Publication:

A comparative study of efficacy of gabapentin in inflammation induced neuropathic animal pain models with conventional analgesic diclofenac

Background Some antiepileptic drugs have been shown to be clinically efficacious in treatment of neuropathic pain and are being used by clinicians. This study is proposed to evaluate the efficacy of these drugs as compared to conventional analgesics.

Methods Formalin  test  has  been  used  as  the  model  of  acute and chronic  inflammatory  pain.  Formalin  has  been  characterized  by  the  occurrence  of  two  characteristic  phases  of  increased  pain  sensitivity  in  rats. The  test  drugs  have  been  administered  orally  and  scored  according  to  a  pain  scale.  Pain  has  been  quantified  by  counting  the  incidence  of  spontaneous  flinches,  shakes  and  jerks  of  the  formalin  injected  paw.  Analgesic  response  or  protection  has been  indicated  if  both  paws  are  resting  on  floor  with  no  obvious  favouring  of  injected  paw. Treatment  group  was  compared  with  appropriate  control  groups  using “student  t  test”.

Results Per oral administration of  gabapentin  produced  no  any  marked  effect  on  early phase  response  of  formalin  test  but  significantly  suppressed  the  late  phase  response  while  diclofenac  produced  significant  antinociceptive  effect  in  both  phases  of  formalin  test.

Conclusions Thus  we  have  observed  that  gabapentin   produced  antinociception  in  second  phase  of  formalin  test  which  reflects  chronic  inflammatory  pain.