Local anesthetics Flashcards
Which property is most associated with local anesthetic potency?
Higher lipid solubility = More potent
Which property is most associated with duration of local anesthetic action?
Higher protein binding = longer duration of action
Which property is associated with a faster onset of action for local anesthetics?
Lower pKa = faster onset of action, because more molecules unionized at physiologic pH
What are the units for epinephrine dilution in a local anesthetic?
g/mL, i.e., 1:200,000 = 5ug/mL
Which block site is associated with the greatest amount of systemic absorption?
Intercostal block, then caudal anesthesia
Which class of local anesthetics is more likely to cause allergic reactions?
Esters, because they are metabolized to PABA
What preservative in local anesthetics may cause an allergic reaction?
Methyl paraben
List the ester local anesthetics
Procaine
Chlorprocaine
Tetracaine
List the amide local anesthetics
Lidocaine Meoivicaine Prilocaine Bupivicaine Ropivicaine Levobupivicaine
What are the risk factors for TNS?
Intrathecal lidocaine
Lithotomy
Outpatient surgery
How long does TNS last?
24 h to 7 days
Why does chloroprocaine have the fastest onset of action of the local anesthetics but the highest pKa?
the concentration delivered is very high
What are the common side effects of procaine?
methemoglobinemia
nausea/vomitting
What are the common side effects of benzocaine?
methemoglobinemia
allergic reactions to PABA
How does chloroprocaine affect the choice of subsequent neuraxial analgesia?
It renders bupivicaine and opioids ineffective so you must continue redosing with chloroprocaine.
