This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
The most impoant channel of elimination of digoxin is 
Select and explain. 
A. Hepatic metabolism, B. Glomerular filtration, C. Tubular secretion, D. Excretion in bile
B: Glomerular filtration
Answer: B: Glomerular filtration 
Explanation: PHARMACOKINETICS Presence of food in stomach delays absorption of digoxin. The volume of distribution of digoxin is large. It is concentrated in the hea, skeletal muscle, liver and kidney. Digoxin is primarily excreted unchanged by the kidney: mainly by glomerular filtration; rate of excretion is altered parallel to creatinine clearance. Its t 1/2 is prolonged in elderly patients and in those with renal insufficiency: dose has to be reduced. Ref:- kd tripathi; pg num:-515,516