Ryousuke Kawai

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Cytochromes P450 (P450) involved in letrozole metabolism were investigated. Among 13 recombinant P450 forms examined, only P450 2A6 and 3A4 showed activities in transforming letrozole to its carbinol metabolite with small K(m) and high Vmax values yielding apparent Vmax/K(m) values of 0.48 and 0.24 nl min(-1) nmol(-1) P450, respectively. The metabolic(More)
The tissue distribution kinetics of i.v. Cyclosporine A (CyA) was investigated extensively in rats. The concentration-to-time data of 11 organs were analyzed separately using local physiologically based pharmacokinetic models, involving nonlinear plasma-to-blood cell distribution, membrane-permeability-limited plasma-to-tissue distribution and either linear(More)
OBJECTIVE The authors compared the pharmacokinetics and pharmacological effects of the immunomodulator fingolimod in healthy white and Asian subjects for potential ethnic differences. METHODS White and Asian (Japanese) healthy subjects were demographically matched for sex, age and weight. Subjects received single 1.25 mg doses of fingolimod (6 ethnic(More)
Cyclosporin A (CyA) tissue distribution kinetics was extensively studied after single 1.2-, 6-, and 30-mg/kg CyA doses (via 2-min i.v. infusion) to rats. Drug concentrations in blood and various tissues were measured using a specific radioimmunoassay. Based on total blood concentration data alone, CyA systemic pharmacokinetics appeared essentially linear.(More)
PSC 833 has been used to overcome the phenomenon of multidrug resistance by inhibiting the P-glycoprotein (P-gp)-mediated efflux of antitumor drugs from tumor cells. Because P-gp expressed in several normal tissues may affect the disposition of its substrates, we examined the dose-dependent effect of PSC 833 on the disposition of vincristine (VCR) and(More)
1. After oral administration of indeloxazine hydrochloride ((+/-)-2-[(inden-7-yloxy)methyl]morpholine hydrochloride) to rats, two conjugates, which were labile to alpha-glucosidase hydrolysis but refractory to beta-glucosidase, were isolated from the urine. 2. Mass spectral and n.m.r. analyses confirmed that these conjugates were alpha-D-glucopyranosides of(More)
A 52-year-old Japanese woman was diagnosed as having angioimmunoblastic T-cell lymphoma (stage IV-B). She received 6 courses of chemotherapy including cyclophosphamide, doxorubicin, vincristine, and prednisolone every two weeks (biweekly CHOP), and was considered to be in partial remission. She complained of loss of visual acuity in her right eye during her(More)
1. The disposition and metabolism of indeloxazine hydrochloride ((+/-)-2-[(inden-7-yloxy)methyl]morpholine hydrochloride) were studied in male Sprague-Dawley rats. 2. After oral administration of 14C-indeloxazine hydrochloride, the plasma concentration of total radioactivity reached a maximum at 15 min and declined with an apparent half-life of 2.2 h in the(More)
BACKGROUND This study was performed to evaluate the ability of contrast-enhanced ultrasonography (CEUS) with time-intensity curve analysis to demonstrate an increased enhancement of the liver parenchyma adjacent to the inflamed gallbladder, as seen on contrast-enhanced computed tomography. METHODS The Ethics Committee of our institution approved the study(More)
A study of the metabolic fate of [14C]SM-1652 after intravenous or intramuscular injection into rats showed that: (i) the elimination of the labeled compound from the blood was the same after intravenous and intramuscular injections; (ii) the radiolabeled drug was distributed rapidly and widely after intravenous administration with the highest concentration(More)