Pharm - Local Anesthetics - Kisby Flashcards Preview

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Flashcards in Pharm - Local Anesthetics - Kisby Deck (14):
1

What is the primary determinant of the onset of action of a LA?

Its pK!

2

What determines potency of an LA?

Lipid solubility (positive correlation) as determined by aromatic side chain

3

What determines duration of action of an LA?

• Amide containing LAs (vs esters) are more stable → longer duration of action
• Hydrophilic amine interaction w/channel proteins also influences duration of action

4

What is the MOA of nerve blocks?

• Cause reversible block of nerve conduction through LA interaction w/Na channels
• Blocking 2-3 nodes of Ranvier is required to inhibit transmission

5

What are some SEs of LAs?

• CNS depression (at low dose)
• Excitation and seizures (at high dose)
• CV effects

6

Which LAs cause allergies and which don't?

• Aminoesters (procaine, etc.) are known dermatitis causing allergens
• Aminoamide LAs very rarely cause allergic reactions

7

Aminoesters

• Drugs: cocaine, procaine, tetracaine, chloroprocaine, benzocaine
• Rapidly hydrolyzed by pseudo-cholinesterases
• Para-aminobenzoic acid (PABA) causes allergies

8

Cocaine HCl

• Only LA with sympathomimetic effects (vasoconstriction & tachycardia)
• Use: topical to control bleeding after ENT procedures

9

Procaine

• Low potency & short duration
• Metabolized to PABA (so may cause allergic reactions)

10

Aminoamides

• Drugs: lidocaine, mepavicaine, prilocaine, bupivicaine, ropivicaine, etidocaine, levobupivicaine
• Metabolized to inactive metabolites → liver impairement
• Allergic reactions are rare

11

Lidocaine

• Intermediate duration
• Use: short-duration procedures (ex: epidural), topical, cardiac (anti-arrhythmic agent), pediatric (for venipuncture, IV cannulation & dental procedures)

12

Prilocaine

• Intermediate duration
• Use: topical & infiltration anesthesia

13

What is methemoglobinemia and what is its tx?

• Caused by high concentrations of amino amide LAs
• Causes cyanosis, decompensation in CV or pulmonary disease pts
• Tx: IV methylene blue

14

Would an ionized or unionized LA perfuse the tissue better?

Unionized