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BECOM II Exam 5 > Singh - Pharmacodynamics > Flashcards

Singh - Pharmacodynamics Flashcards

1
Q

2 key principles of pharmacodynamics

A
  1. dose of the drug is linked to the bodies response

2. drugs act through receptors (rely on kinetics)

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2
Q

drug receptor leading to response

A

can have response immediately (short lasting) or can have response that takes longer (longer lasting)

  • drug + receptor –> response
  • drug + receptor –> effector –> response
  • drug + receptor –> cell signaling –> response
  • drug inhibiting enzymes that metabolize compounds
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3
Q

how does interaction lead to biological response?

A

bind to more receptors –> more response and effect of drug

-linear up to 50% of response then becomes saturated

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4
Q

Kd - dissociation constant

A

[] of drug that occupies 50% of receptors

  • high affinity drug –> low Kd –> high potency
  • low affinity drug –> high Kd –> low potency
  • drug receptor interaction does not make product like enzyme/substrate complex
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5
Q

how does drug amount affect drug receptor binding curve?

A

helps determine the dose needed to have max response & help determine affinity

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6
Q

2 state model for receptor activation

A

receptor can be in active or inactive state - depends on the type of drug you give
-increase or decrease endogenous chemicals

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7
Q

agonist

A

binding to receptor making receptor active

-intrinsic activity of 1 - max response

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8
Q

antagonist

A

binds to inactive conformation of receptor –> no response

-intrinsic activity is 0

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9
Q

partial agonist

A

binds to active or inactive conformation equally

  • can have response but not to extent of agonist
  • used in treating addiction - prevent withdrawal
  • agonist on its own, antagonist when other drug is present
  • intrinsic activity <1
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10
Q

potency

A

dose of drug needed to produce 50% of response bc 50% of receptors are bound
-high potency –> less [] needed to bind those receptors

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11
Q

efficacy

A

max effect drug produces, not potency

  • clinical effectiveness deals with efficacy
  • want drug to have max efficacy
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12
Q

inverse agonist

A

drugs that act on constitutively active receptors bringing response to 0
-lower dose response curve - decrease basal activity of drugs

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13
Q

agonist vs. antagonist

A
  1. agonist - binding activates receptors either increasing or decreasing endogenous chemicals
  2. antagonist - no response when bound; receptor stays in inactive form; can lower agonist binding
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14
Q

competitive/reversible antagonist

A

max response possible when increasing dose of agonist (curve shifts to right when present)

  • still achieve max response, but with higher dose
  • Kd increases bc potency decreases
  • get response if agonist dose exceeds competitive antagonist
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15
Q

noncompetitive/irreversible antagonist

A
  • max response limited bc drug stays bound to receptor
  • lower response bc there is no receptor to occupy (lowers # of available receptors)
  • no change in Kd –> does not affect drug/receptor interaction
  • CAN get same response only if # of receptors needed for max response are available
  • dose needed to produce 50% of response dose not change
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16
Q

drug receptor interaction

A

drug binds to receptor then comes off due to non covalent interaction
-stays bound with covalent

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17
Q

chemical antagonism

A

binding of one drug to another making it unavailable to bind to receptor
-protamine sulfate (+ charge) neutralizes heparin excess

18
Q

physiological antagonism

A

2 drugs have opposite effects

  • want to stop drug response but cannot interfere with drug/receptor interaction
  • activate a receptor that produces opposite effects
  • ex. increase insulin with high glucose
19
Q

allosteric modulation

A

drug binds to receptor at different site than agonist binds

-benzodiazopine does not activate, but increases likelihood of GABA binding

20
Q

graded vs. quantal dose response curve

A
  1. graded - may not work due to studying only single patient (everyone is different)
  2. quantal - study dose response by looking at population
    - determine how many responded to different doses (ED50)
21
Q

therapeutic index/window

A

range at of doses at which it was effective but did not produce toxic effects

  • range of minimum effective dose to minimum toxic dose
  • LD or TD50 divided by ED50
22
Q

