Andrew S. Duxbury, MD
Associate Professor of Medicine
Department of Medicine, Division of Gerontology/Geriatrics/Palliative Care
The University of Alabama at Birmingham
Birmingham, Alabama

Dr. Duxbury does not have any commercial affiliation to disclose.

The University of Alabama School of Medicine is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.

The University of Alabama School of Medicine designates this educational activity for a maximum of 0.25 AMA PRA Category 1 credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

The boards of nursing in many states, including Alabama, recognize Category 1 continuing medical education courses as acceptable activities for the renewal of license to practice nursing.

Inappropriate prescribing of medications for older adults is a significant cause of preventable morbidity and mortality. In the United States, the elderly take medications at a disproportionate rate. While a third of all drug prescriptions are filled for older adults, these individuals comprise only 15% of the population.

“Estimates suggest the average person older than 65 takes seven different drugs a day. Of these, four are prescription medications and three are purchased over the counter,” says UAB geriatrician Andrew S. Duxbury, MD, who notes that in the course of a year, elderly people typically fill prescriptions for more than 28 different medications.

Polypharmacy sets the stage for life-threatening adverse drug effects, nonadherence, and drug-drug interactions. The Institute of Medicine estimates medication-related problems kill more than 100,000 people each year. The cost of complications exceeds $85 billion.

Adverse drug effects are especially problematic in elderly persons who often suffer from several concurrent chronic illnesses that require management with multiple drugs and who have age-related changes in metabolism and excretion that affect pharmacodynamics and pharmacokinetics.

Studies have found that up to 30% of hospital admissions of elderly patients are linked to toxic drug effects and that one in three older patients will have an adverse drug reaction while hospitalized.

DRUGS OF CONCERN

Liver and kidney function change with age, leading to increased drug and metabolite half-lives in older patients. “Aging also causes a natural shift in body composition — people lose lean muscle mass and gain fatty tissue, which alters the volume distribution of drugs,” Duxbury says. “The half-life of a drug that preferentially enters fatty tissue is significantly extended in older persons. With a lipid-soluble agent like diazepam, for example, the drug’s effective half-life is increased from about 24 hours in a healthy middle-aged adult to 4 or 5 days in elderly persons.”

Because older persons rarely meet inclusion criteria for new drug trials, there is little scientific data on the effects of medications in this population. This paucity of data also extends to pediatric populations, and Duxbury notes that while physicians commonly make dose adjustments for age-related differences in drug metabolism in children, they often do not consider similar modifications for elderly patients.

Physiologic issues are compounded by other drug-related practices that increasingly affect older adults, Duxbury says. “These include a health care system that gives seniors access to multiple specialists who may prescribe new medications without full knowledge of patients’ existing drug regimens; cultural attitudes that lead physicians and patients to search for a medicine-based solution to health problems; and a cascade effect in which prescribing one medication leads to a second drug to mask the side effects of the first, and so on.”

Nonadherence is another source of drug-related morbidity among elderly patients. Duxbury notes that while age alone does not increase this problem, the multidrug regimens common in seniors complicate adherence to complex schedules.

“When prescribing new medications to elders, physicians should assess whether patients can afford the drugs and consider less expensive alternatives if necessary; make sure patients fully understand instructions as well as any potential side effects; and ensure that their living situation and physical condition make compliance possible,” he says. “Seniors with cognitive defects, visual and other functional impairments, and limited access to transportation often need a caregiver’s assistance to follow drug regimens correctly and safely.”

When patients present with new symptoms physicians often respond with a new prescription. Duxbury instead advises placing drug side effects at the top of the list of potential causes of new, unexplained symptoms and “trying to alleviate complaints by stopping existing medications before starting new ones.” He also notes physicians may be unaware of their patients’ use of over-the-counter (OTC) drugs, which can interact with prescription medications and cause serious complications.

“Diphenhydramine, which can produce signs and symptoms of Alzheimer’s disease in older adults, is the classic example of an OTC medication that seniors should avoid,” he says. “Most people tend to use it chronically, but even a single dose can cause confusion.”

Many prescription medications carry potential risks for elderly persons, according to the Beers list, expert consensus criteria originally developed in 1991 to guide medication use in nursing home residents and later revised to include all elderly individuals. The current list includes 48 medications and classes of medications that physicians should avoid prescribing for seniors (Arch Intern Med. 2003;163:2716-2724).

A recent study conducted at Duke University found that in 1999, one in five elderly persons was prescribed at least one medication listed by Beers criteria as a “drug of concern.” Among those patients — an estimated 7 million Americans — 15% received two or more unsuitable drugs and 4% filled prescriptions for three or more Beers list medications. Study authors note many drugs were prescribed despite the availability of safer alternatives (Arch Intern Med. 2004;164:1621-1625).

The use of these medications in the elderly can produce a host of problems, including altered mental status, falls resulting in hip fractures, depression, constipation, immobility, and incontinence. If the source of these conditions is not accurately identified as a drug effect, physicians may add yet another medication, compounding patients’ problems.

According to the Duke study, psychotropic drugs account for more than 45% of Beers list medications prescribed to older patients. Another study of prescribing patterns for elderly patients identified high rates of inappropriate prescribing for analgesics and drugs with central nervous system effects. The pain reliever propoxyphene, the antidepressant amitriptyline, and the antianxiolytic diazepam were the three Beers list drugs most often prescribed for elderly patients (Arch Intern Med. 2004;164:305-312).

“Physicians should familiarize themselves with the Beers list, but should not use it as an absolute guide to clinical practice,” Duxbury says. “Many drugs on the list are older medications available as generics. Oxybutin, for example, was until recently one of the few drugs available for general use in elderly patients for control of overactive bladder. Experts added it to the list because of significant anticholinergic side effects. Newer alternatives, which have far fewer side effects, are much more expensive, putting them out of the financial reach of some older patients.”

Despite complexities surrounding medication use in older adults, Duxbury emphasizes that problems associated with geriatric polypharmacy are almost entirely preventable. He and many other geriatric experts advise a critical step in avoiding adverse drug effects is maintaining an accurate list of all patients’ medications.

“Designating one physician as the gatekeeper of a patient’s medication list can reduce the likelihood of adverse effects, especially for individuals with complex medical regimens,” he says. “Patients should be advised to check with their gatekeeper physician before starting any new drug.”

He also recommends physicians develop a good working relationship with a pharmacist who can help identify potentially dangerous drugs and suggest alternatives. “Physicians should never be afraid to stop a non-life-sustaining medication if they suspect it is causing problems. In addition, they should familiarize themselves with Beers list drugs and search for gerofriendly alternatives when indicated. If physicians must add a new medication, they should begin with the lowest therapeutic dose and increase slowly.

“When physicians concentrate on disease processes and diagnoses they can fall into prescribing patterns that are entirely correct for a particular set of conditions, but may not be the most helpful option for the patient,” he says. “Switching the focus of care to the patient as a whole person rather than a collection of symptoms can reveal patterns of overprescription and help avoid adverse drug reactions.”

For more information:

Dr. Andrew Duxbury
1-800-UAB-MIST
mist@uabmc.edu

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