Clinical pharmacokinetics worksheet with answers

Practice exercise (made-up values, not clinical guidance). Just after an IV dose, the gentamicin level is 8 mg/L. The half-life is 2 h, and the drug is eliminated by first-order kinetics. What is the level C 1 h later?

Practice exercise (made-up values, not clinical guidance). A patient starts regular doses of vancomycin, which has a half-life of 6 h. Using the rule that steady state is reached after about five half-lives, after how many hours t_ss is steady state reached?

Practice exercise (made-up values, not clinical guidance). A patient receives an IV bolus of 330 mg of tobramycin. The level back-extrapolated to time zero is 12 mg/L and the half-life is 2.5 h. Find the volume of distribution Vd.

Practice exercise (made-up values, not clinical guidance). After an IV dose of tobramycin, the level is 10 mg/L at 2 h and 2.5 mg/L at 6 h. Assume first-order elimination. Find the half-life t½.

Practice exercise (made-up values, not clinical guidance). A 92 kg patient takes oral aminophylline (S = 0.8, F = 1) every 12 h. The theophylline clearance is 0.045 L/kg/h. Each dose is 250 mg of aminophylline. Find the average steady-state level C_ss,avg.

Practice exercise (made-up values, not clinical guidance). A patient's tobramycin half-life is 3 h. The target is a peak of 10 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.