Perform drug interaction assessments at every visit

Perform drug interaction assessments at every visit

Pharmacists should assess medications for potential problems at patient meetings to improve safety.

Polypharmacy is one of the strongest risk factors for patients who experience drug interactions, given that approximately 33% of adults in the United States take 5 or more medications.1 Drug interactions can contribute to adverse drug events (ADRs), which account for approximately 700,000 emergency department visits and approximately 100,000 hospitalizations per year.1 An ADR occurs when a patient experiences harm due to drug exposure.1 Unfortunately, approximately 1 in 6 people aged 65 and over will experience a serious drug-induced ADR.2 Difficulties often arise when patients see multiple prescribers and fill prescriptions at more than one pharmacy.2

According to the University of Michigan’s National Healthy Aging Survey, about 90 percent of adults between the ages of 50 and 80 surveyed said they were sure they knew how to avoid drug interactions.2 However, only 35% of these people have discussed drug interactions with someone in the past 2 years.2 Additionally, only 36% of study participants said their pharmacists were aware of all their medications when filling prescriptions.2

The survey was administered online in April 2017 and the response rate was 77%.2 The results highlight the importance of assessing drug interactions to prevent drug-related problems (MRP; Figure). Pharmacists play a key role in evaluating patients’ drug therapy regimens for drug interactions during Medication Therapy Management (MTM) consultations to improve medication safety.

It is essential that pharmacists assess drug interactions at each visit to MTM and during the dispensing process. They should encourage patients to take an active role in health care by asking questions about their drug treatment. After completing each MTM consultation, pharmacists should provide patients with an updated personal medication record (PMR), which should include a list of all herbal supplements and over-the-counter and prescription medications.3 Patients should also update their list and give it to their pharmacists and other healthcare professionals to assess for drug interactions.3 The PMR should include drug names, drug dosages, indications, frequency and timing, start and end dates, prescribing provider, and additional instructions.3

In a retrospective study, pharmacists identified MRPs, along with recommendations for solving them.4 There were 36,455 MRPs identified in the study, and 9716 (26.7%) were classified as drug interactions. The results of the study showed that pharmacists play a vital role in the identification of MRPs. Drugs most frequently implicated in drug interactions included amlodipine, atorvastatin, citalopram, clopidogrel, hydrocodone-acetaminophen, metoprolol, simvastatin, tamsulosin, tramadol, trazodone, and warfarin.

One study assessed electronic health record medication lists of 6545 outpatients aged 60 and older to identify multi-drug interactions (MDIs).5 The highest prevalence of metered-dose inhalers was on drug lists containing amiodarone, bupropion, cyclobenzaprine, methotrexate, tramadol, and trazodone.5 Psychotropic drugs (35%) were the most involved in drug interactions, followed by cardiovascular drugs (11%).5 Other drug classes implicated in IMIs included anticoagulants (9%), opioids (9%), immunosuppressants (8%), nonsteroidal anti-inflammatory drugs (4%), and muscle relaxants (3%).5 The most common serious potential AEs associated with drug interactions were bleeding, QT interval prolongation, seizures, and serotonin syndrome.


  1. Medication errors and adverse drug events. Agency for Research and Quality in Health. September 7, 2019. Accessed September 12, 2022.
  2. Drug interactions: how to avoid them. Institute for Healthcare Policy and Innovation National Survey on Healthy Aging. November 29, 2017. Accessed September 12, 2022.
  3. Chapter 1: management of drug therapy. National Drug Therapy Management Council. Accessed September 12, 2022.
  4. Bankes D, Pizzolato K, Finnel S, et al. Medication issues identified by pharmacists in an enhanced drug therapy management model. Am J Manager Care. 2021;27(supplement 16):S292-S299. doi:10.37765/ajmc.2021.88754
  5. Anand TV, Wallace BK, Chase HS. Prevalence of potentially harmful multi-drug interactions on the medication lists of outpatient elderly patients. BMC Geriatrics. 2021;21(1):648. doi:10.1186/s12877-021-02594-z

About the Author

Jennifer Gershman, PharmD, CpH, PACSis a drug information pharmacist and Pharmacy hours® contributor who lives in South Florida.

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