ED50

A

dose where half the population will respond to drug

23
Q

LD50

A

dose tested where half the animals will not survive

24
Q

CSF (certain safety factor)

A

estimate of safety of drug

25
Q

specificity vs. selectivity

A
  1. specificity - drug has one effect only
  2. selectivity - acting on more than one receptor when reaching high []
    - stay within therapeutic index to bind to specific receptors
26
Q

narrow therapeutic index (NTI)

A

small differences in dose may lead to toxic effects –> side effect when exceeding therapeutic window

  • ED50 is high, LD50 is low
  • need more drug to reach effect but is close to toxic dose
  • higher TI –> safer the drug
27
Q

intracellular receptors

A

nuclear receptors

  • ex. corticosteroids, lipid soluble
  • receptors exist in cytosol
  • can stimulate intracellular enzyme or alter gene transcription
  • no effect of drug if body metabolizes proteins
  • slower response for gene transcription but longer lasting
28
Q

plasma membrane bound receptors

A

ligand regulated transmembrane enzymes

  • ex. RTK
  • receptors in inactive state - need ligand binding for activation, dimerization, autophosphorylation, protein docking, and signaling to occur
  • another ex. GPCR
29
Q

cytokine receptors

A
  • no cytokine function without (ex. interleukins)
  • cytokine binding –> recruit JAK for phosphorylation –> docking and phosphorylation of STAT –> STAT dissociates, dimerizes, and goes to nucleus
  • response lasts long time even if you stop taking drug
30
Q

Ligand gates channel

A

drug binds to receptor opening it –> influx of Na+ and Ca++ depolarizing the cell –> signal by AP

  • fast response - rapid transmission
  • regulated by phosphorylation and endocytosis
  • synaptic plasticity –> learning and memory
31
Q

GABA and glycine

A

hyper polarize receptor by Cl- influx –> inhibition

-GABA in brain, glycine in spinal cord

32
Q

ACh, glutamate, serotonin 3

A

depolarize receptor through Na+ and Ca++ influx and K+ efflux –> excitatory

33
Q

GPCR

A

contain G protein –> multiple subunits

  • stimulate or inhibit effects of adenylate cyclase or PLC
  • GDP –> GTP to start signaling cascade –> activate adenylate cyclase, cAMP, PKA –> phosphorylation
  • GTP hydrolyzed back to GDP to stop signal
  • do NOT have to activate all receptors to get desired response
34
Q

cholera

A

bacteria cause continued activation of G protein by binding to GTP –> open Cl- channel through phosphorylation –> water follows Cl- –> diarrhea

35
Q

cannabinoids and opioids

A

stops pain signal to brain by inhibiting GPCR –> analgesia

36
Q

increased responsiveness

A
  • chronic disuse of receptor from antagonist can increase response when reexposed to agonist –> get rid of receptors then upregulate them
  • cutting neural signal –> denervation supersensitivity by up regulating receptors
37
Q

tolerance

A

decreased response to drug or hormone over time by downregulating receptors –> adaptation

  • increase dose to maintain response
  • ex. B-adrenergic bronchodilators and alpha-adrenergic vasoconstrictors
38
Q

mechanism of tolerance

A
  1. phosphorylation of receptor
  2. post receptor adaptation - desensitization –> uncouple G protein from receptor
  3. receptor down regulation - remove receptor on membrane
39
Q

therapeutic vs. side effect

A

deals with dose and how receptor signals

  • benefits and toxicity arise downstream of of separate receptors, which are both activated by the same drug due to low specificity
  • ex. 3 types of histamine receptors coupled to G protein –> produces different responses
  • ex. drug increasing ACh level activating autonomic and skeletal muscle
40
Q

receptor regulation

A

make receptor nonfunctional by removing G protein or another cytosolic protein, or by removing receptor from membrane

  • too much agonist –> can internalize receptor avoiding response
  • stop taking drug –> dephosphorylate receptor and travel back to membrane

BECOM II Exam 5 (24 decks)

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