What happens to the volume of distribution of benzodiazepines in elderly patients?

The volume of distribution of benzodiazepines increases in elderly patients due to several physiological changes that occur with aging. As people grow older, body composition changes, typically resulting in a higher percentage of body fat and a lower percentage of lean body mass. Since benzodiazepines are lipophilic (fat-soluble), they tend to accumulate in fatty tissues. This increased fat stores lead to a larger volume of distribution for these drugs.

Additionally, aging can be associated with decreased liver size and hepatic blood flow, impacting the metabolism of medications, which can further influence how drugs are distributed and eliminated from the body. These factors collectively contribute to an enhanced volume of distribution in elderly patients, making them more susceptible to prolonged effects of benzodiazepines and necessitating careful dosage adjustments and monitoring.