薬理と治療

Abstract

Background　Low back pain is the prevalent disease worldwide. A nonprotein extract isolated from inflamed skin of rabbits inoculated with vaccinia virus （Neurotropin®）and duloxetine are effective analgesics for low back pain. But the combined effect of Neurotropin and duloxetine for low back pain was not known. Objectives　In this study, we examined combined analgesic effect of Neurotropin and duloxetine in low back pain model rats such as nucleus pulposus（NP）implantation model and intervertebral disc（IVD）puncture model. Methods　Adult male Wistar or SD rats were used. NP implantation model were made by application of NP on nerve root and dorsal root ganglion. IVD puncture model were made by needle puncture in lumbar L5/L6 IVD using the 24-gauge needle. In each low back pain model, Neurotropin and duloxetine were orally administered to match the peak analgesic effects, and were orally administered simultaneously. Then analgesic effects were evaluated with 50％ withdrawal threshold using von Frey filaments. Results Neurotropin and duloxetine showed a dose︱dependent analgesic effect in both model rats. The combined analgesic effects of Neurotropin and duloxetine were additive in both model rats, and simultaneous administration of Neurotropin and duloxetine showed rapid onset and prolonged analgesic effects compared with either drug administration in both model rats. Conclusions　In this study, combined administration of Neurotropin and duloxetine was effective for low back pain model rats. These results suggest that combination of Neurotropin and duloxetine may be useful for the treatment of low back pain.