<prompt> A 30 year old patient on digoxin therapy has developed digitalis toxicity. The plasma digoxin level is 4 ngml. Renal function is normal and the plasma t12 for digoxin in this patient is 1.6 days. How long should you withhold digoxin in order to reach a safer yet probably therapeutic level of 1 ngml?1.6 days2.4 days3.2 days4.8 days  <response>: We want to decrease the plasma concentration of digoxin from 4 ngml to 1 ngml. It will take two half lives From 4 ngml to 2 ngml in one half life and from 2 ngml to 1 ngml in second half life. Thus time required will be 2 x t 12 i.e. 2 x 1.6 3.2 days. 