A 20 kg dog requires 5 mg/kg of a drug. If the drug is supplied as 50 mg/mL, how many milliliters are needed?

A 20 kg dog requires 5 mg/kg of a drug. If the drug is supplied as 50 mg/mL, how many milliliters are needed?

• A. 0.5 mL
• B. 1.0 mL
• C. 2.0 mL
• D. 4.0 mL

Answer: (C)

Dosing is found by two steps: first figure out the total amount of drug needed based on weight, then convert that dose to a volume using the medication’s concentration. For this dog: 20 kg at 5 mg/kg means 20 × 5 = 100 mg are needed in total. The drug comes as 50 mg per milliliter, so the volume required is 100 mg ÷ 50 mg/mL = 2 mL. So the dog should receive 2.0 mL. If you used 0.5 mL, you’d be giving 25 mg; 1.0 mL would be 50 mg; 4.0 mL would be 200 mg.

Dosing is found by two steps: first figure out the total amount of drug needed based on weight, then convert that dose to a volume using the medication’s concentration.

For this dog: 20 kg at 5 mg/kg means 20 × 5 = 100 mg are needed in total. The drug comes as 50 mg per milliliter, so the volume required is 100 mg ÷ 50 mg/mL = 2 mL.

So the dog should receive 2.0 mL. If you used 0.5 mL, you’d be giving 25 mg; 1.0 mL would be 50 mg; 4.0 mL would be 200 mg.