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  • ENERGY PRODUCTION AND CONVERSION  (5)
  • triamterene  (3)
  • extent of absorption  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of triamterene and its metabolite in man (1982)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 10 (1982), S. 507-523 
    Details
    ISSN: 1573-8744
    Keywords: triamterene ; sulfate conjugate ; protein binding ; blood/plasma ratio ; renal clearance ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetic profiles of triamterene and hydroxytriamterene sulfuric acid ester, the major metabolite of triamterene, were studied in six normal male volunteers using a newly developed specific HPLC analytical method. Following a 100 mg oral dose of triamterene, the plasma concentration time course of the sulfate conjugate parallels that of triamterene in all subjects, but concentrations of the metabolite were more than 10 times higher than unchanged triamterene concentrations at identical sampling times. Interestingly, the renal clearance of the sulfate conjugate was less than that of triamterene. These characteristic features of triamterene disposition were fitted to a compartment model incorporating a first-pass metabolic process. Unbound fractions of triamterene and metabolite in plasma were 0.39 and 0.10 (mean of 6 subjects), respectively. The low unbound fraction of the metabolite in plasma most probably accounts for the low renal clearance of the sulfate conjugate as compared with triamterene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01059034
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  • 2
    Electronic Resource
    Electronic Resource
    Absence of a significant pharmacokinetic interaction between hydrochlorothiazide and triamterene when coadministered (1984)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 12 (1984), S. 575-586 
    Details
    ISSN: 1573-8744
    Keywords: hydrochlorothiazide ; triamterene ; hydroxytriamterene sulfate ; pharmacokinetics ; bioavailability ; renal clearance ; interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Hydrochlorothiazide, triamterene, and hydroxytriamterene sulfate were monitored in the plasma and urine of 24 healthy young men taking single doses of a liquid preparation containing both hydrochlorothiazide and triameterene, liquid preparations containing either of these drugs alone, and a combination tablet recently formulated with a dose ratio of hydrochlorothiazide: triamterene (1∶1,5) found to give optimal potassium-sparing effect. In contradiction to a recent publication, no interaction between the drugs affecting the bioavailability or renal clearance of either could be demonstrated. The previous report of drug-drug interaction probably arose from formulationrelated problems with bioavailability from the two capsule and two tablet products which had been studied. A well-formulated hydrochlorothiazide-triamterene combination tablet promotes plasma concentrations and urinary excretion of hydrochlorothiazide, triamterene, and hydroxytriamterene sulfate which are virtually identical to those seen after either a combination liquid dosage form or simple liquid forms containing only one of the two drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01059553
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  • 3
    Electronic Resource
    Electronic Resource
    Evaluation of Bioequivalence of Highly Variable Drugs Using Clinical Trial Simulations. II: Comparison of Single and Multiple-Dose Trials Using AUC and Cmax (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 98-104 
    Details
    ISSN: 1573-904X
    Keywords: Bioequivalence ; highly variable drugs ; extent of absorption ; rate of absorption ; Monte Carlo simulations ; single-dose ; multiple-dose bioequivalence trial
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Evaluating of the effects of high intrasubject variability in clearance (CL) and volume of distribution (V), on 90% confidence intervals (CIs) for AUC (Area Under the concentration Curve) in single and multiple-dose bioequivalence studies. The main methodology was Monte Carlo simulation, and we also used deterministic simulation, and examination of clinical trials. The results are compared with those previously observed for Cmax (maximum concentration.) Methods. The time course of drug concentration in plasma was simulated using a one-compartment model with log-normal statistical distributions of intersubject and intrasubject variabilities in the pharmacokinetic parameters. Both immediate-release and prolonged-release products were simulated using several levels of intrasubject variability in single-dose and multiple-dose studies. Simulations of 2000 clinical bioequivalence trials per condition (138 conditions) with 30 subjects in each crossover trial were carried out. Simulated data were compared with data from actual bioequivalence trials. Results. The current simulations for AUC show similar probabilities of failure for single-dose and multiple-dose bioequivalence studies, even with differences in the rate of absorption or fraction absorbed. AUC values from prolonged-release scenario studies are more sensitive to changes in the first order absorption rate constant ka, and to variability in CL and V than AUC from studies of immediate-release studies. Conclusions. We showed that multiple-dose designs for highly variable drugs do not always reduce intrasubject variability in either AUC or Cmax, although the behavior of AUC differs from Cmax. Single dose AUC to the last quantifiable concentration was more reliable than either single dose AUC extrapolated to infinity, or multiple dose AUC during a steady-state interval. Multiple-dose designs may not be the best solution for assessing bioequivalence of highly variable drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011961006297
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of Formulation and Food on the Absorption of Hydrochlorothiazide and Triamterene or Amiloride from Combination Diuretic Products (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 348-352 
    Details
    ISSN: 1573-904X
    Keywords: hydrochlorothiazide ; triamterene ; Dyazide ; Maxzide ; amiloride ; Moduretic ; food–drug interactions ; food-formulation interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The absorption of three combination formulations of hydrochlorothiazide and either triamterene or amiloride was studied over a 5-year period in seven separate investigations under varying conditions of food and fasting. The most widely prescribed combination, containing 25 mg of hydrochlorothiazide and 50 mg of triamterene, demonstrated impaired absorption in the fasting state that was partially corrected by the addition of a breakfast high in fat. The increase in the fat content of the food appeared to correlate directly with the amount of both drugs absorbed from this formulation. The second formulation studied, a new combination formulation of 50 mg of hydrochlorothiazide and 75 mg of triamterene, demonstrated acceptable absorption in the fasting state that was not altered by the concurrent administration of a high-fat breakfast. The absorption of the third formulation, a combination of 50 mg hydrochlorothiazide and 5 mg amiloride, was acceptable in the fasting state and demonstrated a slight reduction in the absorption of the amiloride component when administered concurrently with a high-fat meal. The clinical and biopharmaceutic implications of these observations are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016409606936
