Anxiolytics and Hypnotics Flashcards Preview

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Flashcards in Anxiolytics and Hypnotics Deck (49)
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1

What are the four main proteins that make up the GABA-A receptor?

GABA receptor protein
Benzodiazepine receptor protein
Barbiturate receptor protein
Chloride channel protein

2

What protein links the GABA receptor proteins and the benzodiazepine receptor protein?

GABA modulin

3

Name a competitive antagonist of the GABA receptor protein.

Biciculline

4

Name a competitive antagonist of the benzodiazepine receptor protein.

Flumazenil

5

What are the two main effects of benzodiazepines that facilitate GABA neurotransmission?

They facilitate the GABA-mediated opening of the chloride channel
They facilitate the binding of GABA to its receptor protein (increase the affinity of GABA to the GABA binding site) – this is reciprocated

6

What are the three main effects of barbiturates that facilitate GABA neurotransmission?

They enhance the normal physiological action of GABA
They enhance GABA binding to the GABA receptor protein
At higher concentrations, barbiturates can have a direct action on the chloride channel

7

What is the key difference in the mechanism of action of barbiturates and benzodiazepines?

Benzodiazepines – increase the frequency of chloride channel opening
Barbiturates – increase the duration of chloride channel opening

8

What is the relative difference in selectivity between barbiturates and benzodiazepines?

Barbiturates are LESS selective
This may explain why barbiturates induce surgical anaesthesia and why barbiturates are less safe than benzodiazepines
NOTE: barbiturates also reduce excitatory transmission

9

Name a barbiturate that is used as an anaesthetic.

Thiopentone- only barbiturates can be anaesthetics

10

Name three barbiturates and benzodiazepines that are used as anti-convulsants.

Diazepam
Clonazepam
Phenobarbital

11

Name a benzodiazepine that is used as an anti-spastic.

Diazepam

12

What are two other clinical uses of benzodiazepines and barbiturates?

Anxiolytics
Hypnotics

13

Define anxiolytic.

Remove anxiety without impairing mental or physical activity

14

Define sedative.

Reduce mental and physical activity without producing loss of consciousness

15

Define hypnotic.

Induces sleep

16

What structure is common to all barbiturates?

Six-membered ring (4 carbons and 2 nitrogens)

17

Barbiturates have been largely superseded by benzodiazepines. Which barbiturate is still used relatively commonly?

Amobarbital- for insomnia

18

What are the unwanted effects of barbiturates?

Low safety margin (overdose can be lethal)
Alters natural sleep (reduced REM)
Enzyme inducers
Potentiate the action of other CNS depressants (e.g. alcohol)
Tolerance
Dependence

19

What structure is common to all benzodiazepines?

They are tricyclic

20

What are the three key benzodiazepines?

Diazepam
Oxazepam
Temazepam

21

What is the difference between all the benzodiazepines that are in clinical use?

Their pharmacokinetics

22

Describe the administration of benzodiazepines.

Well absorbed per orally
Peak plasma concentration after about 1 hour

23

When would you give IV benzodiazepines?

Treatment of status epilepticus

24

Describe the distribution of benzodiazepines.

Bind strongly to plasma proteins
Highly lipid soluble

25

Describe the metabolism of benzodiazepines.

Extensively metabolised in the liver

26

Describe the excretion of benzodiazepines.

Excreted in the urine as glucuronide conjugates

27

Describe the duration of action of benzodiazepines.

Varies a lot
This allows classification as short-acting and long-acting benzodiazepines

28

What makes long-acting benzodiazepines have a long duration of action?

They have slower metabolism
They generate active metabolites

29

Name two short-acting benzodiazepines.

Oxazepam
Temazepam

30

Name a long-acting benzodiazepine.

Diazepam