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Pharmacology > Pharmacodynamics III > Flashcards

Pharmacodynamics III Flashcards

1
Q

What kind of curves provide information about potency/EC50 of drugs?

A

Graded curves

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2
Q

What are Quantal dose response curves used for?

A

To indicate variability/frequency among individuals, and to determine the therapeutic index and margin of safety

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3
Q

What is tolerance?

A

When a response to a drug diminishes with repeated or chronic administration

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4
Q

What is pharmacokinetic tolerance? Do drug levels change? What are some examples?

A

Response decreases because the enzymes that metabolize the drug are induced; drug levels change

Ex: barbiturates, ethanol, warfarin

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5
Q

What is pharmacodynamic tolerance? Do drug levels change? What is an example?

A

Response decreases due to changes in receptor number or function (desensitization; receptor down regulation); drug levels do not change

Ex) Chronic exposure to B adrenergic agonists (asthma) results in down regulation and decreased response

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6
Q

What is physiologic tolerance? What is an example?

A

Occurs when two agents with opposing physiological effects are administered together

Ex: histamine a vasodilator and epinephrine a vasoconstrictor

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7
Q

What is competitive tolerance?

A

Occurs when a receptor antagonist is administered with an agonist

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8
Q

What is tachyphylaxis?

A

Very rapid development of tolerance following repeated dose over short period of time

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9
Q

What is the mechanism through which ion channel desensitization occurs? What is an example?

A

Continuous exposure to an agonist results in the conversion of an ion channel to an altered state that remains closed

Ex: succinylcholine on the nicotinic acetylcholine receptor

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10
Q

What is the mechanism through which G protein desensitization occurs? What is an example?

A

Receptor coupling effector is phosphorylated to an inactive form (GRK, beta-arrestin)

Ex: beta-receptor

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11
Q

What is down regulation?

A

Process of ligand-induced endocytosis and degradation of receptors. In general, agonist cause down regulation of receptors if chronically administered.

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12
Q

What factors influence variability in response?

A
  1. Differences in absorption of drug (age, sex, metabolism)
  2. Differences in concentration of endogenous ligands
  3. Differences in number or function of receptors (down and up regulation)
  4. Differences in post receptor effects
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13
Q

What is summation?

A

Two drugs elicit a similar response through different mechanisms and the effect of combining the drugs equals the sum of the two individual effects

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14
Q

What is the difference between summation and additive?

A

Summation- two drugs act through different mechanisms

Additive- two drugs act through the same mechanism

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15
Q

What is synergism? Give an example

A

Drugs that produce similar effects through different mechanisms are administered simultaneously enhancing the response to either agent administered alone.

Ex: depression of CNS produced by diazepam plus ethanol; act on GABA receptor but at different sites

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16
Q

Is the effect of synergism greater than or less than the sum of the two individual agents alone?

A

Greater than the sum

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17
Q

What five things can cause enhanced drug effects/super sensitivity?

A
  1. Administration of antagonist
  2. Chemically induced
  3. Denervation super-sensitivity
  4. Deficiency of metabolic enzymes
  5. Competition for plasma binding sites
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18
Q

How can administration of antagonist produce a supersensitive response?

A

Up regulation due to prolonged presence of antagonist

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19
Q

How can a supersensitive response be chemically induced?

A

Catecholamine sensitivity may be enhanced with general anesthetics

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20
Q

How can denervation super-sensitivity produce a supersensitive response?

A

Develops when the synaptic nerve has been destroyed, resulting in a loss of endogenous ligand and an increase in receptors

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21
Q

How can a deficiency of metabolic enzymes produce a supersensitive response? What is an example?

A

Decrease in number or activity of metabolic enzymes that would normally degrade the drug
Succinylcholine in patients with low cholinesterase

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22
Q

How can competition for plasma binding sites produce an enhanced response? What is an example?

A

Drugs may displace one another from plasma albumin binding sites
If a drug is displaced, the response to that drug is intensified
If the drug is eliminated, the duration of action is shortened

Ex: warfarin must be decreased in patient taking phenytoin, an anticonvulsant

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23
Q

Adverse effects from multiple receptor activation is due to what?

A

A drug acting on a different type of receptor than that responsible for the desired effect

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24
Q

Adverse effects mediated by the same mechanism as the therapeutic effect are termed what?

