ARTHROTEC 50 is effective in treating the signs and symptoms of rheumatoid arthritis and osteoarthritis. This activity is due to the presence of diclofenac which has been shown to have anti-inflammatory and analgesic properties. As with other non-steroidal anti-inflammatory drugs (NSAIDs), the exact mechanism of action of diclofenac is not known. However, it may be related to the ability of diclofenac to inhibit prostaglandin synthetase. Deadline