Methotrexate methotrexate in arthritis been used for the treatment of cancer for many years. It was found to be effective in psoriasis and psoriatic arthritis in the 1960s.
It is also used for a number of other forms of arthritis, including rheumatoid arthritis where it has an indication. Although there are not many studies demonstrating the efficacy of methotrexate in psoriatic arthritis, it is the drug of choice in this disease, particularly when both skin and joint manifestations are active. It is also the drug of choice when there is a significant joint involvement, even if the skin disease is mild. That is because in the clinical setting, methotrexate appears to work very well. The exact mechanism of action of methotrexate is unknown, but it is an antimetabolite, and therefore interferes with cell proliferation.