The effect of aging on the pharmacokinetics of nizatidine.
Department of Pharmacology, IRCCS, Policlinico S. Matteo, Pavia, Italy.European Journal of Drug Metabolism and Pharmacokinetics (Impact Factor: 1.56). 02/1991; Spec No 3:205-10.
A single oral dose of 300 mg of nizatidine was administered to two groups of volunteers: a first group of 12 young healthy subjects and a second group of 12 elderly patients, in order to compare the pharmacokinetic parameters and to verify a possible influence of the age on nizatidine's kinetics. Blood samples were collected periodically and plasma concentrations of the drug were determined by a specific HPLC method. The results evidenced differences among the pharmacokinetic parameters of the two groups: the mean of Cmax was higher in the elderly than in the young (3.28 mg/ml against 2.23 mg/ml), the peak time was prolonged in the elderly (2.1 h against 1.00 h) and the AUC values were higher too (12.17 in the elderly and 7.99 in the young). Only the elimination half-life t1/2 was slightly higher in the elderly (1.8 h against 1.7 h in the young).
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ABSTRACT: Antihistamines are drugs which act by competitive inhibition of the H1 or H2 histamine receptors. Little has been known about their clinical pharmacokinetics and biological responses until the last few years. In this paper, we propose quantitative retention-activity relationship, QRAR, models based on the retention data of antihistamines in a biopartitioning micellar chromatography (BMC) system using a Brij35 mobile phase for describing pharmacokinetic parameters such as half-life and volume of distribution, or the pharmacodynamic parameters, therapeutic plasma levels, lethal doses and drug-receptor dissociation constant. The predictive ability of these models is statistically validated. These results are compared to traditional quantitative structure-activity relationship, QSAR, models using lipophilicity data. The adequacy of QRAR models can be explained taking into account the fact that the retention of compounds in BMC depends on their hydrophobic, electronic and steric characteristics which are of great importance in pharmacokinetic and pharmacodynamic behavior.
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