The effect of age on the pharmacokinetics of diazepam.
1. After intravenous administration to 19 subjects, aged 18-95 years, plasma diazepam concentrations were measured over 160 h. Plasma protein binding of diazepam was also measured in each subject. 2. The terminal plasma half-life of diazepam ranged from 15.0 to 125 h and was positively correlated with age (r = 0.797). Total plasma diazepam clearance was not correlated with age (r = -0.017). 3. The free fraction of diazepam ranged from 0.0137 to 0.0386 and was significantly correlated with age (r = +0.863). Free diazepam clearance, which ranged from 432 to 1870 ml/min, was also correlated with age (r = -0.717). 4. It is concluded that the increased sensitivity of the elderly to diazepam is, at least in part, due to pharmacokinetic factors.
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging; D003975:Diazepam / Q000097:blood / Q000378:metabolism*; D005260:Female; D006207:Half-Life; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D011485:Protein Binding; D012709:Serum Albumin / Q000032:analysis
D012709:Serum Albumin; D003975:Diazepam