Local Anesthetics Flashcards
Local Anesthetics are classified by their linkage what are the 2 classes
Esters and Amides
List 4 esters
Chloroprocaine, Procaine, cocaine, tetracaine
List 5 Amides
Lidocaine, Mepivicaine, Bupivicaine, Prilocaine, Ropivicaine
Name 4 short acting Locals
Procaine, Chloroprocaine, Lidocaine, Tetracaine
Name 3 longer acting Locals
Mepivacaine, Bupivicaine, Ropivicaine
Local anesthetics MOA
Na+ inhibition the the Na+ Ion channels
Which portion of the drug crosses the membrane?
Non-ionized
pKa equated to what - potency, onset, or duration?
Onset
Lipid solubility equates to what- potency, onset, or duration?
Potency
Protein binding equates to what - potency, onset, or duration?
Duration
max dose of Lidocaine and Mepivacaine per Kg with and without Epi
4.5 mg/kg without and 7 mg/kg with epi
Max dose of Bupivacaine or Ropivacaine with and without epi?
2.8 mg/kg without and 3.2mg/kg with epi
Max toxic dose for Lidocaine and Mepivacaine without epi
300 mg
Max toxic dose for Lidocaine and Mepivacaine with epi
500 mg
Max dose of Bupivacaine and Ropivacaine without epi
175 mg
Max dose of Bupivacaine and Ropivacaine with epi
225 mg
Which Locals have a fast onset or closer to physiologic Ph? There is one exception to this?
Lidocaine pKa 7.7 Mepivacaine pKa 7.6 Chloroprocaine Pka 9.1 (THE EXCEPTION)
Which Locals have a slower onset or are further away from physiologic Ph?
Procaine pKa 8.9 Tetracaine pKa 8.6
Which Locals have a moderate onset?
Bupivacaine pKa 8.1 Ropivacaine pKa 8.1
Know this Chem formula

Absorption is influenced by?
Dosage, site of injuection, Vasoconstriction, and Pharmacologic properties
When the vessel is in the nerve bundle will you have ? Increased or Decreased uptake of the LA?
Increased
Cocaine causes vasocontstiction by affecting ?
Dopaimine and norepinephrine decreasing reuptake
Will epi extend short acting or longer acting LA for a longer time period?
It will extend longer acting LA for a longer time period because Longer acting LA are more Lipophilic which is directly related to durration
Amides have a wider distribution because
Increased storage in the tissues because of rapid uptake of highly perfused tissues like the the brain, liver kidneys and heart and a slower uptake from the moderately perfused tissues lik the gut and muscles
LONG ANSWER IT SUCKS
Esters have a shorter duration because
They are broken down by plasma esterase
Which Locals are best for stat C Sections?
Chloroprocaine and procaine
Because they are ESTERS it get hydrolized in < 1 min
LA are excreated in what form Ionized or Nonionized
Nonioinzed - the renal tubules do not reabsorb charged metabolites
MOA of LA
Mechanism of Action:
- Diffusion of the base form across the across the nerve sheath and nerve membrane 2. Re-equilibration between the base and cationic forms in the axoplasm
- Penetration of the cation into and attachment to a receptor site within the sodium channel.
- Blockade of the sodium channel
- Inhibition of sodium conduction
- Decrease in the rate and degree of the depolarization phase of the action potential
- Failure to achieve the threshold potential
- Lack of development of a propagated action potential
- Blockade of impulse conduction
La block conduction in the following order?
Small myelinated axons
non myelinated axons
Large myelinated axons
Because these axons are blocked in this order (Small myelinated axons, non myelinated axons, Large myelinated axons)
__________ and ________ transmission are blocked first?
Nociceptive and sympathetic transmission
LA have use dependence meaning
The increase in action potential frequency increases depth of block (The more u use it the faster it is blocked)
This is important in the use of LA as antiarrhythmics and anticonvulsants
Which of the following elevated extracellularly electrolyte partially antagonizes LA?
Potassium
Sodium
Calcium
Magnesium
Calcium
Which of the following elevated extracellular electrolyte partially enhances LAs?
Potassium
Sodium
Calcium
Magnesium
Potassium
INCREASED Lipophlicity equals???
INCREASED POTENCY
INCREASED Protein Binding equals
INCREASED DURATION
INCREASED Diffusability equals
DECREASED ONSET
INCREASED vasodilation equals
DECREASED POTENCY AND DURATION
Its all moving into the vasculature from the site of infiltration decreasing less drug at the site to work
CNS Toxicity Symptoms
Early: Circumoral numbness, metalic taste, tinnitus, blurred vision and dizziness
Late: Agitation, restlessness, slurring of speach, unconciousness, Seizure, resp arrest and death
Cardiovascular Toxicity symptoms
abnormal automaticity
excitability
arteriolar dilation (except cocaine)
Bupivacaine is the most cardio toxic what the antagonist for this drug?
100cc of 10% Intralipids
Lidocaine toxicity effects respiratory drive by?
Supressing Hypoxic drive
Lidocaine may block bronchospasm or reactive airway with bronchial smooth muscle relaxation at what dose?
1.5 mg/kg
Amide or ester is rare to have an allergic reaction to ??
Amide
Allergic reaction treatment would include?
100% O2
Epi 0.01 to 0.5 IV or IM
Intubate ??????
Benadryl 25-75 mg IV
Hydrocortisone 100-200 mg IV
Prilocaine greater the 10 mg/kg can cause what?
Methemoglobin
3-5 mg/dl causes cyanosis
Damage to neuronal tissue is caused by
high doses
Bupivacaine
Max dose without EPI_______ mg/kg_______
Max dose with EPI_________ mg/kg_______
Max dose without EPI —>175 mg, Weight based ——> 2.8 mg/kg
Max dose with EPI—-> 225 mg, Weight based—–> 3.2 mg/kg
Ropivacaine
Max dose without EPI_______ mg/kg_______
Max dose with EPI_________ mg/kg_______
Max dose without EPI —>175 mg, Weight based ——> 2.8 mg/kg
Max dose with EPI—-> 225 mg, Weight based—–> 3.2 mg/kg
Lidocaine
Max dose without EPI_______ mg/kg_______
Max dose with EPI_________ mg/kg_______
Max dose without EPI —>300 mg, Weight based ——> 4.5 mg/kg
Max dose with EPI—-> 500 mg, Weight based—–> 7 mg/kg
Mepivacaine
Max dose without EPI_______ mg/kg_______
Max dose with EPI_________ mg/kg_______
Max dose without EPI —>300 mg, Weight based ——> 4.5 mg/kg
Max dose with EPI—-> 500 mg, Weight based—–> 7 mg/kg
Prilocaine
Max dose without EPI_______ mg/kg_______
Max dose without EPI —>400 mg, Weight based ——> 8 mg/kg
Chloroprocaine
Max dose without EPI_______ mg/kg_______
Max dose without EPI —> 600mg, Weight based ——> 12 mg/kg
Procaine
Max dose without EPI_______ mg/kg_______
Max dose without EPI —> 500 mg, Weight based ——> 12 mg/kg
Tetracaine
Max dose without EPI_______ mg/kg_______
Max dose without EPI —> 100 mg, Weight based ——> 3 mg/kg