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Posts Tagged ‘lignocaine’

Human body is a collection of trillions of cells.  Life  is nothing but , a bundle of energy flowing across each of these cells  .Every  organ  has a  specailised mode of communication among themselves and others. When a cell is in an excited state , there is a  likelihood of spontaneous electrical activity.This can happen in nerve cells, cardiac cells , GI tract,  or virtually in  any cell  which has a porous cell membrane and ionic fluxes across it .

  • Each cell membrane has a resting membrane potential . It  varies between -60 to – 90mv in most cells. When this potential increases there a propensity for  arrhythmias in heart  and convulsions in the brain , peristalsis in intestines and so on .
  • Drugs  like local anesthetic lignociane acts by blocking the  Na+ channels and there by neural activation .Similarly magesium  acts on these channels to reduce the excitability of these cells.
  • We know,  the sharp ascending stroke of cellular  action potential is mediated by Na + .Blockage of this channel blunts the action potential voltage and thus  the  early and late after depolarisation is prevented
  • Magnesium sulphate’s anticonvulsant action is directly  attributable  to this membrane stabilising action

Thus , membrane stabilising action  can be termed as “membrane sedating”  action

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Lignocaine , probably has saved more lifes  world over  than any other cardiac drug .

It was the only choice for ventricular tachycardia  till 1990s, both in pre and post  thrombolytic era.Every coornary care unit has reverted tens of thousands of  unstable VTs with this simple and cheap intravenous drug.the utility value of lignocaine is not limited to ischemic VT alone it is effective in in almost all forms of VT.It was classically administered in two or more boluses followed by an infusion.

What happened to this wonder drug  with great performance record ?

The  power of   statistics , and inappropriate interpretation by the scientific community  has left a serious blow to this wonder drug .Now the drug has been made redundant, and mainstream cardiac literature has made everyone feel  guilty , if  anybody  uses this drug for VT .

Why did lignocaine lose the battle ?  The reason is three fold

  1. The advent of  much fancied Amiodarone
  2. One negative study  for antiarrhythmic drugs in post MI period (CAST) 
  3. And two so called  positive studies  for Amiodarone (ALIVE & ARREST) has sounded the death bell for this drug  which has resuscitated millions of life !

CAST study http://content.nejm.org/cgi/content/abstract/321/6/406 

All , CAST  said was routine suppression of  asymptomatic ventricular arrhythmias  in the post MI period is unwarranted. But you know , how this  world interpreted it  “Lignocaine  has no role in ventricular arrhythmias in post MI setting ”  The most funny thing  was  lignocine was never used in CAST study .

The  studies involving one to one comparison  of Lignocaine and Amiodarone (ALIVE and ARREST study) was also not interpreted  properly.These studied only shock resistant VTs. What about the role of lignocaine where defibrillator was not available ?

Link to ALIVE and ARREST  read and make your own conclusion.

http://content.nejm.org/cgi/content/abstract/346/12/884

http://content.nejm.org/cgi/content/full/341/12/871?ijkey=8fa241f3cebb86a177632ec6ccadfb5a3ded7bc2

 Final message

  • Lignocaine is not  only a topical anesthetic  , it is powerful and gentle myocardial anesthetic when administered in post MI period.
  • With this property it  successfully cardioverts and prevents dangerous ventricular arrhythmias.
  • Time tested and worthiness proven.
  • While , we are made to believe  the success rate of  Amiodarone in VT is far superior than ligncaine .It is a falsehood.
  • Any experienced cardiologists will recognise ,  many times even  Amiodarone resistant VTs often respond to Lignocaine .
  • The fact of the matter is , without a good quality  one to one study  , lignocaine was ditched. One reason for this could be  Lignocaine ,  is a generic drug and has no market value.

Let us take home , the message (scientific or unscientific ! ) Lignocaine still has a great role to play in the management of dangerous ventricular arrhythmias .The only caution is ,  it should not be used routinely and indiscriminately in all asymptomatic patients with  VPDs or nonsustained VT . (Acknowledging CAST conclusion.)

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