Local anaesthetics

Question 1

Local anaesthetics

• definition
• structure
• permeability
• metabolism

Answer 1

• substances that produce reversible regional loss of sensation or pain without loss of consciousness by blocking voltage-gated Na+ channels
• aromatic group, intermediate chain and tertiary or secondary amino group
• weak bases (charged and uncharged forms)
• hydrolysed (ester) and catabolised in liver (amides)

Question 2

Local anaesthetics toxic effects

Answer 2

• local tissue injury
• effects on CNS (stimulation, respiratory depression)
• effects on CV system (vasodilation and hypotension, depression of myocardium)
• allergic reaction (PABA)

Question 3

Methods for local anaesthetics administration

Answer 3

• surface
• infiltration
• nerve block
• spinal
• epidural
• intravenous regional

Question 4

Procaine

Answer 4

• local anaesthetic

- ester type, hydrolysed by plasma cholinesterase

Question 5

Barbiturates

Answer 5

• protects against local anaesthetic toxic effects on CNS

- aggravate respiratory depression

Question 6

Cocaine

Answer 6

• vasoconstrictor via sympathetic potentiation

Question 7

Surface anaesthesia

Answer 7

• lidocaine and prilocaine (EMLA)

- benzocaine (powder)

Question 8

Infiltration anaesthesia

Answer 8

• lidocaine
• prilocaine
• vasoconstrictors

Question 9

Spinal anaesthesia

Answer 9

• procaine
• tetracaine
• cinchocaine