Adverse drug effects.

Adverse drug effects afflict the elderly with greater frequency than the young. Several factors are responsible, among them the age-related alterations in pharmacokinetics and pharmacodynamics. Most importantly, it is the number of drugs taken on a daily basis that is cited as being the cause. When one extends the concept of adverse drug reactions to the concept of adverse drug events, then errors made by the patient, caregiver, and/or health care provider appear to be responsible to a large degree.