Drugs and the Nervous System

Question 1

What constitutes the nervous system?

Answer 1

The brain, spinal cord and the nerves.

Question 2

What are the excitatory neurotransmitters?

Answer 2

Noradrenaline
Dopamine
Serotonin (5-HT)
Acetylcholine
Glutamate

Question 3

What are the inhibitory neurotransmitters?

Answer 3

GABA

glycine

Question 4

What are the drugs that act on the nervous system?

Answer 4

Anaesthetics (local and general)
Anxiolytic/ hypnotic drugs
Neuromuscular blocking drugs
Antidepressant drugs
Antiparkinsonian drugs
Anticonvulsants

Question 5

Where do general anaesthetics act?

Answer 5

In the central nervous system.

Question 6

How are general anaesthetics administered?

Answer 6

By inhalation or intravenously.

Question 7

Why use anaesthetics?

Answer 7

To promote:
Analgesia
Unconsciousness
Amnesia
Loss of reflexes

Question 8

How do general anaesthetics work?

Answer 8

1. act on CNS to promote insensitivity
2. usually fat soluble – can cross blood-brain barrier
3. may act on membrane receptors to reduce excitability of neurones
4. may affect ion channels

Question 9

What are some common side-effects of general anaesthetics?

Answer 9

1. Nausea/ Vomitting,
2. Breathing difficulties ( Shallow/rapid)
3. Low blood pressure,
4. Low kidney perfusion,
5. Loss of temperature control.

Question 10

What are the stages of anaesthesia?

Answer 10

Stage 1 – analgesia
Stage 2 – excitement
Stage 3 – surgical anaesthesia → skeletal muscle relaxation/ loss of reflexes
Stage 4 – medullary paralysis → loss of respiratory/ vasomotor control

Question 11

What are the 4 types of general anaesthetics?

Answer 11

1. Barbiturates,
2. Gases,
3. Non-barbiturates,
4. Volatile liquids.

Question 12

Why is nitrous oxide used?

Answer 12

To maintain anaesthesia and as a potent analgesic.

Question 13

Three types of inhaled anaesthetics?

Answer 13

Isoflurane, desflurane, sevoflurane.

Question 14

How is the depth of anaesthesia controlled?

Answer 14

By varying the concentration of the vapour.

Question 15

What type of general anaesthetic is Propofol?

Answer 15

An intravenous, non-barbiturate.

Question 16

Advantages of Propofol?

Answer 16

1. Rapid action,

2. Rapid recovery without ‘hangover’.

Question 17

Disadvantage of Propofol?

Answer 17

May cause convulsions or anaphylaxis.

Question 18

What type of general anaesthetic is Thiopental (Thiopentone)?

Answer 18

An intravenous, barbiturate.

Question 19

Advantage of Thiopental?

Answer 19

Useful for brief procedures.

Question 20

Disadvantage of Thiopental?

Answer 20

Can cause rapid awakening or long lasting sedation which may cause problems.

Question 21

What are benzodiazepines?

Answer 21

Anxiolytics or hypnotics.

Question 22

Examples of benzodiazepines…

Answer 22

Midazolam, Temazepam, Diazepam. All end in ‘am’.

Question 23

How are benzodiazepines administered?

Answer 23

Orally, intravenously. intramuscularly and rectally.

Question 24

Side effects of benzodiazepines?

Answer 24

1. Hypotension,
2. Constipation,
3. No analgesic effect.

Question 25

Disadvantages of Hypnotics?

Answer 25

1. May lead to dependence 2. May cause respiratory depression 3. Benzodiazepines interact with alcohol 4. Will cross the placenta in a pregnant woman.

Question 26

How do neuromuscular blocking drugs work?

Answer 26

1. They block transmission in motor nerves. | 2. Relax vocal cords, to allow insertion of tracheal tube.

Question 27

Disadvantages of neuromuscular blocking drugs?

Answer 27

1. Patients require assisted respiration. 2. Prolonged muscle paralysis or pain. 3. May cause the release of histamine which may cause a bronchospasm.

Question 28

How do Narcotic analgesics (opioid) work?

Answer 28

Act on opioid receptors in the central nervous system to relieve pain.

Question 29

What effect do narcotic analgesics have?

Answer 29

Euphoric effect. (to escape from reality).

Question 30

Examples of Narcotic analgesics...

Answer 30

Fentanyl, Alfentanil, Remifentanil. All end in the sound 'nil'.

Question 31

Disadvantages of Narcotic analgesics?

Answer 31

1. May cause nausea/vomiting. 2. Reduced breathing rate. 3. Small risk of addiction.

Question 32

What are local anaesthetics used for?

Answer 32

1. Analgesia, | 2. Paralysis.

Question 33

How do local anaesthetics work?

Answer 33

They act on specific nerve pathways.

Question 34

What is the mechanism of action for a local anaesthetic?

Answer 34

They block transmission of nerve impulses carrying pain signals from nociceptors to the brain.

Question 35

What is the cellular mechanism of action in a local anaesthetic?

Answer 35

Inhibition of Na+ entry through very sensitive Na+ channels, this blocks transmission of nerve impulses.

Question 36

Common methods of administration of local anaesthetics?

Answer 36

1. Epidural - injection into epidural space which affects nerve roots. 2. Intradermal/topical - relieves minor irritation/superficial pain.

Question 37

Commonly used local anaesthetics...

Answer 37

Lidocaine, Prilocaine, Bupivacaine, ropivacaine and proxymetacaine. (all end in 'caine')

Question 38

What is Lidocaine used for?

Answer 38

1. Dental surgery. | 2. To treat premature ejaculation.

Question 39

What is Prilocaine used for?

Answer 39

It is mixed with Lidocaine and used for surface anaesthesia.

Question 40

Side effects of local anaesthetics?

Answer 40

1. Abnormal heart beat. 2. Restlessness. 3. Convulsions. 4. In severe cases, cardiorespiratory arrest.

Question 41

How do vasoconstrictors work?

Answer 41

They enhance potency and prolong duration of action of anaesthetics. They also reduce blow flow meaning that lesson blood is lost in surgery.

Question 42

Examples of vasoconstrictors?

Answer 42

Adrenaline and felypressin.

Question 43

Other drugs that work on the nervous system...

Answer 43

1. Antidepressants, 2. Antiparkinsonian drugs, 3. Anticonvulsants.

Question 44

How do antidepressants work?

Answer 44

Increase levels of excitatory neurotransmitters in the brain.

Question 45

How do antiparkinsonian drugs work?

Answer 45

Increase levels of the neurotransmitter dopamine.

Question 46

How do anticonvulsants work?

Answer 46

Treat epilepsy by reducing the conduction of excitatory nerve impulses and/or increasing GABA activity.

Question 47

What are the 3 types of Antidepressants?

Answer 47

1. Tricyclic antidepressants. 2. Selective serotonin re-uptake inhibitors. 3. Monoamine oxidase inhibitors.