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 starts regular doses of theophylline, which has a half-life of 9 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 53 kg patient is to receive an aminophylline infusion (salt factor S = 0.8: 80% of aminophylline is theophylline). The theophylline clearance is 0.04 L/kg/h. What aminophylline infusion rate R in mg/h gives a steady-state theophylline level of 15 mg/L?

Practice exercise (made-up values, not clinical guidance). An 82 kg patient is to be loaded intravenously with phenytoin sodium to reach a phenytoin level of 20 mg/L. The volume of distribution is 0.7 L/kg and the salt factor is S = 0.92. Find the loading dose LD of phenytoin sodium in mg.

Practice exercise (made-up values, not clinical guidance). A 59 kg patient on regular gentamicin doses is at steady state. The target is a peak of 10 mg/L and a trough of 1 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 50 kg patient takes oral theophylline (F = 1) every 12 h. The clearance is 0.045 L/kg/h. Each dose is 400 mg of theophylline. Find the average steady-state level C_ss,avg.