Clinical pharmacokinetics worksheet with answers

Practice exercise (made-up values, not clinical guidance). A patient who weighs 98 kg needs a loading dose of gentamicin to reach a level of 10 mg/L straight away. The volume of distribution is 0.25 L/kg. Find the loading dose LD in mg.

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 12 h. What percentage f of the steady-state level has been reached after 36 h?

Practice exercise (made-up values, not clinical guidance). A patient has a lidocaine clearance of 700 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 94 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 75 kg patient takes oral theophylline (F = 1) every 12 h. The clearance is 0.03 L/kg/h. Each dose is 450 mg of theophylline. Find the average steady-state level C_ss,avg.

Practice exercise (made-up values, not clinical guidance). A 59-year-old man weighs 93 kg and has a serum creatinine of 3.5 mg/dL (309 µmol/L). Estimate the creatinine clearance with Cockcroft–Gault: CrCl (mL/min) = (140 − age) × weight (kg)/(72 × SCr in mg/dL), × 0.85 for women. The usual vancomycin regimen is 1000 mg every 12 h for a creatinine clearance of 100 mL/min. Keeping the dose, the interval is lengthened in proportion to the fall in clearance. Find the new dosing interval τ. Round to one decimal place.