Term
| Name the ester and amide LA |
|
Definition
esters : cocaine
procaine etc
Amides:
I comes before ine
LIdocINE
PrIlocaINE |
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Term
What channel do LA affect?
What pH are LA?
Ionized/unionized? |
|
Definition
Na+ channel on the axonal membrane
Weak base
unionized form of the drug can penetrate the nerve sheath/ membrane |
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Term
| Why are LA ineffective against bacterial infections? |
|
Definition
bacterial infection makes the ECF acidic,
this makes the basic LA more ionised and thus it cannot penetrate the axonal sheath |
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Term
| mechanism of action of LA? |
|
Definition
blocks the VOLTAGE and TIME dependent gated Na+ channels
bloock influx of Na+ thus stop depol
thus stop conduction of action potential
thus bock and prolong the INACTIVATED state of Na+ channels!! |
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Term
| What is the effect of adding a vasoconstrictor to a LA |
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Definition
prolongs the local effects of LA's
i.e combo of epi + lidocane
(increased neuronal uptake in that specific area)
decreased systemic effect)
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Term
| Cocaine specific properties |
|
Definition
blocks the reuptake of NE
thus causes vasoconstriction on its own |
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Term
| How are are LA metabolised? |
|
Definition
Esters - hydrolysed by pseudocholinesterase enzyme - shorter duration of action
Amide - liver by CYP enzymes, thus liver disease can increase the toxicity of the LA |
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Term
| Liver disease and its effects on LA |
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Definition
| Amides are metabolised by CYP enzymes in the liver thus if there is a defect in the liver it can lead to toxicity of the LA |
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Term
| Water soluble LA.. effects? |
|
Definition
water soluble = less potent = shorter duration of action
Lidocaine
Procaine |
|
|
Term
| Lipid soluble LA.. effects? |
|
Definition
Lipid soluble = longer duration of action = more potent
Tetracaine
bupivacaine
|
|
|
Term
What is differential blockade?
examples? |
|
Definition
the effectiveness of LA depends upon:
Diameter
Myelination
Pain type C fibers are not myelinated and have a small diameter are better blocked than, Type A motor fibres which are myelinated and larger in diameter |
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Term
| What is the order of effectiveness in blockade of types of nerve fibre? |
|
Definition
Best blocked
C
B
Adelta
Agama
Abeta
Aalpha
worst blocked |
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|
Term
What are the signs of LA toxicity?
Tx? |
|
Definition
1st sign: Circumoural tongue mouth numbness
most toxic sign : seizures
- diazepam/thiopentone |
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|
Term
Which LA is most cardiotoxic
alternaives? |
|
Definition
Bupivacine
isoenzymes.. levbupivacine etc.. |
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Term
| which type of LA causes allergic reactions? |
|
Definition
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Term
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Definition
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