The Experts below are selected from a list of 42 Experts worldwide ranked by ideXlab platform

Jun Haginaka - One of the best experts on this subject based on the ideXlab platform.

  • uniform sized molecularly imprinted polymers for 2 arylpropionic Acid derivatives selectively modified with hydrophilic external layer and their applications to direct serum injection analysis
    Analytical Chemistry, 2000
    Co-Authors: Jun Haginaka, Haruyo Sanbe
    Abstract:

    Uniform-sized molecularly imprinted polymers (MIPs) for (S)-naproxen and -ibuprofen selectively modified with hydrophilic external layer, restricted access media (RAM)-MIPs, have been prepared. First, the MIP for (S)-naproxen or -ibuprofen was prepared using 4-vinylpyridine and ethylene glycol dimethacrylate as a functional monomer and cross-linker, respectively, by a multistep swelling and thermal polymerization method. Next, a 1:1 mixture of glycerol monomethacrylate and glycerol dimethacrylate was used for hydrophilic surface modification, and it was added directly to the MIP for (S)-naproxen or -ibuprofen 4 h after the start of molecular imprinting. The obtained RAM-MIP material for (S)-naproxen or -ibuprofen was applied for direct serum injection assays of the drug by a column-switching system, consisting of a RAM-MIP material and conventional C18-silica column. However, leakage of the imprint molecule prevented accurate and precise assays of the drug. This problem has been overcome by using the RAM-MIP for (S)-naproxen for the assays of ibuprofen in rat plasma. The optimized column-switching system was applied successfully to the assay of ibuprofen in rat plasma after oral administration.

  • molecularly imprinted uniform sized polymer based stationary phase for naproxen comparison of molecular recognition ability of the molecularly imprinted polymers prepared by thermal and redox polymerization techniques
    Journal of Chromatography A, 1998
    Co-Authors: Jun Haginaka, Ken Hosoya, Hisako Takehira, Nobuo Tanaka
    Abstract:

    A molecularly imprinted uniform-sized polymer-based stationary phase for (S)-naproxen has been prepared by a multi-step swelling and thermal or redox polymerization method using 4-vinylpyridine and ethylenedimethacrylate as a host functional monomer and cross-linker, respectively. The obtained molecularly imprinted polymers were evaluated using aqueous-rich mobile phases. The molecularly imprinted polymer materials could separate naproxen enantiomers. Further, the materials showed high selectivity for naproxen and moderate selectivity for other 2-Arylpropionic Acid derivatives. On the other hand, the molecularly imprinted polymer materials showed little selectivity for other Acidic compounds, and basic and neutral compounds. With regard to comparison of the molecularly imprinted polymers prepared by thermal and redox polymerization techniques, the latter materials gave higher retentivity and enantioselectivity than the former materials, while the former materials gave higher column efficiency than the latter materials. Thus, naproxen enantiomers were resolved much better on the molecularly imprinted polymer material prepared by a thermal polymerization method.

Neal M. Davies - One of the best experts on this subject based on the ideXlab platform.

  • clinical pharmacokinetics of tiaprofenic Acid and its enantiomers
    Clinical Pharmacokinectics, 1996
    Co-Authors: Neal M. Davies
    Abstract:

    Tiaprofenic Acid is a chiral nonsteroidal anti-inflammatory drug (NSAID) of the 2-Arylpropionic Acid (2-APA) class. A common structural feature of 2-APA NSAIDs is a sp3-hybridised tetrahedral chiral carbon heteroatom within the propionic Acid side chain moiety, with the S-enantiomer possessing most of the beneficial anti-inflammatory activity. However, all tiaprofenic Acid preparations to date are marketed as the racemate. Tiaprofenic Acid has been suggested to exhibit limited pharmacokinetic stereoselectivity.

  • Clinical Pharmacokinetics of Flurbiprofen and Its Enantiomers
    Clinical pharmacokinetics, 1995
    Co-Authors: Neal M. Davies
    Abstract:

    Flurbiprofen is a chiral nonsteroidal anti-inflammatory drug (NSAID) of the 2-Arylpropionic Acid class. Although it possesses a chiral centre, with the S-(+)-enantiomer possessing most of the beneficial anti-inflammatory activity, both enantiomers may possess analgesic activity and all flurbiprofen preparations to date are marketed as the racemate. Flurbiprofen exhibits stereoselectivity in its pharmacokinetics. Stereoselectivity is exhibited at the level of protein binding and metabolite formation. Hence, the data generated using nonstereoselective assays may not be used to explain the pharmacokinetics of individual enantiomers.

Nobuo Tanaka - One of the best experts on this subject based on the ideXlab platform.

  • molecularly imprinted uniform sized polymer based stationary phase for naproxen comparison of molecular recognition ability of the molecularly imprinted polymers prepared by thermal and redox polymerization techniques
    Journal of Chromatography A, 1998
    Co-Authors: Jun Haginaka, Ken Hosoya, Hisako Takehira, Nobuo Tanaka
    Abstract:

    A molecularly imprinted uniform-sized polymer-based stationary phase for (S)-naproxen has been prepared by a multi-step swelling and thermal or redox polymerization method using 4-vinylpyridine and ethylenedimethacrylate as a host functional monomer and cross-linker, respectively. The obtained molecularly imprinted polymers were evaluated using aqueous-rich mobile phases. The molecularly imprinted polymer materials could separate naproxen enantiomers. Further, the materials showed high selectivity for naproxen and moderate selectivity for other 2-Arylpropionic Acid derivatives. On the other hand, the molecularly imprinted polymer materials showed little selectivity for other Acidic compounds, and basic and neutral compounds. With regard to comparison of the molecularly imprinted polymers prepared by thermal and redox polymerization techniques, the latter materials gave higher retentivity and enantioselectivity than the former materials, while the former materials gave higher column efficiency than the latter materials. Thus, naproxen enantiomers were resolved much better on the molecularly imprinted polymer material prepared by a thermal polymerization method.