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  • 5
    Electronic Resource
    Electronic Resource
    Bioequivalence: Performance of Several Measures of Extent of Absorption (1994)
    Springer
    Pharmaceutical research 11 (1994), S. 715-722 
    Details
    ISSN: 1573-904X
    Keywords: pharmacokinetics ; bioequivalence ; extent of absorption ; power analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The determination of the area under the concentration–time curve (AUC) is the method most commonly used by regulatory agencies to assess extent of drug absorption after single-dose administration of oral products. Using simulations, several approaches toward measuring the actual area, in whole or part, were tested. In addition, the performance of the peak concentration (C max), usually taken as a measure of the rate of absorption was assessed evaluating extent. Model scenarios for drugs with typical mean characteristics and statistical distributions were investigated. Using different kinetic models of disposition, the time course of the drug concentration in plasma was simulated. Intraindividual and interindividual variability and assay error were modeled using Monte Carlo techniques. The accuracy, precision, and ease of use of the various measures of extent were evaluated, and statistical power analyses were performed. Among the measures tested, the most reliable were the AUC computed up to the time of the last quantifiable concentration, without extrapolation, and C max. However, being also sensitive to rate, C max as a measure of extent is of limited potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018932430733
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  • 6
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    Reversible thermodynamic cycle for AMTEC power conversion (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The thermodynamic cycle appropriate to an AMTEC (alkali metal thermal-to-electric converter) cell is discussed for both liquid- and vapor-fed modes of operation, under the assumption that all processes can be performed reversibly. In the liquid-fed mode, the reversible efficiency is greater than 89.6 percent of Carnot efficiency for heat input and rejection temperatures (900-1300 K and 400-800 K, respectively) typical of practical devices. Vapor-fed cells can approach the efficiency of liquid-fed cells. Quantitative estimates confirm that the efficiency is insensitive to either the work required to pressurize the sodium liquid or the details of the state changes associated with cooling the low pressure sodium gas to the heat rejection temperature.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: In: IECEC '92; Proceedings of the 27th Intersociety Energy Conversion Engineering Conference, San Diego, CA, Aug. 3-7, 1992. Vol. 3 (A93-25851 09-44); p. 3.123-3.127.
    Format: text
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  • 7
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    Performance projections of alternative AMTEC systems and devices (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: The alkali metal thermoelectric converted (AMTEC) converts heat to electrical power without moving parts. Attention is presently given to two AMTEC devices that have been optimized for conversion efficiencies of the order of 30 percent or more at 1100 K, in conjunction with high volumetric power densities. A 'tube-bundle' AMTEC configuration yields a peak power of 426 W/l; a flat-plate AMTEC system yields 2.4 W/l.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: In: Space nuclear power systems; Proceedings of the 8th Symposium, Albuquerque, NM, Jan. 6-10, 1991. Pt. 1 (A93-13751 03-20); p. 472-481.
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  • 8
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    Alkali metal thermoelectric converter (AMTEC) electrode lifetime studies (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Experimental studies are being conducted at JPL to identify long life, high area power density electrodes for AMTEC. Power versus time measurements are being made in a demountable electrode test cell and, for longer term experiments, a self-contained recirculating cell. The experimental apparatus and procedures are described in detail. The results show that thin film molybdenum electrodes can be designed to produce power near 0.5 W/sq cm for over two hundred hours. Also, platinum/tungsten electrodes exhibit power densities that are stable near 0.5 W/sq cm. If the performance of these electrodes is verified for longer periods (thousands of hours), then practical AMTEC systems will be possible.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: IECEC ''87; Aug 10, 1987 - Aug 14, 1987; Philadelphia, PA; United States
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  • 9
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    AMTEC system performance studies using the detailed electrode kinetic and transport model (1992)
    In:  Other Sources
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    Publication Date: 2019-08-27
    Description: A detailed electrochemical model of the alkali metal thermoelectric converter (AMTEC) electrode and current collector grid has been developed recently. Comparative evaluations of the resulting differences in model predictions reveal that the new detailed model predicts up to 50 percent higher electrode power densities at condenser operating temperatures above 600 K. The new model, with experimentally determined parameters, was used to recalculate the projected system performance of previously reported 1- and 100-kWe AMTEC space power systems that had incorporated earlier electrolyte/electrode models. It was found that when the detailed model was used to determine the electrode power densities, enhanced specific power and efficiencies are predicted.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: In: Space nuclear power systems 1989; Proceedings of the 6th Symposium, Albuquerque, NM, Jan. 8-12, 1989. Vol. 2 (A93-20752 06-20); p. 373-378.
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  • 10
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    AMTEC cell testing, optimization of rhodium/tungsten electrodes, and tests of other components (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-08-27
    Description: Electrodes, current collectors, ceramic to metal braze seals, and metallic components exposed to the high 'hot side' temperatures and sodium liquid and vapor environment have been tested and evaluated in laboratory cells running for hundreds of hours at 1100-1200 K. Rhodium/tungsten electrodes have been selected as the optimum electrodes based on performance parameters and durability. Current collectors have been evaluated under simulated and actual operating conditions. The microscopic effects of metal migration between electrode and current collector alloys as well as their thermal and electrical properties determined the suitability of current collector and lead materials. Braze seals suitable for long term application to AMTEC devices are being developed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: In: Space nuclear power systems; Proceedings of the 8th Symposium, Albuquerque, NM, Jan. 6-10, 1991. Pt. 1 (A93-13751 03-20); p. 464-471.
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