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pharmacology > pharmacodynamics III, lect 4 > Flashcards

pharmacodynamics III, lect 4 Flashcards

1
Q

what does a graded dose response curve tell us

A
  • potency (EC50) of drugs
  • indicate the Emax of a drug
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2
Q

what information do quantal dose response curves tell us

A
  • indicates the variability among individuals
  • used to dermine theraputic index and margin of safety
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3
Q

what does ED50 denote

A

the doses that produce the desired effect in 50% of the population studied

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4
Q

tyrosine kinases (TPK) activate what signaling pathway? What is the end point of TPK activation

A
  • activates the Ras/Raf pathway via Grb2
  • alter gene transcription
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5
Q

Give examples of proteins that use tyrosine kinase signaling

A
  • insulin
  • epidermal growth factor
  • platelet-derived growth factor
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6
Q

cytokines activate what signaling pathway?

A
  • activate JAK/STAT pathway
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7
Q

What are interferons and interleukins? What signaling mechanism do they activate in cells

A

cytokines: activate JAK/STAT pathway

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8
Q

what is the effector of G protein signaling mechanism

A

adenylyl cyclase (AC)

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9
Q

what does Gs and Gi do to levels of cAMP

A
  • Gs proteins increase production of cAMP
  • Gi proteins decrease cAMP production
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10
Q

what are the major intracellular targets for cAMP? What is cAMPs role?

A
  • protein kinases (PKA; PKC)
  • kinases are composed of 2 regulatory and 2 catalytic subunits
  • binding of cAMP releases catalytic subunits that phosphorylate substrates
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11
Q

what do Gq proteins activate?

A

PLC (phospholipase C)

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12
Q

what is the role of PLC

A

hydrolysis of PIP2 into IP3 and DAG

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13
Q

what is the function of IP3 and DAG

A
  • IP3: diffuses through cytoplasm and release Ca2+ from endoplasmic reticulum
  • DAG: activates protein kinase C (PKC)
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14
Q

M1 and M3 muscarinic receptors (ACh) activate what signaling pathway

A
  • polyphosphoinositide signaling
  • Gq proteins activate PLC
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15
Q

What effect does nitric oxide have on vascular smooth muscle

A

relaxation

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16
Q

pharmacokinetic tolerance

A

response decreases because the drug induces the enzymes responsible for its own metabolism; drug levels change

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17
Q

Why must warfarin be increased in patients taking barbituates or phenytoin (anti convulsant)? What type of interaction is this?

A
  • these drugs induce the enzymes that metabolism warfarin
  • pharmacokinetic interaction
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18
Q

pharmacodynamic tolerance

A
  • response decreases due to changes in receptor number of function (receptor down-regulation, desensitization); drug levels do not change
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19
Q

the continuous exposure to B-adrenergic agonists, such as occurs in the treatment of asthma with B2-receptor stimulants, results in receptor downregulation and decreased responsiveness

  • what type of tolerance is this?
A

pharmacodynamic tolerance

20
Q

physiologic tolerance

A

occurs when two agents with opposing physiologic effects are administered together

  • ex: histamine causes vasodilation; epinephrine causes vasoconstriction
21
Q

competitive tolerance

A

occurs when a receptor antagonist is administered with an agonist

  • ex: yohimbine- a natural treatment for impotence may block the hypotensive effect of clonidine or methyldopa
22
Q

tachyphylaxis

A

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

ex: amphetamines

23
Q

desensitization

A
  • a process that occurs rapidly
  • continuous exposure to an agonist results in the conversion of an ion channel to an altered state that remains closed
24
Q

succinylcholine, a drug that relaxes muscle during surgery, acts on the nicotinic acetylcholine receptor. Continuous exposure to this drug causes the ion channel to close. What is this an example of

A

desensitization

25
Q

a receptor coupling element is phosphorylated to an inactive form is an example of what mechanism of tolerance

