PEBC Pharmaceutical Calculations

Question 1

A physician orders amoxicillin 40 mg/kg/day divided every 8 hours for a child weighing 22 kg. How many mg should be given per dose?

Accepted Answer

293 mg

Answer

40 mg/kg/day × 22 kg = 880 mg/day divided into 3 doses (every 8 hours) = 293 mg per dose.

Question 2

A pharmacist needs to prepare 250 mL of a 0.9% NaCl solution. How many grams of NaCl are required?

Accepted Answer

2.25 g

Answer

0.9% means 0.9 g per 100 mL; therefore 0.9 × (250/100) = 2.25 g of NaCl are needed.

Question 3

An IV infusion of 1000 mL is to be administered over 8 hours using a drip set delivering 20 drops/mL. What is the drip rate in drops per minute?

Accepted Answer

42 drops/min

Answer

1000 mL ÷ 8 hr = 125 mL/hr; 125 mL/hr ÷ 60 min × 20 drops/mL ≈ 42 drops/min.

Question 4

A medication is available as 250 mg/5 mL. A patient needs a 375 mg dose. How many mL should be dispensed?

Accepted Answer

7.5 mL

Answer

Using proportion: 375 mg × (5 mL / 250 mg) = 7.5 mL.

Question 5

How many milligrams of drug are contained in 2 L of a 1:5000 solution?

Accepted Answer

400 mg

Answer

1:5000 means 1 g per 5000 mL = 0.2 mg/mL; 0.2 mg/mL × 2000 mL = 400 mg.

PEBC - Pharmacy Examining Board of Canada Practice Test