Dùng
Thuốc An Toàn Cho Người Già
SAFE MEDICATION USE IN THE ELDERLY
Angeline Tran, Pharm.D.
Patients over 65 years of age are most vulnerable for
having adverse drug reactions. Due to aging, pharmacokinetics of medications
are altered in the elderly which can lead to increased absorption, decrease
renal clearance, increased half-life of medications. Unfortunately, these
changes can cause increased sedation, depression, constipation, falls,
hip fractures, delirium, and urticaria in the elderly. More than 40 percent
of patients over 65 years of age will use at least 5 medications per week
and 12 percent will use 10 medications per week. Increased number of medication
usage increases likelihood of medication related events. Often times,
these patients are taking medications to counteract or mask the side effects
of the other medications that they are taking. About one in three patients
will experience an adverse drug reaction each year and 65% will require
doctor’s visit or emergency room visit. Approximately 28% of these adverse
drug reactions are preventable.
Thirty percent of all hospital admissions may be linked
to drug related problems or the toxic effect of drugs. In 2000, the Institute
of Medicine (IOM) estimated that medication related deaths caused 106,000
deaths annually and at a cost of 85 billion dollars in the United States
alone. Other studies have estimated that medication related problems caused
76.6 billion dollars in outpatient setting, 20 billion dollars in hospitals,
and 4 billion dollars to nursing home facilities. Medication related deaths
could be ranked as the 5th leading cause of death in the United States.
As a result, appropriate and safe medication use in the elderly is of
the utmost importance.
There are many factors that contribute to unsafe medication
use in the elderly such as misuse of medications, overuse of medications,
underprescribing and patient noncompliance. Beer’s Criteria, a list of
drugs that should be avoided in the elderly was developed in 1991 by expert
consensus panel. This list was updated in 1997 and recently updated again
in 2002. The Beer’s criteria was adopted in July 1999 by Centers for Medicare
and Medicaid as a quality assurance tool for nursing home. Currently,
there are about 14-24% of patients receiving these potentially inappropriate
medications. If a patient is on medication on this list, alternatives
should be considered. If alternatives cannot be used, then lowest effective
dose is recommended.
According to Beers Criteria, antidepressants such
as Amitryptylline, Doxepin should be avoided due to its anticholinergic
(dry mouth, dry eyes, constipation, urinary retention) and sedating properties
and safer alternatives are available. Fluoxetine should also be avoided
due to its long half-life that could lead to increased CNS stimulation,
sleep disturbances, and agitation. If fluoxetine cannot be avoided, patients
should take it in the morning. Sedatives such as chlordiazepoxide, flurazepam,
and diazepam should be avoided due to its long half-life which could lead
to prolonged sedation, increased risk of falls and fractures. Short acting
benzodiazepines such as lorazepam can be used but at the smallest dose
effective dose possible. Barbiturates that contains butalbital has strong
addictive properties so long-term therapy is not recommended. In addition,
Meprobamate is highly addictive and sedating anxiolytic medication. With
prolonged used, patients need to be titrated off meprobamate slowly. Antipsychotics
such as Mesoridazine and Thioridazine can lead to delirium and EPS side
effects
Anti-arrhythmic such as amiodarone should be used with
caution due to increase risk of QT interval prolongation and torsade de
pointes. Disopryramide has strong anticholinergic properties, and decreases
cardiac output can lead to heart failure. These drugs should be closely
monitored. Digoxin is not recommended at doses greater than 0.125mg once
a day due to reduced renal clearance in elderly patients. Older antihypertensive
such as guanethidine and guanadrel can cause orthostatic hypotension,
therefore increase risk of falls. Nifedipine is also known cause orthostatic
hypotension and constipation in the elderly. Methyldopa can cause bradycardia
and worsen depression. Newer antihypertensives are available with fewer
side effects.
