Transmitters and Receptors Flashcards Preview

MD1 Neuroscience > Transmitters and Receptors > Flashcards

Flashcards in Transmitters and Receptors Deck (53)
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1
Q

What is essential for drugs to do to act in the CNS?

A

Cross BBB

2
Q

Where do drugs interfere with chemical neurotransmission?

A
Synthesis
Storage
Release
Reuptake
Metabolism
Receptor
3
Q

Why isn’t the second line of cocaine as good as the first line?

A

NA depleted from first line

4
Q

What happens to motor nerves in epilepsy?

A

Excessive discharge

5
Q

What is the function of phenytoin?

A

Limits excitatory nerve action in epilepsy

6
Q

On what receptor does phenytoin have an action

A

Na channels on post-synaptic terminals

7
Q

What conformation must Na channels be in for phenytoin to work?

A

Only blocks Na channels when they’re open

8
Q

What is the challenge of administering phenytoin?

A

Firing that gives epileptic seizure one day is different to firing on another day
Means that phenytoin concentrations have to be in window

9
Q

What is the function of benzodiazepines?

A

Enhance GABA receptor activity > enhance inhibitory input in epilepsy

10
Q

What are the therapeutic outcomes of benzodiazepines in epilepsy?

A

Increased tonic inhibition

Decreased excessive discharge

11
Q

Describe GABA

A

Main inhibitory transmitter in CNS

  • GABA A - ligand-gated receptor
  • GABA B - GCPRs
12
Q

What does activating the neuropeptide Y (NPY) 1 receptor do?

A

Reduce anxiety

13
Q

What is the effect of antagonising the H1 receptor in the CNS?

A

Sedative

14
Q

20% of the population has a point mutation in the H1 receptor. How do these people respond to antihistamines?

A

Antihistamines make them hyperexcitable

15
Q

What are benzodiazepines used in?

A
Epilepsy
Anxiety
Sleep disorders
Premedication - sedation for medical procedures
Acute alcohol withdrawal
16
Q

What is insomnia?

A

Not being able to sleep when, or as well as one should

17
Q

Is insomnia a disease or a symptom?

A

Symptom - important to ID and treat underlying cause

18
Q

What is anxiety?

A

Manifestation of fear response in anticipatory manner, independent of external events

19
Q

What do beta-adrenoceptor antagonists do in anxiety?

A
Block physical signs
- Sweating
- Tremor
- Tachycardia
Little effect on CNS
20
Q

What are clinically recognised anxiety disorders?

A

Generalised anxiety states
Panic disorder
Phobias
Post-traumatic stress disorder

21
Q

What are generalised anxiety states?

A

Excessive anxiety lacking clear reason or focus

22
Q

What is panic disorder?

A

Overwhelming fear in association with somatic signs

23
Q

What are phobias?

A

Strong fears of specific things/situations

24
Q

What are the side effects of anxiolytics?

A

Degree of sedation

Drowsiness

25
Q

What are three classes of sedative, hypnotic and anxiolytic agents?

A

Benzodiazepines
Non-benzodiazepines
Barbiturates

26
Q

What are some non-benzodiazepines?

A

Beta-adrenoceptor antagonists
Buspiron
Zopiclone
Zolpidem

27
Q

Describe barbiturates

A

General depressants - produce all levels of CNS depression
Effective but
- Very toxic
- Low therapeutic index
- Induction of liver enzymes
- Abrupt withdrawal could cause death
Obsolete as anxiolytics/hypnotics - used now in controlled situations
- Anaesthetics for people who have prior history of being allergic to other anaesthetics
- Anticonvulsant

28
Q

Why are benzodiazepines safer to administer than barbiturates?

A

Wider therapeutic index

  • Less depression of respiratory and cardiovascular centres
  • Less dependence
  • Safe in overdose
29
Q

When aren’t benzodiazepines safe in overdose?

A

Additive effect when taking multiple benzodiazepines

30
Q

What responses do benzodiazepines elicit?

A
Sedation and induction of sleep
- Reduce time to fall asleep
- Increase duration of sleeep
Reduction of anxiety and aggression
Reduction of muscle tonee
- Anticonvulsant but reduces coordination
Obliterate memory
- Use as premedicant
31
Q

What effect do benzodiazepines have on neurons?

A

Interfere with GABAergic transmission

32
Q

Which receptor do benzodiazepines interact with?

A

GABA A only

33
Q

What do allosteric molecules modulate?

A

Orthosteric ligand affinity
Orthosteric ligand efficacy
Receptor activating level

34
Q

What drug class does diazepam belong to?

A

Benzodiazepines

35
Q

How does diazepam work?

A

Has specific binding sit on GABA A > increase in receptor affinity for GANA
Increases frequency of GABA receptor Cl channel opening

36
Q

What is the mechanism of action of benzodiazepines?

A

Bind regulatory site
- Increase GABA affinity for receptor
- Allosteric modulators
Enhance response to GABA
- Facilitate opening of Cl channels
- Increase frequency - no change in conductance/mean opening time
- Increase sensitivity of receptor with no change in maximum response

37
Q

What is the mechanism of action of barbiturates?

A

Bind GABA receptor > prolongs opening of channel

Increases sensitivity and maximum responses

38
Q

What are the advantages of allosteric modulators?

A

Ceiling of effect of inhibitors
- Increased therapeutic window
Positive modulation of endogenous agonist effect rather than continuous effect of exogenous agonist
- Physiological regulation continues
Great receptor subtype selectivity possible

39
Q

What is the pharmacodynamic profile of benzodiazepines?

A

Similar

40
Q

What are the unwanted effects of benzodiazepines?

A

Drowsiness
Confusion
Impaired coordination

41
Q

What are the disadvantages of benzodiazepines?

A
Interaction with
- Alcohol - acts on GABA receptors dysregulating them > synergistic
- Antihistamines
- Barbiturates
Long lasting hangover effects
Withdrawal symptoms
Dependence
42
Q

Can you develop tolerance to benzodiazepines?

A

Yes

43
Q

What are the signs of physical and psychological withdrawal from benzodiazepines?

A
Nausea
Tremor
Anxiety
Depression
Insomnia
44
Q

What determines the use of benzodiazepines?

A

Pharmacokinetic profile

  • Active orally but differ in duration of action
  • Generation of active and inactive metabolites
45
Q

What is potency?

A

Relative position of dose-effect curve along dose axis

46
Q

Does potency have clinical significance?

A

Not really

More potent drug not clinically superior

47
Q

When is low potency a disadvantage?

A

If dose so large that it’s awkward to administer

48
Q

Why are barbiturates more potent than benzodiazepines?

A

Increase frequency of Cl ion channel opening at GABA A receptor

49
Q

Why are barbiturates more efficacious than benzodiazepines?

A

Increase duration Cl channel is open

50
Q

Why are barbiturates more toxic than benzodiazepines in overdose?

A

Direct opening of Cl ion channel

51
Q

Describe zolpidem

A

Short-term treatment for insomnia
Non-benzodiazepine but binds to benzodiazepine site
Very little anticonvulsant activity
Short duration of action

52
Q

Describe zopiclone

A

Short-term treatment of insomnia

Non-benzodiazepine

53
Q

Describe buspirone

A
Antiolytic
Non-benzodiazepine
Partial agonist at 5HT 1A receptor
- Inhibitory autoreceptors regulating transmitter release
Slow onset
- Up to 2 weeks
Little dependence
Side effects
- Nausea
- Dizziness
- Headache

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