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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of pharmacokinetics and pharmacodynamics 24 (1996), S. 133-149 
    ISSN: 1573-8744
    Keywords: bootstrap ; individual bioequivalence ; moment-based criteria ; population bioequivalence ; probability-based criteria ; scaled criteria ; unscaled criteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Bioequivalence of two drug formulations is currently defined by drug regulatory authorities in terms of the mean responses following administration of the test and reference formulations (average bioequivalence). However, the various potential shortcomings of average bioequivalence are now understood, and switchability, and thus individual bioequivalence, has become a reasonable expectation when changing from one pharmaceutically equivalent drug product to another. Progress has been made in developing criteria for individual bioequivalence, and an overview and classification of most of the different approaches to the assessment of individual bioequivalence have been achieved. As a consequence of this classification, the different character of scaled and unscaled bioequivalence measures has been recognized and, in turn, this leads to the proposal, made in this paper, of using both scaled and unscaled criteria for bioequivalence assessment of different classes of drugs, depending on their within-subject variability and therapeutic range. This strategy addresses the shortcomings of average bioequivalence, and, when applied to data sets from bioequivalence studies with four-period replicate crossover designs, turns out to have some satisfactory properties. Open questions and areas for further research are discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-904X
    Keywords: individual bioequivalence ; within-subject variability ; subject-by-formulation interaction ; subgroups
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The FDA has proposed replacing the current averagebioequivalence criterion with population and individual bioequivalence criteriathat consider variances in addition to the difference of averages. Oneof these variances in the individual bioequivalence criterion measuressubject-by-formulation interaction, the extent to which thetest-reference difference varies from person to person. This paper discussesconceptual and statistical issues raised in various publications andpresentations with respect to the presence and estimation of such aninteraction. Methods. We focus on the importance of subject-by-formulationinteraction, an understanding of what is a large interaction, and theassessment of the magnitude of this interaction in bioequivalence studies.Simulation studies, examples from the literature, and data from FDAfiles are used to demonstrate the magnitude of the interaction and itsdistribution under various conditions. Results. The concept of a large interaction is tied to the concept of alarge mean difference. We suggest that an interaction greater than0.15 is a conservative criterion for a large interaction. Magnitudes ofestimated interaction are affected by variability, sample size, and theselection of data sets that pass average bioequivalence. Conclusions. Examples of substantial interactions are beginning toappear. More data is needed before reaching definitive conclusionsregarding the frequency and importance of observed interactions.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-904X
    Keywords: methylphenidate ; average bioequivalence ; individual bioequivalence ; human ; pharmacokinetics ; replicated design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To determine the relative bioavailability of two marketed,immediate-release methylphenidate tablets. The study used a replicatedstudy design to characterize intrasubject variability, and determinebioequivalence using both average and individual bioequivalencecriteria. Methods. A replicated crossover design was employed using 20subjects. Each subject received a single 20 mg dose of the reference tableton two occasions and two doses of the test tablet on two occasions.Blood samples were obtained for 10 hr after dosing, and plasma wasassayed for methylphenidate by GC/MS. Results. The test product was more rapidly dissolved in vitro and morerapidly absorbed in vivo than the reference product. The mean Cmaxand AUC(0 − ∞) differed by 11% and 9%, respectively. Using anaverage bioequivalence criterion, the 90% confidence limits for theLn-transformed Cmax and AUC(0 − ∞), comparing the two replicatesof the test to the reference product, fell within the acceptable range of80–125%. Using an individual bioequivalence criterion the test productfailed to demonstrate equivalence in Cmax to the reference product. Conclusions. The test and reference tablets were bioequivalent usingan average bioequivalence criterion. The intrasubject variability of thegeneric product was greater and the subject-by-formulation interactionvariance was borderline high. For these reasons, the test tablets werenot individually bioequivalent to the reference tablets.
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2019-07-13
    Description: Improved process for making mechanically strong, dense, phase-pure potassium beta''-alumina solid electrolyte (K-BASE) results in material superior to all previous K-BASE preparations and similar to commercial Na-BASE in strength, phase purity and high-temperature ionic conductivity. Potassium-based alkali-metal thermal-to-electric conversion (AMTEC) cells expected to operate efficiently at lower heat-input temperatures and lower rejection temperatures than sodium-based AMTEC cells, making them appropriate for somewhat different applications.
    Keywords: MATERIALS
    Type: NPO-19209 , NASA Tech Briefs (ISSN 0145-319X); 19; 6; P. 64
    Format: text
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  • 5
    Publication Date: 2019-07-13
    Description: Improved formulations of precursor materials synthesize nearly-phase-pure potassium beta' '-alumina solid electrolyte (K-BASE) powder. Materials are microhomogeneous powders (or, alternatively, gels) containing K(+,) Mg(2+), and Al(3+). K-BASE powder produced used in potassium-working-fluid alkali-metal thermal-to-electric conversion (K-AMTEC), in which heat-input and heat-rejection temperatures lower than sodium-working-fluid AMTEC (Na-AMTEC). Additional potential use lies in purification of pottassium by removal of sodium and calcium.
    Keywords: MATERIALS
    Type: NPO-19210 , NASA Tech Briefs (ISSN 0145-319X); 20; 2; P. 56
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