Comparison of the Intravenous and Epidural Administration of Tumor Necrosis Factor-alpha Antagonists in an Experimental Rat Pain Model

INTRODUCTION: Inflammatory cytokines secreted from the nucleus pulposus are thought to lead to lumbar nerve root compression-like symptoms. Tumor necrosis factor-alpha (TNF-α), an inflammatory cytokine, likely plays an important role in lumbar disc hernia-related leg pain. In this experimental study, we compared the effectiveness of TNF-α antagonists administered through the intravenous or epidural route in lumbar spine pathologies. MATERIALS AND METHODS: After ethics committee approval had been obtained, 24 Sprague Dawley male rats aged 70–90 days and weighing 250–300 g each were allocated to four groups. In Group I, only the surgical procedure was performed; in Group II, 1 ml of saline solution was administered into the epidural field; in Group III, 10 mg/kg of infliximab was administered into the coccygeal vein; and in Group IV (epidural group), 25 mg of etanercept was administered into the epidural region. RESULTS: When the left leg pull values were analyzed on day 14, whereas there was not a significant difference among the three groups, a decreasing difference was observed in Group IV (P < 0.05). When the 21(st) and 28(th) day left leg pull values were compared between groups, the values from Groups II, III, and IV were significantly lower than those of Group I (P < 0.05). CONCLUSION: The absence of a difference between the baseline values and left leg pull values on days 14, 21, and 28 in Group IV indicates that recovery began on day 21 with the epidural administration of etanercept. There was no difference between intravenous saline administration and intravenous infliximab administration with regard to the start of the recovery. In the present study of rats with discopathy, TNF-α antagonists administered epidurally led to earlier recovery from radiculopathy-related allodynia compared to intravenous administration.