Contraindicated drug-drug interactions associated with oral antimicrobial agents prescribed in the ambulatory care setting in the United States.

OBJECTIVES

Antimicrobial agents are commonly used in ambulatory care settings. Our objective was to examine national-level patterns of contraindications between oral antibacterial or antifungal agents and patients' other oral medications in the US ambulatory care setting.

METHODS

This cross-sectional study included multiple year pooled data (2003-2011) from the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey (NHAMCS Outpatient Department). Visits by adults (age ≥18 years) in ambulatory settings in the United States who were prescribed oral antibacterial or antifungal agents were evaluated for potential drug-drug interaction (DDI) contraindications. Findings with relative standard error >30% or unweighted sample size <30 were not reported because these were deemed unreliable estimates.

RESULTS

From 2003 to 2011, there were 1 235 000 outpatient visits (proportion = 0.52%; 95% confidence interval (CI), 0.29-0.74) in which a patient was prescribed an antimicrobial agent associated with a contraindicated DDI. The most prevalent antimicrobials with contraindicated combination among outpatients were simultaneous use of macrolide-containing products (erythromycin or clarithromycin) with statin medication-containing products (simvastatin or lovastatin) (841 864 visits, proportion = 1.91%; 95% CI, 0.96-2.86). The next most common combination was use of fluoroquinolones with antiarrhythmic agents (amiodarone, sotalol, quinidine or procainamide) (365 622 visits, proportion = 0.19%; 95% CI, 0.06-0.32).

CONCLUSIONS

Providers should be aware of potential contraindicated DDIs when prescribing antibiotics, especially macrolides and fluoroquinolones.