Major Finding: Among 52 elderly patients taking 12 or more drugs, 51 had drug combinations that could be dangerous.
Data Source: A retrospective chart study.
Disclosures: Dr. Ilan said he had no relevant disclosures for this study.
CANCÚN, MEXICO — Potentially dangerous drug interactions are almost unavoidable in elderly patients who regularly take 12 or more medications, a chart review study suggests.
Alpha and beta receptor blockers, statins, warfarin, and proton pump inhibitors are some of the drugs most commonly involved in these interactions, which can cause problems ranging from orthostatic hypotension to potentiated blood thinning, and even death, Dr. Heinrich Ilan said at the World Conference of Family Physicians.
“Elderly patients are at an increased risk of drug interactions because they have multiple caregivers, including family doctors, specialists—with or without gatekeeping by primary care—private consultants, and what I call 'physicians in the family'” —trusted family members who offer medical advice with or without the benefit of a medical degree, said Dr. Ilan of the Rav Kook Primary Care Clinic in Kiryat Motzkin, Haifa, Israel. “The huge polypharmacy burden in geriatric care is a direct pathway to harm for these fragile patients.”
Dr. Ilan and his associates investigated drug interactions in a group of 1,124 patients aged 75 years or older. Of those, they identified 52 patients who took at least 12 different medications over a 3-month period; these could have been prescription drugs, over-the-counter preparations, or herbal preparations.
The team used the Lexi-Comp online database to determine unsafe drug combinations. The software identifies three types of possible interactions:
▸ C: A combination that requires monitoring, and of which the physician should be aware and weigh the risks and benefits.
▸ D: A combination that carries a high probability of a serious interaction; the physician should avoid the combination if possible, or consider lowering the dosages. If used, drug levels should be monitored.
▸ X: Potentially fatal interaction that should be avoided at all cost.
Only a single patient had no interactions, Dr. Ilan said.
Two patients had type X combinations. One patient was taking escitalopram and the monoamine oxidase inhibitor selegiline. This combination can cause serotonin syndrome; possible symptoms include hyperthermia, rigidity, myoclonus, autonomic instability with rapid vital sign fluctuation, and extreme agitation progressing to delirium or coma.
The second X-type combination was found in a patient taking clarithromycin and salbutamol (known as albuterol in the United States). Possible reactions to this combination include prolongation of the QT interval and ventricular arrhythmias.
Fifty-seven D-type combinations involving 37 drugs were identified. The most commonly observed included 14 combinations of a beta-blocker and an alpha-1 receptor blocker, which can cause orthostatic hypotension and falls; and 5 combinations of a beta-blocker and alpha-2 receptor blocker, which can cause rebound hypertension if the drugs are suddenly stopped. There also were five cases of warfarin combined with levothyroxine and five cases of warfarin combined with amiodarone. Both of these combinations can potentiate the effects of warfarin, Dr. Ilan explained.
Other type D combinations included five cases of patients taking simvastatin along with a calcium channel blocker, which increases the risk of rhabdomyolysis. There were 23 other different type D combinations.
Nineteen patients were free of D-type combinations. Eighteen patients had one type D combination, 11 patients had two type D combinations, 1 patient each had three, four, and five type D combinations.
There were 328 C-type combinations involving 144 drugs. Thirty-four of those involved a statin and a proton pump inhibitor, which can lead to an increased risk of rhabdomyolysis. “The most common offenders in type C reactions were doxazosin, oxazepam, and statins,” Dr. Ilan said.
Most patients had multiple type C combinations, Dr. Ilan said. Two patients each had 12, while some patients had as many as 18.
In an interview, he suggested avoiding unnecessary polypharmacy may contribute to longevity. “From my clinical impression, it seems that '10th decade' patients—the late survivors—consume less medications, compared to their fellow 9th- and 8th-decade elderly. Therefore, it seems they are the fittest and the healthier, just to survive the very late elderly years, or that their relative lack of multidrug consumption offers some kind of [survival] advantage.”
“The huge polypharmacy burden in geriatric care is a direct pathway to harm,” said Dr. Heinrich Ilan.
Source ©Andrzej Tokarski/Fotolia.com