Question 2#

L. M. has been receiving digoxin 0.25 mg PO tablets daily. Her serum drug level is 1.8 ng/mL. She is no longer able to take PO medications and needs to receive digoxin IV. By what percentage do you need to decrease the dose to maintain the current digoxin level?

A. 10%
B. 25%
C. 40%
D. 50%

Correct Answer is B


b. 25%. The bioavailability of digoxin tablets is 75%. Therefore, when converting from PO to IV administration (bioavailability of 100%), there is a 25% increase in bioavailability. Without altering the dose of digoxin, this patient would most likely have an increase in digoxin level to approximately 2.4 ng/mL. This could lead to potential digoxin toxicity.