Analgesic effect of Keishinieppiittokajutsubu on low barometric pressure-induced pain response in arthritic model rats

Rheumatoid arthritis (RA) is a disease that causes inflammation of joints, resulting in pain and swelling. Reduced barometric pressure induces painful symptom of RA, but there is no appropriate animal model and pharmacological evaluation. Keishinieppiittokajutsubu (KNEIJB), a Kampo medicine used to treat RA; however, its mechanism of action is not clear. Here, we found that KNEIJB suppressed the low barometric pressure (LP)-induced pain response in CFA-induced arthritic model rats. Furthermore, we found that KNEIJB reduced plasma IL-6 levels. These results suggest that KNEIJB might be beneficial in the treatment of RA or some other arthralgia induced by LP.