Question

Sal's plasma contains 0.5 mg/mL of ampicillin. The concentration of ampicillin in Sal's urine is 0.25 mg/mL. In 24 hours, Sal's urine output was 1800 mL. Calculate Sal's ampicillin clearance.

Write your answer in mL/min including 3 decimal places. Do NOT include units in your answer.

Answer 1

Ampicillin clearance = concentration of ampicillin in urine X urine output / concentration of ampicillin in plasma

Given,

• concentration of ampicillin in urine = 0.25 mg/mL
• urine output= 1800 mL / 24 hour

Converting it into mL / minute.

24 hour --------------> 1800 ml

1 hour -----------------> x

By crossing , we get x = 1800 / 24 ( for 60 minutes )

60 minutes --------------> 1800 / 24

1 minute ------------------> y

By crossing , urine out put = 1800 / (24 X 60) mL / minute

• concentration of ampicillin in plasma = 0.5 mg/mL

substituting values= 0.25 X 1800 / 0.5 X 24 X 60

Ampicillin clearance = 0.625 mL / min.