Physiology and pharmacology 1 Flashcards
what is the safety plus system?
- syringe barrel with needle STERILE, single use
- LA cartridges STERILE,single use
- Plunger/handle STERILE and REUSE (black) or SINGLE USE (white)
what is in a cartridge?
- usually 2.2ml or 1.8ml
- anaesthetic agent
- vasoconstrictor
- stabilizer / preservative
- isotonic carrier medium
Name the drug names of LA preparations and their UK trade name.
-Lidocaine
and adrenaline:
UtilycaineTM
Lignospan SpecialTM XylocaineTM
-Mepivacaine:
ScandonestTM
-Prilocaine
and Felypressin:
CitanestTM
-Prilocaine Plain:
Citanest PlainTM
-Articaine
and adrenaline:
BartinestTM
SeptanestTM
what is the basic local anaesthetic?
Has a lipophilic end and a hydrophilic end with an intermediate chain in the middle
what are the two types of intermediate chain in local anaesthetic?
- Ester- O=C-O-R1
- Amide- NH-C=O
Are more drugs amide or ester and why?
More drugs are amide as they have a lower level of allergic potential than esters
Name ester types of local anaesthetic.
- Procaine
- Benzocaine
Name amide types of local anaesthetic.
- Lidocaine
- prilocaine
- mepivacaine
- bupivacaine
- articaine
How do local anaesthetics work?
Local anaesthetic reversibly blocks Na+ channels to block action potentials as it prevents depolarisation by an influx of Na+ into the cell (keeping inside the cell negative)
what are the theories of local anaesthetic action?
- Membrane expansion- makes membrane expand so it physically blocks Na+ channels
- Specific receptor theory - anaesthetic agent gets inside cell and causes Na+ channel to close
what does local anaesthetic need to be?
- Lipid soluble (non-charged): to pass through the axon membrane
- Charged: to bind to receptor in the Na+ channel
How does pH affect the effectiveness of local anaesthetic?
-Equilibrium varies with pH
-more acidic environemnt- the less ions pass into the cell
- LA into an area with absess is less likely to work
LA doesnt work as well in infected tisue (acidic)
Describe the lipid solubility of LA.
-High lipid solubility (partition coefficient)
– Rapid onset as passed though membrane easily
Describe the protein binding of LA.
-LA bound to protein provides a pool of available drug
– High protein binding capability – increases duration
Describe the vasodilator ability of LA.
-most LA have vasodilators effects
-vasodilation results in increase in blood flow
– more rapid removal of LA
– all LAs are vasodilators
so there is an importance of vasoconstrictors
