Problems related to Vd & LD

Problem 01. Lidocaine has a Vd of 1.1 L/kg.

1. What is its Vd in a 70 kg human?

Problem 02. You find in a research project that a new drug has a Vd of 30 L. The subject weighd 50 kg.

1. What is the Vd per kg?

Problem 03. A drug was given IV to an experimental subject that weighed 70 kg. Dose of 2.5 mg/kg. Concentrations in the plasma were found to be as follows (mg/L): 2 hr = 7.07; 4 hr = 5.00; 6 hr = 3.54; 8 hr = 2.50.

1. What is the total dose?
2. What is the Cp(0)?
3. What is the Vd/kg?
4. What is the whole subject Vd?

Problem 04. A drug was given IV to a 60 kg subject at a dose of 5 mg/kg. The resulting Cp(0) was 20 mg/L. The same dose of drug was given 1 month later PO. The subject had no significant changes in weight or hydration status. The resulting Cp(0) was 17 mg/L.

1. What is the approximate F?
2. What formula did you use to calculate F?
3. How does it compare to the approach used in class?

Problem 05. A drug was given IV to a patient that had an estimated Vd of 0.9 L/kg. The dose was 4 mg/kg.

1. What is the estimated Cp(0)?
2. What is the estimated F?
3. How does this calculated Cp(0) correspond to the "A" in the one-compartment pharmacokinetic model?

Problem 06. You are preparing a dosage regimen for a 120 pound patient. The drug is listed as having a Vd of 0.4 L/kg.

1. How much drug should you give IV to produce an initial peak concentration of 15 mg/L? (i.e., what is the loading dose?)