Evaluation of Safety and Efficacy of Intravenous Digoxin Loading Doses Based on Ideal Body Weight

Background: Intravenous digoxin loading dose recommendations differ between clinical guidelines and Food and Drug Administration packaging for acute rate control. Objective: The objective of this study was to assess the safety and efficacy of intravenous digoxin loading in patients who received <= 12 mu g/kg and >12 mu g/kg of digoxin using ideal body weight (IBW). Methods: This single center retrospective cohort study with exempt status from the local Institutional Review Board included patients who received intravenous digoxin and had a serum digoxin concentration (SDC) drawn. Digoxin doses >36 hours after the first dose were excluded. Patients who received a total of >12 mu g/kg and <= 12 mu g/kg IBW were compared. The primary endpoint was frequency of SDCs >= 1.2 ng/mL, which have been shown to be associated with increased mortality. Results: A total of 244 patients were included (144 receiving >12 mu g/kg and 100 receiving <= 12 mu g/kg). There were significantly more SDC >= 1.2 ng/mL in the >12 mu g/kg group than the <= 12 mu g/kg group (50.6% vs. 30.0%; adjusted odds ratio, 3.19; 95% confidence interval [CI]: 1.79-5.84), with no difference in rate control failure. Major limitations of the study include retrospective nature and possible selection bias. Conclusion and Relevance: Compared to patients who received digoxin doses <= 12 mu g/kg IBW, patients who received >12 mu g/kg IBW had higher rates of SDC >= 1.2 ng/mL. This suggests that appropriate weight-based dosing with 8 to 12 mu g/kg IBW has the potential to be a safer approach to digoxin loading, rather than frequently used dosing strategies that result in doses >12 mu g/kg.