Methotrexate  (MTX).

Brand name: Rheumatrex.

What is Methotrexate. Methotrxate is an antimetabolite. It interferes with the uptake of essential nutrients by the body cells. This results in inhibition of the immune system causing decreased inflammation and slowing of the progress of the disease. Methotrexate was originally developed and is still used as a chemotherapeutic drug for the treatment of cancer.

Uses of Methtrexate.

It is used for treating the following conditions.

• Chemotherapy. This drug is used in treating cancers either alone or in combination with other drugs.
• Autoimmune diseases. Being an immunosuppressant (suppresses the immune system of the body), it has also found to be beneficial in the treatment of autoimmune diseases  like rheumatoid arthritis, psoriasis, psoriatic arthritis and Crohn’s disease.  However its doses for these diseases is small
• Pregnancy. It is used in the treatment of ectopic pregnancies. It is also used to terminate pregnancies (for medical reasons) in the early stages.

Methotrexate and Psoriasis.

It is used to treat severe forms of psoriasis and is taken orally. Due to its depressive action on the T cells of the immune system, it inhibits the overproduction of the skin cells (which is seen in psoriasis) and reduces inflammation. It is also beneficial in the treatment of psoriatic arthritis.

In psoriasis, it is used to treat various types of psoriasis mainly pustular psoriasis, erthyrodermic psoriasis and widespread plaque psoriasis and with good effect.

Methotrexate for Rheumatoid Arthritis.

Besides being an immunosuppresant by which it reduces inflammation and halts the progress of the disease, methotrexate also belongs to a class of drugs called  DMARDs (disease-modifying antirheumatic drugs). In treating rheumatoid arthritis, methotrexate  can be used alone or in combination with other DMARDs such as etanercept, inflixinab and adalimumab. Combination therapy gives better results.

Dose of Methotrexate.

It is given orally or by injection. Dosage of methotrexate varies and oral doses are given in weekly small doses of 5 mg to 15 mg. This is taken once a week either singly or in divided doses over 24 hour period.

Methotrecxate injections are also available. Injectable methotrexate can be given intramuscularly, intravenously, by subcutaneous route or intrathecal route. Methotrexate injections are also given in weekly doses.

Methotrxate Monitoring.

Certain blood tests are to be conducted on patients who are taking Methotrexate. These tests are to be done every month or quarterly. They include complete blood count, liver function tests and serum creatine.

When on Methotrxate , medical advice should be taken before taking penicillin  and sulpha based drugs.

Adverse Effects of Methotrexate.

Though tolerance to this drug in small doses is good, its side effects include an upset stomach, ulcerative stomatitis, fever, nausea, loss of appetite, hair loss (which is reversible after stopping methotrexate) and fatigue. It is also seen to adversely affect the production of blood cells such as the RBCs, WBCs and the platlets. Due to its suppressing action on the immune system, risks of infection are high.

Long term use of methotrexate can rarely cause some serious medical side effects such as liver damage. Due to this liver toxicity of methotrexate, alcohol should be avoided when on methotrexate and periodic liver function tests (monthly or quarterly) are sometimes advised. The teratogenic toxicity of methotrexate is explained below.

Rarely, it has been known to cause bone marrow depression and gastrointestinal disorders especially when used with NSAIDs. Use of Methotrexate with these drugs including aspirin is to be avoided.

Methotrexate and Pregnancy.

Methotrexate also has teratogenic toxicity – meaning it can harm or cause death of the developing fetus in the mother’s womb if the pregnant mother is taking methotrexate. It is therefore important that no conception takes place when on therapy with this drug and for a further three months after stopping this therapy. As methotrexate can affect the development of the sperms, similar  precautions should be taken by men also.

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