Term
|
Definition
| local reversible loss of sensation without unconsciousness |
|
|
Term
|
Definition
| block Na+ channel = block nerve conduction |
|
|
Term
| how are LA's semiselective? |
|
Definition
small diameter nerve fibres are more readily blocked than large fibres
and Adelta and C fibres are small diameter fibres |
|
|
Term
| nociceptive impulses are carried by what fibres? |
|
Definition
|
|
Term
| at high doses LA's will effect... |
|
Definition
| ...sk mm and cardiac mm :( |
|
|
Term
|
Definition
| touch sensation and motor control |
|
|
Term
| Adelta transmits what type of pain? |
|
Definition
|
|
Term
| C fibres transmits what type of pain? |
|
Definition
|
|
Term
| LA req what to block Na+ channels? |
|
Definition
| requires the NA+ channels to be open |
|
|
Term
| Na+ channel pore made of... |
|
Definition
| ...transmb 5 & 6 and P loop |
|
|
Term
| LA binds to what part of NA+ channel? |
|
Definition
| phenylalanine on transmb 6 |
|
|
Term
| do LA drugs have any other properties? |
|
Definition
|
|
Term
| what other drugs have LA properties? |
|
Definition
| morphine (analgesic) and propranolol (beta blocker) (contain amine and aromatic groups) |
|
|
Term
| what forms of LA exist in the body? |
|
Definition
uncharged and charged/protonated forms
(protonated/charged form = H+ added to amino end of LA) |
|
|
Term
| uncharged form of LA imp for... |
|
Definition
... penetration of neuronal sheath (=involved in rate of onset)
and crossing plasma mb (access to site of action) |
|
|
Term
| charged/protonated form of LA imp for... |
|
Definition
...interacting with NA+ channel (final action)
as need a + charge so phenylalanines benzine ring of transmb 6 will donate an electron to the LA |
|
|
Term
| how much of drug usually ionised in body at pH 7.4 |
|
Definition
80%
as pka of drug (pka of drug =pH when 50%drug ionised) = 8-9) therefore at body pH of 7.4 = more acidic = XS H+ = more drug protonated/ionised) |
|
|
Term
|
Definition
|
|
Term
| if more ionised LA what happens to the rate of onset of the drug? |
|
Definition
| slower rate of onset (but incr blocking) |
|
|
Term
| name a LA with no amine group |
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| ...hydrophobic pathway only (where dont need charged LA) |
|
|
Term
| disdvantages of benzocaine = |
|
Definition
| no use dependence not v potent |
|
|
Term
|
Definition
...some throat powders
some condoms!!
in cocaine (makes lips go numb) |
|
|
Term
| name a permanently charged/ionised LA |
|
Definition
|
|
Term
| QX-314 only works if introduced to cells, why? |
|
Definition
| cus its permanently charges so cant cross cell mb |
|
|
Term
|
Definition
| LA works on inside of cell |
|
|
Term
| most LA's show some degree of use-dependence, what is use-dependence? |
|
Definition
| the more often a neuron fires an AP the greater the degree of block (as NA+ channel has to open for LA to block it) |
|
|
Term
| is use-dependenceof major importance in LA? |
|
Definition
|
|
Term
| LA's that use hydrophilic and hydrophobic pathways, how much of each pathway occurs usually? |
|
Definition
10% hydrophobic
90% hydrophilic |
|
|
Term
| name a LA with an ester bond |
|
Definition
|
|
Term
| name a LA with a amide bond |
|
Definition
|
|
Term
| plasma half life of ester lAs = |
|
Definition
|
|
Term
| plasma half life of amide lAs = |
|
Definition
|
|
Term
pka of
a) ester LA
b) amide LA |
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| can you give lidocaine orally? |
|
Definition
| no, goes through 1st pass metabolism |
|
|
Term
| duration of action of LAs depends on |
|
Definition
| ...diffusion of drug by circulation (NOT metabolism) |
|
|
Term
|
Definition
mepivacaine
bupivicaine
prilocaine
tetracaine
articaine |
|
|
Term
duration of action of:
a) mepivacaine
b) bupivacaine
c) prilocaine
d) tetracaine
e) articaine |
|
Definition
a) medium
b) long
c) medium
d) medium
e) short |
|
|
Term
onset of:
a) mepivacaine
b) bupivacaine
c) prilocaine
d) tetracaine
e) articaine |
|
Definition
a) rapid
b) slow
c)medium
d)slow
e)rapid |
|
|
Term
| which LA causes less vasodilation and therefore may be admin without a vasconstrictor? |
|
Definition
|
|
Term
| which LA has little cardiotoxicity? |
|
Definition
|
|
Term
| which LA has a toxic metabolite and is therfore not used anymore? |
|
Definition
|
|
Term
| which LA can induce paresthesia (burning, tingling and shooting pains) in a small % of patients as well as a numbness that outlasts the presence of the drug in the body |
|
Definition
|
|
Term
|
Definition
1. surface anaesthetics
2. infiltration anaesthetics
3. IV regional anaesthetia
4. IV admin
5. Nerve block anaesthetia
6. Spinal anaesthetia
7. Epidural anaesthetia |
|
|
Term
| give an example of a surface LA |
|
Definition
| lignocaine - spray on nose, mouth, URT, or solution on cornea |
|
|
Term
|
Definition
| infiltration anaesthetics or Nerve block anaesthetia |
|
|
Term
| infiltration anaesthetics used for |
|
Definition
minor surgery
Inject in sensory field and blocks sensory nerve endings |
|
|
Term
|
Definition
| ...decr BF = prolong duration of LA |
|
|
Term
|
Definition
| ...extremities = ischaemia! |
|
|
Term
|
Definition
| ...inject into bv = tachycardia and death! :( |
|
|
Term
|
Definition
| vasopressin analogues eg felypressin(BUT vasopressin = v expensive) |
|
|
Term
| IV regional anaesthetia gd for... |
|
Definition
...limb surgery
use lignocaine |
|
|
Term
|
Definition
| ...neuropathic pain in humans (use lignocaine) |
|
|
Term
| nerve block anaesthetia used for... |
|
Definition
| ...dentistry, surgery, analgesia |
|
|
Term
| spinal anaesthetia used for... |
|
Definition
| ...abdo, pelvis or leg surgery |
|
|
Term
| with spinal anaesthetia LA is injected into... |
|
Definition
| ...subarachnoid space = inhibition of nerves innervating lower body |
|
|
Term
| LAs used in spinal anaesthetics = |
|
Definition
| lignociane and tertacaine |
|
|
Term
|
Definition
| bupivicaine and lignocaine |
|
|
Term
| epidural = inject into... |
|
Definition
| ...epidural space of s.c. and LA diffuses round s.c. |
|
|
Term
|
Definition
1. high plasma concentration due to accidental injection into bv
2. hypersensitivity (skin reactions)
3. toxic metabolites (Prilocaine ONLY) |
|
|
Term
| if LA accidentally injected into bv what happens? |
|
Definition
-CNS stim = confusion, convulsions, resp depression and death!
-CVS= decr BP due to decr contractility and vasodilation |
|
|
Term
| toxic metabolite produced from prilocaine = |
|
Definition
| methaemoglobine (Hb with incr affinity fro O2 = hypoxia of tissues) |
|
|
Term
| what LA can you use to tx ventricular arrhythmias? |
|
Definition
lignocaine
(selectivly binds to Na+channels in highly excitable tissue as channels open more often here) |
|
|
