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Flashcards in Intro To Pharmacodynamics Deck (21):

When you plot drug dose arithmetically on the X-axis vs. drug effect on the y-axis you typically get what is called a ____________ curve



It is more common for a concentration-efffect curve to be presented by graphing the logarithm of the drug dose vs. the response in which case you get a _____________ curve



What goes on the X and Y axis of a logarithmic dose response curve?

X-axis = log drug dose

Y-axis = % max response


What goes on the X and Y axis of an arithmetical dose response curve?

X-axis = drug dose

Y-axis = response


Define Emax

The maximal effect that can be produced by the drug


Define ED50

AKA effective dose 50

This is the dose of drug that produces 50% of its maximal effect


What is a graded response on a dose response curve?

- answers the question how much?
- magnitude of a response varies continuously
- typically represents the mean value within a population or a single subject


Which of the following processes is studied by pharmacodynamics?
A) metabolis of the drug in the liver
B) excretion of the drug with urine
C) relaxation of bronchial SM by a drug
D) absorption of the drug fro the site of administration

C) Relaxation of bronchial SM by a drug


What is a quintal response?

- all or none, yes or no, binary responses
- answers the questions does the response occur or not? In how many?
- requires a pre-defined response (ex. Death, falling asleep, 10% reduction in BP)
- used to examine the frequency of a response within a large population


What is the therapeutic index?


**The higher the TI the safer the drug**


What is the therapeutic window?

The range of doses of a drug or of its concentration in a bodily system that provides for the safe and effective therapy


Differentiate between cumulative and non-cumulative quintal dose response curves

Non-cumulative = number or % of individuals responding at a dose of a drug and only at that dose -> bell shaped curve

Cumulative = number or % of individuals responding at a dose of a drug and at all doses lower than that dose -> sigmoidal curve


How do you differentiate between whether or not a dose response curve is quantal or graded?

You look at the Y-axis!

Quantal = Y axis with population response or fraction

Graded = effect such as BP or something


Cholestyramine is a bile acid-binding resin that is used for thetreatment of hypercholestrolemia. It absorbs aspirin, preventing its absorption in GI tract and antagonizing its effects. Cholestyramine is an example of:
A)pharmacologic competitive antagonist
B) physiologic antagonist
C) chemical antagonist
D) pharmacologic non-competitive antagonist
E) pharmacologic allosteric antagonist

C) Chemical antagonist


Define selectivity

A property of a drug determined by its affinities at various binding sites

- measured by comparing affinities of a drug to different receptors
- a more selective drug would affect fewer targets over a specific concentration range (therapeutic range)


T/F: Antagonists do not have intrinsic activity but agonists do



Explain pharmacologic antagonism

Action at the same receptor as endogenous ligands or agonist drugs


Explain chemical antagonism

When chemical antagonist makes the other drug unavailable


Explain physiologic antagonism

Occurs between endogenous pathways regulated by different receptors


A physician considers 2 medications, Drug A & B. Drug A is a partial agonist at a receptor. Drug B is a full agonist at the same receptor. Based on this info, which of the following is true regarding drugs A & B?
A. Drug A has a lower Kd than Drug B
A. Drug A has a lower Emax than Drug B
C. Drug A is less potent than Drug B
D. Drug A has a lower ED50 than Drug B
E. Drug A is less safe than Drug B

B. Drug A has a lower Emax than Drug B


In the absence of other drugs, pindolol causes an increase in HR by activating beta receptors. In the presence of highly effective beta receptor stimulants pindolol causes a decrease in HR. THerefore, pindolol should be classified as:
A. An antagonist
B. Full agonist
C. Partial agonist
D. Inverse agonist

C. Partial agonist