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A Pacific Northwest Extension Publication
Oregon State University, Washington State University, University of Idaho
USING MEDICINE SAFELY IN LATER
LIFE
PNW 393
September 1993
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Why Older People Are at Risk
Age Affects How Medicine Reacts in Your
Body
What All This Means
Adverse Drug Reactions
Compliance with Medications Therapy
Possible Solutions to Common Problems
Conclusion
Over several weeks George became increasingly
confused. He just didn't care about anything. George's wife and
daughter were afraid... afraid George was developing Alzheimer's
disease. A visit to the doctor revealed that the problem was
not what they had suspected. George did not have Alzheimer's
disease. The dementia like symptoms he was experiencing resulted
from an adverse reaction to a prescription medication he had
recently started taking. Although he was taking the recommended
dosage, it was not appropriate for George.
George's story is not unusual. As we grow
older, we may become more sensitive to certain medicines, and
consequently the chance for an adverse drug reaction can increase.
Drugs include not only prescription medicine
(those ordered by a doctor and dispensed by a pharmacist) but
over-the-counter medicine (those bought and used without a prescription)
as well. Many people make the mistake of thinking that over-the-counter
medicines are without risk.
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Why Older People
Are at Risk
Older people are at risk of experiencing problems
with medication for several reasons.
Multiple medicines. It's
not unusual for an older person to be taking five or more medications,
perhaps several times a day, for different health problems. The
risk of an adverse reaction increases dramatically with each
additional medicine a person takes. When different medications
are used at the same time, they may interact. The potential risk
of a drug interaction is:
- 5.6 percent for a person taking two medications
- 50 percent for a person taking five medications
- Nearly 100 percent for a person taking 8
or more medications
Multiple diseases. Older
adults are more likely than any other age group to have one or
more chronic illnesses, including heart disease, high blood pressure,
diabetes, and arthritis. Some medical conditions change the way
drugs are used in the body.
Complex dosage schedules. With multiple medications taken at different times
throughout the day, dosage schedules often become complicated.
This increases the risk of making a mistake, such as taking the
dose twice or forgetting to take a medicine as prescribed.
Types of medicine taken. Older adults are more likely to be taking powerful
medications that could potentially cause an adverse reaction.
For example, anticoagulant, antihypertensive, diuretic, cardiac,
and central-nervous-system- depressant medicines are commonly
used by older people, and each can cause adverse effects.
Age-related changes. Normal
aging changes the way drugs are absorbed, metabolized, distributed,
and removed from the body. These changes are described in the
next section.
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Age Affects How
Medicine Reacts in Your Body
Age-related changes that can significantly
affect drug action include the following.
Increase in body fat. As a person ages, the amount of lean body mass (mainly
muscle) decreases and the amount of fat tissue increases, even
though a person's total weight may remain the same. In older
adults, medication distributed in fat has a wider distribution
which may result in a less intense, but prolonged, effect. For
example, the effects of certain sleeping medications and tranquilizers
last longer than when the person was younger.
Decrease in body fluid. The percentage of body weight composed of water decreases
with age. As a result, medicines that are normally distributed
in body water may become more concentrated in an older adult--possibly
exaggerating the medicine's effect--unless the dosage is decreased.
Decrease in action of gastrointestinal
tract. It takes longer for food to
move through the stomach and intestines. In rare instances, this
may affect the absorption of certain medications into the blood
stream.
Decrease in albumin. Albumin,
a protein in the blood stream, decreases with age. Once a drug
is absorbed into the blood stream, it binds in various degrees
to albumin. Only the unbound portion of the drug is active.
As albumin decreases in the body, the amount
of unbound (active) drug increases. Therefore, what would normally
be a therapeutic dose for a younger adult may cause an adverse
reaction in an older person. For example, usually 97 percent
of warfarin (Coumadin), a highly protein-bound drug, is bound,
and only 3 percent of the drug is actually working. In an older
person, the binding of Coumadin to albumin in the blood stream
may be decreased to 94 percent. Consequently, the amount of unbound,
active drug could be twice as much.
Decrease in liver function. Metabolism, or the chemical detoxification of many
medications, takes place in the liver. Some drugs are changed
into water-soluble form in the liver so they can be excreted
from the body. With aging, the liver decreases in size, blood
flow decreases, and some of the enzymes that break down medications
decline. Consequently, certain drugs can accumulate in the body
and cause problems unless the dosage is reduced.
