Pharmacotherapy Considerations in Elderly Adults

James M. Wooten, PharmD


South Med J. 2012;105(8):437-445. 

In This Article

ADRs/Drug Interactions

The risk for developing an ADR is estimated to be 20%.[23] It has been estimated that the risk for developing an ADR that requires hospitalization is approximately 10.7% for elderly patients as compared with 5.3% for the general population. The majority of ADRs requiring hospitalization are thought to be preventable. ADRs are considered the sixth leading cause of death in the United States.[23] The risk for developing an ADR is much higher in elderly adults than in the general population and this increased risk translates into greater mortality for elderly patients.[23,24] The total annual direct medical cost of medication-related problems in the United States is estimated to be $104.2 billion. Much of this owes to the development of adverse drug reactions in elderly patients.[22–24,27,28]

Some ADRs can be prevented, but practitioners must be judicious in the care, use, and monitoring of the medications they prescribe to their elderly patients. Pharmaceutical research brings new drugs to market every year. This science has been instrumental in allowing people to live longer. For elderly adults, however, these new drugs are a double-edged sword; on the one hand, they may improve mortality, but on the other hand, they can induce an unwanted reaction. One national survey showed that 50% of community-dwelling people older than 65 years use five or more prescription and over-the-counter medications per week, and 12% use ≥ 10. The sheer number of medications used by elderly patients contributes much to the development of ADRs. Table 4 lists drugs and their adverse effects that are commonly used by elderly adults.[22–24,28]

ADRs that affect functional status are frequently observed in elderly patients. The following reactions are common:

  • Anticholinergic symptoms

  • Mental status changes

  • Orthostatic hypotension

  • Mood and behavior changes

  • GI tract disturbances (constipation or diarrhea)

What is notable about this list is the commonality of many of these effects and that many drug classes can be involved in causing these adverse reactions. Because older adults, in general, take a number of medications, identifying the exact cause of a specific reaction can be difficult. Table 5 is an attempt to illustrate this issue further. Extremely common adverse drug effects are listed, along with common manifestations of the effects. Because these problems occur with drugs that are commonly taken by elderly people and they occur with many types of drugs and drug classes, identifying the exact problem and cause can be a difficult process. A patient may have been taking many of the possible culprits for some time, making identification even more difficult.[23,24]

A common cause of adverse drug reactions in elderly patients is drug interactions. This is not surprising considering that the number of medications taken by many elderly patients is high. Various studies have documented a direct correlation between number of medications and the risk of an adverse drug reaction. A study from Brazil reported that the potential drug interaction risk when patients are taking 2 to 3, 4 to 5, and 6 to 7 medications are 39%, 88.8%, and 100%, respectively.[29] Contributing to this problem are pharmacokinetic and pharmacodynamic changes. Essentially, elderly patients are "set up" to have numerous drug interactions, all of which may induce an adverse drug effect.[23,30–32]

Some medications induce problems because they can aggravate a specific disease state while treating another problem. Because most elderly patients have various comorbidities, this is a common problem in these patients (Table 6).[31,32]

Preventing medication problems in elderly people is difficult. Many patients take a large number of drugs over many years. Many physicians are reluctant to stop medications started by a different physician, so the drugs are continued and the list increases. The most important concept for all practitioners to remember is that ADRs in elderly adults are extremely common and the only way to prevent them is to look for them and learn how to properly monitor their occurrence.[29,31–35]