Bryan - Pharmacology - Midterm 1 - Fall 2Nd Year

Front 1

Oldansetron is a 5-HT3 receptor antagonist used for severe vomiting. Bioavailability is usually 50-60% after an oral dose of this drug due to hepatic metabolism. The process that decreases bioavailablity of this drug after oral absorption but before the drug reaches systemic circulation is commonly referred to as:
A. Extraction Ratio
B. First Pass Effect
C. Minimum Effective Concentration
D. Cmax
E. Steady State

Back 1

B. First Pass Effect

Front 2

Your patient has impaired liver function which increases the bioavailability of Oldansetron to nearly 90%. Which of the following is the MOST LIKELY change in half-life that you would expect from this increase in bioavailability?
A. Half-life will increase because of decreased elimination
B. Half-life will remain the same because excretion rate is not effected
C. Half-life will decrease because of increased elimination
D. Half-life will increase because of higher plasma concentrations
E. None of the above

Back 2

A. Half-life will increase because of decreased elimination

Front 3

You wish to prevent emesis with metoclopramide, a dopamine antagonist. You find information in Plumb’s Veterinary Drug Handbook that indicates that doses above 870 mg/kg are toxic and doses below 1 mg/kg and not effective. The range of doses between the toxic dose and the ineffective dose is known as which of the following?
A. Therapeutic index
B. ED90
C. MEC
D. Toxic threshold
E. None of the above

Back 3

A. Therapeutic index

Front 4

The graph above shows the effects of two dosing regimens. Regimen A and Regimen B represent multiple dosing regimens that differ in dose but not in dosing interval.
Regimen A and B are most likely which type of administration?
A. oral
B. intravenous
C. enteral
D. intramuscular
E. subcutaneous

Back 4

B. intravenous

Front 5

Assume that the line marked with a D is the MEC and that you wish to reach effective concentrations quickly but avoid toxicity. Which of the following scenarios is the MOST reasonable way to achieve both goals? (4 points)
A. Follow regimen A
B. Begin with the dose in regimen B and switch to the dose in regimen A after two doses.
C. Use the dose in regimen B but double the dosing interval (longer dosing interval).
D. Give the dose in regimen A twice as often (shorter dosing interval).
E. Not possible to do both

Back 5

B. Begin with the dose in regimen B and switch to the dose in regimen A after two doses.

Front 6

If regimen B is toxic the line marked with a C is most likely which of the following?
A. MEC
B. Toxic Threshold
C. ED90
D. Therapeutic index
E. None of the above

Back 6

B. Toxic Threshold

Front 7

Regimen A is half the dose of regimen B with the same drug and dosing interval. Elimination rate is first order and each dosing interval is 24 hours. Which of the following dosage adjustments to regimen A will most likely produce the same steady state plasma concentration as regimen B?
A. Change the route of administration to oral route
B. Double the dosing interval to 48 hours
C. Reduce the dosing interval to 12 hours
D. Double the dose and the dosing interval to 48 hours
E. None of the above

Back 7

C. Reduce the dosing interval to 12 hours

Front 8

You realize that regimen B is producing symptomatic toxicity in your patient. You are at steady state and you wish to reduce your steady state plasma concentration to that achieved in regimen A. Which of the following will allow you to reach, and maintain, the steady state plasma concentration of regimen A in the least amount of time.
A. Reduce the dose by one-half
B. Double the dosing interval to 48 hours
C. Wait five half-lives and begin a 48 hour dosing interval
D. Wait two half-lives and resume treatment with half the dose (Regimen A)
E. None of the above

Back 8

D. Wait two half-lives and resume treatment with half the dose (Regimen A)

Front 9

What is a drug?

Back 9

any chemical agent which effects any biological process

Front 10

A chemical agent which effects any biological process describes...

Back 10

...a drug

Front 11

What the body does to a drug describes...

Back 11

...pharmacokinetics

Front 12

What the drug does to the body describes...

Back 12

...pharmacodynamics

Front 13

What are the 4 main ways to classify a drug?

Back 13

Mechanism of action
Chemical structure
Therapeutic use
Main effect

Front 14

What are some examples of enteral drug administration?

Back 14

Anything involving GI - oral, rectal, sublingual

Front 15

What are some examples of parenteral drug administration?

Back 15

Not involving GI - IM, IV, inhalation, IP, topical, subcut

Front 16

What are some examples of central drug administration?

Back 16

into brain or spinal cord - intrathecal; ICV

Front 17

Mach each parameter to the letter on the graph:
MEC
Duration
Tmax
Cmax
Toxic Threshold

Back 17

MEC - D
Duration - B
Tmax - C
Cmax - A
Toxic Threshold - E

Front 18

Match each parameter to the letter:
Plasma half-life
Kel (elimination constant)
CPo
97% of drug eliminated
AUC

Back 18

Plasma half-life - C
Kel (elimination constant) - E
CPo - A
97% of drug eliminated - B
AUC - D

Front 19

Does this graph depict first or zero order elimination?

Back 19

First order (semi-log scale)

Front 20

Adjusting the dosing via trial-and-error describes the ______________ approach to pharmacology.

