anaesthetics

Question 1

structure of a local anaesthetic

Answer 1

aromatic region + ester/amide bond: amide bonds have longer half lives and are more widely distributed

Question 2

MOA of local anaesthetics

Answer 2

are weak bases, ionised form blocks Na+ channels, act on inner part, block nerve conduction in order of C fibre, A delta, A beta, A alpha

Question 3

what rapidly hydrolyses ester type local anaesthetics?

Answer 3

pseudo-cholinesterase

Question 4

what hydrolyses amide type local anaesthetics?

Answer 4

liver microsomal P450 enzyme

Question 5

Why are adrenaline and felypressin (non catecholamine) used with local anaesthetics?

Answer 5

vasoconstrictors, temporarily limit the spread of the local anaesthetic into systemic circulation

Question 6

ADRs of local anaesthetics?

Answer 6

CNS - dose-dependent: depression, excitation
- restlessness, shivering, tongue numbness/metallic taste
- CNS depression/convulsions (depression of cortical inhibitory pathways)
- respiratory depression
CV: - myocardial depression/conduction block
- vasodilation
- pronounced fall in BP and death