2025 Southeastern Residency Conference

Title:  Evaluation of digoxin dosing and therapeutic drug monitoring in adult patients receiving continuous venovenous hemodiafiltration   


Author Names: Madison Nordin, Jenna Cox, Bryan Love, Breanne Mefford 


Background: Digoxin is a cardiac glycoside used in the treatment of heart failure and rate control to manage arrhythmias such as atrial fibrillation. The narrow therapeutic nature of digoxin is further complicated by renal dysfunction, leading to accumulation and toxicity, such as nausea, vomiting, visual symptoms (yellow-green discoloration), heart palpitations, bradycardia, and heart block. Currently, there is minimal evidence to guide digoxin dosing in continuous renal replacement therapy. Current recommendations are driven by data from a single case report of a patient administered digoxin while receiving continuous venovenous hemofiltration (CVVH) and expert opinion. The purpose of this study is to investigate the impact of digoxin dosing regimens on therapeutic drug monitoring for patients receiving continuous venovenous hemodiafiltration (CVVHDF).   


Methods: This single-system retrospective case study included patients 18 years of age or older admitted to a Prisma Health ICU from September 1, 2019, to September 1, 2024, who received digoxin during CVVHDF. Patients were excluded if they did not have a digoxin level drawn while receiving digoxin and CVVHDF. The primary objective of the study is to describe the impact of digoxin dosing on therapeutic drug monitoring in adult patients receiving CVVHDF. The secondary objective is to determine the safety and tolerability of digoxin for patients receiving CVVHDF by reviewing incidence of bradycardia (HR < 60 bpm) and administration of digoxin immune fab. The primary and secondary objectives will be analyzed using descriptive statistics. Medians and interquartile range (IQR) will be calculated for continuous variables and counts and percentages for categorical variables.   


Results: The initial data query yielded 44 patients. Six met criteria for inclusion, with ten levels drawn during CRRT. Half of patients (50%) received digoxin for the indication of heart failure and 66.7% were receiving amiodarone inpatient prior to the initiation of CRRT. The median CRRT effluent rate was 30.7 ml/kg/hr. The median digoxin level was 0.75 ng/mL overall and in patients who had levels drawn >72 hours after the first dose. Over half (80%) of the levels drawn occurred at least 72 hours after the first dose of digoxin. All digoxin levels over 1.2 ng/mL were drawn in patients who only received loading doses and were not started on maintenance regimens. The median total loading dose was 8.9 mcg/kg (using ideal body weight).  Loading doses ≥ 8 mcg/kg IBW (n=2) resulted in levels ≥ 1.2 ng/mL, whereas < 8mcg/kg IBW (n=1) resulted in levels < 1.2 ng/mL. Half (50%) of patients received a digoxin load but were not initiated on maintenance regimens. Of the patients that received maintenance therapy, all received 125 mcg every 48-hour regimens. All maintenance dose levels (n=7) on this regimen resulted in levels < 1.2 ng/mL. One-third (33%) of patients experienced bradycardic events while receiving digoxin and CRRT, and no patients received digoxin immune fab.


Conclusion: All maintenance digoxin regimens (n=3) administered were doses of 125 mcg every 48 hours. This maintenance regimen on CVVHDF yielded digoxin levels less than 1.2 mcg/mL. The findings of this study contribute to the paucity of data surrounding appropriate digoxin dosing for patients receiving digoxin while on CRRT, specifically CVVHDF.