PSI Pharmaceutical Calculations 2 — Questions and Answers
Question 1: An IV infusion of 1000 mL is prescribed to run over 8 hours. What is the required flow rate in mL/hour?
- 80 mL/hr
- 100 mL/hr
- 125 mL/hr (Correct answer)
- 150 mL/hr
Correct answer: 125 mL/hr
1000 mL ÷ 8 hours = 125 mL/hour.
Question 2: A giving set delivers 20 drops/mL. An infusion of 500 mL must run over 4 hours. What is the drip rate in drops per minute?
- 20 drops/min
- 35 drops/min
- 42 drops/min (Correct answer)
- 50 drops/min
Correct answer: 42 drops/min
500 mL ÷ 240 min = 2.08 mL/min × 20 drops/mL ≈ 42 drops/min.
Question 3: A child weighing 25 kg requires ibuprofen 10 mg/kg. The suspension is 100 mg/5 mL. What volume should be administered?
- 5 mL
- 10 mL
- 12.5 mL (Correct answer)
- 25 mL
Correct answer: 12.5 mL
Dose = 10 mg/kg × 25 kg = 250 mg; volume = 250 mg ÷ 20 mg/mL = 12.5 mL.
Question 4: You need to prepare 200 mL of a 0.9% NaCl solution from a 20% NaCl stock. What volume of stock solution is required?
- 1.8 mL
- 4.5 mL
- 9.0 mL (Correct answer)
- 18.0 mL
Correct answer: 9.0 mL
Using C1V1 = C2V2: 20% × V1 = 0.9% × 200 mL; V1 = 9 mL.
Question 5: A KCl infusion contains 20 mmol in 500 mL. The maximum safe infusion rate is 10 mmol/hour. What is the minimum infusion time?
- 1 hour
- 2 hours (Correct answer)
- 4 hours
- 5 hours
Correct answer: 2 hours
20 mmol ÷ 10 mmol/hr = 2 hours minimum infusion time.
Question 6: A 10 mg/mL solution needs to be diluted to a final concentration of 2 mg/mL. What is the dilution factor?
- 2
- 5 (Correct answer)
- 8
- 10
Correct answer: 5
Dilution factor = original concentration ÷ target concentration = 10 mg/mL ÷ 2 mg/mL = 5.
Question 7: Heparin is prescribed at 1000 units/hour. The infusion bag contains 25,000 units in 50 mL. At what rate should the infusion pump be set?
- 1 mL/hr
- 2 mL/hr (Correct answer)
- 5 mL/hr
- 10 mL/hr
Correct answer: 2 mL/hr
25,000 units ÷ 50 mL = 500 units/mL; 1000 units/hr ÷ 500 units/mL = 2 mL/hr.
PSI Pharmaceutical Calculations 2
An IV infusion of 1000 mL is prescribed to run over 8 hours.
What is the required flow rate in mL/hour?