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Pharmacology > Principles Of Drug Therapy 1 > Flashcards

Principles Of Drug Therapy 1 Flashcards

1
Q

What are pharmacodynamics and pharmacokinetics?

A

What the drug does to the body

What the body does to the drug

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2
Q

Tylenol names?

A

N 4 hydroxyl phenyl acetamide

Acetaminophen

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3
Q

How does a drug exert its effects?

A

Via a receptor

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4
Q

How does epi affect BP?

A

Binds to a receptor
2nd mssgrs pass on and amplify the message
Inactive G binds, becomes active which leads to: Vasoconstriction, ⬆️HR and B
Via smooth m or heart cell

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5
Q

What does [G-active] depend on?

A

Rate of activation

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6
Q

How does a full agonist work, specifically?

A

It binds a receptor which causes a conf change which A+ the receptor

G protein linked receptors transduce the signal by A+ GTP binding proteins

Activated G proteins then A+ or I- other enz

End result: phys or pharm change (ex: HR, BP)

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7
Q

How does a partial agonist differ from a full agonist?

A

When bound to receptor it’s less effective, A+ G pro slower

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8
Q

How are the terms “full” and “partial” used?

A

Comparing different agonists at a given receptor. Not absolute quantities

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9
Q

How does an antagonist work?

A

It’s a molecule similar to agonist

Binds recep, but no conf change/no receptor activation

Has no effect by itself

Blocks action of agonist (endo or drug)

May cause neg effect if agonist is present

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10
Q

What is efficacy?

A

Relative term, compares effect of 2 or more drugs, no units

Full ago, eff = 1, partial < 1, anta = 0

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11
Q

What determines response to a drug?

A

Efficacy, potency, aff and dose

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12
Q

What does aff measure and what determines potency?

A

How long a drug binds to its receptor

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13
Q

If a drug is only bound for a short time how can we increase the reponse to the drug?

A

Increase chances of rebinding

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14
Q

How do you increase chances of rebinding?

A

Increasing the concentration

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15
Q

What does the activity of a receptor depend on?

A

How tight and how long the drug binds

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16
Q

What does Rmax depend on?

A

Drug efficiency

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17
Q

What does max rate represent?

A

The activity of the receptor when occupied by the agonist all the time

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18
Q

An increase in EC50?

A

Decrease in potency

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19
Q

What is EC50?

A

Dose that produces half the max effect

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20
Q

Features of drugs that bind less tightly?

A

Use higher dose for same effect on receptor
Have higher EC50 value
Less potent
If full ago, at high dose, Rmax will be same for each drug

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21
Q

With Rmax, what’s the deal with EC50?

A

It’s independent of efficacy

22
Q

With partial ago, what happens when you increase the conc?

A

The effect will increase but the max effect will be less than with full ago

23
Q

The effect at each conc depends on?

A

Efficacy and potency

24
Q

If an antagonist binds tightly?

A

Low EC50, 0 efficacy

25
Q

What happens if comp anta is in presence of ago?

A

Higher conc of ago is needed for response

EC50 is increased

26
Q

What happens if you increase the anta conc?

A

Ago dose response curve shifts right, higher dose of anta (fixed for each curve), further shift

More anta, more ago needed for same effect

27
Q

When does anta have an effect?

A

Only in presence of ago

28
Q

What is the EC50 of the anta dependent on? Why?

A

The ago conc

Because they compete

29
Q

In the absence of full ago, partial ago does what?

A

Stimulates the process by activating the receptor with lower efficacy

30
Q

In the presence of full ago, partial does….?

A

Displaces/antagonizes full ago and since it has lower efficacy, the net effect can be diminished

31
Q

Re: eff, partial ago acts like?

A

Like a partial anta

Efficacy between 0 and 1

32
Q

What does increasing the # of receptors do?

A

Increase the response

But no changes in eff, potency or drug dose

33
Q

What happens with irr anta?

A

Prob that ago binds to any one receptor is unchanged

of receptors decreases

Prob that ago will dissc is unchanged

Can allow 100% inhibition

Response to ago only after new receptors are made

34
Q

Does an irr anta stay bound?

A

Yes even after free drug is out of system

Never leaves binding site

So ago and anta don’t compete

35
Q

When do anta and ago not compete?

A

When there’s no free anta

In this case the % occupancy of free receptors is not affected by loss of receptors

36
Q

Adding more anta leads to?

A

Blockade of all receptors

37
Q

What’s the effect of an irr non comp anta on response to ago?

A

The potency (E50) of ago is unaffected because of no competition for binding

Response to ago is lessened at all doses of ago so Rmax is decreased which looks like decrease in efficacy

38
Q

What are some features of receptor #s?

A

Variation in response with time
Tolerance
Tachyphylaxis (appearance of a decrease in response after repetitive administration)
Variation in response w/ diff ppl

39
Q

Response w/ lots of receptors?

A

Will increase with more receptors until a ceiling is hit and no extra effect

40
Q

Consequences of limiting receptors?

A

Max response b4 all receptors are filled (w/ decrease in EC50)

Low doses of irr anta may not decrease Rmax

Due to spare receptors

41
Q

How is # of receptors regulated?

A

Persistent A+ of receptors may lead to down reg

Short term phosphorylation of receptors

Decrease in #s over longer term

42
Q

Prolonged blockade of receptors can lead to?

A

Increase in receptor #

Stimulation of adverse effects with abrupt withdrawal

Tolerance???

43
Q

Examples of pharmacodynamic tolerance w/ opioids and benzodiazepines?

A

Opioids: tolerance for all actions except miosis and constipation, DR curve to right with large shift, increase dose to maintain analgesia

Benzo: tolerance to antiepileptic effect

44
Q

What does potency relate to?

A

Dose required to get a given effect

More potent drug has lower EC50

45
Q

Effects of antas?

A

Comp anta:
DR curve for ago R
Ago acts as if less potent but raising dose can restore effect
No change in Rmax

Irr non comp anta:
Decrease max effect of drug
Drug acts like less efficacious 
No R shift
Potency unaffected
46
Q

Ppl drug diff?

A

Diff responses, diff EC50s

Measured response = quantal

47
Q

What’s ED50?

A

Dose at which 50% of population has defined response

48
Q

Features of sigmoidal quantal DR curve?

A

Reflects variation in response in pop, so can have diff slopes

Steeper slope

Non log plot also sigmoidal

Steepness different for each drug effect examined

49
Q

EC50 differs due to?

A

Receptor density

Diff isoforms of expressed receptors

50
Q

DR curve features?

A

Each drug has one
Each might have diff ED50 for each effect
Can define therapeutic range/window

51
Q

TD50 and LD50?

A

TD50 = toxic effect LD = lethal effect

52
Q

Therapeutic Index (TI)?

A

LD50/ED50 (Ratios may be diff for 20 or 80)

Ratio of lowest TD50 and ED50 for desired effect

Higher the TI, lower risk of seeing toxic effect

Alone not a good predictor of drug safety, need more info on slope of curve

Pharmacology (7 decks)

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