Haruyo Sanbe - One of the best experts on this subject based on the ideXlab platform.

  • uniform sized molecularly imprinted polymers for 2 arylpropionic Acid derivatives selectively modified with hydrophilic external layer and their applications to direct serum injection analysis
    Analytical Chemistry, 2000
    Co-Authors: Jun Haginaka, Haruyo Sanbe
    Abstract:

    Uniform-sized molecularly imprinted polymers (MIPs) for (S)-naproxen and -ibuprofen selectively modified with hydrophilic external layer, restricted access media (RAM)-MIPs, have been prepared. First, the MIP for (S)-naproxen or -ibuprofen was prepared using 4-vinylpyridine and ethylene glycol dimethacrylate as a functional monomer and cross-linker, respectively, by a multistep swelling and thermal polymerization method. Next, a 1:1 mixture of glycerol monomethacrylate and glycerol dimethacrylate was used for hydrophilic surface modification, and it was added directly to the MIP for (S)-naproxen or -ibuprofen 4 h after the start of molecular imprinting. The obtained RAM-MIP material for (S)-naproxen or -ibuprofen was applied for direct serum injection assays of the drug by a column-switching system, consisting of a RAM-MIP material and conventional C18-silica column. However, leakage of the imprint molecule prevented accurate and precise assays of the drug. This problem has been overcome by using the RAM-MIP for (S)-naproxen for the assays of ibuprofen in rat plasma. The optimized column-switching system was applied successfully to the assay of ibuprofen in rat plasma after oral administration.

Su Zeng - One of the best experts on this subject based on the ideXlab platform.

  • enantiomeric separation of 2 arylpropionic Acid nonsteroidal anti inflammatory drugs and β blockers by rp hplc using an amylose chiral stationary phase for the enantioselective skin permeation study
    Analytical Methods, 2014
    Co-Authors: Liang Zhang, Zhengrong Shen, Yi Rong, Xia Guo, Su Zeng
    Abstract:

    The enantioselectivities of eight 2-Arylpropionic Acid nonsteroidal anti-inflammatory drugs (2-APA NSAIDs) and two β-blockers on an amylose-tris(3,5-dimethylphenylcarbamate)-based Chiralpak AD-RH (150 × 4.6 mm, 5 μm) column were studied in reverse phase (RP) elution mode. The influencing factors such as mobile phase composition, organic modifiers, and column temperature were investigated. For most of the selected NSAIDs, baseline enantioseparation was achieved using a mobile phase composition of acetonitrile–0.05% trifluoroacetic Acid aqueous solution. For the β-blockers, baseline enantioseparation was achieved using a mobile phase composition of acetonitrile–borate buffer solution with 0.1% triethylamine (pH 9.0; 10 mM). Our study has demonstrated for the first time that the addition of an organic modifier, ethanol, in the mobile phase dramatically improves the resolution of the analytes such as flurbiprofen, suprofen, propranolol and metoprolol under reverse phase chromatographic conditions. The methods for the enantioselective determination of ibuprofen, flurbiprofen and propranolol were validated. The enantioselective skin permeation studies of propranolol hydrochloride presented here showed that there was no observable enantioselective permeation of propranolol across the excised rat skin, but L-linalool, a chiral enhancer, resulted in enhanced enantioselectivity, with a better permeation enhancing effect on R-propranolol than on S-propranolol and RS-propranolol across the excised rat skin.

  • enantiomeric separation of 2 arylpropionic Acid nonsteroidal anti inflammatory drugs by hplc with hydroxypropyl beta cyclodextrin as chiral mobile phase additive
    Biomedical Chromatography, 2010
    Co-Authors: Guosheng Chen, Zhengrong Shen, Su Zeng
    Abstract:

    The enantio-separations of eight 2-Arylpropionic Acid nonsteroidal anti-inflammatory drugs (2-APA NSAIDs) were established using reversed-phase high-performance liquid chromatography with hydroxypropyl-beta-cyclodextrin (HP-beta-CD) as chiral mobile phase additive for studying the stereoselective skin permeation of suprofen, ketoprofen, naproxen, indoprofen, fenoprofen, furbiprofen, ibuprofen and carprofen. The effects of the mobile phase composition, concentration of HP-beta-CD and column temperature on retention and enantioselective separation were investigated. With 2-APA NSAIDs as Acidic analytes, the retention times and resolutions of the enantiomers were strongly related to the pH of the mobile phase. In addition, both the concentration of HP-beta-CD and temperature had a great effect on retention time, but only a slight or almost no effect on resolutions of the analytes. Enantioseparations were achieved on a Shimpack CLC-ODS (150 x 4.6 mm i.d., 5 microm) column. The mobile phase was a mixture of methanol and phosphate buffer (pH 4.0-5.5, 20 mM) containing 25 mM HP-beta-CD. This method was flexible, simple and economically advantageous over the use of chiral stationary phase, and was successfully applied to the enantioselective determination of the racemic 2-APA NSAIDs in an enantioselective skin permeation study.