Alprazolam kinetics in the elderly. Relation to antipyrine disposition
D. J. Greenblatt, M. Divoll, D. R. Abernethy, L. J. Moschitto, R. B. Smith and R. I. Shader
The pharmacokinetics of alprazolam, a triazolobenzodiazepine
anxiolytic-antidepressant, were assessed in 32 healthy men and women aged
21 to 78 years after a single 1.0-mg oral dose. Peak alprazolam levels
averaged 20.4 ng/mL and were reached a mean of 1.25 hours after dosage.
Mean elimination half-life did not differ significantly between elderly and
young women, nor did total metabolic clearance. However, half-life was
significantly prolonged, and total clearance significantly reduced, in
elderly v young men. Antipyrine oxidizing capacity was also evaluated, and
half-life for the two drugs was highly correlated, as were their metabolic
clearances. Thus, old age is associated with impaired capacity to oxidize
alprazolam, but this effect is far more apparent in men than in women. A
test of antipyrine half-life and clearance may help identify slow or rapid
metabolizers of alprazolam.
