Pharm.D. Doctor of Pharmacy Pharmaceutical Calculations and Compounding 2

Question 1

A pharmacist prepares a compound by mixing 30 g of a 2.5% hydrocortisone cream with 70 g of a plain base. What is the final concentration?

Accepted Answer

0.75%

Answer

Active drug = 30 g × 0.025 = 0.75 g; total weight = 100 g; final concentration = 0.75/100 = 0.75%.

Question 2

Which type of balance is most commonly required by USP standards for prescription compounding?

Accepted Answer

Class A prescription balance (sensitivity: 6 mg)

Answer

USP requires a Class A prescription balance with a sensitivity requirement (SR) of 6 mg for compounding prescriptions involving small quantities.

Question 3

The beyond-use date (BUD) for a non-aqueous compounded preparation in a non-sterile environment, per USP <795>, is:

Accepted Answer

6 months or shelf life of the ingredient, whichever is earlier

Answer

USP <795> sets the BUD for non-aqueous preparations at the earlier of 6 months or the shortest remaining shelf life of any ingredient.

Question 4

Alligation medial is used to calculate:

Accepted Answer

The strength of a mixture of two concentrations of the same drug

Answer

Alligation medial (or alternate) is a mathematical shortcut to determine the proportions needed to mix two strengths of a substance to achieve a desired intermediate strength.

Question 5

A prescription calls for 240 mL of a 1:400 w/v solution. How many grams of drug are required?

Accepted Answer

0.6 g

Answer

1:400 means 1 g per 400 mL; for 240 mL: (1/400) × 240 = 0.6 g.

Pharm.D. Doctor of Pharmacy Practice Test

Pharm.D. Doctor of Pharmacy Practice Test

Pharm.D. Doctor of Pharmacy Pharmaceutical Calculations and Compounding 2