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Flashcards in Transmitters and receptors Deck (30):
1

What must drugs do in order to access the CNS?

Cross the blood brain barrier

2

What effect do drugs that cross the blood brain barrier have?

Interfere with chemical neurotransmission within CNS

3

Which processes of chemical neurotransmission can drugs that enter the CNS affect?

Synthesis

Storage

Release

Inactivation (reuptake and metabolism)

Receptor interactions

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4

Describe the effects of cocaine and amphetamine on noradrenergic nerves?

Both increase NA in synaptic cleft

5

How can excitatory input be reduced to treat epilepsy?

Phenytoin

Limits excitatory nerve activation 

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6

Describe the action of phenytoin?

Decreases excitatory fibre activity (glutamate) by inhibiting Na channels 

Only binds Na channel while it is open 

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7

How can inhibitory input be enhanced to treat epilepsy?

Benzodiazepines

Enhance GABA receptor activity

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8

Which neurotransmitters are implicated in the use of sedative, hypnotic and anxiolytic agents?

GABA (sedation and anxiety)

Serotonin (sedation and anxiety)

NA (anxiety)

NPY (anxiety)

HA (sedation)

9

What are the clinical applications of benzodiazepines?

Epilepsy

Anxiety

Sleep disorders 

Premedication (sedation for procedures)

Acute alcohol withdrawal

10

Why can beta-andrenoceptor antagonists be useful in the treatment of anxiety?

Can block the physical symptoms 

(sweating, tremor, tachycardia)

11

Which drug class is now obsolete as hypntoic/anxiolytics?

Barbiturates

12

What are barbiturates?

General depressants

Produce all levels of CNS depression

13

Why are barbiturates no longer used?

Exceedingly toxic

Highly addictive

14

Why are benzodiazepines more favourable than barbiturates?

Wider therapeutic index

Less depression of resp and cardio centres

Less dependence

Safe in overdose

15

Describe the effects of benzodiazepines?

Elicit sedation and induction of sleep

Reduce anxiety and aggression

Reduce muscle tone

Obliterate memory

16

How do benzodiazepines exert their effect?

Interact with GABA A receptor and interfere with GABAergic transmission

GABA A receptors are ligand-gated ion channels that let Cl into cell

17

Where do benzodiazepines bind to the GABA A receptor?

Allosteric site

18

What do benzodiazepines modulate on the GABA A receptor?

Orthosteric ligand affinity

Orthosteric ligand efficacy

Receptor activation level

19

Describe the effect that benzodiazepines have when they bind the GABA A receptor?

Bind > increase in receptor affinity for GABA > increases frequency of Cl channel opening > increased sensitivity, no change in maximum response

20

Describe the effect that barbiturates have when they bind the GABA A receptor?

Bind receptor > prolong opening of Cl channel > increased sensitivity and maximum response

21

Why are benzodiazepines considered safe in overdose, whereas barbiturates are not?

Benzodiazepines increase the frequency of Cl channel opening, and do not change the maximum response. Therefore, they have a celing effetc.

Barbiturates prolong the opening of Cl channels, and increase the maximum response. Therefore, there is no ceiling effect. 

 

 

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22

Describe the advantages of allosteric modulators?

Celing effect of inhibitors

Positive modulation of endogenous agonist effect, rather than continuous effect of exogenous agonist

Great receptor subtype selectivity possible 

23

Describe some of the disadvantages of usinjg benzodiazepines?

Unwanted effects: drowsiness, confusion, impaired coordination 

Interaction with alcohol, antihistamines and barbiturates

Long lasting hangover effects

Withdrawal symptoms

Dependence

24

Describe the tolerance effect of benzodiazepines?

Gradual escalation of dose needed

 

25

Describe the dependence effect of benzodiazepines?

Signs of physical and psychological withdrawal

26

What determines the route of administration of benzodiazepines?

Pharmacokinetic profile

Active orally, but differ in duration 

27

Describe the differences in characterisitcs and usage between short and medium/long acting benzodiazepines?

Short: no daytime anxiety, can be used by elderly and drivers

Medium/long: 3-4 daily doses needed, fast onset, muscle tension 

28

Is low potency a disadvantage in drugs?

Only if the dose is so large that it is awkward to administer

29

Describe the difference between pharmacological efficacy and clinical efficacy?

Pharmacological efficacy: strength of receptor activation 

Clinical efficacy: strength of beneficial effect

30