Evaluation of the cinical use of silymarin in knee osteoarthritis: application of the dual inhibitory concept of cyclooxygenaseand 5-lipoxygenase

ABSTRACT

Many compounds from natural sources, including silymarin, proved to have effective inhibitory effects on cyclooxygenase [COX] and 5-lipoxygenase [5-LO] in vitro qnd experimental animals. The exellent phannacological pre-clinical profile of these compounds indicates a broad range anti- inflammatory effectiveness devoid of the most troublesome side effects, which have at least impart impaired the clinical use of the classical COX inhibitors, including the newer selective COX-2 inhibitors. This project designed to evaluate the clinical utility of silymarin, as a dual inhibitor of COX and 5- LO, as a single agent or in combination with non-steroidal anti-inflammatory drugs [NSAIDs] of both types, selective and non-selective COX inhibitors, in the treatment of knee osteoarthritis [OA]. Randomized, double blinded clinical study was performed on 220 patients who have symptomatic and radiologic evidence of painful OA of the knee. Patients were allocated into five groups, treated with either meloxicam [15mg/day], piroxicam; [20mg/day], silymarin [300mg/day] + pirtxicam [20mg/day], silymarin [300mg/day] + meloxicam [15mg/day] or silymarin [300mg/day] alone. The treatment was followed for 8 weeks through measurement of the clinical effects of drugs each 7 days, using the Knee Injury and Osteoarthritis Outcome Score [KOOS] system. The results showed that silymarmn, when used alone or in combination with NSAIDs resulted in significant improvement in the components of KOOS, higher than that produced by meloxicam or piroxicam when each used alone. In conclusion, oral administration of 300mg/day silymarin in OA patients produced very well characterized analgesic and anti-inflammatory activities, and when co-administered with piroxicam or miloxicam improves their therapeutic profile