Block 1: Anesthetics- Local
Terms
undefined, object
copy deck
- 3 parts of LA
-
lipophilic group- aromatic ring
intermediate chain- ester or amide
hydrophilic group- secondary or tertiary amine - increasing _____ increases the anesthetic potency and duration but also increases side effects
- hydrophobicity
- more likely to cause allergic reax
- esters (cocaine and procaine) from PABA metabolites
- topical anesthesia in URT
- cocaine
- prototype ester
- procaine
- inhibition of catecholamine uptake
- cocaine
- infiltration anesthesia and diagnostic nerve blocks
- procaine
- inhibit action of sulfonamides
- procaine
- aka novocain
- procaine
- prototype amide
- lidocaine
- antiarrhythmic agent
- lidocaine
- metabolism in liver and plasma
- cocaine
- metabolism by pseudocholinesterase
- procaine
- metabolism by liver CYP450
- lidocaine
- _________ form is required to cross the membrane
- unprotonated
- ______ form is most active at receptor site
- protonated, charged
- LAs are typically strong/weak acid/base
- weak bases, pka 8-9
- Do LAs change resting membrane potential
- no
- the degree of block depends on
- voltage and frequency
- puffer fish
- tetrodotoxin
- dinoflagellates (red tide)
- saxitoxin
- tetrodotoxin and saxitoxin...
- reversibly block sodium channel like LAs, but they do it from the outside
- critical length
- shorter blocks first
- firing frequency
- sensory if faster - blocked first
- fiber position
- outer fiber blocked first
- susceptibility
- C > Ad > Ag > Ab > Aa
- sensation lost
- pain-> temp-> touch-> deep press-> motor
- sensations regained
-
opposite of
pain, temp, touch, deep pressure, motor - epinephrine and clonidine
-
may enhance spinal anesthesia by acting at A2 ADRENERGIC RECEPTORS to
dec. firing of SENSORY NEURONS
and
inhibit release of SUBSTANCE P -
LA's...(decrease/increase)
___ myocardial electrical excitability
___ conduction rate
___ blood pressure
exception... -
decrease
decrease
decrease
exception = cocaine --> increases heart rate and blood pressure