What is the primary cause of decreased drug efficacy in older patients?

The primary cause of decreased drug efficacy in older patients is related to decreased renal function. As individuals age, their renal clearance of medications often declines due to structural and functional changes in the kidneys. This reduction in renal function can lead to accumulation of drugs in the body, as renally excreted medications are not being eliminated as effectively. Consequently, this can cause variations in pharmacokinetics, potentially leading to either reduced efficacy or increased toxicity of medications.

In older adults, increased lipid solubility, as would occur with certain medications, does not directly note a primary cause of decreased drug efficacy, although it may influence the distribution of lipophilic drugs. However, decreased renal function is a more significant factor impacting drug metabolism and excretion, leading to overall altered drug efficacy. Thus, the correct understanding centers on the decline in renal function, which is a critical consideration in geriatric pharmacotherapy.