A

Overextension of the therapeutic effect

25
Q

Overextension-type toxicity from sedative hypnotics can lead to what?

A

Excessive CNS depression

26
Q

Overextension-type toxicity from antiarrhythmic agents can lead to what?

A

Arrhythmias

27
Q

Overextension-type toxicity from insulin can lead to what?

A

Hypoglycemia

28
Q

Overextension-type toxicity from aspirin, warfarin, or heparin can lead to what?

A

Hemorrhage

29
Q

Organ directed toxicity from aminoglycoside antibiotics can lead to what?

A

Renal and ototoxicity

30
Q

Organ directed toxicity from acetaminophen can lead to what?

A

Hepatotoxicity

31
Q

Organ directed toxicity from tetracycline can lead to what?

A

Teeth discoloration, retardation of bone growth

32
Q

Organ directed toxicity from thalidomine, methotrexate, phenytoin, and warfarin can lead to what?

A

Teratogenic effects

33
Q

Organ directed toxicity from acetaminophen and isoniazid hepatotoxicity can lead to what?

A

Metabolite toxicity

34
Q

What is a drug idiosyncrasy?

A

An abnormal response to a drug that is not immunologically mediated
Usually genetically determined (mutations)

35
Q

What is an example of a drug idiosyncrasy?

A

Apnea a caused by succinylcholine in patients with abnormal serum cholinesterase

36
Q

Explain the mechanism of hypersensitivity reactions.

A

Abnormal response to an antigen resulting from previous exposure (sensitization phase)

Activates an immunologic mechanism (effector phase)

Being small molecules, most drugs by themselves are not immunogenic. They must bind to a macromolecule or alter the structure of a macromolecule to evoke the production of antibodies.

37
Q

Which type of drug allergies are antibody mediated?

A

Types I-III

38
Q

Which types of drug allergies are cell mediated?

A

Type IV

39
Q

In a type I drug allergy will the response be immediate or slow acting?

A

Response is immediate

40
Q

In a type I drug allergy what type of antibody will the drug bind to?

A

IgE antibody

41
Q

What are the target tissues and symptoms of a type I drug allergy?

A

GI tract
Skin - uticaria (hives)
Lung - asthma
Vasculature - anaphylactic shock

42
Q

What is an example of a drug that causes a type I-III drug allergy?

A

Penicillin

43
Q

In a type II drug allergy what type of antibody will the drug bind to?

A

IgM or IgG antibody

44
Q

A type II drug allergy is what type of reaction?

A

Cytolytic or cytotoxic reaction

45
Q

What are the major target for type II drug allergies?

A

Red blood cells

46
Q

A type III drug allergy is what type of reaction?

A

Arthrus reaction

47
Q

What are the major targets for a type III drug allergy?

A

Blood vessels, skin, joints*, kidney

48
Q

What type of drug allergy causes an inflammatory response called serum sickness?

A

Type III

49
Q

What are the symptoms of a type III drug allergy?

A

ARTHRITIS, uticaria, lymphadenopathy, and fever

50
Q

A type IV drug allergy is what type of reaction?

A

Delayed hypersensitivity reaction

51
Q

A type IV drug allergy is mediated by what type of cells?

A

T cells

52
Q

What is the main symptom of a type IV drug allergy

A

Contact dermatitis

53
Q

What is placebo toxicity?

A

Subjective effects such as stomach upset, insomnia, and sedation

54
Q

How would you treat a type 1 drug allergy?

A

IV or IM injection of epinephrine; corticosteroids

55
Q

What type of drug reaction is SJS and erythema multiforme?

A

Type IV- delayed hypersensitivity reactions

56
Q

What type of drug reaction is penicillin induced hemolytic anemia?

A

Type II- Cytolytic/Cytotoxic reactions

57
Q

What kind of drugs are commonly known to be associated with drug allergies?

A

Penicillin, heparin

58
Q

Smoking and charbroiled foods can increase the metabolism of many drugs including warfarin. What is this type of tolerance called?

  1. Pharmacodynamic
  2. Cross
  3. Physiological
  4. Pharmacokinetic
  5. Competitive
A

Pharmacokinetic

Pharmacology (25 decks)

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