How does age influence pharmacokinetics?

The influence of age on pharmacokinetics is significant, as it can impact all four key processes: absorption, distribution, metabolism, and excretion. As individuals age, physiological changes occur that affect how drugs are processed in the body.

In terms of absorption, the rate at which drugs are absorbed may change due to factors like gastrointestinal motility and blood flow. For example, older adults may exhibit delayed gastric emptying, which can affect how quickly a drug reaches systemic circulation.

When it comes to distribution, age-related changes in body composition, such as increased body fat and decreased total body water, can alter the volume of distribution for hydrophilic and lipophilic drugs. This means that the concentration of a drug in the bloodstream may vary between younger and older adults, impacting dosing considerations.

Metabolism is also significantly affected by age. Liver size and blood flow can decrease with age, leading to a reduced capacity to metabolize drugs. This is particularly important for drugs that undergo significant first-pass metabolism.

Finally, excretion processes can be influenced by age as well. Renal function often declines with advancing age, which can decrease the elimination of drugs that are primarily excreted by the kidneys. This necessitates careful monitoring and potential dosage adjustments in