A

desensitization

26
Q

down regulation

A

process of ligand-induced endocytosis and degradation of receptors

  • in general, agonists cause a down-regulation of receptors if chronically administered
27
Q

summation

A

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

28
Q

additive drug interaction

A

two drugs act by the same mechanism to produce the degree of effect expected by addition of thier individual actions

29
Q

Synergism drug interaction

A

drugs that produce similar effects through different mechanisms are administered simultaneously enhancing the response to either agent administered along. The effect is greater than the sum of the two individual agents alone

30
Q

how does administration of antagonist alter the response to an agonist that has become desensitized

A
  • up-regulation of receptors due to prolonged presence of antagonist
  • receptor endocytosis and degradation is reduced, increasing receptor number and the response to an agonist
31
Q

catecholamine sensitivity may be enhanced with general anesthetics. What is this an example of?

A

chemically induced supersensitivity

32
Q

how does surgically induced denervation super-sensitivity increase receptor number

A
  • presynaptic nerve has been surgically destroyed or lesioned
  • causes decrease in the amount of endogenous agonist and an increase in receptor number
  • creates super-sensitivity of postsynaptic receptors to agonist
33
Q

if two drugs displace one anotoher from plasma albumin binding sites, how does this enhance the response to one agent?

A
  • if a drug is displaced from a plasma protein-binding site, the response to it is intensified
  • if the drug is eliminated by first order kinetics, the duration of action is shortened
  • ex: the dose of warfarin must be decreased in patients taking phenytoin, an anticonvulsive agent, which will displace warfarin from plasma albumin
34
Q

what are acceptable drug adverse reactions

A
  • HA, fatigue, dizziness
  • upset GI
  • N/V
35
Q

give an example of an overextension of a theraputic effect as an adverse effect

A
  • **occurs if a toxic reaction is mediated by the same “receptor-effector” mechanism as the therapeutic effect
  • managed by using an appropriate dose
  • ex:
  • excessive fall in BP by an antihypertensive drug
  • excessive CNS depression via sedative hypnotics
  • hemorrhage via ASA, wafarin
  • hypoglycemia via insulin
36
Q

idiosyncratic drug response: pharmacogenetic disorders

A
  • abnormal response to a drug that is not immunologically mediated
  • likely genetically determined abnormalities of enzymes and receptors
37
Q

sensitization phase and effector phase of drug allergy

A
  • sensitization phase: abnormal response to an antigen resulting from previous exposure
  • effector phase: activation of immunologic mechanism
38
Q

drug allergy type 1: what type of response is it? What immunoglobin is involved?

A
  • anaphylactic reaction
  • response is immediate; inflammatory response
  • drug binds to IgE antibody, results in release of inflammatory mediators that cause injury
39
Q

type 1 drug allergy targets what tissues? What is the treatment?

A

target tissues

  1. Gi tract
  2. skin - urticaria
  3. lung -asthma
  4. vasculature: anaphylactic shock

Treatment

  • injection of epinephrine; corticosteroids
40
Q

What is type II drug allergy? What cell types are attacked? What immunoglobulins are involved

A
  • cytolytic or cytotoxic reaction
  • mediated by IgM and IgG
  • generates an attack complex that lyses RBC
41
Q

treatment for Type II drug allergy

A
  • often subside within months after drug withdrawal
  • immunosuppresive therapy is required only in unusually severe cases
42
Q

What are Type IV drug allergies?

A
  • cell mediated
  • mediated by sensitized T-cells which cause an inflammatory reaction
43
Q

What are Type III drug allergies? What are the target organs?

A
  • Arthus reaction
  • formation of antigen-antibody complexes
  • target organs: blood vessels; skin; joints; kidney
44
Q

what are the symptoms of Type III drug allergy

A
  • inflammatory response = serum sickness
  • symptoms: urticaria, arthritis, lymphadenopathy, fever
45
Q

treatment for type III drug allergy

A
  • last 6-12 days and subside once drug is stopped
  • corticosteroids are useful in treating severe cases

pharmacology (9 decks)

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