Clinical pharmacokinetics worksheet with answers

Practice exercise (made-up values, not clinical guidance). In a patient, digoxin has an elimination half-life of 48 h. Find the elimination rate constant k in h⁻¹.

Practice exercise (made-up values, not clinical guidance). A patient who weighs 53 kg needs a loading dose of gentamicin to reach a level of 10 mg/L straight away. The volume of distribution is 0.25 L/kg. Find the loading dose LD in mg.

Practice exercise (made-up values, not clinical guidance). A 57 kg patient is to receive an aminophylline infusion (salt factor S = 0.8: 80% of aminophylline is theophylline). The theophylline clearance is 0.045 L/kg/h. What aminophylline infusion rate R in mg/h gives a steady-state theophylline level of 10 mg/L?

Practice exercise (made-up values, not clinical guidance). After an IV dose of tobramycin, the level is 8 mg/L at 2 h and 1.5 mg/L at 8 h. Assume first-order elimination. Find the half-life t½.

Practice exercise (made-up values, not clinical guidance). A 60 kg patient on regular tobramycin doses is at steady state. The target is a peak of 6 mg/L and a trough of 0.5 mg/L, and the volume of distribution is 0.25 L/kg. Assuming rapid IV doses, what dose D raises the level from the trough to the peak?

Practice exercise (made-up values, not clinical guidance). A patient's gentamicin half-life is 2 h. The target is a peak of 8 mg/L and a trough of 1 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.