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SAN DIEGO, CALIFORNIA. Adverse drug reactions (ADRs) are a
serious problem in the United States and in many other developed
countries. More than two million serious ADRs occurred in the USA
in 1994 of which 76,000 to 137,000 were fatal. It is estimated
that 76 per cent of these ADRs were due to drug overdosing. The
doses given in many cases followed the manufacturer's
recommendation, but just happened to be excessive for the
particular patient being treated. Dr. Jay Cohen, MD of the
University of California points out that over half of all ADRs
involve patients age 60 years and older. He believes this is
largely because older patients metabolize many drugs slower than
do younger patients and therefore end up with higher systemic
levels which may precipitate an ADR. He also points out that the
Physicians' Desk Reference used by many medical doctors
when prescribing drugs rarely recommends lower dosages for older
patients - in other words, one dose fits all!
Dr. Cohen has reviewed numerous studies that clearly show that
reduced doses of many popular drugs are entirely adequate and much
safer for older patients. For example, the stomach drug
omeprazole (Losec) is cleared from the system much slower in older
people and particularly in older people of Asian descent. He
suggests that 10 mg/day of this drug may be quite adequate in
older people (standard dosage is 20 mg/day). Fluoxetine (Prozac)
is well known for causing sexual dysfunction at its standard dose
of 20 mg/day in about 34 to 74 per cent of patients taking it.
Studies have shown that this effect can be eliminated without
affecting the antidepressant effect by reducing the dose to 10
mg/day; as a matter of fact, dosages as low as 2.5 mg/day may be
quite effective in older people. Other studies have shown that as
little as 10 mg of sildenafil (Viagra) may do the trick and yet
the recommended dosages are 25, 50 and 100 mg. Dr. Cohen lists
many other drugs where reduced dosages are quite adequate and much
safer. For example, Celebrex 5 mg twice daily instead of 10 mg
twice daily, lovastatin (Mevacor) 10 mg/day instead of 20 mg/day,
and simvastatin (Zocor) 5 to 10 mg per day instead of the
recommended dose of 20 mg/day. Nonsteroidal anti-inflammatory
drugs (NSAIDs) are significant contributors to ADRs resulting in
more than 100,000 hospitalizations and between 8,000 and 16,000
deaths every year in the USA alone. Studies involving diclofenac
(Voltaren) and ibuprofen have shown that older people receive the
same effects from half the dose recommended for younger people.
Dr. Cohen concludes that "little is lost and much may be gained"
by starting older people off at low yet effective drug
doses.
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