations of structure with retention and enantioselectivity as well as the choice of a semipreparative support to provide the quantities for biological tests. Copyright 1999 Wiley-Liss, Inc.
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Affiliation(s)
- S Visentin
- Dipartimento di Scienza e Tecnologia del Farmaco, Universita degli Studi di Torino, Facolta di Farmacia, Via P. Giuria 9, 10125, Torino, Italy
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37
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Abstract
The chromatographic and electrophoretic enantiomeric separation and analysis of several clinically used cardiovascular drugs have been reviewed. Several examples of recently reported applications of enantioselective analysis and various cardiovascular agents are presented.
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Affiliation(s)
- J Bojarski
- Department of Organic Chemistry, College of Medicine, Jagiellonian University, Krakow, Poland
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38
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Abstract
Understanding the mechanism of action and the pharmacokinetic properties of vasodilatory drugs facilitates optimal use in clinical practice. It should be kept in mind that a drug belongs to a class but is a distinct entity, sometimes derived from a prototype to achieve a specific effect. The most common pharmacokinetic drug improvement is the development of a drug with a half-life sufficiently long to allow an adequate once-daily dosage. Developing a controlled release preparation can increase the apparent half-life of a drug. Altering the molecular structure may also increase the half-life of a prototype drug. Another desirable improvement is increasing the specificity of a drug, which may result in fewer adverse effects, or more efficacy at the target site. This is especially important for vasodilatory drugs which may be administered over decades for the treatment of hypertension, which usually does not interfere with subjective well-being. Compliance is greatly increased with once-daily dosing. Vasodilatory agents cause relaxation by either a decrease in cytoplasmic calcium, an increase in nitric oxide (NO) or by inhibiting myosin light chain kinase. They are divided into 9 classes: calcium antagonists, potassium channel openers, ACE inhibitors, angiotensin-II receptor antagonists, alpha-adrenergic and imidazole receptor antagonists, beta 1-adrenergic agonist, phosphodiesterase inhibitors, eicosanoids and NO donors. Despite chemical differences, the pharmacokinetic properties of calcium antagonists are similar. Absorption from the gastrointestinal tract is high, with all substances undergoing considerable first-pass metabolism by the liver, resulting in low bioavailability and pronounced individual variation in pharmacokinetics. Renal impairment has little effect on pharmacokinetics since renal elimination of these agents is minimal. Except for the newer drugs of the dihydropyridine type, amlodipine, felodipine, isradipine, nilvadipine, nisoldipine and nitrendipine, the half-life of calcium antagonists is short. Maintaining an effective drug concentration for the remainder of these agents requires multiple daily dosing, in some cases even with controlled release formulations. However, a coat-core preparation of nifedipine has been developed to allow once-daily administration. Adverse effects are directly correlated to the potency of the individual calcium antagonists. Treatment with the potassium channel opener minoxidil is reserved for patients with moderately severe to severe hypertension which is refractory to other treatment. Diazoxide and hydralazine are chiefly used to treat severe hypertensive emergencies, primary pulmonary and malignant hypertension and in severe preeclampsia. ACE inhibitors prevent conversion of angiotensin-I to angiotensin-II and are most effective when renin production is increased. Since ACE is identical to kininase-II, which inactivates the potent endogenous vasodilator bradykinin, ACE inhibition causes a reduction in bradykinin degradation. ACE inhibitors exert cardioprotective and cardioreparative effects by preventing and reversing cardiac fibrosis and ventricular hypertrophy in animal models. The predominant elimination pathway of most ACE inhibitors is via renal excretion. Therefore, renal impairment is associated with reduced elimination and a dosage reduction of 25 to 50% is recommended in patients with moderate to severe renal impairment. Separating angiotensin-II inhibition from bradykinin potentiation has been the goal in developing angiotensin-II receptor antagonists. The incidence of adverse effects of such an agent, losartan, is comparable to that encountered with placebo treatment, and the troublesome cough associated with ACE inhibitors is absent.
