Why must lower dosages of medications be considered for older adult patients?

Consideration of lower dosages of medications for older adult patients is primarily due to physiological changes associated with aging that impact drug pharmacokinetics and pharmacodynamics. As people age, various bodily systems undergo changes that can affect how drugs are absorbed, distributed, metabolized, and excreted. For instance, there is often a decline in renal function, liver size, and hepatic blood flow, which can lead to slower drug metabolism and elimination. As a result, medications may remain in the system longer or be more potent, increasing the risk of adverse effects or toxicity if standard dosages are used.

In addition to metabolic changes, older adults often experience alterations in body composition, such as increased body fat and decreased lean body mass and total body water, which can influence the distribution of water-soluble and fat-soluble drugs. Therefore, starting with lower doses and carefully monitoring responses can enhance safety and therapeutic effectiveness in this population, making it critical to tailor pharmacotherapy accordingly to mitigate potential risks.

While metabolic rates can vary among individuals, older adults typically experience a decline in metabolism, rather than a higher rate, which contradicts that option as a reason for lower dosages. Moreover, weight considerations do play a role; however, it is primarily the physiological