RT Book, Section
A1 Keddis, Robert N.
A2 Atchabahian, Arthur
A2 Gupta, Ruchir
SR Print(0)
ID 57262333
T1 Chapter 120. Local Anesthetics and Adjuvants
T2 The Anesthesia Guide
YR 2013
FD 2013
PB The McGraw-Hill Companies
PP New York, NY
SN 978-0-07-176049-2
LK accessanesthesiology.mhmedical.com/content.aspx?aid=57262333
RD 2024/04/19
AB Weak  bases,  hydrophilic,  tertiary  amines  that  block  voltage-gated  Na+  channels,  preventing  depolarizationSensitivity  of  nerve  fibers  to  blockade:  More  sensitive:  small  diameter  and  lack  of  myelinSpinal  and  peripheral  nerves:  autonomic  >  sensory  >  motorOnset/duration  of  action:  Unionized  (uncharged)  form:  lipid-soluble,  crosses  membranesIncreased  lipid  solubility  =  decreased  onset  time,  increased  duration,  increased  potencyIncreased  concentration  and  total  dose  =faster  onsetSite  of  injection:  more  vascularized  means  shorter  duration  due  to  systemic  uptakeNote:  Epinephrine  is  frequently  added  to  increase  duration  of  blockade;  however,  it  is  unstable  in  alkaline  conditions:  Bottles  containing  epinephrine  have  an  acidic  pH  =  slower  onset  than  when  epinephrine  added  extemporaneouslySystemic  vascular  absorption  (greatest  to  least):  Intercostal  nerve  block  >  caudal  >  epidural  >  brachial  plexus  >  sciatic–femoral  >  subcutaneousDivided  into  two  groups:  Amides  (mnemonic:  have  two  I's  in  the  name):  Metabolized  in  the  liver;  liver  disease  can  increase  duration  and  toxicityEsters:  Mostly  metabolized  by  pseudocholinesterasePseudocholinesterase  deficiency  severely  prolongs  duration;  avoid  in  these  patients