Final answer:
The physiologic change in older adults affecting drug administration is lower cardiac output. This can alter drug distribution, metabolism, and excretion, among other factors such as decreased glomerular filtration rate and decreased intestinal peristalsis.
Step-by-step explanation:
The physiologic change seen in the older adult that has an effect on drug administration is lower cardiac output. This is a significant factor because the heart's ability to pump blood may decrease with age, impacting the distribution of drugs throughout the body. Lower cardiac output can affect the concentration and the rate at which drugs are delivered to their sites of action, as well as their metabolism and excretion.
Aging can also lead to changes in other areas of the body that impact drug administration. For instance, there may be decreased glomerular filtration rate due to a loss of nephrons, which affects how the kidneys filter drugs, potentially leading to the accumulation of drugs in the body and increasing the risk of adverse effects. Moreover, decreased intestinal peristalsis can slow the rate at which drugs are absorbed in the digestive system.