Methotrexate in rheumatic diseases.

Methotrexate is a medicine used to suppress the immune system. When the immune system is not working properly, it can cause diseases. It has been used in the treatment of rheumatoid arthritis since the 1980s. It is believed that Methotrexate increases adenosine – a substance that inhibits inflammation – in the body.

Methotrexate can be taken orally (liquid or tablets) or as an injection. It is usually taken once a week; I recommend taking it after supper so patients feel less nausea, which is one of the most common side effects.

Methotrexate has been proven to slow the progression of disease in several studies and it possibly does so in about 50% of patients. In other studies, it has been shown to improve symptoms and signs of rheumatic diseases. It also has a low incidence of side effects when used at the doses used fro rheumatic diseases. Overall, the American College of Rheumatology recommends the use of Methotrexate first for most moderate to severe cases of rheumatoid arthritis.

Other possible side effects include: mouth sores; hair loss (uncommon); bone marrow and liver toxicity (for which patients are asked to do frequent laboratory monitoring); lung reaction; rash; and lymphoma (possibly higher incidence due to disease, no medications).

Methotrexate should not be used with medicines such as Septra or Probenecid.

It is contraindicated during pregnancy and should not be used 6 months prior to conception.

It does not damage the kidneys, but because it is excreted through the kidneys, it should be avoided in patients with severe renal damage.

Laboratories should always be taken the day before, or the morning of, the day when the patient takes Methotrexate.

Adahli E. Massey, MD, FACR