A consulting pharmacist in a skilled nursing facility is asked by a nurse: "What is meant by peak digoxin body stores in the following chart order?" The patient has received the following new orders:

Lanoxin (Digoxin)

Administer (immediately) a dose to get peak digoxin body stores of 10 mcg/kg. Administer a second dose 6 hours later, after confirming with the prescriber.

The pharmacist may tell her that:

a. He hasn't heard of it before.
b. It means a loading dose of the drug.
c. It means a maintenance dose of the drug.
d. It should be clarified with the prescribing physician.
e. It means AUC at t1/2.

Answer:(b). Digitalization may be accomplished by either of two general approaches that vary in dosage and frequency of administration, but reach the same endpoint in terms of total amount of digoxin accumulated in the body.

If rapid digitalization is considered medically appropriate, it may be achieved by administering a loading dose based upon projected peak digoxin body stores. Maintenance doses can be calculated as a percentage of the loading dose.

Peak digoxin body stores (i.e. loading dose) of 8 to 12 mcg/kg should provide therapeutic effect with minimum risk of toxicity in most patients with heart failure and normal sinus rhythm. Because of altered digoxin distribution and elimination, projected peak body stores for patients with renal insufficiency should be conservative (i.e. 6 to 10 mcg/kg).

The loading dose should be administered in several portions, with roughly half the total given as the first dose. Additional fractions of this planned total dose may be given at 6- to 8-hour intervals, with careful assessment of clinical response before each additional dose.

**This sample question is from Clinical NAPLEX Practice Test 3.** For more information please visit www.pharmacyexam.com