(ASPOT31) Trends in the Concurrent Use of Illicit Drugs and Interacting Prescription Medications Among Adults in the United States

Background: Despite increases in illicit drug use, polydrug use and drug overdose deaths in the U.S., information on the extent and nature of the concurrent use of illicit drugs and prescription medications, including in interacting drug combinations, is not known.

Objectives: In this study, we assessed patterns in the concurrent use of illicit drugs (cannabis, heroin, cocaine, and methamphetamine) with prescription medications, including in contraindicated and potentially fatal drug-drug interactions, among US adults.

Methods: We used the 2013-2014 through 2017-2018 cycles for the National Health and Nutrition Examination Survey (NHANES), a nationally representative survey of the community-dwelling US population. Use of any prescription medication or illicit drug was defined as use in the past month. Concurrent use was defined as the current use of at least 1 illicit drug with at least one, 2 or more, and at least one interacting prescription medication. We used Micromedex to identify medications classified as having a major or contraindicated drug interaction with cannabis or heroin, cocaine, and methamphetamine (HCM). For each survey cycle, we calculated weighted prevalence and 95% CIs for current use and concurrent use of illicit drugs (overall and by type) with prescription medications and interacting prescription medications among the US adult population.

Results: While the prevalence in the use of any interacting medication has remained stable at ~30% between 2013-14 and 2017-2018, the use of cannabis has significantly increased (from 15% to 20%; p< 0.002). Concurrent use of cannabis with any medication also increased (from 6.1% to 8.3%;P=0.01), while the concurrent use of cannabis with interacting medications did not significantly change (from 3.8% to 4.8%; p=0.24). The prevalence in concurrent HCM and interacting medications nearly doubled during this period (from 0.5% to 1%; p=0.25), but was not statistically significant. Cannabis use was higher in younger (18-39 years) than middle-aged (40-59 years) adults in both men and women. Nearly 1 in 4 adults (22.1% [95% CI, 19.3% to 25.2%]) use cannabis concurrently with at least one interacting medication. Among cannabis users, the concurrent use of interacting medications was significantly greater in the middle-aged adults, particularly women (43.1% [95% CI,33.8%-53.0%]).

Conclusions: In this nationally representative study of US adults, more than 1 in 12 adults concurrently use cannabis - and 1 in 100 concurrently use HCM - with interacting medications and may be at risk for an adverse drug event and unintentional overdose. Efforts that focus on improving the safe use of medications among illicit drug users should incorporate the use of interacting prescription medications among adults in the United States.