Nagelhout Chapter 10 Local Anesthetics
UPDATED ACTUAL Questions and
CORRECT Answers
*what are the 2 classes of local anesthetics - CORRECT ANSWER - esters and amides
(also have miscellaneous
*how to differentiate esters and amides - CORRECT ANSWER - one "i" in the generic
name for esters and two "i"s in the generic name for amIde
first local ever used; what makes this guy so special? - CORRECT ANSWER - cocaine;
naturally occurring from coca leaf
*for a drug to have local anesthetic properties, what 3 chemical compounds - CORRECT
ANSWER - 1. lipophyllic portion (lipid soluble) usually a benzene ring
2. water soluble portion (the nitrogen containing molecule in the structure)
3. lipid soluble and water soluble portions must be separated by a certain distance and this is
either by an ester or amide chemical chain
*explain the structure of an ester local anesthetic; explain for amide structure - CORRECT
ANSWER - ester is C==O, O and both the Os are negative (-);
amide is C==O, N where the N is positive (+) and O is negative (-) and brings closer together
and makes harder to break
(== reads as "double bond"
*what is the significance for both the Os being negative in a ester bond - CORRECT
ANSWER - both negative means they push away from each other and make bond easier to
break (metabolism)
, *how are esters metabolized - CORRECT ANSWER - plasma and tissue cholinesterases
via hydrolysis that occurs throughout the body and is rapid (they are metabolized right in the
tissue they are in bc water and cholinesterase are everywhere)
*what is special about tetracaine? - CORRECT ANSWER - we mostly used amides. Esters
tend to be short acting, but tetracaine is the longest acting ester we have
talk about what we need to know regarding the esters and amide locals and allergies to them -
CORRECT ANSWER - local anesthetic allergies are uncommon, yet esters are more
commonly associated with allergies than the amides (99%). if you have an allergy to an ester,
then you most likely have allergy to all the other esters (cross allergy within class). Though very
unlikely, if you're allergic to an amide, then there is no cross allergy and the other amides will be
okay.
how are amides metabolized - CORRECT ANSWER - in the liver by CYP1A2 and
CYP3A4 (would take longer than the esters and therefore higher blood levels may develop with
rapid absorption)
between esters and amides, which are shorter acting? why? - CORRECT ANSWER -
esters are shorter acting because they are readily metabolized by esterases throughout the entire
body and at the tissue where they are injected. amides are longer acting bc they are more
lipophilic and protein bound and require transport to liver for metabolism
why are esters more associated with allergy? - CORRECT ANSWER - the lipophilic
group of ester is called PABA (paraminobenzoic acid) which is a component of a los of
cosmetics and some food products that we are exposed to. then when get the local they
experience the allergy
what is the MOA of the local anesthetics? - CORRECT ANSWER - block Na+ channels in
nerves.
UPDATED ACTUAL Questions and
CORRECT Answers
*what are the 2 classes of local anesthetics - CORRECT ANSWER - esters and amides
(also have miscellaneous
*how to differentiate esters and amides - CORRECT ANSWER - one "i" in the generic
name for esters and two "i"s in the generic name for amIde
first local ever used; what makes this guy so special? - CORRECT ANSWER - cocaine;
naturally occurring from coca leaf
*for a drug to have local anesthetic properties, what 3 chemical compounds - CORRECT
ANSWER - 1. lipophyllic portion (lipid soluble) usually a benzene ring
2. water soluble portion (the nitrogen containing molecule in the structure)
3. lipid soluble and water soluble portions must be separated by a certain distance and this is
either by an ester or amide chemical chain
*explain the structure of an ester local anesthetic; explain for amide structure - CORRECT
ANSWER - ester is C==O, O and both the Os are negative (-);
amide is C==O, N where the N is positive (+) and O is negative (-) and brings closer together
and makes harder to break
(== reads as "double bond"
*what is the significance for both the Os being negative in a ester bond - CORRECT
ANSWER - both negative means they push away from each other and make bond easier to
break (metabolism)
, *how are esters metabolized - CORRECT ANSWER - plasma and tissue cholinesterases
via hydrolysis that occurs throughout the body and is rapid (they are metabolized right in the
tissue they are in bc water and cholinesterase are everywhere)
*what is special about tetracaine? - CORRECT ANSWER - we mostly used amides. Esters
tend to be short acting, but tetracaine is the longest acting ester we have
talk about what we need to know regarding the esters and amide locals and allergies to them -
CORRECT ANSWER - local anesthetic allergies are uncommon, yet esters are more
commonly associated with allergies than the amides (99%). if you have an allergy to an ester,
then you most likely have allergy to all the other esters (cross allergy within class). Though very
unlikely, if you're allergic to an amide, then there is no cross allergy and the other amides will be
okay.
how are amides metabolized - CORRECT ANSWER - in the liver by CYP1A2 and
CYP3A4 (would take longer than the esters and therefore higher blood levels may develop with
rapid absorption)
between esters and amides, which are shorter acting? why? - CORRECT ANSWER -
esters are shorter acting because they are readily metabolized by esterases throughout the entire
body and at the tissue where they are injected. amides are longer acting bc they are more
lipophilic and protein bound and require transport to liver for metabolism
why are esters more associated with allergy? - CORRECT ANSWER - the lipophilic
group of ester is called PABA (paraminobenzoic acid) which is a component of a los of
cosmetics and some food products that we are exposed to. then when get the local they
experience the allergy
what is the MOA of the local anesthetics? - CORRECT ANSWER - block Na+ channels in
nerves.
