PSI Pharmaceutical Calculations 2

Question 1

An IV infusion of 1000 mL is prescribed to run over 8 hours. What is the required flow rate in mL/hour?

Accepted Answer

125 mL/hr

Answer

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?

Accepted Answer

42 drops/min

Answer

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?

Accepted Answer

12.5 mL

Answer

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?

Accepted Answer

9.0 mL

Answer

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?

Accepted Answer

2 hours

Answer

20 mmol ÷ 10 mmol/hr = 2 hours minimum infusion time.

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