Effects of Age, Gender, and Comorbid Diseases on Serum Digoxin Levels During Digoxin Treatment

Objective: Digoxin is widely used in controlling ventricular rhythm in atrial fibrillation and heart failure. Therapeutic serum levels of digoxin are 0.5-2 ng/mL. Toxicity may occur after acute accidental or suicidal ingestion or with chronic therapy. In this study, we aimed to determine the frequency of high serum digoxin levels and its association with factors, such as age, gender, and comorbidities. Methods: A 3-year (January 2009-December 2011) cross-sectional study was performed, and a total of 2480 patients who were hospitalized or visited the outpatient clinics were included in this study. Details of serum digoxin levels, age, gender, and comorbidities were retrospectively retrieved from the laboratory data system. Results: The mean (range) age was 71.33 +/- 12.24 (min. 18, max. 97) years and 74.1% of the patients were elderly (age >= 65). The rate of high serum digoxin levels was found to be 17.8% in our study population (n=439). A total of 87.9% of the patients with high serum digoxin levels were elderly and 71% of them were females. The most common symptoms and comorbidities in patients who had serum digoxin levels >2 ng/mL were dyspnea and vomiting in females, heart failure and chest pain in males. Conclusion: This study shows that higher serum digoxin levels are associated with older age and female gender. Increased awareness of medication safety in geriatric population is important. Because of altered pharmacokinetics of digoxin with age, therapeutic monitoring is needed.