Local Anesthetics Flashcards by Dwayne Thibeault

Local Anesthetics are classified by their linkage what are the 2 classes

Esters and Amides

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List 4 esters

Chloroprocaine, Procaine, cocaine, tetracaine

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List 5 Amides

Lidocaine, Mepivicaine, Bupivicaine, Prilocaine, Ropivicaine

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Name 4 short acting Locals

Procaine, Chloroprocaine, Lidocaine, Tetracaine

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Name 3 longer acting Locals

Mepivacaine, Bupivicaine, Ropivicaine

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Local anesthetics MOA

Na+ inhibition the the Na+ Ion channels

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Which portion of the drug crosses the membrane?

Non-ionized

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pKa equated to what - potency, onset, or duration?

Onset

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Lipid solubility equates to what- potency, onset, or duration?

Potency

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Protein binding equates to what - potency, onset, or duration?

Duration

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max dose of Lidocaine and Mepivacaine per Kg with and without Epi

4.5 mg/kg without and 7 mg/kg with epi

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Max dose of Bupivacaine or Ropivacaine with and without epi?

2.8 mg/kg without and 3.2mg/kg with epi

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Max toxic dose for Lidocaine and Mepivacaine without epi

300 mg

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Max toxic dose for Lidocaine and Mepivacaine with epi

500 mg

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Max dose of Bupivacaine and Ropivacaine without epi

175 mg

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Max dose of Bupivacaine and Ropivacaine with epi

225 mg

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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)

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Which Locals have a slower onset or are further away from physiologic Ph?

Procaine pKa 8.9 Tetracaine pKa 8.6

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Which Locals have a moderate onset?

Bupivacaine pKa 8.1 Ropivacaine pKa 8.1

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Know this Chem formula

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Absorption is influenced by?

Dosage, site of injuection, Vasoconstriction, and Pharmacologic properties

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When the vessel is in the nerve bundle will you have ? Increased or Decreased uptake of the LA?

Increased

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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: 1. 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 3. Penetration of the cation into and attachment to a receptor site within the sodium channel. 4. Blockade of the sodium channel 5. Inhibition of sodium conduction 6. Decrease in the rate and degree of the depolarization phase of the action potential 7. Failure to achieve the threshold potential 8. Lack of development of a propagated action potential 9. 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