CSPT Compounding Calculations 4 — Questions and Answers
Question 1: What volume of a 20% lipid emulsion provides 200 kcal? (Fat = 9 kcal/g; 20% = 20 g/100 mL)
- 50 mL
- 100 mL
- 111 mL (Correct answer)
- 200 mL
Correct answer: 111 mL
20 g/100 mL × 9 kcal/g = 1.8 kcal/mL; 200 kcal ÷ 1.8 kcal/mL ≈ 111 mL.
Question 2: A TPN order calls for 50 mEq of sodium bicarbonate. The stock vial is 8.4% (1 mEq/mL). How many mL are needed?
- 8.4 mL
- 25 mL
- 50 mL (Correct answer)
- 84 mL
Correct answer: 50 mL
8.4% sodium bicarbonate = 1 mEq/mL; 50 mEq ÷ 1 mEq/mL = 50 mL.
Question 3: You prepare 500 mL of a parenteral solution. The label requires a 1:200 concentration of drug. How many grams of drug are in the bag?
- 0.25 g
- 0.5 g
- 2.5 g (Correct answer)
- 5 g
Correct answer: 2.5 g
1:200 = 1 g per 200 mL; for 500 mL: 500/200 = 2.5 g.
Question 4: An order requires tobramycin 5 mg/kg/day divided every 8 hours for a 60 kg patient. What is the dose per administration?
- 50 mg
- 100 mg (Correct answer)
- 150 mg
- 300 mg
Correct answer: 100 mg
Daily dose = 5 × 60 = 300 mg/day; divided q8h = 300 ÷ 3 = 100 mg per dose.
Question 5: Which calculation correctly determines the flow rate (mL/hr) for a 1 g drug infused over 30 minutes in 100 mL NS?
- 50 mL/hr
- 100 mL/hr
- 200 mL/hr (Correct answer)
- 300 mL/hr
Correct answer: 200 mL/hr
100 mL over 0.5 hr = 100 ÷ 0.5 = 200 mL/hr.
Question 6: A stock solution contains 250 mg/5 mL. How many mL are needed to provide a 75 mg dose?
- 1 mL
- 1.5 mL (Correct answer)
- 2 mL
- 3 mL
Correct answer: 1.5 mL
Concentration = 50 mg/mL; 75 mg ÷ 50 mg/mL = 1.5 mL.
Question 7: A compounder adds 20 mEq of KCl and 30 mEq of NaCl to a 1 L TPN. The combined mEq of monovalent electrolytes is:
- 20 mEq
- 30 mEq
- 50 mEq (Correct answer)
- 100 mEq
Correct answer: 50 mEq
Both KCl and NaCl contribute 1 mEq/mEq of monovalent ions; total = 20 + 30 = 50 mEq.
CSPT Compounding Calculations 4
What volume of a 20% lipid emulsion provides 200 kcal? (Fat = 9 kcal/g; 20% = 20 g/100 mL)