Pharmacokinetic changes that occur with aging
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Geriatrics: Overview
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There are many age-related changes that can have a significant effect on drug
therapy. It is important to be aware of the complexities involved in
treating this patient population in order to
reduce the likelihood of an adverse event.
-Clinical Concerns-
Multiple diseases: The elderly in general have an increased incidence of
chronic disease. 80% of the elderly have at least one chronic disease, and
many of them have multiple diseases. This is
particularly evident after age 75. The most common diseases include:
arthritis, hypertension, hearing impairment, heart disease, vision impairment,
orthopedic disabilities and diabetes mellitus.
Multiple medications: The elderly make up approximately 13% of the U.S.
population, however, as a group they use approximately one-third of all
prescriptions written each year and 40% of all
over-the-counter medications used annually. On average, the elderly take
approximately three times as many medications as younger patients. Thus, the
elderly have ample potential for drug-related
adverse events based on the number of medications alone. This is intensified
by the age-related changes discussed above. It is important to use the lowest
possible dose without sacrificing
efficacy. Dosage reductions in many cases may help eliminate or reduce the
risk of an adverse event.
Adverse drug reaction rate: The elderly experience an ADR rate that is
conservatively reported to be 2-3 times that of younger adults. Most of the
higher rate can be explained by changes in renal
and hepatic function, and body composition associated with aging. Another
important factor is the number of medications the elderly consume.
Clinically significant changes in metabolism, distribution and excretion occur
in the elderly. It is vitally important to make appropriate changes in drug
therapy to account for these age related
changes.
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References
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