Practice exercise (made-up values, not clinical guidance). In a patient, vancomycin has an elimination half-life of 12 h. Find the elimination rate constant k in h⁻¹.
Clinical pharmacokinetics worksheet with answers
Practice exercise (made-up values, not clinical guidance). A patient who weighs 89 kg needs a loading dose of gentamicin to reach a level of 8 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). After an IV dose of tobramycin, the level is 8 mg/L at 2 h and 3.2 mg/L at 6 h. Assume first-order elimination. Find the elimination rate constant k.
Practice exercise (made-up values, not clinical guidance). After an IV dose of tobramycin, the level is 8 mg/L at 1 h and 2 mg/L at 5 h. Assume first-order elimination. Find the elimination rate constant k.
Practice exercise (made-up values, not clinical guidance). A 49-year-old woman weighs 73 kg and has a serum creatinine of 2.2 mg/dL (194 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 digoxin dose is 250 mcg for a creatinine clearance of 120 mL/min, and a fraction fe = 0.7 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.
Practice exercise (made-up values, not clinical guidance). A theophylline infusion runs at 20 mg/h with no loading dose. The patient's clearance is 2 L/h and the half-life is 6 h. What is the level C after 10 h?
Answer key
- 1. k = 0.05776 h⁻¹
- 2. LD = 178 mg
- 3. k = 0.2291 h⁻¹
- 4. k = 0.3466 h⁻¹
- 5. D = 127 mcg
- 6. C = 6.85 mg/L
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