Anti-inflammatory activity of silymarin in patients with knee osteoarthritis. A comparative study with piroxicam and meloxicam.

OBJECTIVE To evaluate the anti-inflammatory effect of Silymarin in patients with knee osteoarthritis (OA) in comparison with piroxicam and meloxicam. METHODS A double-blind clinical trial was performed at the Department of Rheumatology, Baghdad Teaching Hospital, Baghdad, Iraq during the period from October 2004 to September 2005, in which 220 patients (79 males and 141 females) with painful knee osteoarthritis were randomized into 5 groups, treated with either silymarin (300 mg/day), piroxicam (20 mg/day), meloxicam (15 mg), or a combination of silymarin with piroxicam or meloxicam. Serum levels of interleukin-1 alpha, interleukin-8, and the complement proteins C3 and C4 were assessed at zero time, and after 8 weeks. RESULTS Silymarin reduces significantly serum levels of IL-1 alpha and IL-8, C3 and C4 after 8 weeks compared to the pre-treatment levels. Piroxicam showed no significant reduction in IL-1 alpha levels, while IL-8 decreased significantly, compared to pre-treatment value. Meloxicam elevates serum levels of IL-1 alpha significantly, while IL-8 did not significantly change compared to the pre-treatment value. Piroxicam or meloxicam produced slight, non-significant increase in serum levels of complement proteins after the 8-week treatment period. Adjunct use of silymarin with piroxicam results in significant reduction in both cytokines (IL-1 alpha and IL-8), and serum levels of C3 and C4. However, its adjunct use with, meloxicam did not reveal any significant changes in this respect. CONCLUSION Silymarin reduces the elevated levels of interleukins and complement proteins, when used alone, or in combination with NSAIDs for the treatment of knee OA.