A patient is prescribed 80 mg of a medication, and the bottle lists 160 mg per 5 mL. How many milliliters should be administered?

A patient is prescribed 80 mg of a medication, and the bottle lists 160 mg per 5 mL. How many milliliters should be administered?

• A. 5 mL
• B. 1 mL
• C. 2.5 mL
• D. 0.5 mL

Answer: (C)

Concentration and proportional dosing: when the medication’s strength is fixed, the volume you administer scales with the dose. The label 160 mg per 5 mL means each mL contains 160/5 = 32 mg. To give 80 mg, you need 80 / 32 = 2.5 mL. Since 80 mg is half of 160 mg, you could also see it as half of 5 mL, which is 2.5 mL. So the correct administration volume is 2.5 mL.

Concentration and proportional dosing: when the medication’s strength is fixed, the volume you administer scales with the dose. The label 160 mg per 5 mL means each mL contains 160/5 = 32 mg. To give 80 mg, you need 80 / 32 = 2.5 mL. Since 80 mg is half of 160 mg, you could also see it as half of 5 mL, which is 2.5 mL. So the correct administration volume is 2.5 mL.