A solution is 0.5% w/v. You need 6 mg of the drug. Draw up the volume in the syringe: what volume V is that?
Pharmacy calculations worksheet with answers
Practice exercise (made-up values, not clinical guidance). How many g of dextrose are in 50 mL of 50% w/v solution? Find m.
A solution has a ratio strength of 1:1000. You need 0.36 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 of penicillin G contains 5 000 000 units. Its practice label gives three strengths (see the table). You add 18.2 mL of diluent. The prescribed dose is 2 000 000 units. What volume V do you draw up? Round to one decimal place.
A vial holds 250 mg of powder. You add 4.2 mL of diluent, and the powder adds 0.8 mL of volume. The prescription is 230 mg. Draw up the dose: what volume V do you give?
Practice exercise (made-up values, not clinical guidance). You must prepare 200 mL of 4% chlorhexidine from a 20% stock and purified water. How many mL V of water do you need? Round to the nearest whole mL.
Answer key
- 1. V = 1.2 mL
- 2. m = 25 g
- 3. V = 0.36 mL
- 4. V = 8 mL
- 5. V = 4.6 mL
- 6. V = 160 mL
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