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Anthony R. West - One of the best experts on this subject based on the ideXlab platform.

  • Effect of annealing treatments on positive temperature coefficient of resistance properties of barium titanate ceramics and a new model for the positive temperature coefficient of resistance effect
    Journal of Applied Physics, 2001
    Co-Authors: Marina Martinez Gallego, Anthony R. West
    Abstract:

    Alternating current impedance has shown the presence of three electrical components in a semiconducting barium titanate ceramic that has been processed to give a positive temperature coefficient of resistance (PTCR) effect. Two of the component resistances, R1 and R2, each present a PTCR effect and, from the temperature dependence of their capacitances, they are attributed to different regions, nonferroelectric and ferroelectric, respectively, at the surfaces of individual grains or in the region of inter-grain contacts. The influence of isothermal annealing in air at 1000, 1100, and 1200 °C on these PTCR effects was investigated. At the resistance maxima, Rmax and Tmax, two types of dependence were found for both R1 and R2. At short times, Rmax decreased and Tmax shifted to higher temperatures; at long times, the reverse occurred and Rmax increased while Tmax shifted to lower temperature. Capacitance values for both regions were constant at short times but decreased at long times, indicating a thickening...

Kazuhiro Hanazaki - One of the best experts on this subject based on the ideXlab platform.

  • Pharmacokinetics of Active Components of Yokukansan, a Traditional Japanese Herbal Medicine after a Single Oral Administration to Healthy Japanese Volunteers: A Cross-Over, Randomized Study
    2015
    Co-Authors: Hiroyuki Kitagawa, Masaya Munekage, Kengo Ichikawa, Ian Fukudome, Eri Munekage, Yuka Takezaki, Takashi Matsumoto, Yasushi Igarashi, Haruo Hanyu, Kazuhiro Hanazaki
    Abstract:

    ContextYokukansan (YKS) is a traditional Japanese herbal medicine called kampo medicine in Japan. Its extract comprises seven crude drugs: Atractylodis lanceae rhizoma, Poria, Cnidii rhizoma, Uncariae uncis cum ramulus, Angelicae radix, Bupleuri radix, and Glycyrrhizae radix. YKS is used to treat neurosis, insomnia, as well as behavioral and psychological symptoms of dementia.ObjectiveTo confirm the exposure and pharmacokinetics of the active components of YKS in healthy volunteers.Design, Setting, and ParticipantsA randomized, open-label, 3-arm, 3-period, crossover trial was conducted on 21 healthy Japanese volunteers at the Kochi Medical University between May 2012 and November 2012.InterventionsSingle oral administration of YKS (2.5 g, 5.0 g, or 7.5 g/day) during each period.Main Outcome MeasurePlasma concentrations of three active compounds in YKS, namely 18β-glycyrrhetinic acid (GA), geissoschizine methyl ether (GM), and hirsuteine (HTE).ResultsThe mean maximum plasma concentrations (Cmax) of GM and HTE increased dose-dependently (ranges: 0.650–1.98 ng/mL and 0.138–0.450 ng/mL, respectively). The times to maximum plasma concentration after drug administration (Tmax) were 0.500 h for GM and 0.975–1.00 h for HTE. The apparent elimination half-lives (t1/2) were 1.72–1.95 h for GM and 2.47–3.03 h for HTE. These data indicate the rapid absorption and elimination of GM and HTE. On the other hand, the Cmax, Tmax, and t1/2 of GA were 57.7–108 ng/mL, 8.00–8.01 h, and 9.39–12.3 h, respectively.ConclusionWe demonstrated that pharmacologically active components of YKS are detected in humans. Further, we determined the pharmacokinetics of GM, HTE, and GA. This information will be useful to elucidate the pharmacological effects of YKS.Trial RegistrationJapan Pharmaceutical Information Center JAPIC CTI-121811

  • Pharmacokinetics of Active Components of Yokukansan, a Traditional Japanese Herbal Medicine after a Single Oral Administration to Healthy Japanese Volunteers: A Cross-Over, Randomized Study.
    Public Library of Science (PLoS), 1
    Co-Authors: Hiroyuki Kitagawa, Masaya Munekage, Kengo Ichikawa, Ian Fukudome, Eri Munekage, Yuka Takezaki, Takashi Matsumoto, Yasushi Igarashi, Haruo Hanyu, Kazuhiro Hanazaki
    Abstract:

