Clinical pharmacokinetics worksheet with answers

Practice exercise (made-up values, not clinical guidance). A patient who weighs 72 kg needs a loading dose of theophylline to reach a level of 10 mg/L straight away. The volume of distribution is 0.5 L/kg. Find the loading dose LD in mg.

Practice exercise (made-up values, not clinical guidance). A patient receives lidocaine as a constant IV infusion without a loading dose. The half-life is 2 h. What percentage f of the steady-state level has been reached after 3 h?

Practice exercise (made-up values, not clinical guidance). A 79 kg patient receives a theophylline infusion. The clearance is 0.04 L/kg/h. What infusion rate R in mg/h gives a steady-state level of 15 mg/L?

Practice exercise (made-up values, not clinical guidance). A patient receives an IV bolus of 170 mg of gentamicin. The level back-extrapolated to time zero is 12 mg/L and the half-life is 2.5 h. Find the clearance CL in L/h.

Practice exercise (made-up values, not clinical guidance). A 52 kg patient has a phenytoin level of 8 mg/L; the target is 20 mg/L. The drug is given intravenously as phenytoin sodium (S = 0.92), and the volume of distribution is 0.7 L/kg. What extra loading dose LD raises the level to the target?

Practice exercise (made-up values, not clinical guidance). A patient's gentamicin half-life is 2 h. The target is a peak of 6 mg/L and a trough of 0.5 mg/L. Assuming rapid IV doses and first-order elimination, what dosing interval τ lets the level fall from the peak to the trough? Round to one decimal place.