Review: Failure of current digoxin monitoring for toxicity: new monitoring recommendations to maintain therapeutic levels for efficacy

Drug-Induced Complete Atrioventricular Block in an Elderly Patient: A Case Report Highlighting Digoxin-Beta Blocker Interactions and a Paradoxical State

Complete atrioventricular (AV) block is a severe conduction abnormality caused by intrinsic cardiac disease, ischemia, electrolyte imbalances, or drug interactions. Elderly patients on multiple medications are particularly vulnerable to polypharmacy-related interactions. This case report describes an 82-year-old female presenting to the emergency department with fatigue, syncope, and disorientation. Her medical history included atrial fibrillation, hypertension, and heart failure, with a medication regimen of digoxin 0.25 mg given daily 5 days out of 7, metoprolol 50 mg twice daily, lisinopril 10 mg daily, furosemide 40 mg daily, and spironolactone 50 mg daily. Clinical examination revealed bradycardia and a holosystolic murmur in the mitral valve area, while the electrocardiogram showed complete AV block at a ventricular rate of 35 bpm. Laboratory results indicated mild hyperkalemia (4.9 mmol/L). Suspecting a digoxin-beta-blocker interaction, antiarrhythmic therapy was discontinued. Within three days, the AV block resolved, transitioning to atrial fibrillation with a high ventricular rate. Bisoprolol was introduced for rate control, and hemodynamic stability was achieved. The patient was discharged with a revised medication regimen and showed no recurrence of AV block. This case emphasizes the importance of recognizing drug interactions as a reversible cause of AV block and using drug interaction checkers to manage polypharmacy, especially in elderly patients with multiple comorbidities. It also highlights the rare and paradoxical combination of atrial flutter and complete AV block.

Falling into complexity: A case of digitalis-induced fall, trauma, symptomatic bradycardia, and syncope

Digoxin, a cardiac glycoside, functions by inhibiting the sodium potassium ATPase pump. It's crucial to note that digoxin has a very narrow therapeutic range. Its serum level vary due to changes in body weight, age, renal function, hepatic impairment and concomitant drug therapy. Chronic toxicity can lead to different types of arrrythmia,which span from heart blocks to ventricular tachycardia. This report present a case of an elderly male, where Digoxin toxicity resulted in syncope and mild traumatic brain injury. Initially upon patient's presentation ECG indicated myocardial infarction, subsequently bradycardia and complete heart block. The patient had a known history of chronic kidney disease and was prescribed 0.25mg of digoxin regularly without dose adjustment, which might have resulted in reduced digoxin elimination, leading to toxicity. Thus this case demonstrates a classic presentation of digoxin toxicity. Multiple risk factor such as old age, impaired renal function with continued digoxin treatment without dose adjustment was likely the cause of toxicity.

Identification and characterization of critical values in therapeutic drug monitoring: a retrospective analysis

Therapeutic drug monitoring (TDM) is a crucial clinical practice that improves pharmacological effectiveness and prevent severe drug-related adverse events. Timely reporting and intervention of critical values during TDM are essential for patient safety. In this study, we retrospectively analyzed the laboratory data to provide an overview of the incidence, distribution pattern and biochemical correlates of critical values during TDM. A total of 19,110 samples were tested for nine drug concentrations between January 1, 2019, and December 31, 2020. Of these, 241 critical values were identified in 165 patients. The most common critical values were vancomycin trough (63.4%), followed by tacrolimus trough (16.9%) and digoxin (15.2%). The primary sources of drug critical values were the department of general intensive care unit (ICU), cardiology, and surgery ICU. At baseline or the time of critical value, significant differences were found between the vancomycin, digoxin, and tacrolimus groups in terms of blood urea nitrogen (BUN), creatinine, N-terminal Pro-B-Type Natriuretic Peptide (NT-proBNP), and lymphocyte percentage, P < 0.05. Therefore, it is important to prioritize and closely monitor drug concentrations to reduce laboratory critical values during TDM.

A Comprehensive Review on Unveiling the Journey of Digoxin: Past, Present, and Future Perspectives

Digoxin, a cardiac glycoside derived from the foxglove plant (Digitalis spp.), has been utilized for centuries in managing various cardiac conditions due to its ability to increase myocardial contractility and regulate heart rate. This comprehensive review explores the historical context, pharmacological properties, clinical applications, efficacy, safety profile, challenges, and future perspectives of digoxin. Tracing its journey from traditional medicine to modern cardiovascular therapeutics, we delve into its mechanism of action, therapeutic indications, and clinical guidelines. While digoxin remains a cornerstone therapy for heart failure and atrial fibrillation, its narrow therapeutic index and individual variability in response pose challenges in clinical practice. Nevertheless, ongoing research efforts aim to elucidate its role in emerging therapeutic areas and technological advancements in drug delivery. Despite the advent of newer pharmacological agents, digoxin's enduring relevance lies in its established efficacy, affordability, and global accessibility. This review underscores the symbiotic relationship between tradition and progress in cardiovascular medicine, highlighting the timeless pursuit of medical innovation to optimize patient care.

Safety profile of intravenous digoxin in Chinese patients with acute heart failure with reduced ejection fraction: a small-scale prospective cohort study

Background: Adverse effects of intravenous digoxin vary from patients and disease status, which should be closely monitored. Aims: To explore the safety profile of intravenous digoxin in acute heart failure with reduced ejection fraction (HFrEF) among Chinese patients. Methods: A clinical prospective, single-center, single-arm, open-label exploratory clinical trial was performed in patients with acute HFrEF at Wuhan Asia Heart Hospital. A fixed dose of 0.5 mg digoxin was used intravenously once per day for 3 days. The normalized dosage of digoxin (NDD), toxic serum digoxin concentration (SDC), and adverse reactions of intravenous digoxin were recorded. Results: A total of 40 patients were recruited in the study. The SDC increased from 1.03 ± 0.34 ng/mL to 1.95 ± 0.52 ng/mL during treatment. 50% (20/40) patients reached a toxic SDC of 2.0 ng/mL, and toxic effects were seen in 30% (12/40) patients. Estimated glomerular filtration rate (eGFR) < 60 mL/min [HR: 5.269; 95% CI: 1.905-14.575, p = 0.001], NDD ≥7 μg/kg [HR: 3.028; 95% CI: 1.119-8.194, p = 0.029], and ischemic cardiomyopathy [HR: 2.658; 95% CI: 1.025-6.894, p = 0.044] were independent risk factors for toxic SDC. Toxic SDC was effectively identified [area under the receiver operating characteristic (ROC) curve = 0.85, p < 0.001] using this model, and patients would have a higher risk of toxicity with more risk factors. Conclusion: Intravenous digoxin of 0.5 mg was safe and effective for initial dose but not suitable for maintenance treatment in Chinese patients with acute HFrEF. Patients who had lower eGFR, received higher NDD, and had ischemic cardiomyopathy should be closely monitored to avoid digoxin toxicity.