Older Adults at Greater Risk for Drug-Supplement Interactions

Older adults are increasingly putting themselves at risk for adverse effects by concurrently taking multiple prescription drugs and supplements.

Many patients believe nutritional supplements lack adverse effects, and so the consequences of potential drug-supplement interactions are not necessarily understood.

Although drug-supplement interactions can be harmful to anyone, the elderly are considered to be at the greatest risk because this population is more likely to take multiple medications, including dietary supplements, because of their comorbidities.

A recent study published in JAMA Internal Medicine investigated changes in prescription drug, OTC medication, and dietary supplement use in older populations in order to determine the potential for major drug interactions. They compared 2351 participants in 2005-2006 with 2206 participants in 2010-2011—all of whom were aged between 62 and 85 years. The researchers performed in-home interviews and direct medication inspections to determine the participants’ drug product use.

The researchers observed increased use of all types of medications, except those in the OTC category.

Their key findings included that:

· Concurrent use of at least 5 prescription drugs increased from 30.6% in 2005-2006 to 35.8% in 2010-2011.

· Concurrent use of 5 or more medications or supplements of any kind increased from 53.4% to 67.1%.

· Use of OTC medications decreased from 44.4% to 37.9%.

· Use of dietary supplements increased from 51.8% to 63.7%.

· Multivitamin or mineral supplements were the most commonly used supplements throughout the study period.

· Approximately 15.1% of older adults in 2010-2011 were at risk for a major drug interaction, compared with an estimated 8.4% in 2005-2006.

The study authors noted that they did not anticipate such a stark increase in supplement use.

The increase in the number of older adults taking fish oil supplements was especially confounding, as 18.6% of older adults in the study were taking the supplement in 2010-2011, compared with only 4.7% in 2005-2006. Fish oil is touted as good for the heart, though the authors noted that there is very limited clinical evidence of cardiovascular benefit.

Surprisingly, the number of older patients buying fish oil when filling a prescription for warfarin increased. Notably, this drug-supplement interaction actually increases the risk for heart disease and is associated with major bleeding.

“These findings suggest that the unsafe use of multiple medications among older adults is a growing public health problem. Therefore, health care professionals should carefully consider the adverse effects of commonly used prescription and nonprescription medication combinations when treating older adults and counsel patients about these risks,” the authors wrote.

The most important step pharmacists and other health providers can take to try and limit the number of adverse drug-supplement interactions is to ask patients about their medication regimens. Studies have shown that patients don’t normally disclose their use of complementary and alternative medicines without being asked about it directly.

Patients with chronic diseases may greatly benefit from a pharmacist’s intervention. Taking more of a specific nutrient to ward off chronic diseases may not be effective, as there is no evidence supporting the claim that supplements can effectively fight chronic diseases. In fact, FDA regulations don’t allow supplement manufacturers to claim that their product can cure, treat, or prevent a disease.

While most vitamins and supplements can be safe when used properly, the FDA regularly issues warnings about products that may pose a threat to public health. In one FDA sweep of potentially unsafe or tainted supplements in November 2015, more than 100 dietary supplement manufacturers and distributors faced civil injunctions and criminals actions.