Ponstan. Two capsules of Ponstan (250mg), a drug for sufferers of rheumatoid arthritis. The active ingredient in this drug is mefenamic acid. Ponstan is a nonsteroidal anti-inflammatory drug (NSAID). Rheumatoid arthritis is the most severe type of inflammatory joint disease, in which the body's immune system acts against itself. The hands, feet, ankles, wrists, arms, hips and shoulders are commonly affected. The joints become extremely painful and often deformed. Treatment includes anti-inflammatory and painkilling drugs to relieve joint pain and stiffness. In severe cases, joint surgery may be required for rheumatoid arthritis sufferers.