PTCB Sterile Compounding & Pharmacy Calculations 3

Question 1

What is the formula for calculating a percentage concentration (w/v)?

Accepted Answer

(Weight of solute in grams ÷ volume of solution in mL) × 100

Answer

A w/v percentage = (grams of solute ÷ mL of solution) × 100; e.g., 5 g in 100 mL = 5% w/v.

Question 2

An order requires 250 mg of a drug from a stock solution of 50 mg/5 mL. How many mL are needed?

Accepted Answer

25 mL

Answer

50 mg/5 mL = 10 mg/mL; 250 mg ÷ 10 mg/mL = 25 mL needed.

Question 3

Which of the following is an isotonic IV solution?

Accepted Answer

0.9% NaCl (normal saline)

Answer

0.9% NaCl (normal saline) is isotonic with a tonicity of approximately 308 mOsm/L, close to plasma osmolarity.

Question 4

When using dimensional analysis to convert 2.5 kg to grams, the answer is:

Accepted Answer

2500 g

Answer

2.5 kg × 1,000 g/kg = 2,500 g.

Question 5

What does the term 'aseptic technique' refer to in sterile compounding?

Accepted Answer

Procedures that prevent contamination of sterile preparations with microorganisms

Answer

Aseptic technique encompasses all practices used to prevent microbial contamination during the preparation of sterile products.

PTCB - Pharmacy Technician Certification Board Practice Test