A solution is 0.5% w/v. You need 7.5 mg of the drug. Draw up the volume in the syringe: what volume V is that?
Pharmacy calculations worksheet with answers
A solution is 5% w/v. You need 140 mg of the drug. Draw up the volume in the syringe: what volume V is that?
A solution has a ratio strength of 1:1000. You need 0.85 mg. Draw up the volume in the 1 mL syringe: what volume V is that?
Practice exercise (made-up values, not clinical guidance). A vial contains ampicillin 1000 mg as a powder. The practice label says to add 3.5 mL of sterile water; the powder adds 0.5 mL to the volume. What is the concentration C in mg/mL after reconstitution?
A vial holds 500 mg of powder. You add 4.2 mL of diluent, and the powder adds 0.8 mL of volume. The prescription is 120 mg. Draw up the dose: what volume V do you give?
Practice exercise (made-up values, not clinical guidance). You must prepare 1000 mL of 20% dextrose by mixing 50% and 10% dextrose. How many mL V of the 10% solution do you need? Round to the nearest whole mL.
Answer key
- 1. V = 1.5 mL
- 2. V = 2.8 mL
- 3. V = 0.85 mL
- 4. C = 250 mg/mL
- 5. V = 1.2 mL
- 6. V = 750 mL
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