Background Digoxin is a high-alert medication because of its narrow therapeutic range and high drug-to-drug interactions. Fifty per cent of cases of digoxin toxicity can be prevented by improving treatment with digoxin.

Purpose Checking whether the dosage of digoxin in intoxicated patients accords with clinical guidelines’ recommendations.

Material and methods Retrospective study of patients discharged fbetween 2015–2017, presented as a primary or secondary diagnosis of digitalis toxicity. Variables: date of birth, sex, weight, size, diagnosis for treatment with digoxin – atrial fibrillation (AF) or heart failure (HF) – daily dose of digoxin, serum creatinine, digoxinemia and Potasemia (K +). It was estimated whether the dosage of digoxin was correct based on anthropometric data and doses of daily digoxin using PKS. For those inadequately dosed patients, daily doses of adequate digoxin were calculated. The glomerular filtration rate (GFR) was calculated by MDR/CKD-EPI.

Results Sixty-four patients (47 females), median age: 83.7 years (55–102), median weight: 69.2 kg (45.5–10 5 kg) with 52% below 70 kg were considered in the dosage recommendations. The mean value of GFR 50, 65 mL/min (SD=19.9) (77%<60 ml/min): 67% [k +]≤4.5 meq/dl. Diagnosis for treatment: HF in 34 patients and AF in 30 patients. The average dose of digoxin prior to admission was 0.163 mg/day (SD=0.06). The average digoxinaemia at income was two, 94 ng/mL (SD=1.36). The serum digoxin concentrations justified intoxication in most patients. Only two patients presented with serum digoxin concentrations below 1 ng/ml: 81% greater than 2 ng/ml. No significant differences were found between doses, concentrations or level/dose index of digoxin of patients diagnosed with HF and AF. A significant relationship (p<0,003) was found between dose or level/dose index and patient’s GFR. Doses estimated to obtain concentrations within therapeutic range were 0, 110 mg/dia (considering age, sex, weight and GFR), that is, 32.4% less than the pre-admission dose. Nine patients met the STOPP criterion of inappropriate prescription for administering doses of digoxin >0.125 mg/day to patients older than 65 years with GFR <50 mL/min.

Conclusion Clinical guidelines recommend evaluating renal function (K +) and serum digoxin concentration, considering the appropriate range for HF (0.6–0.8 ng/dl) and AF (0.8–1.0 ng/dl). Control of potassium levels would be insufficient, and doses administered higher than those necessary for the recommended therapeutic range. Monitoring of serum digoxin concentrations could reduce digitalis toxicity.

References and/or acknowledgements No conflict of interest.