A solution is 0.5% w/v. You need 19 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 75 mg of the drug. Draw up the volume in the syringe: what volume V is that?
Practice exercise (made-up values, not clinical guidance). A vial contains oxacillin 2000 mg as a powder. The practice label says to add 11.5 mL of sterile water; the powder adds 1 mL to the volume. What is the concentration C in mg/mL after reconstitution?
A solution has a ratio strength of 1:10 000. You need 0.52 mg. Draw up the volume in the 10 mL syringe: what volume V is that?
Practice exercise (made-up values, not clinical guidance). You have 20 g of 2.5% hydrocortisone ointment. How many grams m of 0.5% hydrocortisone ointment must you add to make a 1.5% ointment? Round to the nearest whole gram.
A vial holds 1000 mg of powder. You add 1.7 mL of diluent, and the powder adds 0.8 mL of volume. The prescription is 400 mg. Draw up the dose: what volume V do you give?
Answer key
- 1. V = 3.8 mL
- 2. V = 1.5 mL
- 3. C = 160 mg/mL
- 4. V = 5.2 mL
- 5. m = 20 g
- 6. V = 1 mL
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