Disposition of Antipyrine and Phenytoin Correlated with Age and Liver Volume in Man
作者:
Bodil Bach,
J. Mølholm Hansen,
J.P. Kampmann,
S.N. Rasmussen,
Lis Skovsted,
期刊:
Clinical Pharmacokinetics
(ADIS Available online 1981)
卷期:
Volume 6,
issue 5
页码: 389-396
ISSN:0312-5963
年代: 1981
出版商: ADIS
数据来源: ADIS
摘要:
The half-life and metabolic clearance rate (MCR) of antipyrine and phenytoin were determined in 14 young [mean age: 28.8 ± 8.3 (SD) years] and in 14 elderly [mean age: 83.5 ± 7.1 (SD) years] subjects and correlated with liver volume, which was determined by ultrasonic scanning, to see if an age-dependent difference in drug metabolism could be explained by a reduced liver weight with age.The size of the liver was smaller in the elderly subjects even when related to decreased body surface. A significant decrease in serum albumin in the elderly compared with the younger group was also noted. The half-life of antipyrine was significantly longer in the elderly than in the younger group, 756 ± 318 and 465 ± 110 minutes, respectively, and the MCR was correspondingly lower in the elderly even when calculated per litre of liver volume, 22.8 ± 7.8 and 36.3 ± 8.9ml/minute/L liver volume, respectively. No significant differences in the 2 age groups were found in half-life and total clearance of phenytoin, but a reduced free phenytoin clearance was demonstrated in the elderly (240 ± 92ml/minute/L liver volume) compared with the younger (325 ± 81 ml/minute/L liver volume) group. No significant correlation was found between liver volume and the half-life of antipyrine and phenytoin. However, a significant correlation was demonstrated between liver volume and MCR of antipyrine as well as between total and free clearance of phenytoin. No correlation was found between the half-lives of the 2 drugs, while a significant correlation existed between the clearance values.It is suggested that the age-dependent reduction in drug clearance is due not only to a smaller liver volume, but is also a result of a reduced capacity of the liver microsomes per unit of liver in the elderly. With regard to age-dependent changes in drug metabolism, the protein binding of the actual drug has to be taken into consideration.
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