Back 20

empirical

Front 21

Adjusting the dosing using mathematical models describes the ________________ approach to pharmacology.

Back 21

pharmacokinetic

Front 22

What are some examples of Phase I reactions?

Back 22

Oxidation, Reduction, hydrolysis, cyclization, and decyclization reactions

Front 23

What are some examples of Phase II reactions?

Back 23

Conjugation reactions

Front 24

T or F:
Phase II reactions typically inactivate a drug.

Back 24

True.

Front 25

What is a major enzyme of Phase I reactions?

Back 25

Cytochrome P450

Front 26

What are the 4 pharmacokinetic phases?

Back 26

ADME
Absorption
Distribution
Metabolism
Excretion

Front 27

Which of the 4 pharmacokinetic phases are involved in disposition?

Back 27

Distribution, Metabolism, and Excretion;
Disposition is everything that occurs after absorption

Front 28

Which of the 4 pharmacokinetic phases are involved in elimination?

Back 28

Metabolism and Excretion

Front 29

T or F:
A single compartment model would have a zero order elimination plot.

Back 29

False! It is first order.

Front 30

Irreversible conversion of a drug to another chemical entity describes...

Back 30

..METABOLISM

Front 31

Reversible transfer of a drug to and from the site of measurement describes...

Back 31

...DISTRIBUTION

Front 32

Process by which unchanged drug proceeds from the site of administration to the site of measurement describes...

Back 32

...ABSORPTION

Front 33

Irreversible loss of chemically unchanged drug describes...

Back 33

...EXCRETION

Front 34

The irreversible loss of drug from the site of measurement describes...

Back 34

...ELIMINATION

Front 35

The loss of drug as it passes through sites of elimination for the first time during the absorption process describes the...

Back 35

...FIRST PASS EFFECT

Front 36

Which pharmacokinetic phase is liked with the first pass effect?

Back 36

ABSORPTION

Front 37

Why do parenteral drugs with a high first pass effect have a smaller dose than the same drug taken orally?

Back 37

High first pass effect means that, if taken orally, the liver excretes/eliminates much of the drug while IV bypasses the liver.

Front 38

T or F:
Degree of hepatic impairment is inversely proportional to the extraction rate.

Back 38

True!
A bad liver can't extract drugs, thus the more damage the liver receives, the lower the extraction rate.

Front 39

Is hepatic function usually proportional or inversely proportional to a drug's half-life?

Back 39

Inversely proportional. A bad liver can't extract a drug, thus increasing the half life.

Front 40

What is the AUC proportional to?

Back 40

AUC = area under curve
AUC is proportional to bioavailability

Front 41

The longest dosing interval that still provides non-toxic peak plasma levels of drug while providing therapeutically effective trough plasma levels of drug describes...

Back 41

...MAXIMUM DOSING INTERVAL

Front 42

T or F:
Therapeutic window is synonymous with therapeutic index.

Back 42

False!
TI = LD50/ED50
TW = Highest safe Cp/Lowest effective Cp

Front 43

What factors are important in the calculation of a maximum dosing interval?

Back 43

half life of drug
target plasma concentration
therapeutic window

Front 44

You administer Odansetron, a 5-HT3 receptor agonist for severe vomiting. F=50-60% PO due to hepatic metabolism. Cmax is achieved at 1hr. 2 blood samples (arterial and venous) are taken at the same time and Odensetron plasma conc is measured in each.

Which of the following parameters can be calculated using BOTH plasma concentrations?

A. Extraction ratio
B. First pass effect
C. MEC
D. Cmax
E. Steady State

Back 44

A. Extraction ratio

Front 45

You administer Odansetron, a 5-HT3 receptor agonist for severe vomiting. F=50-60% PO due to hepatic metabolism. Cmax is achieved at 1hr. 2 blood samples (arterial and venous) are taken at the same time and Odensetron plasma conc is measured in each.

Your patient has impaired liver fxn which increases the bioavailability of the drug to ~90%. What is the MOST LIKELY change in the half-life?

A. increase due to decreased elimination
B. remain the same because excretion rate is unaffected
C. decrease due to increased elimination
D. increase due to higher Cp
E. none of the above

Back 45

A. half life increases due to decreased elimination

Front 46

Which of the following options is LEAST likely to produce Cp that will reach MEC but avoid toxic levels?

A. 2x dose in regimen A
B. 5x dose in regimen A
C. 2x dose in regimen B
D. 3x dose in regimen B
E. 4x dose in regimen A

Back 46

A. 2x dose in regimen A

Front 47

Which of the following options is likely to produce Cp that will reach toxic levels?

A. 2x the dose in regimen A
B. 5x the dose in regimen A
C. 2x the dose in regimen B
D. 3x the dose in regimen B
E. 4x the dose in regimen A

Back 47

D. 3x the dose in regimen B

Front 48

What are the units for clearance?

Back 48

volume/time

Front 49

What are the units for AUC?

Back 49

AUC = area under curve
mass/(time x volume) or mass/volume/time

Front 50

What are the units for Vd?

Back 50

volume