Although you can’t prevent every adverse drug reaction, you need to watch for drug classes that are most likely to cause trouble to help your patient avoid problems.
JOHN HEAVENER, 66, IS ADMITTED TO YOUR EMERGENCY department with a 4-inch (10-cm) laceration on his temple. neurontin. He reports that he got dizzy and fell while getting out of bed during the night to go to the bathroom.
During your assessment, you learn that Mr. Heavener is taking ibuprofen (Advil) for osteoarthritis and amitriptyline (Elavil) for depression. He’s also taking propranolol (Inderal) for high blood pressure (BP).
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You know that Mr. Heavener’s antidepressant may oversedate an elderly patient and that his BP medication can cause dizziness. Both drugs can cause postural hypotension. You suspect that this combination of adverse reactions may well have led to his injury. And because Mr. Heavener doesn’t seem to realize that he should have been more careful when getting out of bed, you wonder whether he received adequate patient teaching about how to avoid adverse reactions from his drug regimen.
To some extent, adverse drug reactionsunintended or undesired responses to a standard drug dose-are unavoidable. And, as Mr. Heavener’s injury shows, they can have serious consequences-especially in elderly patients.
In this article, I’ll review some common adverse reactions that drugs cause and what you should teach your patient to do-and not do-if he suffers an adverse reaction (see Strategic Maneuvers). Because you spend the most time with patients, you’re in an excellent position to prevent an adverse drug reaction or recognize and react to it quickly.
Keep in mind that your task is complicated by the increasing number of new drugs that reach the market each year. In 1996, for example, the Food and Drug Administration approved a record 53 new drugs-many via a fasttrack acceptance-and approved new indications or routes for many more drugs. Some adverse effects may not be uncovered before a new drug is distributed widely.
Also remember that some patient groups are more prone to adverse drug events: immunocompromised patients, patients with renal or liver dysfunction that may affect drug absorption and elimination, infants, children, and elderly patients. I’ll concentrate on adverse reactions often seen in elderly patients, but you can apply the information to all patients. First, let’s look at reasons why the elderly are especially at risk. Drugs and aging
Why are elderly patients more susceptible to adverse drug reactions? Reasons include the following:
Normal physiologic changes that accompany aging alter how a person metabolizes and eliminates certain medications.
Older persons are often excluded from premarketing clinical trials, so drug reactions specific to the elderly may not be discoverd.
The older person typically takes more medications than a younger person, which increases the chance of drug interactions and adverse drug reactions.
The older person may develop sensitivity to specific medications, particularly those that affect the cardiovascular and central nervous systems.
The older person may also develop musculoskeletal disorders and functional declines in hearing, sight, and mental alertness that impair his ability to take his medications correctly.
Whenever a physician prescribes a new medication for your patient, review the drugs that the patient is already receiving (including over-the-counter medications and herbal supplements) to check for possible duplications or drug interactions. Take the opportunity to ask the patient how all his medications are affecting him and to respond to his questions or new complaints (see Drug Do’s and Don’ts).
Now let’s look at several types of medications that typically cause adverse reactions in elderly patients: cardiovascular drugs, antianxiety drugs, antidepressants, and analgesics. This review isn’t meant to be a listing of all drugs or all possible effects, but rather a set of reminders about commonly used drugs.
Cardiovascular drugs: Class-related effects
Most cardiovascular drugs share adverse effects with others within the same class. This means you can apply much of what you learn about one drug’s adverse effects to another drug in the same class. Even so, a patient may respond differently to drugs within the same class. So if your patient has an adverse reaction to a drug, the physician may choose to substitute another drug in the same class.
Antihypertensive medications make up the largest class of cardiovascular drugs. Besides their use for high BP, many antihypertensive drugs are also used for other cardiovascular conditions.
All drugs that lower BP can cause orthostatic or postural hypotension. This type of low BP occurs with changes in position, especially after a person rises to a standing position after lying supine for long periods (for example, when first getting up in the morning). The patient’s vasculature can’t compensate quickly enough when he changes positions abruptly, and his BP drops. A common cause of patient falls, this adverse reaction occurs more often early in antihypertensive therapy.