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Drugs, Brain and Behaviour > Pharmacodynamics > Flashcards

Pharmacodynamics Flashcards

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The Brain flashcards
1
Q

What is pharmacodynamics?

A

when a drug binds to a receptor causing intracellular activity or enters the receptor altering gene expression

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2
Q

What are agonists?

A

drugs that bind to receptors and cause a biological response; they have intrinsic activity

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3
Q

What do drug-receptor interactions involve?

A 
usually weak (covalent) bonds
constant binding and dissociation
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4
Q

What is drug affinity?

A

the rate of dissociation

high affinity = low rate of dissociation

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5
Q

What are the principles of drug-receptor interactions?

A

magnitude of drug effect is proportional to the number of receptors occupied
up to a point, more drug = more effect

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6
Q

What is the law of mass action?

A

a drug produces its maximal effect when all receptors are occupied

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7
Q

What is the effective dose 50?

A

the dose that produces a response in 50% of subjects

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8
Q

What is the toxic dose 50?

A

the dose that produces a toxic effect in 50% of subjects

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9
Q

What is the lethal dose 50?

A

the dose that kills 50% of subjects

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10
Q

What is the therapeutic index?

A

TD50/ED50

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11
Q

What is the safety margin?

A

LD50 - ED50

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12
Q

What is drug potency?

A

how much drug is needed to produce an effect

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13
Q

Why does drug potency differ?

A

drug access to the brain

drug affinity; how efficiently it binds to a receptor

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14
Q

What is drug efficacy?

A

the maximum effect of a drug

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15
Q

Why does drug efficacy differ?

A

the mechanism by which they act at a receptor

amount of intrinsic activity at the receptor once bound

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16
Q

What is an antagonist?

A

drugs which bind to receptors and have no intrinsic activity, block the effect of agonists or endogenous ligands

17
Q

What is a competitive antagonist?

A

a drug that competes with an agonist for receptor sites
maximum effect remains the same but potency is reduced
increased amounts of agonist are required for the same effect

18
Q

What is a non-competitive antagonist?

A

reduces the effect of an agonist but does not compete for binding sites
binds to an inactive part of the receptor and interrupts intracellular processes
maximum effect and potency are reduced

19
Q

What is an irreversible antagonist?

A

a drug which forms long-lasting bonds with a receptor

recovery is only possible by synthesis of new receptors

20
Q

What is a partial agonist?

A

act as an agonist or an antagonist depending on the local concentration of other agonists
maximum effect remains the same but potency is reduced

21
Q

What is tolerance?

A

when a drug effect because smaller after administration

22
Q

How does overdose relate to tolerance?

A

tolerance build up means that the effective dose increases, making the margin of safety smaller, this dose is too close to the toxic/fatal dose

23
Q

What is acute tolerance?

A

tachyphylaxis; drug effect decreases rapidly, within a single session

24
Q

What is protracted tolerance?

A

drug effect decreases with repeated administration e.g. alcoholism

25
Q

What is cross-tolerance?

A

when the effect of a drug decreases after administration of another drug e.g. regular alcohol drinkers are less effected by barbiturates

26
Q

How does tolerance influence homeostasis?

A

tolerance reflects homeostatic adaptations to drugs; can be pharmacokinetic or metabolic e.g. chronic drinkers have increased levels of alcohol dehydrogenase

27
Q

What are the mechanisms of tolerance?

A

homeostatic adaptations
behavioural learning
conditioning
receptor signalling

28
Q

What is dependence?

A

when tolerance has developed, ceasing drug use will cause withdrawal effects opposite to the action of the drug abused

29
Q

What is sensitisation?

A

when a drug effect gets bigger after administration

30
Q

When can sensitisation occur?

A

in a chronic drinker, alcohol can cause cirrhosis of the liver, meaning alcohol is not metabolised as efficiently so more reaches the brain

31
Q

How does affinity affect a drugs action?

A

high affinity = longer binding time

does not determine the maximum effect of a drug

Drugs, Brain and Behaviour (6 decks)

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