Antinociceptive effects of intrathecal cimifugin treatment: a preliminary rat study based on formalin test.

Background: Cimifugin is one of the components of the root of . The extract derived from is traditionally used as an analgesic. This study was conducted to evaluate the analgesic effect of intrathecal cimifugin in the formalin test.

Methods: Male Sprague-Dawley rats (n = 20) were randomized into four groups for intrathecal administration of 70% dimethylsulfoxide and various doses of cimifugin (100 μg, 300 μg, and 1,000 μg). The typical flinch response after the injection of 5% formalin into the hind paw was assessed in two distinct phases: phase 1 until 10 min, and phase 2 from 10 min to 60 min. ED values were calculated via linear regression.

Results: Intrathecal cimifugin significantly reduced the flinch response in both phases of the formalin test. Significant antinociceptive effects of cimifugin were found with the dose of 300 μg in phase 1 and the dose of 100 μg in phase 2. The ED value (95% confidence intervals) of intrathecal cimifugin was 696.1 (360.8-1,342.8) μg during phase 1 and 1,242.8 (42.0-48,292.5) μg during phase 2.

Conclusions: Intrathecal cimifugin has an antinociceptive effect against formalin-induced pain. Cimifugin has an anti-inflammatory effect at low concentrations, and non-inflammatory analgesic effect at higher concentrations.