Methotrexate +nitrofurantoin >>> excess risk of hepatic injury
Methotrexate induced marrow supression >>> ttt by folinic acid …folic acid is used for prevention .
In patients with RA and positive ANA >>> do not use sulfasalazine with methotrexate to induce remission ( use hydroxychloroquine ) as there is a risk for lupus and significant skin reaction .
Mesalazine + azathioprine >>> significant risk of pancreatitis .
Do not combine azathioprine with allopurinol >> significant marrow supression , if needed , reduce dose of azathioprine .