Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
41 Cards in this Set
- Front
- Back
|
Are local anesthetics weak acids or bases?
|
Bases
|
|
|
Is the aromatic ring in local anesthetics lipophilic or hydrophilic?
|
Lipophilic
|
|
|
What are the 2 types of intermediate groups on local anesthetics?
|
1. Ester
2. Amide |
|
|
What is the easiest way to remember if a local anesthetic is an amide or ester?
|
Amides have TWO "I"s
Ex: Bupivicaine |
|
|
What is the voltage when continued stimulation is no longer needed and local processes can lead to a complete AP?
|
Threshold potential
|
|
|
What are the 3 states of the Na channel?
|
Open, Closed, Inactive
|
|
|
What is the MOA of local anesthetics?
|
Binds to the internal membrane of the NaCh and blocks the permeability of Na
|
|
|
In what 2 NaCh states do local anesthetics bind?
|
Open and Inactive
|
|
|
Nerves that have what characteristic are more easily blocked?
|
Nerves that fire more frequently
|
|
|
Why does a local anesthetic not work in the case of a tooth abscess?
|
Because the abscess is acidic and therefore local anesthetic is not as effective
|
|
|
What are 5 effects that local anesthetics have on the AP?
|
1. Decrease AP amplitude
2. Slow rate of depolarization 3. Increase firing threshold 4. Slow impulse conduction 5. Prolong the refractory period |
|
|
In the blood, what do local anesthetics bind to?
|
Alpha1-glycoprotein and albumin
|
|
|
In which organ is there considerable first pass uptake of local anesthetics?
|
Lung
|
|
|
What are the 2 mechanisms by which local anesthetics enter the blood stream?
|
1. Direct Injection
2. Absorption |
|
|
What are the 3 phases of distribution of local anesthetics?
|
1. Alpha Phase
2. Beta phase 3. Gamma Phase |
|
|
What occurs in the alpha phase?
|
Rapidly distributed to well-perfused tissue
Ex: Brain, heart, Liver |
|
|
What occurs in the beta phase?
|
Less perfused or slow equilibrating tissue
Ex: Muscle, Fat |
|
|
What occurs in the gamma phase?
|
Clearance representing metabolism and excretion
|
|
|
Which organs are at greatest risk of toxicity from overdose of a local anesthetic?
|
Brain, Heart, and Liver
|
|
|
What enzyme metabolizes ester local anesthetics?
|
Pseuodocholinesterase
|
|
|
What is the breakdown product of ester metabolism and what is its significance?
|
Para-aminobenzoic acid (PABA)
It's an ALLERGEN |
|
|
Where are amides broken down?
|
ER of hepatocytes
|
|
|
A patient with end state liver disease is most susceptible to what type of local anesthetic?
|
Amides (because broken down in liver)
|
|
|
What characteristic of a local anesthetic corresponds to its potency?
|
Lipid Solubility
More Soluble = More potent |
|
|
What characteristic of local anesthetics corresponds to duration?
|
Lipid Solubility
More soluble = greater duration |
|
|
What property of local anesthetics dictates the speed of onset?
|
pKa
pKa closer to BODY'S pH (7.4) = faster onset Because at that pKa anesthetics are unionized and can cross membrane |
|
|
A newly discovered local anesthetic has a pKa of 7.4, what % of it is unionized in the plasma?
|
50% (H-H equation)
|
|
|
Why are esters usually put in OC drugs?
|
Because they are metabolized quickly so if misused, less likely to cause OD
|
|
|
What are the 2 types of local anesthetic toxicity?
|
1. CNS
2. Cardiovascular |
|
|
Why are convulsions seen in LA toxicity?
|
Because inhibitory neurons are more susceptible that excitatory
|
|
|
Why is cardiovascular toxicity seen?
|
Because of interference with calcium signaling
|
|
|
In terms of toxicity, why is Bupivicaine an exception?
|
Cardiac dysrhythmias are seen at subconvulsant doses of bupivicaine
|
|
|
Which isomer of Bupivicaine is 40x more cardiotoxic?
|
D isomer
|
|
|
What is given as an antidote in the case of cardiac toxicity due to local anesthetics?
|
Intralipid
|
|
|
What are the effects of local anesthetics on vascular smooth muscles at
1. Low Concentrations 2. High Concentration |
Low = vasoconstriction
High = Vasodilation |
|
|
What is the exception to the rule that high concentrations give vasodilation?
|
Cocaine
|
|
|
Which anesthetics are prepared soley as the S isomer and are much less cardiotoxic than bupivicaine?
|
1. Ropivacaine
2. Levobupivicaine |
|
|
What is the snesory nerve blocking mecanisms of levobupivicaine?
|
Same as bupivicaine
|
|
|
Which anesthetic is metabolized to alpha-orthotoludine and in doses greater than 600mg results in methemoglobinemia?
|
Prolocaine
|
|
|
What is the duration and onset of Lidocaine?
|
rapid onset, medium duration
|
|
|
What is lidocaines other use?
|
Anti-arrhythmic
|
