Background Surgeries causing nerve injury can result in chronic
neuropathic pain, which is clinically managed by using
antidepressant or
anticonvulsant drugs. Currently, there is a growing interest for investigating preemptive treatments that would prevent this long-term development of
neuropathic pain. Our aim was to compare
analgesic drugs using two distinct treatment modalities: either treatment onset at surgery time or following a couple of weeks of
neuropathic pain. Methods In male C57BL/6J mice,
neuropathic pain was induced by cuffing the sciatic nerve, and
allodynia was assessed using von Frey filaments. We tested the effect of
anticonvulsants (
gabapentin 10 mg/kg and
carbamazepine 40 mg/kg),
antidepressants (
desipramine 5 mg/kg,
duloxetine 10 mg/kg, and
fluoxetine 10 mg/kg),
dexamethasone (2 mg/kg), and
ketamine (15 mg/kg). Drugs were injected daily or twice a day, starting either at surgery time or on day 25 postsurgery (15 days of treatment for
antidepressants and 10 days for other drugs). Results
Ketamine was the only effective treatment during the early postsurgical period. Although early
anticonvulsant treatment was not immediately effective, it prevented chronification of
allodynia. When treatments started at day 25 postsurgery,
desipramine,
duloxetine, and
anticonvulsants suppressed the
mechanical allodynia. Conclusions Our data show that
allodynia measured in experimental
neuropathic pain model likely results from a combination of different processes (early vs. late
allodynia) that display different sensitivity to treatments. We also propose that early
anticonvulsant treatment with
gabapentin or
carbamazepine may have a prophylactic effect on the chronification of
allodynia following nerve injury.