Drug therapy in the elderly.

Special considerations must be invoked when prescribing medications for the elderly. Although basic absorption is unchanged, many elderly patients are prone to chronic diarrhea or constipation, either of which may alter intestinal contact time and, thus, absorption. Concurrent use of such drugs as antacids or iron preparations may affect the availability of some compounds for absorption. The problem of drug interactions after absorption is also important, since studies have shown that elderly patients commonly receive several drugs concurrently.