Lecture 15- Pharmacodynamic receptor theory Flashcards

(43 cards)

1
Q

drug targets include

A
  • Mainly GPCR
  • Ion channels
  • Kinases
  • Few nuclear receptors
  • Enzymes
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2
Q
A
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3
Q

drugs are

A

ligands for a receptor

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4
Q

how many GOCRs in man

A

800

  • 400 olfactory receptors e.g. sigh and smell
  • non-olfactory receptors
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5
Q

olfactory receptors are regulated by

A

light, odorants, hormones, NT and ions

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6
Q

what is critical in determining drug action

A

the concentration of drug moelcule around receptors

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7
Q

uM

A

10-6M

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8
Q

nM

A

10-9M

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9
Q

pM

A

10-12M

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10
Q

how many moles in a uM

A

100,000

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11
Q

most drugs bind to receptors in an

A

irreversible manner

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12
Q

drugs either act

A

as antagonists

as agonists

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13
Q

antagonists

A

block the binding of endogenous agonists

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14
Q

agonists

A

activate the receptor

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15
Q

to bind to a receptor (as an antagonist or agonist)

A

drug must have affinity

higher affinity= stronger binding

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16
Q

mode of action: antagonists

A
  • goverened by affinity
  • no intrinisc efficacy
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17
Q

intrinsic efficacy and antagonists

A

wont switch the receptor to active state

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18
Q

mode of action of agonists

A

have both affinity and intrinsic efficacy

19
Q

ligands bind tor eceptor due to

A

affinity

  • both antagonists and agonists
20
Q

intrinsic efficacy means that

A

ligand activates rthe recpetor and causes a response inside the cell

21
Q

pharmacology efficacy

A

if drug causes blood vessel to dilate

22
Q

clinical efficacy

A

if the drug actually lowes BP

23
Q

lock and key analogy of antaognists and agonists

A

both bind due to affinity

Agonists- cause activation of receptor and repsosne inside cell (intrinsic efficacy)

Antagonists- have affinity but do not have intirnsic efficacy (block response of effector)

24
Q

two ways the effect of drug concnenreation can be looked at

A

1) binding to the receptor
2) functional response

25
how do we measure binding
* Many cells/ many receptors e.g. 10,000- 1000,0000 receptors per cell * Incubate radioligand and receptors —\> binding * Low ligand conc= low binding * High ligand conc= high ligand binding
26
quantifying binding
using conentration of drug vs proption of bound receptors graph
27
Bmax
the maximum binding capacity - gives info about receptor no.
28
Kd
dissociation constat - concentration of ligand needed to occupy 50% of available receptors
29
the lower the Kd
the higher the affinity the ligand has for the receptor
30
high affinity (low kd) allows
binding at low conc of ligand
31
to treat morphine or heroin overdose
* **Naloxone** used to treat overdose : * High affinity antagonist of u-opioid receptors * Outcompetes opioid
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nalaxone
has a higher affinity for the receptor than morphine or heroine (antagonist)
33
[drug] on graph usually presented
in logarithmic and not linear way
34
Log10 of a no.
power by which 10 has to be raised to get that number e.g. 0.001 or 1mM = 10-3
35
scale on a logarithmic graph for receptor binding
between -11 and -7 ( ligand concentration at receptors usually \<\<1M
36
response by a cell requries
drug efficacy - onyl agonists give this
37
conenctration reponse curve
graphs which plot receptor binding usually use the sigmoidal log curve
38
Emax
maximum effect evoked by a ligand (intrinsic activity)
39
EC50
effecitve concetration giving 50% of the maximal response
40
EC50 is a measure of agonist
Potency depends on both affintiy and intrinsic efficacy
41
concentration is the
known concentration of drug at site of action e.g. in cells and tissue * usually unknown* * so we use **DOSE***
42
dose
concentrationa t site of action generally unknown however we can quanitify have much of a drug a patient is getting in mg or mg/kg
43