Early detection of adverse drug reactions (ADR) increases patient safety. Our objective was to identify ADR by monitoring laboratory parameters and high-risk drugs. We carried out a two-month prospective observational study in a Internal Medicine Department, with daily recording of drugs prescribed and the following parameters: Na, K, Ca, serum creatinine, glomerular filtration rate (GFR), INR, glucose, haemoglobin, platelets, ALT, AST, bilirubin, GGT, alkaline phosphatase, TSH, T4, and blood digoxin. High-risk drugs were closely monitored. 52 patients included, of whom 46.2% experienced an ADR. We observed an association with drugs in 25.5%, as follows: reduction in GFR, 26.9% (associated with loop diuretics [41.7%], angiotensin-converting enzyme [ACE] inhibitors [33.3%], angiotensin II receptor blockers [ARB] [16.6%], andanti-diabetic drugs [8.3%]); hypokalemia, 22.3% (associated with loop diuretics [50.0%], potassium-free fluid [37.5%], and salbutamol [12.5%]); hyperkalemia, 14.4% (associated with ACE inhibitors [60.0%] and ARB [40.0%]); INR out of range, 10.8% (associated with drug interactions [66.7%]); hyperglycemia, 8.1% (associated with corticosteroids [66.7%] and anti-diabetic drugs [33.3%]); and other conditions, 18.8%. We conclued that patient safety could be improved by implementing warnings in electronic prescriptions in cases of a decrease in GFR or modification of potassium levels in patients who are prescribed loop diuretics, ACE inhibitors, or ARBs.Key words: Adverse drug reaction, clinical decision support, high-risk drug, safety