Decrease in kidney function. Changes in the kidney are more dramatic than those
in any other organ. The kidneys become smaller, blood flow decreases,
and filtering capacity decreases with age. Between the ages of
20 and 80 there is an average decline in kidney function of 35
percent. As a result, certain drugs are excreted more slowly,
thus remaining active in the body longer. Medical conditions
such as heart failure, anemia, or dehydration may further impair
kidney function.
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What All This
Means
The action of a medicine may be less predictable
in an older person, and its intended action may be altered. Sometimes
the effect is insignificant; other times it can be dramatic.
For example, while 10 mg of Valium might relax the muscles of
a young adult, it could cause unsteadiness in an older person
and result in a fall and possibly a broken hip. Older people
more frequently experience dizziness from medications such as
antihypertensives.
A drug may remain active longer in an older
person's body and accumulate to toxic levels. Less medication
may be required, so the standard adult dose may be inappropriate.
Dosages for some medications may need to be reduced by one-third
or one-half of the usual adult dose.
The more medicines a person takes, the higher
the risk of drug interaction. A drug interaction occurs when
the effect of one drug is altered by the presence of another
drug in the body. One drug might reduce or increase the effects
of another, with harmful consequences. Two drugs used concurrently
may produce a new and dangerous reaction. Two similar drugs taken
together may produce an effect that is greater than expected
from one drug.
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Adverse Drug Reactions
On the average, the chances of an adverse
drug reaction occurring in older people is three times greater
than in younger adults. Forty percent of people who suffer an
adverse drug reaction are over age 60. Adverse drug reactions
frequently go unnoticed or are misdiagnosed in older people for
the following reasons.
- Changes resulting from adverse drug reactions
may be assumed to be the result of normal aging.
- Symptoms may be attributed to worsening of
an existing medical condition or the onset of a new health problem.
- Drug reactions often mimic signs or symptoms
of disease, such as Alzheimer's disease.
- Adverse drug reactions in older adults sometimes
differ from those characteristic in younger adults, or they may
appear in some unexpected way. For example, confusion could be
caused by a medication taken for stomach or heart problems.
Signs of adverse drug reactions vary, but
may include:
- A change in health
- Fatigue
- Constipation
- Diarrhea
- Anorexia
- Confusion, fluctuating mental status
- Incontinence
- Frequent falls
- Depression
- Weakness or tremor
- Excess drowsiness
- Hallucinations
- Agitation, anxiety, or excitation
- Dizziness
- Decreased sexual response
- Rash
It's easier to recognize that a change in
a person's behavior or physical condition may be due to a medicine
if problems develop shortly after the person begins taking the
medicine. However, sometimes it takes several weeks or even
months for an adverse reaction to become apparent. When the
onset of symptoms is far removed from the time the person first
started taking the medicine, you may be less likely to associate
changes with the medicine.
When a change occurs in an older person's
behavior or physical or mental condition, consider that a medication
may be the cause. The first sign of an adverse drug reaction
in an older adult is often a change in mental functioning. The
person may appear forgetful, confused, "spaced out,"
or hallucinating.
Do not attribute such changes to "old
age." There is a cause! Changes in mental functioning
are not normal in an older person.
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Compliance with
Medication Therapy
Although aging affects how medicines are processed
in our bodies, a major factor affecting how well a medicine works
is whether or not medicine is taken correctly. Approximately
50 percent of people taking medications do not take them correctly.
The consequences of mistakes in medication-taking can be dangerous
and expensive. Sometimes mistakes can also be life threatening.
There are many reasons people do not take
a medicine as prescribed. If you or someone you know is not taking
medication as prescribed, use this checklist to determine the
reason. Ask whether the person:
Thought
more was better or a larger dose would make them well sooner.
Believed
medicine was not working, so stopped taking it. (All medicines
work differently. It may take several days or weeks to get the
full benefit.)
Felt
better so stopped taking medicine.
Didn't
understand instructions. (The person may not have heard instructions
correctly or misinterpreted them.)
Didn't
get prescription filled/refilled.
Thought
the taste was unpleasant.
