Drug interactions and adverse events induced by drugs used in an intensive care unit

Eleven percent of hospitalized patients experience drug-drug interactions (DDIs), elevating morbidity, mortality and health care costs. Polypharmacy is very common in intensive care units (ICUs), increasing the risks of drug adverse events (AEs). To assess DDIs in ICU patients. A prospective study conducted in the ICU of a private hospital, evaluating the frequency of DDIs, AEs developed and their relationship. Patients admitted to the ICU were included if they stayed at least three days in the ICU and received at least one studied drug. Thirty-five patients aged 59+/-16 years (24 women) were enrolled in the study. Seventy six DDIs and 60 AEs were recorded. Statistically significant associations were only found for midazolam-fentanyl-propofol with bradycardia and hypotension and amphotericin B-vancomycin and vancomycin-amikacin with acute renal failure (ARF). Relative risks were 10.4 (95% confidence intervals (CI) 1.59-68) for bradycardia, 5 (95% CI 1.082-23.4) for hypotension and 6.4 (95% CI 1.9-21.6) for ARF. The odds ratios were 125.2 (95% CI 3-250), 12.6 (95% CI 1.3-77) and 10.8 (95% CI 1.3-282) respectively. DDIs associated with risk of AEs were fentanyl, propofol and midazolam for bradycardia and hypotension and amphotericin B-vancomycin and vancomycin-amikacin for ARF.