This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Digoxin can accumulate to toxic levels in patients with: 
Select and explain. 
A. Renal insufficiency, B. Chronic hepatitis, C. Advanced cirrhosis, D. Chronic pancreatitis
A: Renal insufficiency
Answer: A: Renal insufficiency 
Explanation: Digoxin is primarily excreted unchanged by the kidney, mainly by glomerular filtration. Rate of excretion is altered parallel to creatinine clearance. Its  t½  is prolonged in elderly patients and in those with renal insufficiency: dose has to be reduced. 
Digoxin is a cumulative drug. When maintenance doses are given from the beginning, steady state levels and full therapeutic effect are attained after 4 x t½, i.e. 6-7 days.
Reference: Essentials of Medical Pharmacology Eighth Edition KD  TRIPATHI  page no 560