Older adults face higher risk of adverse drug reactions, expert says

Dr. Frank Pedonado, professor emeritus of the University of Montana School of Pharmacy and Allied Health Sciences, told a Missoula Aging Services program that older adults take a disproportionate share of prescription drugs and face higher risks of medication-related harm.

Pedonado said older people — who account for about one-sixth of the U.S. population — consume nearly 40% of prescription drugs and are more likely than younger people to suffer adverse drug reactions, hospitalizations and other harms. "Adverse Drug Reactions are simply an abnormal response to the normal dose of a drug," he said.

The risks are driven by several factors that change with age, Pedonado said: lower body weight and water content, higher body fat, reduced liver and kidney function, increased sensitivity to many medicines and the growing use of multiple prescriptions and over-the-counter products. Those effects can prolong drug action, increase blood levels and magnify side effects such as dizziness, mental confusion and postural hypotension (lightheadedness on standing), he said.

Pedonado cited specific patterns of use and consequences discussed on the program. He said older adults take about four medications daily on average and have 13 to 16 prescriptions filled each year. He listed commonly implicated drug classes and proportions of total U.S. use attributed to older adults: major tranquilizers (about one-third), sleeping pills (about one-half), antidepressants (about one-third), antihypertensives (about two-thirds), digoxin (about 87%) and gastrointestinal drugs (about 43%).

Those patterns contribute to measurable harms, Pedonado said, citing a 1985 U.S. study and other estimates: an estimated 240,000 hospitalizations among people 60 and older in 1985 for adverse drug reactions; about 29,000 hospital cases of life-threatening digoxin toxicity annually; roughly 9,000,000 adverse drug reactions each year among older Americans; 32,000 hip fractures attributable to drug-induced falls; about 163,000 cases of serious mental impairment linked to drugs or worsened by them; 2,000,000 older adults addicted or at risk of addiction to minor tranquilizers or sleeping pills after long-term use; 71,000 cases of drug-induced tardive dyskinesia; and 61,000 cases of drug-induced Parkinsonism.

Pedonado emphasized that some symptoms commonly attributed to aging can instead be drug-related and therefore preventable. "We very often blame old age, just getting old for many symptoms which are really caused by the medication we take," he said. He urged patients to "know why you're taking a drug," to understand dosing instructions and to report any new symptoms to their physician or pharmacist.

He also warned about interactions between prescription drugs and over-the-counter products, alcohol, caffeine and tobacco, and about the danger of receiving prescriptions from multiple providers or filling them at different pharmacies without coordination. Pedonado noted that historically many drugs were not adequately tested in older adults before approval by the Food and Drug Administration, though he said the FDA is taking steps to improve representation of older people in drug testing.

Program participants were given practical guidance: ask prescribers and pharmacists for clear directions; be assertive about understanding indications and side effects; and consider lifestyle approaches for some conditions (for example, weight loss, salt restriction and exercise for mild hypertension) when appropriate.

To receive a copy of the program video or for more information, the broadcast directed listeners to Missoula Aging Services at 227 West Front, Missoula, Montana 59802. The presenter said the next episode will discuss problems from multiple drug use, seeing more than one doctor, and rules for safer medication use.