Clinical pharmacokinetics worksheet with answers

Practice exercise (made-up values, not clinical guidance). A patient receives aminophylline as a constant IV infusion without a loading dose. The half-life is 6 h. What percentage f of the steady-state level has been reached after 15 h?

Practice exercise (made-up values, not clinical guidance). Just after an IV dose, the gentamicin level is 9 mg/L. The half-life is 3 h, and the drug is eliminated by first-order kinetics. What is the level C 11 h later?

Practice exercise (made-up values, not clinical guidance). After an IV dose of tobramycin, the level is 6 mg/L at 2 h and 2.1 mg/L at 5 h. Assume first-order elimination. Find the elimination rate constant k.

Practice exercise (made-up values, not clinical guidance). A 68 kg patient is to be loaded with digoxin tablets to reach a level of 0.8 mcg/L. The volume of distribution is 7 L/kg and the tablets have a bioavailability F = 0.7. Find the total oral loading dose LD in mcg.

Practice exercise (made-up values, not clinical guidance). A 53 kg patient on regular tobramycin doses is at steady state. The target is a peak of 8 mg/L and a trough of 0.5 mg/L, and the volume of distribution is 0.3 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 78 kg patient takes oral aminophylline (S = 0.8, F = 1) every 8 h. The theophylline clearance is 0.03 L/kg/h. What dose D in mg gives an average steady-state level of 12 mg/L?