Supplements are not regulated in the same way that prescription medications are regulated in the United States; consequently, the supplement market, which includes vitamins, probiotics, fish oils, etc, has greatly expanded over the past decade. The expanded market reflects increased use of supplements by people of all ages; however, older and elderly adults are at risk for medication interactions with supplements since they are the age group most likely to be taking one or more prescription medications.
Researchers in Chicago and Baltimore conducted a survey to determine the prevalence of medication use, including concurrent use of prescription and over-the-counter medications and dietary supplements, and to quantify the frequency and types of potential major drug–drug interactions.
A longitudinal, nationally representative sample of older adults aged 62 to 85 years was selected. The study cohort consisted of 2351 participants in 2005-2006 and 2206 in 2010-2011, and both groups had in-home interviews with direct medication. Medication use
was defined as the use of at least one prescription or over-the-counter medication or dietary supplement at least daily or weekly, and concurrent use was defined as the regular use of at least two medications. Micromedex was used to identify potential major drug–drug interactions.
The use of at least one prescription medication slightly increased from 84% in 2005-2006 to 88% in 2010-2011. Concurrent use of at least five prescription medications increased from 31% to 36%, and the use of dietary supplements increased from 52% to 64%. Not surprisingly, use of statins, antiplatelet agents, and omega-3 fish oil increased during this time.
In 2010-2011, 15% of the older adults were at risk for a potential major drug–drug interaction, compared with an 8% risk in 2005-2006. Most of these interacting regimens involved medications and dietary supplements increasingly used in 2010-2011.
These study findings reflect what many clinicians are observing in practice: medication use, including supplements, has increased among older adults and polypharmacy has increased the risk of medication interactions.
Qato DM, Wilder J, Schumm L, et al. Changes in prescription and over-the-counter medication and dietary supplement use among older adults in the United States, 2005 vs 2011 [published online before print March 21, 2016]. JAMA Intern Med.