Transmitters and Receptors Flashcards Preview

MD1 Neuroscience > Transmitters and Receptors > Flashcards

Flashcards in Transmitters and Receptors Deck (53):
1

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

Cross BBB

2

Where do drugs interfere with chemical neurotransmission?

Synthesis
Storage
Release
Reuptake
Metabolism
Receptor

3

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

NA depleted from first line

4

What happens to motor nerves in epilepsy?

Excessive discharge

5

What is the function of phenytoin?

Limits excitatory nerve action in epilepsy

6

On what receptor does phenytoin have an action

Na channels on post-synaptic terminals

7

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

Only blocks Na channels when they're open

8

What is the challenge of administering phenytoin?

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

9

What is the function of benzodiazepines?

Enhance GABA receptor activity > enhance inhibitory input in epilepsy

10

What are the therapeutic outcomes of benzodiazepines in epilepsy?

Increased tonic inhibition
Decreased excessive discharge

11

Describe GABA

Main inhibitory transmitter in CNS
- GABA A - ligand-gated receptor
- GABA B - GCPRs

12

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

Reduce anxiety

13

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

Sedative

14

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

Antihistamines make them hyperexcitable

15

What are benzodiazepines used in?

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

16

What is insomnia?

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

17

Is insomnia a disease or a symptom?

Symptom - important to ID and treat underlying cause

18

What is anxiety?

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

19

What do beta-adrenoceptor antagonists do in anxiety?

Block physical signs
- Sweating
- Tremor
- Tachycardia
Little effect on CNS

20

What are clinically recognised anxiety disorders?

Generalised anxiety states
Panic disorder
Phobias
Post-traumatic stress disorder

21

What are generalised anxiety states?

Excessive anxiety lacking clear reason or focus

22

What is panic disorder?

Overwhelming fear in association with somatic signs

23

What are phobias?

Strong fears of specific things/situations

24

What are the side effects of anxiolytics?

Degree of sedation
Drowsiness

25

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

Benzodiazepines
Non-benzodiazepines
Barbiturates

26

What are some non-benzodiazepines?

Beta-adrenoceptor antagonists
Buspiron
Zopiclone
Zolpidem

27

Describe barbiturates

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

Why are benzodiazepines safer to administer than barbiturates?

Wider therapeutic index
- Less depression of respiratory and cardiovascular centres
- Less dependence
- Safe in overdose

29

When aren't benzodiazepines safe in overdose?

Additive effect when taking multiple benzodiazepines

30

What responses do benzodiazepines elicit?

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

What effect do benzodiazepines have on neurons?

Interfere with GABAergic transmission

32

Which receptor do benzodiazepines interact with?

GABA A only

33

What do allosteric molecules modulate?

Orthosteric ligand affinity
Orthosteric ligand efficacy
Receptor activating level

34

What drug class does diazepam belong to?

Benzodiazepines

35

How does diazepam work?

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

36

What is the mechanism of action of benzodiazepines?

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

What is the mechanism of action of barbiturates?

Bind GABA receptor > prolongs opening of channel
Increases sensitivity and maximum responses

38

What are the advantages of allosteric modulators?

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

What is the pharmacodynamic profile of benzodiazepines?

Similar

40

What are the unwanted effects of benzodiazepines?

Drowsiness
Confusion
Impaired coordination

41

What are the disadvantages of benzodiazepines?

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

42

Can you develop tolerance to benzodiazepines?

Yes

43

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

Nausea
Tremor
Anxiety
Depression
Insomnia

44

What determines the use of benzodiazepines?

Pharmacokinetic profile
- Active orally but differ in duration of action
- Generation of active and inactive metabolites

45

What is potency?

Relative position of dose-effect curve along dose axis

46

Does potency have clinical significance?

Not really
More potent drug not clinically superior

47

When is low potency a disadvantage?

If dose so large that it's awkward to administer

48

Why are barbiturates more potent than benzodiazepines?

Increase frequency of Cl ion channel opening at GABA A receptor

49

Why are barbiturates more efficacious than benzodiazepines?

Increase duration Cl channel is open

50

Why are barbiturates more toxic than benzodiazepines in overdose?

Direct opening of Cl ion channel

51

Describe zolpidem

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

52

Describe zopiclone

Short-term treatment of insomnia
Non-benzodiazepine

53

Describe buspirone

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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