Non-Steroidal Anti-Inflammatory Drugs such as Piroxicam,
Naproxen, and Oxaprozin are most commonly used in elderly for chronic
pain but they have many unwanted effects such as gastrointestinal bleed,
hypertension, heart failure, and renal failure. Ketorolac causes the most
GI side effects and Indomethacin causes the most CNS side effects. Safer
NSAIDS can be used such as Nambumetone. Muscle relaxants such as methocarbamol,
carisoprodol, metaxalone, cyclobenzaprine, and oxybutinin’s effectiveness
is questionable and they can cause anticholinergic effects, weakness,
sedation, and delirium. Orphenadrine also has strong anticholinergic properties
and sedation. Narcotics such as Merperidine (Demerol) is not effective
as an oral analgesic and its metabolite can accumulate in patients with
decreased renal clearance causing seizures. Talwin is a narcotic analgesic
can cause CNS side effects including confusion, hallucinations more commonly
than other narcotics.
Antihistamines such as diphenhydramine (Benadryl),
hydroxyzine (Atarax), promethazine (Phenergan), cyprohepatadine (Periactin),
chlorpheniramine (Chlortrimeton), and dexchlorpheniramine (Polararimine)
have potent anticholinergic properties and cause prolonged sedation that
can lead to confusion and falls. Patients should be counsel to use these
medications on as needed short term and on as needed basis. Non-sedating
antihistamines should be used.
Antispasmodic such as dicyclomine and hyoscyamine have
anticholinergic properties and should be avoided with long term use. Antiemetic
Tigan is the least effective of all the antiemetics can cause EPS side
effects and should be avoided. Stimulant laxatives like castor oil, bisacodyl,
and cascara sagrada should be avoided because they can worsen bowel function.
Patients are encouraged to have a complete medication review
every 6-12 months by their pharmacist or physician. Patients should have
a list of their medications with them when they see their physician so
that their physician can determine if a listed medication is still appropriate.
Patients are advised to use one pharmacy so that a complete list of their
medication is available for the pharmacist to check for drug interactions
and drug disease interactions to prevent medication related events. Patients
should have one primary care physician who is aware of patients overall
health history.
Nonpharmacological therapy should be considered in the
geriatric population. Instead of taking medicine for back spasms, patients
should consider physical therapy and exercise. If patient has no physical
limitation, patient should exercise 30 minutes per day to reduce their
blood pressure, blood sugar, and cholesterol. Eating foods low in salt,
fat, and sugar is also best to reduce the number of medication that patients
have to take. Patients should consider counseling, relaxation technique
before taking any anxiolytic or an antidepressant.
Majority of elderly patients have renal insufficiency so
renally adjusted dose may be required. Patients should never take more
than prescribed dose of medication. Medication non compliance or non adherence
occurs in about 40-60 percent of prescriptions which can be due to lack
of communication between physicians and patients, patient forgetfulness,
and medication cost. Before discontinuing a medication, patients needs
to ask or informed their physician. In some cases, lack of knowledge can
lead to non-adherence. For example, patients with coronary artery disease
or history of myocardial infarction must remember that they have to take
aspirin, beta-blocker, ace-inhibitor, and statin if there are no contraindications,
allergies, or intolerances. Besides lowering blood pressure, cholesterol,
these medications have shown time and time again to have cardioprotective
effects.
Elderly are especially prone to medication related reactions
due to many age related factors. However, safe and appropriate medication
use can lead to decrease in office visits and hospitalizations and deaths.
Clinicians need to be vigilant not to prescribe inappropriate medications
in the elderly and invite dialogue with patients regarding safe medication
practices. Patients should keep accurate list of medications that they
currently take so that their pharmacists and physicians can review and
monitor their medication use periodically. Safe medication use is everyone’s
responsibility.
References:
Fick DM, Cooper JW, Wade We, Waller JL, Maclean
JR, Beers MH. Updating the Beers criteria for potentially inappropriate
medication use in older adults: results of US consensus panel of experts.
Arch Intern Med 2003:163:2716-24.
Pham CB, Dickman RL. Minimizing Adverse Drug Events
in Older Patients. Am Fam Physician 2007:76:1837-44.
Angeline Tran, Pharm.D.
Copyright, 2007. Muốn phổ biến bài viết này, cần xin phép tác giả và xin ghi rõ nguồn Y Dược Ngày Nay, www.yduocngaynay.com