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Affiliation(s)
- R Kirsten
- Department of Clinical Pharmacology, University of Frankfurt, Germany
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39
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Anderson DJ, Guo B, Xu Y, Ng LM, Kricka LJ, Skogerboe KJ, Hage DS, Schoeff L, Wang J, Sokoll LJ, Chan DW, Ward KM, Davis KA. Clinical chemistry. Anal Chem 1997; 69:165R-229R. [PMID: 9195857 DOI: 10.1021/a1970008p] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- D J Anderson
- Department of Chemistry, Cleveland State University, Ohio 44115, USA
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40
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Langtry HD, Spencer CM. Nisoldipine coat-core. A review of its pharmacodynamic and pharmacokinetic properties and clinical efficacy in the management of ischaemic heart disease. Drugs 1997; 53:867-84. [PMID: 9129871 DOI: 10.2165/00003495-199753050-00013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Nisoldipine coat-core is an extended-release once-daily formulation of a dihydropyridine calcium antagonist effective in the treatment of chronic stable angina pectoris. With immediate-release formulations of nisoldipine, plasma drug concentrations that produce therapeutic effects result rapidly, but are not sustained and do not maintain the effects throughout a 12-hour dosage interval. In contrast, with nisoldipine coat-core, a gradual increase in plasma nisoldipine concentrations occurs over 12 hours and therapeutic concentrations are then maintained for the duration of a 24-hour dosage interval. In dosages of 10 to 60 mg once daily, nisoldipine coat-core controls symptoms of angina and improves exercise-induced signs of ischaemia in patients with stable angina. Compared with placebo, daily nisoldipine coat-core doses of > or = 20 mg provide statistically significant increases in total exercise time and time to produce angina and a trend towards an increase in the time to produce 1 mm ST segment depression, in exercise tests conducted approximately 23 hours postdose. When administered in 20 and 40 mg daily doses, nisoldipine coat-core produces improvements in exercise test parameters that are similar to those seen with amlodipine 5 or 10 mg/day or regular-release or sustained-release (SR) diltiazem 240 mg/day. The frequency of daily angina attacks and consumption of short-acting nitrates are also reduced by nisoldipine to a similar extent to that observed with these other agents. After longer term (1 year) administration of 10 to 60 mg daily, improvements in exercise test parameters are maintained, with equivalent anti-ischaemic efficacy seen in patients receiving nisoldipine coat-core alone or with background nitrate or beta-blocker therapy. Adverse events associated with nisoldipine coat-core are typical of the dihydropyridine class of calcium antagonists, with peripheral oedema and headache being most common. Nisoldipine coat-core appears to be associated with fewer deaths than placebo, notably in the DEFIANT-II (Doppler Flow and Echocardiography in Functional Cardiac Insufficiency: Assessment of Nisoldipine Therapy II) study, where only 1 death occurred with nisoldipine compared with 7 in the placebo group. Nisoldipine should not be taken during phenytoin therapy. In addition, grapefruit juice should be avoided during nisoldipine therapy and nisoldipine should not be taken concurrently with high-fat meals. Thus, the coat-core formulation of nisoldipine appears to have overcome the limitations of the shorter duration of action of immediate-release nisoldipine. Nisoldipine coat-core is well tolerated and once-daily administration produces a long duration of effective anti-ischaemic relief in patients with chronic stable angina pectoris.
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Affiliation(s)
- H D Langtry
- Adis International Limited, Auckland, New Zealand.
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41
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Schall R, Müller FR, Müller FO, Luus HG. Bioequivalence of controlled-release calcium antagonists. Clin Pharmacokinet 1997; 32:75-89. [PMID: 9012557 DOI: 10.2165/00003088-199732010-00004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In this review, several deficiencies of published bioequivalence studies for controlled-release calcium antagonists have become apparent. As a consequence, some of the published conclusions based on such studies must be viewed with care. A proper statistical analysis of bioequivalence is not frequently reported. A proper statistical analysis of the pharmacokinetic variables involves the calculation of 90% confidence intervals (CI) for the test: reference ratio of the means of the pharmacokinetic variables of the test and reference product. The CI must fall completely within the predetermined bioequivalence range (usually 0.8 to 1.25) for the products to be declared bioequivalent. Serious methodological errors, such as a conclusion of bioequivalence based on a lack of statistically significant difference between products, and conversely, a conclusion of bioequivalence because of a statistically significant difference, or because of a mere failure to show bioequivalence, are still made. With calcium antagonists in particular, an assessment of the rate of absorption and of the maximum concentration is important, as those characteristics may have implications for the safety profile with this class of drugs. As a minimum, in single doses studies the maximum concentration (Cmax), and the time to the maximum concentration (tmax), and in multiple-dose studies the Cmax, and the peak-trough fluctuation (%PTF) must be considered. Some bioequivalence studies of calcium antagonists are deficient in this respect. To show bioequivalence for controlled-release formulations, multiple-dose studies are required but some published bioequivalence studies contain only single-dose assessments. Similarly, bioequivalence studies under fed conditions are rarely published, although food may have a significant effect on the absorption rate of these drugs. Some calcium antagonists, such as verpamil, show stereo-selective pharmacokinetics, so that enantiomers may have to be investigated. Unfortunately, few of the published studies of controlled-release calcium antagonists satisfy all requirements. One would expect that data submitted to regulatory authorities for approval of generic formulations are more complete; published data are in many cases not satisfactory.
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Affiliation(s)
- R Schall
- FARMOVS Research Centre for Clinical Pharmacology and Drug Development, Department of Pharmacology, University of the Orange Free State, Bloemfontein, South Africa.
