Clinical pharmacokinetics worksheet with answers

Practice exercise (made-up values, not clinical guidance). In a patient, tobramycin has an elimination half-life of 3 h. Find the elimination rate constant k in h⁻¹.

Practice exercise (made-up values, not clinical guidance). A patient starts regular doses of gentamicin, which has a half-life of 3 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 110 mg of tobramycin. The level back-extrapolated to time zero is 6 mg/L and the half-life is 2 h. Find the clearance CL in L/h.

Practice exercise (made-up values, not clinical guidance). A patient has a lidocaine clearance of 750 mL/min. What infusion rate R in mg/min keeps the steady-state level at 4 mg/L?

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 6 mg/L and a trough of 1 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). An 85 kg patient takes oral aminophylline (S = 0.8, F = 1) every 12 h. The theophylline clearance is 0.04 L/kg/h. Each dose is 250 mg of aminophylline. Find the average steady-state level C_ss,avg.