Can a 1 mL vial supply a 30 mg dose?

Can a 1 mL vial supply a 30 mg dose?

• A. Yes
• B. No
• C. Only with dilution
• D. Only if the dose is split between two vials

Answer: (B)

The key idea is that the amount of drug you can get from a vial depends on its concentration, not just the vial size. Dose (mg) = concentration (mg/mL) × volume drawn (mL). A 1 mL vial can provide up to 1 mL, but how many milligrams that contains depends on how concentrated the solution is. If the concentration were 30 mg/mL, drawing 1 mL would give 30 mg. But the concentration isn’t given here, so you can’t assume that 1 mL contains 30 mg. If the concentration is lower than 30 mg/mL, you would need more than 1 mL (impossible from this vial) to reach 30 mg; if it’s higher, you could reach 30 mg with less than 1 mL. Because the information needed to confirm a 30 mg dose isn’t specified, you can’t guarantee supplying 30 mg from a 1 mL vial.

The key idea is that the amount of drug you can get from a vial depends on its concentration, not just the vial size. Dose (mg) = concentration (mg/mL) × volume drawn (mL). A 1 mL vial can provide up to 1 mL, but how many milligrams that contains depends on how concentrated the solution is. If the concentration were 30 mg/mL, drawing 1 mL would give 30 mg. But the concentration isn’t given here, so you can’t assume that 1 mL contains 30 mg. If the concentration is lower than 30 mg/mL, you would need more than 1 mL (impossible from this vial) to reach 30 mg; if it’s higher, you could reach 30 mg with less than 1 mL. Because the information needed to confirm a 30 mg dose isn’t specified, you can’t guarantee supplying 30 mg from a 1 mL vial.