Potential Interactions between Drugs Taken by Emergency Department Patients of an Australian Hospital

Background While drug interactions are reported to be common, there are no published reports of the prevalence of such interactions among Australian emergency department (ED) patients. Aim To determine the prevalence and characteristics of potential drug interactions among Australian ED patients, the drugs most frequently involved and identify high‐risk patient groups. Method An analytical cross‐sectional survey of 409 patients who were taking at least two drugs. Drug lists were compiled from a range of resources. Analyses of potential interactions were made using Micromedex Drug‐Reax software. Multivariate analysis was used to determine factors associated with potential drug interactions. Results 855 potential drug interactions were identified among 254 (62.1%, 95%CI 57.2–66.8) patients. The mean number of potential interactions among all patients was 2.1 ± 2.7 per patient. The most common potential interactions were between angiotensin converting enzyme inhibitors and loop diuretics (11.3% of patients at risk), beta‐blockers and antidiabetics (7.3%) and frusemide and aspirin (9.1%). Drugs most commonly involved were aspirin (27.7% of potential interactions), beta‐blockers (11.1%) and warfarin (9.9%). Only the number of drugs taken correlated significantly with the number of potential interactions (p < 0.001). Conclusion The possibility of potential drug interactions should be considered when prescribing and ED pharmacists should target patients on multidrug regimens for specific evaluation.