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Pharmacology basic knowledge > L3 antagonist > Flashcards

L3 antagonist Flashcards

1
Q

What is an antagonist?

A

A drug which blocks the response to an agonist

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2
Q

What are the two types of dose-response relationships?

A
  • Graded
  • Quantal
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3
Q

What characterizes a competitive antagonist?

A

Binds reversibly to the receptor and can be overcome by increased agonist concentration

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4
Q

What is the relationship between agonist potency and EC50?

A

The higher the potency, the lower the EC50

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5
Q

Define ‘quantal’ in the context of dose-response curves.

A

A dose-response relationship that reflects population responses

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6
Q

What are the general classes of antagonists?

A
  • Chemical
  • Physiological
  • Pharmacological
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7
Q

What is a chemical antagonist?

A

Binds two agents to render an active drug inactive

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8
Q

What is a physiological antagonist?

A

Two agents with opposite effects that cancel each other out

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9
Q

What is pharmacological antagonism?

A

Binds to receptor and blocks the normal action of an agonist

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10
Q

What effect do pure antagonists have on efficacy?

A

They do not cause any ‘action’ by binding to the receptor

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11
Q

What happens to the agonist-response curve in the presence of a competitive antagonist?

A

It causes a parallel shift to the right

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12
Q

What is the Schild equation used for?

A

Quantifying antagonism

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13
Q

What does pA2 value represent?

A

The negative logarithm of the molar concentration of antagonist required to produce an agonist dose ratio equal to 2

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14
Q

True or False: Irreversible antagonists can be overcome by increasing the concentration of an agonist.

A

False

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15
Q

What is the therapeutic index (TI)?

A

The ratio of TD50 or LD50 to ED50

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16
Q

What are the implications for the clinician regarding antagonist inhibition?

A

Depends on the concentration of the competing agonist and the antagonist’s concentration

17
Q

Fill in the blank: Full agonists have ______ efficacy.

A

high

18
Q

Fill in the blank: Partial agonists have ______ efficacy.

A

lower

19
Q

What is the effect of irreversible antagonists on the agonist-response curve?

A

Reduces maximal response and causes a parallel shift to the right

20
Q

What are examples of competitive antagonists?

A
  • Cimetidine at the H2 receptor
  • Tamoxifen at the estrogen receptor
21
Q

What are examples of irreversible antagonists?

A
  • Phenoxybenzamine at the a1 adrenoceptor
22
Q

What is the role of spare receptors?

A

Allow full response at sub-saturating agonist concentrations

23
Q

What is the significance of the therapeutic window?

A

Defines the dose range between therapeutic and toxic effects

Pharmacology basic knowledge (10 decks)

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