Local Anesthetics Flashcards
What would the effect of metabolic acidosis be on the onset of action of local anesthetics?
It would cause a more rapid onset bc there is more H+ available to bind to the tertiary amine of the local anesthetic, giving it the necessary positive charge to bind to the Na channel that it inhibits.
When giving aminoamides, what do you have to worry about that you don’t necessarily have to worry about when giving aminoesters?
Hepatotoxicity. This is bc aminoamides are metabolized in the liver by P450 and aminoesters are metabolized in the tissues and plasma by esterases.
MOA of local anesthetics is…
…blocking / inhibiting voltage gated Na channels in any of their conformational states.
Why are proximally located areas anesthetized before distally located areas?
As a nerve runs from distal to proximal, it picks up fibers from more proximal areas. These fibers from more proximal areas are the more superficial fibers in the nerve. Therefore, when LA are administered, they attack the more superficial fibers before diffusing into the deeper fibers, therefore causing proximal anesthesia prior to distal anesthesia.
What is used commonly as a pediatric dental anesthetic?
Mepivacaine bc it does not have vasodilating effects, so you don’t have to give a second injection of a vasoconstrictor (we know how kids are with injections, so the fewer you have to give, the better)
Best anesthetic for wound care and small cuts
TAC (tetracaine, adrenaline, cocaine)
Best LA for lengthy dental procedures
Bupivacaine
Drug used in epidural anesthesia and its potential toxicity
Bupivacaine. Cardiotoxicity
For IV regional anesthesia, you want to use a short-acting local anesthetic such as
A. Lidocaine
B. Bupivacaine
C. Cocaine
D. Candy cane
A. Lidocaine
Which of the following are not uses of procaine or its analogs?
A. Infiltration anesthesia
B. Long-term dental procedures
C. Obstetrics
D. Short-term dental procedures
B. Procaine is a short-acting LA, so you would not want this to be given during a lengthy dental procedure.
Tetracaine is a long-acting aminoester (kinda counterintuitive given that aminoesters are usually easier to metabolize) that is used for…
…spinal and topical anesthesia.
Clinical uses of cocaine (!)
- Ophthalmic analgesia (remember to never send this home w/ pt)
- Wound and cut care in combo w/ tetracaine and epinephrine
- Grinding your feet into Eddie’s couch
Lidocaine uses
- Peripheral nerve block
- Infiltration
- Spinal and topical anesthesia
Be careful giving this LA to pts who have had past seizures
Lidocaine
A patient has hypertension but needs a peripheral nerve block. What could you give them?
A. Lidocaine
B. Prilocaine
C. Bupivacaine
D. Tetracaine
B. Prilocaine is a medium-length LA like lidocaine. However, it has its own vasoconstriction effects, so you don’t have to give epinephrine with it. Epinephrine should not be given to pts w/ hypertension bc it is a very potent vasoconstrictor.
