Publications by authors named "Hironari Tanaka"

Article Synopsis
  • The study investigates how plasma levels of the drug vonoprazan and its metabolic activity vary among patients with digestive disorders, aiming to identify factors influencing these variations.
  • A total of 53 patients were analyzed, revealing significant individual differences in plasma vonoprazan levels, which were influenced by dosing and metabolic ratios.
  • The findings suggest that while genetic variants in CYP3A5 and ABCB1 had no impact on plasma vonoprazan concentrations, CYP3A activity indicated by plasma 4β-OHC levels partially accounted for the observed variations.
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This study aimed to evaluate the influence of CYP2D6 activity and cachexia progression on the enantiomeric alteration of plasma tramadol and its demethylated metabolites in head and neck cancer patients. Fifty-three head and neck cancer patients receiving oral tramadol were enrolled. The plasma concentrations of tramadol, O-desmethyltramadol (ODT) and N-desmethyltramadol (NDT) enantiomers were determined.

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Article Synopsis
  • This study developed a new method for measuring tramadol and its metabolites in human plasma using liquid chromatography and mass spectrometry.
  • The method was validated with plasma samples from 20 cancer patients, showing different plasma concentrations for the enantiomers of tramadol and its metabolites.
  • The research found that while the CYP2D6 enzyme plays a role in the metabolism of tramadol, there were no significant differences in the plasma levels of the two forms of one of its metabolites.
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Purpose: Clinical responses to oral tramadol show a large variation in cancer patients. This study aimed to evaluate the impacts of cytochrome P450 (CYP) genotype and serum inflammatory markers on the plasma concentrations of tramadol and its demethylated metabolites and drug tolerability in cancer patients.

Methods: The predose plasma concentrations of tramadol and its demethylated metabolites were determined at day 4 or later in 70 Japanese cancer patients treated with oral tramadol.

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Plinabulin and KPU-300 are promising anti-microtubule agents; however, the low water solubility of these compounds (<0.1µg/mL) has limited their pharmaceutical advantages. Here, we developed five water-soluble derivatives of plinabulin and KPU-300 with a click strategy using disodium salts of amino acids.

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A PDMS microfluidic chip with T-junction channel geometry, two inlet reservoirs, and one outlet reservoir was reversibly adhered on a glass plate through the viscoelastic properties of PDMS. This formed a detachable microfluidic device for creation of water-in-oil emulsion droplets that were used as discrete reaction compartments for the droplet digital PCR. The PDMS/glass device could continuously produce monodisperse droplets without leakage of fluids using a vacuum-driven autonomous micropumping method.

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Background: This study aimed to develop a simultaneous determination method for tramadol and its desmethylates in human plasma using isocratic liquid chromatography coupled to tandem mass spectrometry and to validate it for pharmacokinetic evaluation in patients with cancer pain or non-cancer pain.

Methods: The pretreatments for human plasma involved protein precipitation using acetonitrile and methanol under basic conditions. Tramadol, -desmethylate, -desmethylate, and -didesmethylate were separated on an octadecylsilyl column filled with 3-μm particles using isocratic mixture of methanol and 0.

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A fully autonomous method of creating highly monodispersed emulsion droplets with a low sample dead volume was realized using a degassed poly(dimethylsiloxane) (PDMS) microfluidic chip possessing a simple T-junction channel geometry with two inlet reservoirs for oil and water to be loaded and one outlet reservoir for the collection of generated droplets. Autonomous transport of oil and water phases in the channel was executed by permeation of air confined inside the outlet reservoir into the degassed PDMS. The only operation required for droplet creation was simple pipetting of oil and aqueous solutions into the inlet reservoirs.

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Plinabulin (1) is a potent anti-microtubule agent, however, its low water solubility has to be improved for the advantage in pharmacokinetics and chemotherapy. In this report, the replaceable water-solubilizing moiety of the water-soluble prodrug of plinabulin (1) was investigated. The properties of the water-soluble prodrugs of plinabulin (1), in which the water-solubilizing part was replaced with a new functionality, were evaluated.

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