Clinical pharmacokinetics worksheet with answers

Practice exercise (made-up values, not clinical guidance). A patient who weighs 73 kg needs a loading dose of theophylline to reach a level of 10 mg/L straight away. The volume of distribution is 0.5 L/kg. Find the loading dose LD in mg.

Practice exercise (made-up values, not clinical guidance). A patient who weighs 104 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). A patient has a lidocaine clearance of 500 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). After an IV dose of tobramycin, the level is 10 mg/L at 2 h and 4 mg/L at 6 h. Assume first-order elimination. Find the half-life t½.

Practice exercise (made-up values, not clinical guidance). A theophylline infusion runs at 35 mg/h with no loading dose. The patient's clearance is 3.5 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). An 81-year-old man weighs 80 kg and has a serum creatinine of 1.9 mg/dL (168 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 atenolol dose is 100 mg for a creatinine clearance of 100 mL/min, and a fraction fe = 0.9 of the drug is excreted unchanged by the kidneys. Using the Dettli dose fraction Q = 1 − fe·(1 − CrCl/normal CrCl), find the adjusted dose D. Round to the nearest whole number.