Drugs

Question 1

Describe the actions of analgesics

Answer 1

Can regulate the whole pain pathway, generally influencing the chemical mediators of the pain and can also influence the neurotransmitters
- DON’T STOP THE AP just regulate it

Question 2

Describe the actions of local anaesthetics

Answer 2

Work on the afferents, either in the periphery or in the CNS

• regionalised inhibition of pain/sensory pathways, stop the transmission of the AP but no loss of consciousness
• can affect other nerves in the region

Question 3

Describe the actions of general anaesthetics

Answer 3

Depresses cortical processing of pain/sensory signal

• loss of consciousness
• not regionalised

Question 4

How do local anaesthetics work and what are some examples? What is the difference between a local anaesthetic and a toxin?

Answer 4

Drugs reversibly block conduction of nerve impulses at the axonal membrane

• procaine, short acting
• lignocaine, longer acting
• • local application to limit systemic distribution, how they are used makes them safe
• local anaesthetics bind the intracellular transmembrane domain, toxins bind the extracellular domains

Question 5

What are the stages of anaesthesia?

Answer 5

Stage 1 - amnesia, euphoria
Stage 2 - excitement, delirium, resistance to handling
Stage 3 - “surgical anaesthesia” - unconscious, regular respiration, decreasing eye movement
Stage 4 - “medullary depression” - respiratory arrest, cardiac depression and arrest

Question 6

What are the methods of administration of general anaesthetics?

Answer 6

Intravenous and inhalation - usually IV to start then inhalation to maintain
IV - propofol, thiopentone
Inhalation - desflurane, sevoflurane, isoflurane

Question 7

What are tricyclic antidepressants and how do they work?

Answer 7

First generation antidepressant drugs

• inhibit neuronal uptake of NA and serotonin
• takes weeks to work
• narrow therapeutic window

Question 8

What are monoamine oxidase inhibitors and how do they work?

Answer 8

First generation antidepressant drugs

• increase levels of NA, 5-HT and DA
• moclobemide most commonly used, less likely to cause the cheese reaction

Question 9

What are SSRIs and how do they work?

Answer 9

Second generation antidepressant drugs

• selective for 5-HT uptake
• high therapeutic index, minimal toxicity unless combined with other drugs