Principles of Pharmacology
Final Exam
March 24, 2005
This is a closed book exam. All questions are multiple
choice or short answer. Numerical computations should
not require a calculator (although you may use one).
Please keep your answers brief and legible. Write your
name on all pages.
Good Luck!
1. The graph below shows the results of experiments in which
contraction of a segment of guinea pig ileum was used to test the
effects of fentanyl and an opioid peptide, D-Ala, D-Leu Enkephalin
(DADL). The concentration-response curves for fentanyl or DADL
alone were identical. Each was then tested in the presence of 10-7M
drug X.
, What is the nature of the interaction between Fentanyl or
DADL and X? [3]
X is a competitive antagonist of both fentanyl and DADL
What is the Ka in each case? What does this tell you about the
two drugs? [8]
EC50 with antag − = [A]
1
EC50 without antag K
A
K ( fent ) = [A] ×
1 = 10−7 M × 1 = 10 −7 M × 1 = 2.04 × 10−9 M
A EC50 with antag − 5x10 − - 6 49
1 -7 1
EC50 without antag 10
− 1 = 10 −7 M × 1 = 2.5 × 10 −8 M
K ( DADL ) = 10 7 M ×
A 5x10 − - 7 4
10
-7
1
Different KA for X = different receptors for Fentanyl and DADL
2. You are asked to consult for a company developing a new
antiepileptic drug. It suppresses seizure activity in mice, and it has
the following in vitro properties:
Final Exam
March 24, 2005
This is a closed book exam. All questions are multiple
choice or short answer. Numerical computations should
not require a calculator (although you may use one).
Please keep your answers brief and legible. Write your
name on all pages.
Good Luck!
1. The graph below shows the results of experiments in which
contraction of a segment of guinea pig ileum was used to test the
effects of fentanyl and an opioid peptide, D-Ala, D-Leu Enkephalin
(DADL). The concentration-response curves for fentanyl or DADL
alone were identical. Each was then tested in the presence of 10-7M
drug X.
, What is the nature of the interaction between Fentanyl or
DADL and X? [3]
X is a competitive antagonist of both fentanyl and DADL
What is the Ka in each case? What does this tell you about the
two drugs? [8]
EC50 with antag − = [A]
1
EC50 without antag K
A
K ( fent ) = [A] ×
1 = 10−7 M × 1 = 10 −7 M × 1 = 2.04 × 10−9 M
A EC50 with antag − 5x10 − - 6 49
1 -7 1
EC50 without antag 10
− 1 = 10 −7 M × 1 = 2.5 × 10 −8 M
K ( DADL ) = 10 7 M ×
A 5x10 − - 7 4
10
-7
1
Different KA for X = different receptors for Fentanyl and DADL
2. You are asked to consult for a company developing a new
antiepileptic drug. It suppresses seizure activity in mice, and it has
the following in vitro properties:
