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HDT > Pharmacodynamics > Flashcards

Pharmacodynamics Flashcards

1
Q

A clinician wants to calculate the therapeutic index of a drug, but only has information from a graded dose-response curve. Is this possible?

A

No, a quantal dose-response curve is needed to determine TI

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2
Q

A patient is prescribed two drugs. The effect of taking the two drugs together than each drug individually is much greater. What term describes this relationship?

A

Synergistic

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3
Q

What term describes a drug response that is not often observed?

A

Idiosyncratic

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4
Q

What is Kd?

A

Kd is the dose of a drug necessary for half of the receptors to be bound

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5
Q

What term describes a decreased response to a drug compared to most individuals?

A

Hyporeactive

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6
Q

True/False. An antagonist has no physiological effect.

A

True. An antagonist binds the receptor and prevents the agonist from binding, but has no physiologic effect itself.

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7
Q

The heart achieves a maximum effect to catecholamines when only 10% of its receptors are bound. The remaining 90% are termed what kind of receptors?

A

Spare receptors - that is, extra receptors that need not be bound in order to achieve maximal effect

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8
Q

A drug has a high Kd value. What does this indicate about the drug’s affinity for the receptor?

A

Kd and affinity are inversely related. A high Kd indicates low affinity for the receptor.

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9
Q

What is an antagonistic drug relationship?

A

The combined effect of two drugs is less than the sum of the effect of each individual drug

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10
Q

What is a chemical antagonist?

A

An antagonist that does not bind a receptor. It makes some drug/protein unavailable via ionic binding

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11
Q

What is drug potency?

A

The amount of drug necessary in order to produce a given effect

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12
Q

True/False. A partial agonist may out-compete a full agonist.

A

True. In this case, the effect will be diminished.

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13
Q

These types of bonds are responsible for drug-receptor interactions.

A

Weak ionic bonds

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14
Q

This type of agonist produces a lower response at full receptor occupancy.

A

Partial agonist - formation of active and inhibitory complexes

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15
Q

What term describes a drug relationship in which neither drug influences the effect of the other?

A

Additive/Summation

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16
Q

A competitive antagonist causes an increased in EC50, but maintains Emax. What is the effect of a non-competitive antagonists on EC50 and Emax?

A

Emax will decrease, but EC50 will remain the same assuming no spare receptors are present

17
Q

What formula is used to calculate therapeutic index?

A

TI = TD50/ED50

18
Q

What is the difference between receptor downregulation and tolerance?

A

Downregulation causes a decrease in the overall number of receptors due to prolonged exposure to an agonist. Tolerance is a gradual loss of response to the agonist after repeated exposure.

19
Q

This type of receptor regulation leads to increased sensitivity to an agonist.

A

Receptor upregulation

20
Q

What is the difference between hyperreactive and hypersensitivity in drug responsiveness?

A

Hyperreactivity is an increased drug response. Hypersensitivity refers to an immunologic or allergic reaction to a drug.

21
Q

What is Emax?

A

Emax is the greatest effect an agonist can produce at the the highest tolerable dose

22
Q

How do inverse agonists differ from antagonists?

A

Antagonists have no effect. Inverse agonists form inhibitory complexes that produce an effect below constitutive activity.

23
Q

What are the four primary roles of receptors?

A

Detect signals, determine dose-response, mediate actions of drugs, responsible for selectivity

24
Q

True/False. Partial and inverse agonists behave as competitive antagonists in the presence of a full agonist.

A

True

25
Q

These types of bonds are extremely strong and considered unbreakable.

A

Convalent bonds

26
Q

What information can be calculated using information from a quantal dose-response curve?

A

ED50 (dose at which 50% patients exhibit quantal effect), TD50 (toxic dose), LD50 (lethal dose), TI (therapeutic index)

27
Q

What is a functional/physiological antagonist?

A

An antagonist that binds to a different receptor in order to exert a response opposite that of the agonist (ex: glucocorticoids increase blood glucose, but insulin decreases blood glucose)

28
Q

Drug A has an EC50 of 5mg. Drug B has an EC50 of 12mg. Which drug is more potent?

A

Drug A - lower dose is necessary in order to produce an effect

29
Q

What receptor state is favored under normal conditions?

A

Inactive receptor state. A continuous equilibrium always exists between active and inactive receptor, but inactive is favored in the absence of an agonist.

30
Q

A graph shows a dose-response and drug binding curves. The dose-response curve has a lower Kd than the drug binding curve. What does this indicate?

A

The presence of spare receptors - the maximum effect of the drug is being achieved before all receptors are bound

31
Q

What protein is involved in the destruction of receptors by lysosomes?

A

Beta-arrestin

32
Q

An antagonist binds to a receptor. The agonist dose is increased, but no change in effect is observed. What type of antagonist is bound to the receptors?

A

Non-competitive antagonist - irreversible and cannot be overcome

33
Q

True/False. Receptors may be immediately desensitized following activation.

A

True. This prevents harmful continuous activation. The desensitization is only temporarily and may last milliseconds.

34
Q

What type of agonist produces maximal effects?

A

Full agonist

35
Q

What is the relationship between Emax and efficacy?

A

Higher Emax = better clinical efficacy

36
Q

A researcher wants to compare the Emax of three drugs using a dose-response curve. What type of curve is needed?

A

Graded dose-response curve

37
Q

What is tachyphylaxis?

A

A form of desensitization that occurs very rapidly

38
Q

What is the therapeutic window?

A

Dosage range between minimum effective dose and minimum toxic dose

HDT (36 decks)

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