Record Display for the EPA National Library Catalog

RECORD NUMBER: 9 OF 14

Main Title Pharmacokinetic Basis of Age-Related Changes in Sensitivity to Toxicants.
Author Birnbaum., L. S. ;
CORP Author Health Effects Research Lab., Research Triangle Park, NC. Environmental Toxicology Div.
Publisher c1991
Year Published 1991
Report Number EPA/600/J-91/093;
Stock Number PB91-200279
Additional Subjects Toxic substances ; Pharmacokinetics ; Aging ; Sensitivity ; Environmental pollutants ; Adrenergic receptors ; Environmental exposure pathways ; Metabolism ; Absorption ; Excretion ; Reprints ;
Holdings
Library Call Number Additional Info Location Last
Modified
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Status
NTIS  PB91-200279 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 28p
Abstract
The article examines the pharmacokinetic behavior of environmental chemicals and drugs that are altered during aging. Absorption may be the least sensitive parameter to age-related perturbations. However, pulmonary and dermal absorption, which are both dependent upon passive diffusion, do appear to decline. In contrast, no evidence supports a decrease in passive transport across the gut wall, while active processes in the GI tract do decline in the aged. Distribution is affected by changes in body composition, the decrease in lean body mass resulting in a decreased Vd for water-soluble chemicals and enhanced persistence of lipophilic ones. Changes in protein binding and blood flow also alter the concentration of unbound chemicals reaching the target site. The changes in metabolism are extremely complex, with increases, decreases, and no change being observed for different enzymes with varying substrates in different tissues, sexes, strain, and species. Only excretion tends to consistently change with age, in large part due to the altered blood flow, structure, and physiology of the kidney. Hepatic and pulmonary elimination also tend to decline with age.