| |
The liver and kidneys have the vital job of eliminating waste from the
body. These wastes are usually by-products of the various metabolic functions
that keep the body fueled and functioning, excess biochemical substances
that, if allowed to build up unchecked, would sicken or even kill the
individual.
This same pathway is vital for eliminating
medicines from the body once they have done their job. Researchers carefully
calibrate dosages of each medication so that just the right level of the
active ingredient stays in the bloodstream just long enough to do its
job before the liver and kidneys flush it from the system.
However, even in people in good health,
there are changes in the way their liver and kidneys function as they
frow older, changes that can have far-reaching and unexpected consequences.
Like many other parts of the human body, these organs begin to slow down
a bit with age—they still get their jobs done, but they don't do
it nearly as efficiently as they once did.
By itself, this slowdown can make older
people a little more vulnerable to metabolic imbalances—a little
more waste-product sticking around in the bloodstream a little longer
than was once the norm can make a person feel a bit indisposed. But when
coupled with the increased number of prescription medicines taken by typical
seniors to treat their increased numbers of ailments, this slowdown in
the liver and kidneys can cause some serious health problems.
Take, for example, a standard dosage of
a medication X. When given to a thirty year old patient, Medication X
treats the symptoms it was given for and is eliminated from the patient's
body without incident. Give that same dosage of Medication X to a patient
of the same body mass but fifty years older, and too much of that X sticks
around in the patient's blood stream for far too long. It's as if the
eighty-year-old patient has received an effective dosage far higher than
the thirty-year-old. If that medication was, for instance, a sedative
such as diazepam (Valium), the resulting overdose could put the patient
in a confused, befogged state. Too many more days of this overdose could
throw our older patient into a serious delirium.
Then suppose the eighty-year-old patient
is receiving not only doses of X more suited to a thirty-year-old, but
also similar overdoses of medications Y, Z, Q, and R. Each additional
overdose puts more of a strain on his overworked liver and kidneys, making
them work even slower, leading to higher levels of all five of these medications
sticking around too long in his bloodstream. The effects begin to snowball,
such that even if none of the medications in question have any psychoactive
effects under normal circumstances, the poor senior patient is still thrown
into a mental fog due to overmedication.
And even when this problem is noticed and
the medications stopped or their dosages greatly reduced, it can take
our hypothetical eighty-year-old weeks longer to recover than would his
thirty-year-old peer from a proportional overdose. Again, because the
liver and kidneys work that much more slowly, it takes them that much
longer to clear the last of the excess drugs. In addition, many other
systems in the older patient's body have also undergone age-related changes
that make them more sensitive to drugs: the blood/brain barrier, for example,
is much easier for drugs to cross in older people, contributing to the
length of time it takes an older patient to throw off that overdose fog.
Clearly, then, it is vital that doctors
treating older patients understand these differences in the way they process
medicines, and prescribe accordingly. If the patient has several different
health conditions, each requiring its own medication for treatment, there
isn't much the doctor can do about that. But the doctor can certainly
adjust the dosages of each medication downward to take into account the
patient's slower waste metabolism. The doctor can also select medications
that are better tolerated by older patients to begin with, and in other
ways be conservative in the type and number of medications to give.
Ultimately, more research is needed to keep
on finding newer and better medications for the diseases prevalent among
seniors—medicines which, in addition to treating those diseases
more effectively, also function more gently within the senior patient's
maturing body.
|
|