Had
problems remembering when to take the medicine. (Multiple medicines
and a complex dosage schedule make it difficult to keep track
of when and how to take medicines; verbal instructions may not
be remembered or doses may be missed due to short-term memory
loss; or sometimes the medicine causes confusion and creates
problems in taking the correct dose.)
Tried
to make up for a forgotten dose by doubling the next dose. Experienced
adverse effects.
Disliked
or feared side effects.
Feared
becoming drug dependent.
Was
not able to afford the medicine. (Tried to reduce costs by taking
old medicine, taking half the dose, diluting the dose, skipping
a day, or not having a prescription filled.)
Accidentally
misused the medicine. (Produced an undesirable effect by taking
a prescription medicine with an over-the-counter medicine, a
food, or beverage with which it should not be mixed.)
Found
it difficult to get to the pharmacy or store to purchase medicine.
Had difficulty taking the medicine (e.g., swallowing a pill,
putting drops in eyes, or giving insulin injection).
Could
not read medication labels because of poor vision.
Could
not open childproof containers.
Found
the drug-taking schedule too complicated.
Felt
taking the medicine disrupted daily activities and normal functioning.
Disliked
or distrusted taking the medicine. (Person may have felt the
medicine was not needed, the doctor was wrong, or just did not
want to take it.)
There may be more than one reason a person
is not taking medicine as prescribed. Once you know why a medicine
is not being taken properly, talk to the doctor or pharmacist.
Possible Solutions to Common Problems
In later life, certain conditions are more
common and may make a person more vulnerable to errors in taking
medication properly. Some possible solutions are listed below.
| PROBLEM |
POSSIBLE SOLUTION |
| Impaired vision |
- Ask pharmacist to use larger print on label.
- Use a magnifying glass to check labels before
taking medication.
|
| Impaired hearing |
- Let others know if you did not hear the instructions.
- Ask doctor and pharmacist to write instructions.
- Ask someone to go with you to the doctor.
|
| Forgetfulness |
- Use memory aids and daily or weekly medicine
dispensers.
|
| Limited mobility |
- Use a pharmacy that delivers prescriptions.
|
| Limited use of hands |
- Ask pharmacist for easy-to-open medication
caps (keep out of reach of children).
|
| Multiple medications |
- Have doctor evaluate medication regime regularly.
- Use a pharmacy that keeps a patient medication
profile for customers.
|
| Multiple doctors |
- Make sure each doctor knows all medications,
including over-the-counter, you are taking.
- Purchase your prescriptions at only one pharmacy.
(This enables the pharmacist to check for drug interactions.)
|
| Cost of medications |
- Take advantage of discount programs.
- Call local pharmacies and compare prices.
- Ask doctor or pharmacist whether a generic
drug will be as effective and less costly.
- Ask doctor to prescribe generic medications
if possible.
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Conclusion
Today's medicines have tremendous benefits--they
cure disease, help manage symptoms, reduce pain, and speed recovery.
But along with benefits, some medications carry risks, and all
medicines can produce undesirable side effects. Although medication
problems can increase in later life, many complications are both
predictable and preventable.
Proper use of medicines can enhance quality
of life. However, improper use or not recognizing adverse effects
of a medicine can deprive a person of self-control and independent
living. If you are taking medicines, you have a responsibility
to be knowledgeable about the medicines you use and to take them
as instructed. Find out how to maximize the treatment results
of your medications and how to reduce risks.
If you are responsible for helping someone
to take medicines, learn all you can about the person's medicines,
how they should be taken, and the side effects to watch for.
If you see more than one doctor, be sure that
each doctor knows about all medicines you take. Remember to tell
about over-the-counter medicines you take, such as cold remedies,
pain relievers, laxatives, and antacids. If you drink alcohol,
tell the doctor the amount and frequency. Have all of your prescriptions
filled at the same pharmacy--one that maintains a patient medication
profile.
If you are taking prescription medicines,
be cautious about self-treating with over-the-counter medicines.
Even common over-the-counter medicines--for example, aspirin,
cough and cold products, and laxatives--contain chemicals that
can produce side effects or interact adversely with prescription
medicines. Before purchasing an over-the-counter medicine, check
with the pharmacist to be sure the product is safe for you.
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Prepared
by Vicki Schmall, Extension Gerontology Specialist And
Janice Leno, Extension agent, Josephine County, Oregon
State University.
September 1993.
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