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42
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Josefsson M, Norlander B. Coupled-column chromatography on a Chiral-AGP phase for determination of amlodipine enantiomers in human plasma: an HPLC assay with electrochemical detection. J Pharm Biomed Anal 1996; 15:267-77. [PMID: 8933429 DOI: 10.1016/0731-7085(96)01836-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A sensitive enantioselective high performance liquid chromatographic assay for determination of the dihydropyridine-type calcium antagonist amlodipine in human plasma samples is described. Chiral chromatography is performed on an alpha 1-acid glycoprotein column (i.e. Chiral-AGP) and the eluted enantiomers are trapped and compressed on two short columns before final achiral chromatography on a narrow bore column (i.e. Zorbax SB-Ph) using electrochemical detection. Both stereoselective quantitative analysis and enantiomeric ratio analysis, for samples with a known total concentration of amlodipine are described. The quantitative assay shows linearity over the range 0.5-10 ng ml-1 for the two enantiomers and the limit of detection is about 0.2 ng ml-1. The method has been applied to a pharmacokinetic study of the enantiomers of amlodipine in human subjects.
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Affiliation(s)
- M Josefsson
- Department of Clinical Pharmacology, Faculty of Health Sciences, Linköping University, Sweden
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43
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Abstract
The principles and applications of chromatographic separation of enantiomers in pharmaceutical analysis have been reviewed. Several of recently reported enantioselective analysis of various racemic drugs using both the 'indirect' and 'direct' methods have been presented.
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Affiliation(s)
- J Bojarski
- Department of Organic Chemistry, College of Medicine, Jagiellonian University, Krakow, Poland
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44
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Dorsey JG, Cooper WT, Siles BA, Foley JP, Barth HG. Liquid Chromatography: Theory and Methodology. Anal Chem 1996. [DOI: 10.1021/a19600202] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- John G. Dorsey
- Department of Chemistry, Florida State University, Tallahassee, Florida 32306-3006
| | - William T. Cooper
- Department of Chemistry, Florida State University, Tallahassee, Florida 32306-3006
| | - Barbara A. Siles
- Department of Chemistry, College of William and Mary, Williamsburg, Virginia 23187-8795
| | - Joe P. Foley
- Department of Chemistry, Villanova University, Villanova, Pennsylvania 19085-1699
| | - Howard G. Barth
- Central Research and Development Department, E. I. du Pont de Nemours & Company, P. O. Box 80228, Experimental Station, Wilmington, Delaware 19880
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45
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Gilar M, Uhrová M, Tesarová E. Enantiomer separation of dihydropyridine calcium antagonists with cyclodextrins as chiral selectors: structural correlation. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1996; 681:133-41. [PMID: 8798922 DOI: 10.1016/0378-4347(95)00556-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Native and substituted cyclodextrins (CDs) were used as chiral selectors both in high-performance liquid chromatography and capillary electromigration separations (HPCE and MEKC). Chromatographic data of five dihydropyridine calcium antagonists obtained on three beta-CD chiral stationary phases in reversed-phase mode were compared with those of capillary electrophoresis using beta-CDs in the presence and absence of sodium dodecyl sulfate (SDS). Competition of separated compounds with SDS molecules for penetration into the CD cavity can limit their necessary interaction with the chiral selector and consequently even preclude enantiomer separation. Some insight into this problem can be brought about by comparing the experimental data with computer-aided energy minimization of CD-solute and CD-SDS inclusion complexes.
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Affiliation(s)
- M Gilar
- Department of Analytical Chemistry, Institute of Chemical Technology, Prague, Czech Republic
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46
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Caccamese S, Chillemi R, Principato G. Fluorenone 1,4-dihydropyridine derivatives with cardiodepressant activity: enantiomeric separation by chiral HPLC and conformational aspects. Chirality 1996; 8:281-90. [PMID: 8777149 DOI: 10.1002/(sici)1520-636x(1996)8:3<281::aid-chir8>3.0.co;2-k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The direct HPLC enantiomeric separation of five fluorenone-1,4-dihydropyridine-3,5-dicarboxylic diesters has been achieved using a Chiralpak AD stationary phase obtaining simultaneously good enantioselectivities, resolution factors, and elution times. CD spectra of the individual enantiomers for two compounds were measured. Thermodynamic parameters associated with the adsorption equilibria of the enantiomers with the chiral stationary phase were obtained from HLPC runs at various temperatures. The conformational preferences of the synperiplanar fluorenone group and of the cis/cis ester groups were obtained by 1H NMR spectra, including NOE experiments.
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Affiliation(s)
- S Caccamese
- Dipartimento di Scienze Chimiche, Università di Catania, Italy
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