    Yokukansan (YKS) is a traditional Japanese herbal medicine called kampo medicine in Japan. Its extract comprises seven crude drugs: Atractylodis lanceae rhizoma, Poria, Cnidii rhizoma, Uncariae uncis cum ramulus, Angelicae radix, Bupleuri radix, and Glycyrrhizae radix. YKS is used to treat neurosis, insomnia, as well as behavioral and psychological symptoms of dementia.To confirm the exposure and pharmacokinetics of the active components of YKS in healthy volunteers.A randomized, open-label, 3-arm, 3-period, crossover trial was conducted on 21 healthy Japanese volunteers at the Kochi Medical University between May 2012 and November 2012.Single oral administration of YKS (2.5 g, 5.0 g, or 7.5 g/day) during each period.Plasma concentrations of three active compounds in YKS, namely 18β-glycyrrhetinic acid (GA), geissoschizine methyl ether (GM), and hirsuteine (HTE).The mean maximum plasma concentrations (Cmax) of GM and HTE increased dose-dependently (ranges: 0.650-1.98 ng/mL and 0.138-0.450 ng/mL, respectively). The times to maximum plasma concentration after drug administration (Tmax) were 0.500 h for GM and 0.975-1.00 h for HTE. The apparent elimination half-lives (t1/2) were 1.72-1.95 h for GM and 2.47-3.03 h for HTE. These data indicate the rapid absorption and elimination of GM and HTE. On the other hand, the Cmax, Tmax, and t1/2 of GA were 57.7-108 ng/mL, 8.00-8.01 h, and 9.39-12.3 h, respectively.We demonstrated that pharmacologically active components of YKS are detected in humans. Further, we determined the pharmacokinetics of GM, HTE, and GA. This information will be useful to elucidate the pharmacological effects of YKS.Japan Pharmaceutical Information Center JAPIC CTI-121811

James C. Cloyd - One of the best experts on this subject based on the ideXlab platform.

  • Clinical utility of topiramate extended-release capsules (USL255): Bioequivalence of USL255 sprinkled and intact capsule in healthy adults and an in vitro evaluation of sprinkle delivery via enteral feeding tubes.
    Epilepsy & behavior : E&B, 2016
    Co-Authors: Annie Clark, John M. Pellock, Mary Holmay, Bob Anders, James C. Cloyd
    Abstract:

    Abstract Objective The objectives of these two studies were to determine if beads from extended-release topiramate capsules sprinkled onto soft food are bioequivalent to the intact capsule and if beads from the capsule can be passed through enteral gastrostomy (G-) and jejunostomy (J-) feeding tubes. Methods Bioequivalence of 200-mg USL255 (Qudexy® XR [topiramate] extended-release capsules) sprinkled onto soft food (applesauce) versus the intact capsule was evaluated in a phase 1, randomized, single-dose, crossover study (N = 36). Pharmacokinetic evaluations included area under the curve (AUC), maximum plasma concentration (Cmax), time to Cmax (Tmax), and terminal elimination half-life (t1/2). If 90% confidence intervals (CI) of the ratio of geometric least-squares means were between 0.80 and 1.25, AUC and Cmax were considered bioequivalent. In separate in vitro experiments, 100-mg USL255 beads were passed through feeding tubes using gentle syringe pressure to develop a clog-free bead-delivery method. Multiple tube sizes (14- to 18-French [Fr] tubes), dilutions (5 mg/15 mL–25 mg/15 mL), and diluents (deionized water, apple juice, Ketocal, sparkling water) were tested. Results Area under the curve and Cmax for USL255 beads sprinkled onto applesauce were bioequivalent to the intact capsule (GLSM [90% CI]: AUC0–t 1.01 [0.97–1.04], AUC0–∞ 1.02 [0.98–1.05]; Cmax 1.09 [1.03–1.14]). Median Tmax was 4 h earlier for USL255 sprinkled versus the intact capsule (10 vs 14 h; p = 0.0018), and t1/2 was similar (84 vs 82 h, respectively). In 14-Fr G-tubes, USL255 beads diluted in Ketocal minimized bead clogging versus deionized water. Recovery of USL255 beads diluted in deionized water was nearly 100% in 16-Fr G-, 18-Fr G-, and 18-Fr J-tubes. Significance For patients with difficulty swallowing pills, USL255 sprinkled onto applesauce offers a useful once-daily option for taking topiramate. USL255 beads were also successfully delivered in vitro through ≥ 14-Fr G- or J-tubes, with tube clogging minimized by portioning the dose and using glidant diluents for smaller tubes.

