Unique Pharmacokinetic Characteristics of the One-Compartment First-Order Absorption Model with Equal Absorption and Elimination Rate Constants

1 The excretion of antipyrine metabolites over 48 h as percentage dose and the antipyrine kel and metabolite formation rate constants have been measured for 20 healthy Venda Africans. 2 To allow comparison with published data from inter-ethnic studies with antipyrine, subjects were selected who had assumed a western life and diet. 3 The values (mean ± SE) for excretion of the metabolites, 4-hydroxyantipyrine (4OHA), norantipyrine (NORA) and 3-hydroxymethylantipyrine (3HMA) as percentage dose were 26.17 ± 0.34, 7.44 ± 0.34 and 13.28 ± 0.31 respectively. The total of the three metabolites was 49.56 ± 0.33. These results differ significantly from the values found for groups of Canadian students of Oriental and Caucasian backgrounds. 4 The values (mean ± SE) found for the antipyrine elimination rate constant and the metabolite formation rate constants of 4OHA, NORA and 3OHA were 6.56 (± 0.56) × 10 -2, 2.05 (± 0.24) x 10-2, 0.60 (± 0.09) x 10-2 and 1.06 (± 0.16) x 10-2 respectively. Only the NORA formation rate constant showed any significant difference with the results obtained for Americans, although the Venda exhibited a wider distribution of the 3HMA data. 5 The linearity of the probit plots obtained suggest that the subjects selected are homozygous for the oxidations investigated. The marked difference found in comparison with Caucasian and Oriental data on the one hand and American data on the other, also implies a marked difference between the Caucasian and Oriental data and the American data. Thus the relative contributions of environmental induction and heredity to these types of oxidation are still unclear and much work remains to be carried out in this field.

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Erratum to: Simplified methods for the evaluation of the parameters of the time course of plasma concentration in the one-compartment body model with first-order invasion and first-order drug elimination including methods for ascertaining when such rate constants are equal

Journal of Pharmacokinetics and Biopharmaceutics ◽

10.1007/bf02353543 ◽

1994 ◽

Vol 22 (2) ◽

pp. 179-179

Author(s):

Edward R. Garrett

Keyword(s):

Plasma Concentration ◽

Rate Constants ◽

Time Course ◽

Drug Elimination ◽

First Order ◽

Body Model ◽

The One

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Vulcanization of Elastomers. 12. Perbunan with Thiuram Monosulfide and Sulfur. I

Rubber Chemistry and Technology ◽

10.5254/1.3542369 ◽

1959 ◽

Vol 32 (1) ◽

pp. 128-138 ◽

Cited By ~ 1

Author(s):

Walter Scheele ◽

Horst-Eckart Toussaint

Keyword(s):

Activation Energy ◽

Natural Rubber ◽

Temperature Dependence ◽

Induction Period ◽

Rate Constants ◽

The Other ◽

Tetramethylthiuram Disulfide ◽

First Order ◽

The One ◽

Limiting Value

Abstract The vulcanization of Perbunan 2818 by tetramethylthiuram monsulfide plus sulfur (1 mole monosulfide per gram-atom S) was thoroughly studied. The following results were shown: The limiting value for dithiocarbamate formation is 66 mole per cent of the initial thiuram monosulfide, indicating a two-thirds transformation. The limiting value is practically independent of temperature. The formation of dithiocarbamate can be described as a reaction of the first order. The formation of dithiocarbamate is characterized by an induction period which grows longer with lowering of the temperature, and at 100° C it amounts to about 100 minutes. The rate constants for dithiocarbamate formation were calculated, and it was shown that they were practically the same as those for the vulcanization of Perbunan with tetramethylthiuram disulfide. The activation energies as derived from the temperature dependence of the rate constants for dithiocarbamate formation in the vulcanization of Perbunan by thiuram monosulfide plus sulfur on the one hand and with thiuram disulfide on the other, are only very slightly different and are practically the same as the activation energy for dithiocarbamate formation during the vulcanization of natural rubber with thiuram monosulfide plus sulfur. The results were thoroughly discussed in light of the present conceptions of the course of thiuram vulcanizations.

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