Sickle cell anemia Methotrexate in Rheumatoid ahritis Methotrexate is now considered the first line DMARD agent for most patients with Rheumatoid ahritis. - Methotrexate is effective in reducing the signs and symptoms of Rheumatoid ahritis as well as slowing or halting radiographic damage. - It has relatively rapid onset of action at therapeutic doses good efficacy, .ourable toxicity profile, ease of administration and relatively low cost. - The antiinflammaory effect of methotrexate in rheumatoid ahritis appears to be related at least in pa to interruption of adenosine and possible effect on TNF pathways. Which DMARD should be the drug of first choice remains controversial and trials have .failed to demonstrate a consistent advantage of one over the other. - Despite this, methotrexate has emerged as the DMARD of choice especially in individuals with risk factors for the development of bone erosions or persistent synovitis of > 3 months duration because of its relatively rapidity of action, its capacity to effect sustained improvement with ongoing therapy and the higher level of patient retention on therapy. Methotrexate in Psoriasis Methotrexate is a plate antagonist. It causes reduction in cells reproductive abilities. Methotrexate affects cells which divides quickly. - In psoriasis cells divide more than usual. - Methotrexate binds to these cells and inhibits enzymes involved in rapid growth of skin cells. It is commonly used to stop the progression of psoriatic ahritis and less commonly used in the tit of severe psoriasis with no ahritis component. Methotrexate is an effective antipsoriasis agent. It is especially useful in. - Acute generalized pustular psoriasis. - Psoriatic erythroderma - Psoriatic ahritis and - Extensive chronic plaque psoriasis Methotrexate in Ankvlosing spondylitis Methotrexate although widely used has not been shown benefit in ankylosing spondylitis. - There is not enough evidence to be ceain of the benefit and harms of methotrexate for ankylosing sponylitis and more research is needed. In ankylosing spondylitis the use of methotrexate is not recommended for the axial manifestations. - The drug may have some efficacy in the peripheral involvement. - For this disease there is lack of clinical trials and most of the trials did not show efficacy on the axial symptoms of the disease.