Methotrexate

Methotrexate (also known as Trexall and Rheumatrex) is used for treating certain types of cancer, severe psoriasis, or rheumatoid arthritis in certain patients. It may be used alone or with other medicines. Methotrexate is an antimetabolite. It works to treat cancer and psoriasis by blocking an enzyme needed for cell growth. This helps to slow the growth of cancer cells and abnormal skin cells. It reduces symptoms of inflammation (eg, pain, swelling, stiffness) caused by rheumatoid arthritis.

Methotrexate interferes with the growth of certain cells of the body, especially cells that reproduce quickly, such as cancer cells, bone marrow cells, and skin cells.

PRESCRIBED FOR: Methotrexate is used for cancer treatment generally in higher doses than for other uses and is often administered intravenously or intramuscularly. Methotrexate is used to treat psoriasis, an inflammatory skin disease, as well as the arthritis that occurs in 10 percent of these patients (psoriatic arthritis). It is also used to treat active rheumatoid arthritis in adults and children and other rheumatic diseases, including polymyositis and systemic lupus< erythematosus. Methotrexate has been used to induce miscarriage in patients with ectopic pregnancies.

DOSING: Methotrexate may be taken with or without food.

For rheumatoid arthritis and psoriasis, the dose of methotrexate is given WEEKLY, by injection or orally.

For psoriasis, the starting oral dose is a single 7.5 mg dose weekly or 2.5 mg every 12 hours for three doses, once weekly.

DRUG INTERACTIONS: Using nonsteroidal anti-inflammatory drugs (NSAIDs) before or during methotrexate treatment may result in serious adverse events because NSAIDS may increase the blood concentrations of methotrexate. Combining methotrexate with drugs that adversely affect the liver or kidneys may result in additional liver or kidney toxicity.

PREGNANCY: Methotrexate should not be used in pregnancy, as it can be toxic to the embryo and can cause fetal defects and spontaneous abortion (miscarriage). It should be discontinued prior to conception if used in either partner. Male patients should stop taking methotrexate at least 3 months prior to a planned conception and females should discontinue use for at least one ovulatory cycle before conception.

NURSING MOTHERS: Methotrexate is excreted in breast milk and should not be used by nursing mothers.

SIDE EFFECTS: Methotrexate can be well tolerated, but also can cause severe toxicity which is usually related to the dose taken. The most frequent reactions include mouth sores, stomach upset, and low white blood counts. Methotrexate can cause severe toxicity of the liver, kidneys and bone marrow, which require regular monitoring with blood tests. It can cause headache and drowsiness which may resolve if the dose is lowered. Methotrexate can cause itching, skin rash, dizziness, and hair loss. A dry, non-productive cough can be a result of rare lung toxicity.
Reference: FDA Prescribing Information