Potentially Harmful Drug–Drug Interactions in the Elderly: A Review

Center for Health Outcomes and PharmacoEconomic Research, University of Arizona College of Pharmacy, Tucson, USA.
The American journal of geriatric pharmacotherapy 11/2011; 9(6):364-77. DOI: 10.1016/j.amjopharm.2011.10.004
Source: PubMed


Elderly patients are vulnerable to drug interactions because of age-related physiologic changes, an increased risk for disease associated with aging, and the consequent increase in medication use.
The purpose of this narrative review was to describe findings from rigorously designed observational cohort and case-control studies that have assessed specific drug interactions in elderly patients.
The PubMed and International Pharmaceutical Abstracts databases were searched for studies published in English over the past 10 years (December 2000-December 2010) using relevant Medical Subject Headings terms (aged; aged, 80 and over; and drug interactions) and search terms (drug interaction and elderly). Search strategies were saved and repeated through September 2011 to ensure that the most recent relevant published articles were identified. Additional articles were found using a search of review articles and reference lists of the identified studies. Studies were included if they were observational cohort or case-control studies that reported specific adverse drug interactions, included patients aged ≥65 years, and evaluated clinically meaningful end points. Studies were excluded if they used less rigorous observational designs, assessed pharmacokinetic/pharmacodynamic properties, evaluated drug-nutrient or drug-disease interactions or interactions of drug combinations used for therapeutic benefit (eg, dual antiplatelet therapy), or had inconclusive evidence.
Seventeen studies met the inclusion criteria. Sixteen studies reported an elevated risk for hospitalization in older adults associated with adverse drug interactions. The drug interactions included: angiotensin-converting enzyme (ACE) inhibitors and potassium-sparing diuretics, ACE inhibitors or angiotensin receptor blockers and sulfamethoxazole/trimethoprim, benzodiazepines or zolpidem and interacting medications, calcium channel blockers and macrolide antibiotics, digoxin and macrolide antibiotics, lithium and loop diuretics or ACE inhibitors, phenytoin and sulfamethoxazole/trimethoprim, sulfonylureas and antimicrobial agents, theophylline and ciprofloxacin, and warfarin and antimicrobial agents or nonsteroidal anti-inflammatory drugs. One study reported the risk for breast cancer-related death as a function of paroxetine exposure among women treated with tamoxifen.
Several population-based studies have reported significant harm associated drug interactions in elderly patients. Increased awareness and interventions aimed at reducing exposure and minimizing the risks associated with potentially harmful drug combinations are needed.

Download full-text


Available from: Lisa E Hines, Jun 06, 2014
    • "However, there are challenges in appraising the current evidence. Estimates vary significantly between studies, reflecting differences in study populations , settings, drug interactions considered, and information sources used to define drug interactions[5,7]. Additionally , there is a lack of consensus in defining and identifying clinically relevant drug interactions[5]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Purpose Statins are among the most frequently prescribed medications internationally. Older people are commonly prescribed multiple medications and are at an increased risk of drug-drug interactions, including statin-drug interactions. The aim of this study was to conduct a systematic review of current evidence on the prevalence of statin-drug interactions in older people. Methods A systematic search of observational studies in Embase, Medline, and PubMed was conducted. Articles were included if they were published in English during the period July 2000–July 2014 and reported on the prevalence of statin-drug interactions in people over 65 years of age. Two reviewers independently assessed the articles for eligibility and extracted the data. Results The search returned 1556 eligible articles. A total of 19 articles met the inclusion criteria. In studies (n = 7) that focused on statin users only, the prevalence of potential statin-drug interactions assessed using different measures ranged from 0.19 to 33.0 %. In studies that examined drug interactions across a population of both statin users and non-users (n = 12), the prevalence of potential statin-drug interactions ranged from 0.1 to 7.1 % (n = 8), and the prevalence of clinically relevant statin-drug interactions ranged from 1.5 to 4 % (n = 4). Conclusions Current published evidence suggests substantial variations in the prevalence of statin-drug interactions and their clinical relevance. Further studies are necessary to provide a better understanding of the prevalence of clinically significant statin-drug interactions, the medications most frequently contributing to statin-drug interactions, and impact on relevant clinical outcomes in older people.
    No preview · Article · Jan 2016 · European Journal of Clinical Pharmacology
  • Source
    • "The potential for drug–drug interactions (DDI) is increasing exponentially[1]with increasing drug intake. Especially in the elderly, polypharmacy[2]increases the risk of DDI[3]and therefore the probability of adverse drug reactions (ADRs)[4,5]. DDI are classified into two main groups. "

    Preview · Article · Jan 2015
  • Source
    • "They showed that around 20% of hospitalized patients were susceptible to DDIs and incidence was higher in patients with heart disease and the elderly. Another review has summarized and described findings from studies that assessed harmful DDIs in elderly patients [20]. It has been conclusively shown that significant harm is associated with DDIs in elderly patients. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Drug-drug interactions (DDIs) are an important type of adverse drug events. Yet overall incidence and pattern of DDIs in Iran has not been well documented and little information is available about the strategies that have been used for their prevention. The purpose of this study was to systematically review the literature on the incidence and pattern of DDIs in Iran as well as the used strategies for their prevention. PubMed, Scopus, electronic Persian databases, and Google Scholar were searched to identify published studies on DDIs in Iran. Additionally, the reference lists of all retrieved articles were reviewed to identify additional relevant articles. Eligible studies were those that analyzed original data on the incidence of DDIs in inpatient or outpatient settings in Iran. Articles about one specific DDI and drug interactions with herbs, diseases, and nutrients were excluded. The quality of included studies was assessed using quality assessment criteria. Database searches yielded 1053 potentially eligible citations. After removing duplicates, screening titles and abstracts, and reading full texts, 34 articles were found to be relevant. The quality assessment of the included studies showed a relatively poor quality. In terms of study setting, 18 and 16 studies have been conducted in inpatient and outpatient settings, respectively. All studies focused on potential DDIs while no study assessed actual DDIs. The median incidence of potential DDIs in outpatient settings was 8.5% per prescription while it was 19.2% in inpatient settings. The most indicated factor influencing DDIs incidence was patient age. The most involved drug classes in DDIs were beta blockers, angiotensin-converting-enzyme inhibitors (ACEIs), diuretic agents, and non-steroidal anti-inflammatory drugs (NSAIDs). Thirty-one studies were observational and three were experimental in which the strategies to reduce DDIs were applied. Although almost all studies concluded that the incidence of potential DDIs in Iran in both inpatient and outpatient settings was relatively high, there is still no evidence of the incidence of actual DDIs. More extensive research is needed to identify and minimize factors associated with incidence of DDIs, and to evaluate the effects of preventive interventions especially those that utilize information technology.
    Full-text · Article · Jun 2014 · DARU Journal of Pharmaceutical Sciences
Show more