17. Clinical Pharmacokinetics II

Question 1

What is the PCss of a drug that is given once every 2 half lives with a PC1 of 150.

A. 1,600 
B.1,800 
C. 800 
D.2,200 
E.2,500

RFA

Answer 1

Ans C

.75= fraction lost between each dose, 2 half lives so .50 after 1 and .75 after 2

1/.75= 14.66= AF

AFx PC1= PCss

14.66 x 150=2,200

Question 2

Determine the amount of IV Drug Z that is required to maintain a steady state in the body given the following information: Concentration= 40 mg, Half Life = 8 hrs, Clearance= 5 mg/hr, Volume Distribution = 45 mg/L.

A. 300 mg/hr
B. 200 mg/hr
C. 2,000 mg/hr
D. 500 mg/hr
E. 800 mg/hr

SZ

Answer 2

Ans. B 200 mg/hr

Amount of drug to maintain a steady state aka dosing rate = CL x C/F. F=1 (due to IV drug).

5mg/hr x 40 mg = 200 mg/hr

Question 3

When comparing a rapid release oral drug to a slow release oral drug which of the following is/are true? (May be more than 1 correct answer)

A. Slow release drug have higher levels at later times
B. Slow release drug have delayed peaks
C. Slow release drugs require less frequent administrations
D. Slow release drugs have lower peaks
E. Slow release drugs have higher peaks
F. Slow release drugs have longer half lives

SZ

Answer 3

Ans. A, B, C, D, are all correct