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.