PHAR 4634 Pharmaceutics III

Chapter 6

Homework Assignment - 1995 #3

1. Assuming a one compartment linear pharmacokinetic model, with kel = 0.16 hr-1; and V = 16.2 L, calculate the plasma concentration at 0.5, 1, 2, 3, 4, 6, 9, and 12 hours after starting a 200 mg/hr i.v. infusion of 3 hours duration. Plot the data on linear and semi-log graph paper.

Answer

2. Given the data in Table, calculate kel, and V. Assume a one compartment linear model.

Plasma Concentration Measured during and after a 200 mg/hr I.V. Infusion of 45 minutes duration
Time Since Start of Infusion (hr) Concentration (mg/L)
0.5 4.37
1 6.27
2 4.79
3 4.37
6 2.3

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3. A given drug follows linear one compartment pharmacokinetics. If the drug half-life is 7 hr and the apparent volume of distribution is 25 L, calculate the i.v. infusion necessary to achieve a steady state concentration of 25 mg/L (1). What i.v. bolus loading dose would you use to achieve 25 mg/L more rapidly (2)? What rapid i.v. infusion rate would you need to get to 25 mg/L in 30 minute (3)? Describe all three dosing regimen and sketch (not graph) the three plasma concentration versus time profiles.

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