Sterile Compounding Calculations Flashcards

An 80-kg patient needs phenytoin 15 mg/kg in 250 mL of NS. Stock vial is 250 mg/5 mL. What volume should be withdrawn?

Answer: 24 mL

Loading dose is 1,200 mg. Stock is 50 mg/mL. Volume is 1,200 divided by 50 equals 24 mL.

Calculate the drip rate for 500 mL over 4 hours using a 15 drops/mL set.

Answer: 31.3 drops/min

500 mL times 15 drops/mL divided by 240 minutes equals 31.25 drops/min.

A TPN order calls for 50 mL of 8.5% amino acids. How many grams does this provide?

Answer: 4.25 g

8.5% means 8.5 g per 100 mL. For 50 mL: 8.5 divided by 100 times 50 equals 4.25 g.

How many mL of a 1:1,000 epinephrine solution are needed for a 0.3 mg dose?

Answer: 0.3 mL

1:1,000 means 1 g per 1,000 mL which is 1 mg/mL. For 0.3 mg: 0.3 mL.

Prepare 30 syringes of morphine 2 mg/mL, each 20 mL. Stock is 15 mg/mL. What total stock volume is required?

Answer: 80 mL

Each syringe needs 40 mg. Total: 1,200 mg. Volume: 1,200 divided by 15 equals 80 mL.

What is the osmolarity of 0.9% sodium chloride? (MW 58.44, dissociation factor 2)

Answer: 308 mOsm/L

0.9% equals 9 g/L. Molarity is 154 mmol/L. Osmolarity is 154 times 2 equals 308 mOsm/L.