Sebastian Straube - One of the best experts on this subject based on the ideXlab platform.

  • Effects of food on pharmacokinetics of immediate release oral formulations of aspirin, dipyrone, paracetamol and NSAIDs - a systematic review.
    British Journal of Clinical Pharmacology, 2015
    Co-Authors: R A Moore, Sheena Derry, Philip J Wiffen, Sebastian Straube
    Abstract:

    Aims It is common to advise that analgesics, and especially non-steroidal anti-inflammatory drugs (NSAIDs), be taken with food to reduce unwanted gastrointestinal adverse effects. The efficacy of single dose analgesics depends on producing high, early, plasma concentrations; food may interfere with this. This review sought evidence from single dose pharmacokinetic studies on the extent and timing of peak plasma concentrations of analgesic drugs in the fed and fasting states. Methods A systematic review of comparisons of oral analgesics in fed and fasting states published to October 2014 reporting kinetic parameters of bioavailability, time to maximum plasma concentration (Tmax), and its extent (Cmax) was conducted. Delayed-release formulations were not included. Results Bioavailability was not different between fasted and fed states. Food typically delayed absorption for all drugs where the fasting Tmax was less than 4 h. For the common analgesics (aspirin, diclofenac, ibuprofen, paracetamol) fed Tmax was 1.30 to 2.80 times longer than fasted Tmax. Cmax was typically reduced, with greater reduction seen with more rapid absorption (fed Cmax only 44–85% of the fasted Cmax for aspirin, diclofenac, ibuprofen and paracetamol). Conclusion There is evidence that high, early plasma concentrations produces better early pain relief, better overall pain relief, longer lasting pain relief and lower rates of remedication. Taking analgesics with food may make them less effective, resulting in greater population exposure. It may be time to rethink research priorities and advice to professionals, patients and the public.

Daniel C. Howey - One of the best experts on this subject based on the ideXlab platform.

  • Tmax: an unconfounded metric for rate of absorption in single dose bioequivalence studies.
    Pharmaceutical research, 1996
    Co-Authors: Rodney P. Basson, K A Desante, Benito J. Cerimele, Daniel C. Howey
    Abstract:

    Purpose. While peak drug concentration (Cmax) is recognized to be contaminated by the extent of absorption, it has long served as the indicator of change in absorption rate in bioequivalence studies. This concentration measure per se is a measure of extreme drug exposure, not absorption rate. This paper redirects attention to Tmax as the absorption rate variable. Methods. We show that the time to peak measure (Tmax), if obtained from equally spaced sampling times during the suspected absorption phase, defines a count process which encapsulates the rate of absorption. Furthermore such count data appear to follow the single parameter Poisson distribution which characterizes the rate of many a discrete process, and which therefore supplies the proper theoretical basis to compare two or more formulations for differences in the rate of absorption. This paper urges limiting the use of peak height measures based on Cmax to evaluate only for dose-dumping, a legitimate safety concern with, any formulation. These principles and techniques are illustrated by a bioequivalence study in which two test suspensions are compared to a reference formulation. Results. Appropriate statistical evaluation of absorption rate via Tmax supports bioequivalence, whereas the customary analysis with Cmax leads to rejection of bioequivalence. This suggests that the inappropriate use of Cmax as a surrogate metric for absorption rate contributes to the unpredictable and uncertain outcome in bioequivalence evaluation today.