Spinal gabapentin is antinociceptive in the rat formalin test

Gabapentin is a novel anticonvulsant that may be of value for the relief of clinical pain. To determine whether gabapentin is antinociceptive after spinal administration, the drug was given via an intrathecal catheter in doses from 6 to 200 mu g/rat 10 min prior to intraplantar formalin. Five percent formalin injected subcutaneously in the right hind paw produced a biphasic reaction consisting of flinching and licking behaviors (phase 1, 0-10 min; phase 2, 10-60 min). Gabapentin dose-dependently reduced the numbers of flinches and the duration of licking during phase 2 of the formalin test. The highest dose of gabapentin (200 mu g/rat) did not affect the tail-flick response. These results demonstrate that spinal gabapentin is antinociceptive in the formalin test. (C) 1997 Elsevier Science Ireland Ltd.