Pharmacy Dosage Calculations 2

Question 1

A physician orders 500 mg of amoxicillin. The available stock is 250 mg/5 mL. How many mL should be dispensed per dose?

Accepted Answer

10 mL

Answer

Using the ratio: 250 mg/5 mL = 500 mg/x. Solving: x = (500 × 5) / 250 = 10 mL.

Question 2

A patient needs 0.4 mg of clonidine. The available tablets are 0.2 mg each. How many tablets should be given?

Accepted Answer

2 tablets

Answer

0.4 mg ÷ 0.2 mg/tablet = 2 tablets.

Question 3

An IV infusion of 1,000 mL is to run over 8 hours. What is the flow rate in mL/hr?

Accepted Answer

125 mL/hr

Answer

1,000 mL ÷ 8 hr = 125 mL/hr.

Question 4

A prescription calls for 1.5 g of a drug. How many milligrams is this?

Accepted Answer

1,500 mg

Answer

1 g = 1,000 mg, so 1.5 g = 1,500 mg.

Question 5

A technician needs to prepare 240 mL of a 2% solution using a 10% stock solution. How many mL of stock solution are needed?

Accepted Answer

48 mL

Answer

Using alligation or C1V1 = C2V2: 10% × V1 = 2% × 240 mL → V1 = 480/10 = 48 mL.

Pharmacy Practice Test