Local Anesthetics Flashcards
Drugs which upon topical application or local injection cause reversible loss of sensory perception especially of pain in a restricted area of the body?
Local anesthetics (LA).
LAs block nerve conduction of ________ impulses and in higher concentration blocks ______ Impulses.
Sensory,
Motor.
Which fibers are most susceptible to LA?
Type B fibers (pre-ganglionic autonomic fibers), and type C fibers (carrying pain).
List the 2 classifications of LA?
1- injectable anesthetics.
2- surface anesthetics.
List the 3 types of injectable anesthetics?
1- low potency, short duration.
2- intermediate potency and duration.
3- high potency, long duration.
List the 2 types of surface anesthetics?
1- soluble.
2- insoluble.
Give examples of injectable anesthetics with low potency, and short duration?
1- procaine.
2- chloroprocaine.
Give examples of injectable anesthetics with intermediate potency and duration?
1- lidocaine (lignocaine).
2- prilocaine.
Give examples of injectable anesthetics with high potency and long duration?
1- tetracain (amethocaine).
2- bupivacaine.
3- ropivacaine.
4- dibucaine (cinchocaine).
Give examples of surface anesthetics that are soluble?
1- cocaine.
2- lidocaine.
3- tetracaine.
4- benoxinate.
Give examples of surface anesthetics that are insoluble?
1- benzocaine.
2- oxethazaine.
Which drug is the only naturally occurring LA?
Cocaine.
Why is cocaine not used clinically?
Because of its adverse effects and abuse potential.
All LAs (other than cocaine) are ________ derived?
Synthetically.
list ester-linked LAs
(one I)
1- cocaine
2- procaine.
3-chloroprocaine.
4- tetracaine.
5- benzocaine.
list amide- linked LAs
(two Is)
1- lidocaine.
2- bupivacaine.
3- dibucaine.
4- prilocaine.
5- ropivacaine.
which LA produces more intense and longer lasting anesthesia?
amide LA.
which LA rarely cause hypersensitivity reactions?
amide LA.
local anesthetics are _______
weak bases.
the relative proportion of these two forms is governed by?
1- their pKa.
2- pH of the body fluids.
which for of LA is lipid-soluble and can enter nerve cell membrane?
non-ionized form.
LAs can interact with a receptor situated ____ the voltage sensitive Na+ channel?
within
the active species is the ionic form of the LA which able to reach the receptor only when?
the channel is open at the inner face.
binding of LA prolongs what?
the inactivated state.
adrenaline should not be co-administered for nerve block where? why? and what do we use instead?
in fingers and toes.
vasoconstriction of end arteries can lead to ischemia and necrosis.
we use ring block instead.
All LAs are cardiac _____
depressants.
LA can induce cardiac ______
arrhythmias.
which LA is cardiotoxic?
bupivacaine.
which LAs are used as anti-arrhythmics?
lignocaine and procainamide.
list the 5 uses and techniques of LA?
1-surface anesthesia.
2- infiltration anesthesia.
3- conduction anesthesia.
4- spinal anesthesia.
5- epidural anesthesia.
which LAs are capable of anesthetizing intact skin?
eutectic lidocaine/ prilocaine.
what are the uses of surface anesthesia?
ocular tonometry.
intubation.
endoscopic procedures.
which LAs are used during ocular tonometry, intubation, and endoscopic procedures.
tetracaine and lignocaine.
which LAs are combined to make EMLA?
lidocaine, prilocaine.
EMLA is commonly used for which age group?
peds
infiltration anesthesia is used for what?
minor operations
which LAs are commonly used as infiltration anesthesia?
lignocaine and bupivacaine.
list the 2 types of conduction block?
1- field block.
2- nerve block.
field block is commonly done for what?
herniorrhaphy, appendicectomy, dental procedures, scalp stitching, operations on forearms and legs.
nerve block is used for what?
lingual, intercostal,ulnar, sciatic, femoral, brachial plexus, trigeminal, facial, phrenic.
what is the advantage of nerve block?
even with a small amount of drug, a large area can be anesthetized.
spinal anesthesia is used for which procedures?
operations on the lower limbs, pelvis and lower abdomen.
which LAs are used in spinal anesthesia?
lignocaine, bupivacaine.
in spinal anesthesia LA is injected where?
subarachnoid space between L2-3 OR L3-4
primary site of action of spinal anesthesia is?
nerve roots in the cauda equina.
what are the complications of spinal anesthesia?
1- hypotension.
2- headache.
3- septic meningitis.
4- nausea and vomiting.
5- cauda equina syndrome.
which LA is used in epidural anesthesia?
lignocaine and bupivacaine.
