1. Practice Problems
Biopharmaceutics-I

2. Problem 1
Using the equation C = C0e-Kt, determine the plasma concentration of a drug 24 hours after a peak level of 10 mg/L is observed if the elimination rate constant is 0.05 hr-1.
A mg/L
B mg/L
C mg/L

3. Problem 2
Which of the following is a proper unit for the elimination rate constant?
A. minutes
B. mg/minute
C. hr-1
D. mg/L

4. Problem 3
If the elimination rate constant is 0.2 hr-1 the percent of drug removed per hour is:
A. 20%.
B. 1%.
C. 0.1%.
D. 10%.

5. Problem 4
If the plasma concentration just after a gentamicin dose is 10 mg/L and the patient's elimination rate constant is 0.15 hr-1, predict what the plasma concentration will be 8 hours later.
A. 6.0 mg/L
B. 3.0 mg/L
C. 1.5 mg/L
D. 1.0 mg/L

6. Problem 5
For a drug that has an initial plasma concentration of 120 mg/L and a half-life of 3 hours, what would the plasma concentration be 12 hours after the initial concentration?
A. 15 mg/L B
C. 7.5 mg/L
D. 60

7. Problem 6
If a drug has an elimination rate constant of hr-1, what is the half-life?
A hours
B hour
C hours

8. Problem 7
From 1 M HCl stock solution, how will you make 10 ml of 0.1 M solution?

9. Problem 8
You have 50 ml of 50 mg/ml stock solution of a vaccine which is very expensive. You have 5 ml and 10 ml volumetric flasks available in your lab.
Show the calculation for preparation of 45, 40, 35, 30, 25, 20, 15, 10, 5 mg/ml solution of the vaccine using both 5 ml and 10 ml volumetric flasks. Design a table for the process showing the volume to be added in each flask.
You just require 2 ml sample of each concentration for your analysis. Which volumetric flasks will you choose to use and why? Explain with calculations.