This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
H a t year old patient on Oxygen therapy has developed digital toxicity. The plasma peacocks in level is 4ng/ml. Renal function is normal and the plasma half life for digoxin in this patient is 1.6 days. How long should give with hold digoxin in order to reach a safer yet probably therapeutic level of 1ng/ml 
Select and explain. 
A. 1.6days, B. 2.4days, C. 3.2days, D. 4.8days
C: 3.2days
Answer: C: 3.2days 
Explanation: Ref-Katzung 10/e p48 WeWwant to decrease a plama concentration of digoxin from 1ng/ml.it will take two half lives.thus time required is 2x1.6=3.2days