CPTP 3.23 Local anaesthetics Flashcards
1
Q
Procaine
- ester/amide
- how fast is metabolism, by what enzymes
A
Ester
Rapid metabolism by tissue & plasma cholinesterases
2
Q
Lidocaine
- ester/amide
- how fast is metabolism, by what enzymes
A
Amide
Slowly metabolised by liver CYP450
3
Q
What leads to side effects of LAs
A
Blocking of Na+ channels
4
Q
Cardiovascular side effects of LAs
A
- cardiac arrhythmias
- might progress to cardiac arrest
5
Q
CNS side effects of LAs
A
- Numbness of tongue, mouth, lips
- Metallic taste
- Light headedness, tinnitus
- Slurred speech, muscle switching
- Grand mal convulsions, coma, apnoea
6
Q
Effect of acidosis on efficacy of LA
A
REDUCED EFFICACY
lower pH, increased ionised proportion, less drug able to cross membrane
7
Q
LA most readily blocks neurons of what myelination/diameter
A
- Small diameter
- Little/no myelination
e.g. neurons for light touch are myelinated - less susceptible to blockade
8
Q
Which form of LA is active form + which form crosses lipid bilayer
A
Active: ionised
Crosses lipid bilayer: unionised
