Many Alzheimer’s patients get drugs with
opposing effects
But no higher risk of death or nursing home
entry with choline drug conflict
October 27, 2011—You wouldn’t brake your
car while stepping on the gas—or wash
down a sleeping pill with espresso. Yet
many people taking common Alzheimer’s
disease medications—cholinesterase
inhibitors—are given medications with
anticholinergic properties, which oppose
their effects.
Group
Health Research Institute
scientists investigated how often that
happens and reported on the consequences in
an “Early View” study e-published in
the Journal of the American Geriatrics
Society.
“Cholinesterase inhibitors are today’s
primary therapy for slowing Alzheimer's disease,” said
study leader Denise
Boudreau, PhD, RPh, an
associate scientific investigator at Group Health
Research Institute.
“Anticholinergic properties are often found in drugs
commonly used to treat gastrointestinal disorders,
allergies, urinary incontinence, depression, and
Parkinson’s disease, and they can have negative effects
on cognition and function in the elderly. There’s
concern that if someone is taking both types of
drugs—cholinesterase inhibitors and anticholinergic
medications—they will antagonize each other, and neither
will work.”
In clinical trials, cholinesterase
inhibitors show modest effects against the
functional and cognitive decline of people
with Alzheimer’s disease. These medications,
such as donepezil (Aricept) work by
inhibiting the breakdown of acetylcholine,
which sends signals in the nervous system.
By contrast, anticholinergics—such as diphenhydramine
(Benadryl) and oxybutynin (Ditopan)—block the action of
acetylcholine. Since the two types of drugs have
opposite effects, it makes sense not to give both kinds
of drugs to an individual person. But until Dr.
Boudreau’s study, few researchers had explored how often
patients are prescribed both types of medications and
which harms this might cause.
Dr. Boudreau and colleagues conducted a retrospective
cohort study of 5,625 people aged 50 or older who
received a new prescription for cholinesterase
inhibitors between 2000 and 2007.
The researchers used electronic pharmacy
records of Group
Health Cooperative and Kaiser
Permanente Colorado,
nonprofit health care systems that together
provide care to more than a million people.
The research team found patients who also
had a prescription for anticholinergics from
the year before their cholinesterase
prescription until the analysis ended on
December 31, 2008, or the patient left the
health care system or died. The study was
the first to use state death records and
insurance claims for nursing home care to
look for effects of taking both drug types.
The researchers found:
§ Of the cholinesterase inhibitor
users, 37 percent were also taking at least one
anticholinergic drug, and more than 11 percent took two
or more. This was similar to other studies of Medicare
beneficiaries.
§ For those using both medication
types, dual use generally lasted three to four months,
but 25 percent used both classes of drugs for more than
a year.
§ Anticholinergics were already being
used in 23 percent of people receiving a new
cholinesterase inhibitor prescription, and 77 percent
continued, even after starting the cholinesterase
inhibitor.
§ Subjects using both medication
types were not more likely to enter a nursing home or to
die than those taking only cholinesterase inhibitors.
“It’s reassuring
that we did not observe an association between
simultaneous use of the two types of drugs and increased
risk of death or nursing home placement,” said Dr.
Boudreau. “But concomitant use of these drugs is, at the
very least, not optimal clinical practice.” Preventing
concurrent use of opposing drugs could also be a chance
to reduce waste in health care spending, since a month
of donepezil treatment costs approximately $180.
One reason that
health care providers might prescribe conflicting
medications is that dementia patients often have
multiple medical conditions. Also, anticholinergics are
often given to counteract the side effects of
cholinesterase inhibitors, which are one of the few
available treatments for people with Alzheimer’s. Dr.
Boudreau hopes the study raises awareness about the
potential inappropriateness of prescribing both types of
drugs—and stimulate discussions about the best way to
make therapeutic decisions for people with Alzheimer’s.
“Providers,
families, and patients should carefully consider the
extent to which demonstrated benefits or harms in an
individual patient justify long-term use of these
drugs,” said Dr. Boudreau. “A good first step is to have
clearly agreed-upon goals for therapy and a plan to
monitor for effects and side effects.” Now Group Health
Research Institute scientists have started to work with
Group Health Cooperative on steps like these to improve
the quality of care.
Dr. Boudreau’s
co-authors are Senior Biostatistician Onchee
Yu, MS, Group Health Vice President for Research and
Executive Director Eric
B. Larson, MD, MPH, and Jeanene Johnson, MPH, of
Group Health Research Institute, in Seattle; Shelly L.
Gray, PharmD, MS, of the University of Washington; and
Marsha A. Raebel, PharmD, of the Kaiser Permanente
Colorado Institute for Health Research and the
University of Colorado at Denver. Drs. Boudreau and
Larson are also affiliated with the University of
Washington.
The Journal of
the American Geriatrics Society
The Journal of the American Geriatrics Society is a
comprehensive and reliable source of monthly research
and information about common diseases and disorders of
older adults.
Group Health
Research Institute
Group Health Research Institute is the research arm
of Seattle-based Group
Health Cooperative, a consumer-governed, nonprofit
health care system. Founded in 1947, Group Health
Cooperative coordinates health care and coverage. Group
Health Research Institute changed its name from Group
Health Center for Health Studies in 2009. Since 1983,
the Institute has conducted nonproprietary
public-interest research on preventing, diagnosing, and
treating major health problems. Government and private
research grants provide its main funding.
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