Local Anesthetics Flashcards
List the Esters
1 letter i
- Procaine
- Tetracaine
- Cocaine, Benzocaine
List the Amides
2 letter i
- Lidocaine
- Bupivacaine
- Levobupivicaine
- Ropivacaine
Esters and Amides MOA
- Blocks Na+ channels
- Reduce influx of Na+ ions
- Prevents depolarization of membrane
- Blocks conduction of AP
Describe the nonionized and ionized relationship
Non-ionized=uncharged=Reaches receptor site
Ionized=Charged=Causes local anesthetic EFFECT
How can you accelerate the onset of action of local anesthetic?
Sodium Bicarb
How can you PROLONG the duration of SHORTER acting local anesthetic agents?
Epi= Alpha-agonist sympathomimetic
What significantly decreases the amount of anesthesia delivered?
Acidic environment:
- Abscess
- Infxn
How are esters metabolized?
Plasma Cholinesterases=Very rapid
How are amides metabolized?
Liver
List the fiber types that will respond quicker to local anesthetics?
- Small fibers
- Mylenated fibers
- Fibers located in the periphery
Which type of nerve fibers are blocked first?
Delta: Pain, temperature
Which type of nerve fibers are blocked last?
Alpha: Proprioception, motor
What are the possible ADE/SE’s of Central Neuraxial Techniques (spinal or epidural)
- Impair respiratory activity d/t motor paralysis
2. Hypotension d/t autonomic nerve blockade
What are the disadvantages of motor paralysis during/post surgery?
- Limit ability to push during delivery (epidural)
- Increased risk of fall: limits ability to ambulate
- Bladder dysfunction/urinary retention: residual autonomic block
List the order evolution of block components
- Sympathetic transmission
- Temperature
- Pain
- Light touch
- Motor block
Define Epidural Block
Local anesthetic injected EXTRADURALLY
Define Caudal block
Specific epidural block: Needle inserted into CAUDAL CANAL via sacral hiatus
Define Perineural block
Injection around PERIPHERAL NERVES
Define Spinal block
Injection into CSF in SUBARACHNOID SPACE
Why did the FDA ban Bupivacaine in OB?
Cardiotoxicity
Bupivacaine antidote
Lipid resuscitation
What is the average elimination half-life of Lidocaine?
1.6 hrs
What is the elimination half-life of Lidocaine in patient’s with severe liver dz?
6 hrs
Amides and Esters CNS Effects
- Light headedness or sedation
- Restlessness
- Nystagmus
- Tonic-Clonic Sz’s
Amides and Esters CV Effects
- Vasodilator
- Heart block
- Arrhythmias
- Hypotension
What is a unique ADE of Prilocaine?
Converts hemoglobin to Methemoglobin
How do you manage the ADE’s of Amides/Esters?
IV Diazepam for convulsions
No antidote
What is EMLA cream?
Lidocaine 2.5% + Prilocaine 2.5% Topical Cream
Used in kids prior to venipuncture or IV
