older people’s health issues
Aging and Medications
Benefits and Risks of Prescription Drugs
Many of the improvements in the health and function of older people during the past several decades can be attributed to the benefits of drugs. Vaccines help prevent many infectious diseases (such as influenza and pneumonia) that once killed many older people. Antibiotics are often effective in treating serious infections, including pneumonia. Drugs to control high blood pressure (antihypertensives) help prevent strokes and heart attacks. Drugs to control blood sugar levels (insulinand other antihyperglycemic drugs) enable millions of people with diabetes to lead normal lives. These drugs also reduce the risk of eye and kidney problems that diabetes can cause. Drugs to control pain and other symptoms enable millions of people with arthritis to continue to function. However, drugs can have effects that are not intended or desired (side effects). Starting in late middle age, the risk of side effects related to the use of drugs increases. Older people are more than twice as susceptible to the Overview of Adverse Drug Reactions as younger people. Side effects are also likely to be more severe, affecting quality of life and resulting in visits to the doctor and in hospitalization. Older people are more susceptible to the side effects of drugs for several reasons: As people age, the total amount of water in the body decreases, and the amount of fat tissue increases. Thus, in older people, drugs that dissolve in water reach higher concentrations because there is less water to dilute them, and drugs that dissolve in fat accumulate more because there is relatively more fat tissue to store them (see Drug Distribution ). As people age, the kidneys are less able to excrete drugs into urine, and the liver is less able to break down (metabolize) many drugs (see Drug Metabolism ). Thus, drugs are less readily removed from the body (see Older people usually take more drugs and have more disorders. People who take more drugs have a higher risk of Drug Interactions . Fewer studies have been done in older people to help identify appropriate doses of drugs. Older people are more likely to have chronic medical disorders that may be worsened by drugs or that may affect how the drugs work. Because of these age-related changes, many drugs tend to stay in an older person’s body much longer, prolonging the drug’s effect and increasing the risk of side effects. Therefore, older people often need to take smaller doses of certain drugs or perhaps fewer daily doses. For example,digoxin, a drug sometimes used to treat certain heart disorders, dissolves in water and is eliminated by the kidneys. Because the amount of water in the body decreases and the kidneys function less well as people age,digoxinconcentrations in the body may be increased, resulting in a greater risk of side effects (such as nausea or abnormal heart rhythms). To prevent this problem, doctors may use a smaller dose. Or sometimes other drugs can be substituted. Older people are more sensitive to the effects of many drugs. For example, older people tend to become sleepier and are more likely to become confused when using certain antianxiety drugs (see table Drugs Used to Treat Anxiety Disorders ) or Many commonly used drugs have Anticholinergic: What Does It Mean? . These drugs include some antidepressants ( Anticholinergic effects are caused by drugs that block the action of acetylcholine. Acetylcholine is a chemical messenger (neurotransmitter) released by a nerve cell to transmit a signal to a neighboring nerve cell or a cell in a muscle or gland. Acetylcholine helps cells talk to each other. Acetylcholine helps with memory, learning, and concentration. It also helps control the functioning of the heart, blood vessels, airways, and urinary and digestive organs. Drugs that block the effects of acetylcholine can disrupt the normal functioning of these organs. Many commonly used drugs have anticholinergic effects. Most of these drugs were not designed to have these unwanted effects. Anticholinergic effects include the following: Confusion Blurred vision Constipation Dry mouth Light-headedness and loss of balance Difficulty urinating However, anticholinergic drugs can also have useful effects, such as helping control tremors, nausea, or overactive bladder. Older people are more likely to experience anticholinergic effects because the amount of acetylcholine in the body decreases with age. Consequently, anticholinergic drugs block a higher percentage of acetylcholine, so that the aging body is less able to use what little acetylcholine is present. Also, cells in many parts of the body (such as the digestive tract) have fewer sites where acetylcholine can attach. As a result, doctors usually try to avoid using drugs with anticholinergic effects in older people if possible. A drug may have a side effect because it interacts with A disorder, symptom, or condition other than the one for which the drug is being taken (drug–disease interaction) Another drug (drug–drug interaction) Food (drug–food interaction) A medicinal herb (drug–medicinal herb interaction) Because older people tend to have more diseases and take more drugs than younger people, they are more likely to have drug–disease and drug–drug interactions. In many drug-disease interactions, taking a dug can worsen a disorder, symptom, or condition (see table Some Disorders and Symptoms That Can Be Worsened by Drugs in Older People ). Patients, doctors, and pharmacists can take steps to reduce the risk of drug–disease and drug–drug interactions. Because over-the-counter drugs and medicinal herbs can interact with other drugs, people should ask their doctor or pharmacist about combining the use of these drugs with prescription drugs. Not following a doctor’s directions for taking a drug (called nonadherence) can be risky (see Adherence to Drug Treatment ). Older age alone does not make people less likely to take drugs as directed. However, up to half of older people do not take drugs as directed. Not taking a drug, taking too little, or taking too much can cause problems. Taking less of a drug because it has side effects may seem reasonable, but people should talk to a doctor before they make any changes in the way they take a drug. 