Clinical pharmacokinetics worksheet with answers

Practice exercise (made-up values, not clinical guidance). A patient starts regular doses of phenobarbital, which has a half-life of 80 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 who weighs 85 kg needs a loading dose of vancomycin to reach a level of 30 mg/L straight away. The volume of distribution is 0.7 L/kg. Find the loading dose LD in mg.

Practice exercise (made-up values, not clinical guidance). Vancomycin is given as a continuous infusion to a patient whose vancomycin clearance is 85 mL/min. What infusion rate R in mg/h gives a steady-state level of 20 mg/L?

Practice exercise (made-up values, not clinical guidance). A 73 kg patient receives a theophylline infusion. The clearance is 0.03 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 vancomycin infusion runs at 100 mg/h with no loading dose. The patient's clearance is 5 L/h and the half-life is 8 h. What is the level C after 21 h?

Practice exercise (made-up values, not clinical guidance). A patient's tobramycin half-life is 3 h. The target is a peak of 6 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.