Methotrexate

Methotrexate is used as a drug for chemotherapy in various malignant tumor diseases. It is a cytostatic agent that prevents cancer cells from dividing rapidly. The active ingredient is also used successfully not only in cancer therapy, but also as a basic therapeutic in chronic inflammatory processes.

What is methotrexate?

Methotrexate is also under the name Amethopterin known. As a cytostatic, methotrexate is a cell poison that prevents the natural rate of division of body cells, also known as mitosis. That is why the active ingredient is mainly used for tumor diseases of the blood-forming system with a high division rate.

As with all cytostatic drugs, healthy body cells are also affected to a certain extent when they are used, which can be noticeable for the patient through unpleasant side effects. There are different classes of cytostatics for tumor therapy and for the treatment of chronic inflammation.

Methotrexate is one of the so-called folic acid antagonists, which means that the active ingredient inhibits the enzyme dihydrofolate reductase, but this important enzyme is essential for cell division. Chemically speaking, methotrexate is very similar to folic acid and is therefore recognized by the organism like folic acid and introduced into the cell metabolism. Folic acid is urgently needed for the formation of DNA and RNA in the cell nucleus, but this formation can no longer be carried out by introducing methotrexate instead of folic acid.

Pharmacological effect

The pharmacological effects of methotrexate, in short MTX, extends to all organs and organ systems because of its systemic application. In addition to the desired pharmacological effect on rapidly dividing tumor cells, the active ingredient is always introduced into the metabolism of healthy cells as the wrong folic acid, which also limits their rate of division and thus causes functional disorders and side effects.

In addition to inhibiting the enzyme which is responsible for the introduction of folic acid into the cell metabolism, MTX also inhibits other enzymes. The most important among them is the enzyme thymidilate synthase. This endogenous protein component catalyzes the metabolic steps of pyrimidine synthesis, which is also required for the unhindered build-up of genetic material in the cell nucleus, i.e. DNA and RNA.

As a chemotherapeutic agent, methotrexate thus attacks several interfaces at the same time, so that the rate of division of tumor cells can be stopped. The active ingredient is mainly excreted via the kidneys and ultimately the patient's urine. This excretion process with the active substance methotrexate puts a considerable strain on healthy kidneys during chemotherapy. That is why constant monitoring of the kidney values, especially creatinine, is very important during chemotherapy with MTX. As soon as the values ​​indicate that there is a functional impairment of the kidneys, the therapy must be discontinued as a precaution to prevent terminal kidney failure, which can be life-threatening for the patient.

Medical application & use

Methotrexate, MTX, is a cytostatic agent and is therefore primarily known as a chemotherapeutic agent in cancer medicine. There very high, systemically effective doses of the drug, which is only available on prescription, are administered. The mechanism of action for fighting malignant tumor cells is based on the ability of methotrexate to greatly reduce the rate of proliferation of malignant cells.

However, methotrexate is not only a chemotherapy drug, but also an immunosuppressant. The cellular and humoral body defense is greatly reduced under the administration of methotrexate, the affected patients are therefore particularly susceptible to infections during a therapy cycle.

Good therapeutic success can also be achieved with the active ingredient methotrexate in the treatment of psoriasis and chronic rheumatic diseases. Methotrexate is considered to be helpful in the treatment of chronic rheumatoid arthritis. MTX is used as a basic therapeutic agent for this type of chronic inflammatory rheumatism.

In addition, there are other autoimmune diseases for which MTX promises good therapeutic success. These include, for example, multiple sclerosis, Crohn's disease and lupus erythematosus. In contrast to tumor therapy, MTX is only used in very low doses for all these diseases, which is why the side effects are significantly lower than in cancer therapy.

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Risks & side effects

Methotrexate is a highly effective cell poison that, strictly indicated, may only be used under medical supervision. Due to the direct intervention in the cell metabolism, the side effects are often very pronounced, especially in the treatment of malignant tumor diseases. During the therapy, the patients often suffer from general exhaustion, as well as from tiredness and headaches. The most common side effects include disorders of the gastrointestinal tract, which is due to the fact that the active ingredient methotrexate is also responsible for the undesired destruction of epithelial cells of the sensitive mucous membranes in the stomach and small intestine. It is therefore not uncommon for nausea, vomiting or inflammation of the mucous membranes to occur. These side effects cannot be prevented, at least temporarily, with high-dose therapy.

Due to the side effects of myelosuppression, the bone marrow also no longer produces enough blood cells, which can lead to anemia.

The greatest risk in therapy with MTX are pre-damaged kidneys, which can completely or partially stop their service and thus lead to a patient requiring dialysis. Absolute contraindications for the administration of methotrexate are pregnancy, breastfeeding, known renal insufficiency or immune deficiencies of any cause.