Special populations
Changes in the absorption, distribution, metabolism and excretion of benzodiazepines have been reported in a variety of disease states including alcoholism, impaired hepatic function and impaired renal function. Changes have also been demonstrated in geriatric patients. A mean half-life of alprazolam of 16.3 hours has been observed in healthy elderly subjects (range: 9.0-26.9 hours, n = 16) compared to 11.0 hours (range: 6.3-15.8 hours, n = 16) in healthy adult subjects. The co-administration of oral contraceptives to healthy women increased the half-life of alprazolam as compared to that in healthy control women (mean: 12.4 hours, n = 11 versus 9.6 hours, n = 9). There was a prolongation in the mean half-life of alprazolam from 12.4 hours (range: 7.2-18.4 hours, n = 9) to 16.6 hours (range: 10.0- 24.3 hours, n = 9) by the co-administration of cimetidine to the same healthy adults. In patients with alcoholic liver disease the half-life of alprazolam ranged between 5.8 and 65.3 hours (mean: 19.7 hours, n = 17) as compared to between 6.3 and 26.9 hours (mean = 11.4 hours, n = 17) in healthy subjects. In an obese group of subjects the half-life of alprazolam ranged between 9.9 and 40.4 hours (mean = 21.8 hours, n = 12) as compared to between 6.3 and 15.8 hours (mean = 10.6 hours, n = 12) in healthy subjects.
Because of its similarity to other benzodiazepines, it is assumed that alprazolam undergoes transplacental passage and that it is excreted in human milk.
Race - Maximal concentrations and half-life of alprazolam are approximately 15% and 25% higher in Asians compared to Caucasians.
Gender - Gender has no effect on the pharmacokinetics of alprazolam.
Cigarette Smoking - Alprazolam concentrations may be reduced by up to 50% in smokers compared to non-smokers.
