Local Analgesia Flashcards
How do NSAIDs affect the kidney?
Prostaglandins promote blood flow there
NSAIDs inhibit this so vasoconstriction
How does aspirin cause tinnitus?
NMDA receptors
What is Reye’s syndrome?
Swelling of the lover and brain Diarrhea and rapid breathing Vomiting Confusion Seizures
Where do local anesthetics act?
Prevent transmission of pain
Numbness
Loss of sensation
Where do local anesthetics act?
Block sodium channels
What are the three structural components of local anesthetics?
Hydrophobic - potency, duration of action, toxicity
Intermediate linker component - two class, ester and amide.
Esters are rapidly broken down and high allergy rate
Amides are more stable
Hydrophilic component - an amine, determines pka, impacts onset of action
What pk are local anesthetics?
Weak bases
Pk 8-9
What form of the drug is important?
Both the ionized and unionized form
Ionized has the proton
What form of the drug can go through the membrane?
The unionized form
What form of the drug blocks sodium channels?
The ionized form
What pk acts faster?
Lower
What states do local anesthetics act on?
The open or inactive state
What do local anesthetics preferentially block?
Smaller diameter fibers
Myelinated
What other effects do local anesthetics have?
Vasodilation - risks clearance and diffuse effect
How do you decrease the risk of toxicity for local anesthetics?
Add a vasoconstriction
What is the metabolite of ester local anesthetics that produce an allergic reaction?
PABA para-amino benzoic acid
What are common vasocontrictors that are used with local anesthetics?
Epinephrine
What do you have to worry about using local anesthetics?
Inflammation and pus because they lower the pH to 6.5 and 5.5 respectively
Which local anesthetic is fastly metabolized in the plasma and by what?
Ester form
By pseudo choline esterases
What is EMLA?
Enteric mixture of Local anesthetics
A mixture of two drugs that together has a lower mp
What route of anesthetic is most common?
Infiltration
Subcutaneous or submucosal injection
What is a nerve block?
Major or minor block of a peripheral nerve
What is a IV region block?
In the blood stream with a tourniquet to localize the drug placing
When do you use an epidural anesthesia?
Long procedures
Labor
When do you use a spinal anesthetic?
Some time
What is procaine?
An ester type
Short acting
Not useful as a topical drug
What is lidocaine?
Amide type
Metabolized by liver
Death if systemic
Work hoarse.
What is mepivacaine?
Amide like lidocaine
Long acting
Not topically
What is bupivacaine?
Amide
Longest acting
Most common for prolonged surgery
What is ropivacaine?
Amide type
Long
Less cv and CNS toxicity that bupivacaine
What is tetracaine?
Ester type
Used in the eye, nose, throat and spinal
What is cocaine?
Ester type
Good penetration
Upper respiratory, mucosal membrane
Abuse potential
