A medication has a concentration of 50 mg/mL. How many milliliters should a 500 g guinea pig receive if the dosage is 10 mg/kg?

A medication has a concentration of 50 mg/mL. How many milliliters should a 500 g guinea pig receive if the dosage is 10 mg/kg?

• A. 0.1 mL
• B. 0.3 mL
• C. 0.5 mL
• D. 5.0 mL

Answer: (A)

To determine the dose, convert the animal’s weight to kilograms, calculate the required milligrams, then convert that amount to milliliters using the drug’s concentration. The guinea pig weighs 500 g, which is 0.5 kg. At 10 mg/kg, the needed dose is 10 × 0.5 = 5 mg. With a concentration of 50 mg/mL, 5 mg corresponds to 5 mg ÷ 50 mg/mL = 0.1 mL. So the correct volume to administer is 0.1 mL. For context, 0.3 mL would carry 0.3 × 50 = 15 mg (three times the target), 0.5 mL would be 25 mg, and 5.0 mL would be 250 mg, far exceeding the prescribed dose.

To determine the dose, convert the animal’s weight to kilograms, calculate the required milligrams, then convert that amount to milliliters using the drug’s concentration. The guinea pig weighs 500 g, which is 0.5 kg. At 10 mg/kg, the needed dose is 10 × 0.5 = 5 mg. With a concentration of 50 mg/mL, 5 mg corresponds to 5 mg ÷ 50 mg/mL = 0.1 mL. So the correct volume to administer is 0.1 mL. For context, 0.3 mL would carry 0.3 × 50 = 15 mg (three times the target), 0.5 mL would be 25 mg, and 5.0 mL would be 250 mg, far exceeding the prescribed dose.