Clinical pharmacokinetics worksheet with answers

Practice exercise (made-up values, not clinical guidance). A patient starts regular doses of gentamicin, which has a half-life of 2 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 vancomycin as a constant IV infusion without a loading dose. The half-life is 8 h. What percentage f of the steady-state level has been reached after 28 h?

Practice exercise (made-up values, not clinical guidance). An 80 kg patient is to be loaded intravenously with phenytoin sodium to reach a phenytoin level of 15 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 patient receives an IV bolus of 270 mg of tobramycin. The level back-extrapolated to time zero is 12 mg/L and the half-life is 3 h. Find the clearance CL in L/h.

Practice exercise (made-up values, not clinical guidance). A 78 kg patient on regular tobramycin doses is at steady state. The target is a peak of 8 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). A patient receives vancomycin IV every 12 h; the vancomycin clearance is 4.5 L/h. What dose D in mg gives an average steady-state level of 25 mg/L?