Local Anesthetics Flashcards
- The _______ form of a chemical will freely move across a membrane
- Normal body pH is ______?
- Intracellular spaces have a slightly more acidic enviroment. This traps the anesthetic inside the cell in its _____ form.
- The unionized form of a chemical will freely move across a membrane
- Normal body pH is 7.4?
- Intracellular spaces have a slightly more acidic enviroment. This traps the anesthetic inside the cell in its ionized form.
**anaesthetics are made as weak bases. When they enter the intracellular space they are trapped in the LAH+ form. It can then bind to the Na receptor on the intracellular side of the membrane and block the channel
All amides are metabolized by _______ and excreted in the _________.
All amides are metabolized by CYP450 in the liver and excreted by the kidney in the urine in the charged form.
Mechanism of Action
- Low concentration
- High Concentration
Mechanism of Action
- Low concentration- decreases the rate of rise of the action potential, increasing its duration and reducing the firing rate
- High Concentration- prevents action potential firing
when the Na current is blocked over a significant length of nerve, propagation is no longer possible (nerve block)
Orderly Blockade
- Order of blockade of nerves (autonomics)
- Spinal cord blockade
Orderly Blockade
- Order of blockade of nerves (autonomics)
autonomic→sensory→motor
**effects diminish in reverse order
- Spinal cord blockade
sympathetic transmission→temperature→pain→light touch→motor block
Cocaine
uses:
Location:
Duration of action:
Cocaine
uses: topical anesthetic properties
Location: topical anesthesia for ENT proceedures
Duration of action: medium
Procaine/ Chlorprocaine
uses:
Location:
Duration of action:
Procaine/ Chlorprocaine
uses: infiltration and peripheral nerve blocks
Location: dental/spinal anesthesia
Duration of action: short onset and druation of action
Tetracaine
uses:
Duration of action:
Tetracaine:
uses: systemically (spinal anesthesia), Topically- N/T or opthalamic
Duration of action: Long
Benzocaine:
Uses:
Benzocaine:
Uses: Topical- bee stings, insect bites, sunburn, boils, sore throats, hemorrhaoid, mouth and gum irritation
**highly lipophilic. May induce methemoglobinemia when used in high concentrations or on broken skin/mucosa exposure
Lidocaine:
Uses:
Duration of action
Lidocaine:
- Uses:
- Systemically: Local and regional infiltration, block, epidural or spinal preparation
- Topically:
Duration of action: medium
**High incidence of transient neurologic symptoms when given systemically. It can cross the BBB so can induce excitatory or depressant CNS Symptoms
Mepivacaine
Uses:
Duration of action:
Mepivacaine- similar properties to lidocaine
Uses: major peripheral blocks, more intense surgeries
Duration of action: medium (longer duration than lidocaine)
**slowly metabolized by the fetus, so not the best choice for OB
Bupivacaine/Levobupivacaine
Uses:
Duration of action:
Black Box warning:
Bupivacaine:
Uses: Infiltration, nerve blocks, and spinal anesthesia
*high concern for cardiotoxicity- avoid for anesthesia that requires high volumes (epidural or peripheral nerve blocks.)
**Low concentrations are used to prolong peripheral anesthesia and analgesia for post-op pain
Duration: long- not well suited for outpatient surgery/ambulatory surgery
Black Box: Obsteteric epidural anesthesia leads to Cardiac arrest with difficult resuscitation and/or death
Ropivacaine
Uses:
Ropivacaine
simialr to bupiacaine and mepivacaine but lower cardiotoxicity.
Uses: Widespread use for high volume peripheral blocks
infiltration, nerve blocks, spinal anesthesia
**popular for epidural infusions for labor and post op pain
Articaine
uses:
duration:
Articaine
uses: Dental anesthetic- formulated with epinephrine
duration: very short (about 20 minutes) so you have less systemic toxicity
Dibucaine/Prilocaine
Uses:
Dibucaine: topical treatment for hemorrhoids or minor burns
Prilocaine: oral dental anesthesia
