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17 Cards in this Set

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CLASSIFICATION OF LA

Name local anesthetics which are ESTERS
Cocaine

Procaine

Tetracaine

Benzocaine
CLASSIFICATION OF LA

Name local anesthetics which are AMIDES
Lidocaine

Bupivocaine

Etidocaine

Prilocaine
ROLE OF LOCAL pH

1.Most Local anesthetics are what in terms of pH?

2.At physiologic pH _ form prevails, _ form is required to penetrate membrane

3. Receptor site is _ to cell membrane

4. _ form is active at the receptor site - protonation occurs _
WEAK BASES (pKa = 8-9)

2. Cationic, neutral

3. Internal

4. Ionic - intracellularly
Infection causes _ pH which causes less local anesthetics which are neutral to penetrate membrane (may require injection more proximally)
Low extracellular
SYSTEMIC ABSORPTION

1. What happens to blood flow when epinephrine is co-administered with LA? What happens to systemic absorption of anesthetic from depot site

2. Local neuronal uptake is enhanced by _

3. Which drug is exception to this?

4. _ and _ also less dependent on vasoconstriction
1. Local blood flow DECREASES - systemic absorption DECREASES

2. Higher concentration of the drug

3. COCAINE - NE uptake inhibition

4. Bupivocaine and Tetracaine
SPINAL ANESTHESIA

1. Epi produces _ mediated inhibition of release of _ - this _ sensory nerve firing and produces analgesia

2. Epi - _ systemic absorption, _ neuronal uptake and _ alpha 2 activity prolongs local anesthetic effect by 50%
1. Alpha 2 mediated - Substance P - decreases

2.Decreased, Increased, Increased
SURFACE ACTIVITY - ability to reach superficial nerves when applied to skin or mucous membranes

1. Which drugs can do that?

2. EMLA (eutectic mixture of LA) can also do that - what does it include?

3. When is this used?
1. Cocaine and Benzocaine

2. Lidocaine and prilocaine combination applied as cream or patch

3. For vennipuncture, arterial cannulation, lumbar puncture, dental procedures and in children who dread injections
METABOLISM AND EXCRETION

1. Ester type local anesthetics are hydrolyzed in blood by _

2. Amide local anesthetics are metabolized in _

3. Metabolites are _ and excreted in _
1. Butyrylcholinesterase (tetracaine (long acting), procaine short acting)

2. Liver (prilocaine fastest, bupivocaine slowest) - IMPAIRED LIVER or LIVER DISEASE might result in toxicity by amide drug

3. POLAR - URINE
MECHANISM OF ACTION OF LA

1. Blockade of _ channels - prevents _

2. Access to receptor site gained from _

3. Receptor affinity is _ or _ dependent
1. Voltage dependent Na channels - depolarization and conduction of AP

2. Cytoplasm or membrane

3. Voltage or use
ACTION OF LA ON NERVES

1. Susceptibility according to nerve diameter - In a nerve root _ fibers are blocked first. Small type _ fibers are blocked next

2. Susceptibility according to myelination - _ fibers tend to be blocked more readily

3. Susceptibility according to location of nerve fiber in bundle - fibers in _ blocked sooner than those _, exposed earlier to higher concentration of anesthetic
1. Smaller B and C fibers firtst, A delta next (pain fibers first, motor function next)
2. Myelinated fibers are blocked more readily than unmyelinated fibers of the same diameter

3. Periphery sooner than in core
Name clinical applications of LA
- Surface (topical ) anesthesia
- Minor surgical procedures - infiltration, nerve block
- Spinal anesthesia - into CSF
- Epidural anesthesia - into epidural space
Which condition antagonizes effects of LA? What is the mechanism of that?
HYPERCALCEMIA - antagonizes effects of LA's - shuts down Na channels, increased surface potential favors resting state
Which condition enhances action of LA's ? What is the mechanism?
HYPERKALEMIA - extracellular K depolarizes membrane and favors open states (more Na channels open)
Describe CNS effects (toxicities ) of local anesthetics
MOST IMPORTANT - most serious are seizures/convulsions followed by coma with respiratory and CV depression

Lower levels- nystagmus, light headedness, restlessness
Except _ all local anesthetics are vasodilators
COCAINE
Cocaine as drug of abuse causes what CV effects?
Severe hypertension with cerebral hemorrhage, cardiac arrhythmia and MI
Prilocaine metabolite causes what (toxicity) ?
Methemoglobinemia (oxidized Hb - anemia)