Why would statin medications contraindict with the lupus medications ?

Statins and lupus: Some studies indicate statins would be beneficial in lupus as this autoimmune disease accelerates atherosclerosis or plaquing of the arteries. However some animal studies have shown the oppisite effect. There is a human clinical study going on right now to evaluate the side effects. The contraindication has been that it increases muscle pain and weakness in lupus patients, Hope this helps

?: The liver is responsible for metabolizing and eliminating medications. Sometimes if two drugs are competing for the same metabolic pathway for elimination the blood level of one may go too high. In other cases one drug can speed up the elimination of another and it's blood level can go too low. Methotrexate doesn't list any interactions with most statins, so there shouldn't be a contraindication.