Methotrexate (MTX) is used in chronic inflammatory diseases such as rheumatism, psoriasis and Crohn's disease. In high doses, it can also be used as part of chemotherapy for the treatment of leukemia and other cancers.
The drug inhibits an enzyme in folic acid metabolism and thus interferes with the division of cancer cells and cells of the immune system that require folic acid for growth. Therefore, treatment with methotrexate can cause significant side effects: Often, gastrointestinal problems occur. It can also cause rashes and itching and liver and kidney damage.
Effect of methotrexate
Methotrexate belongs to the group of so-called cytostatic drugs and inhibits cell division in the body in the following way: In order for a cell to divide, it needs folic acid. The chemical structure of methotrexate is very similar to folic acid. As a result, methotrexate "fits" an enzyme that normally provides the cell with folic acid in the required form and blocks it. As a result, not enough folic acid is available to the cell and cell division is prevented.
For example, methotrexate is effective against cancer, as it prevents the growth of tumor cells. Second, it can be used against chronic inflammatory diseases, because in these so-called autoimmune diseases, the immune system fights cells of the body. Here methotrexate causes that the immune cells can not proliferate so much and slows down the course of the disease. However, the division of other cells of the human body is also slowed down, which can cause numerous side effects during ingestion.
Application and dosage
In rheumatism, the dosage ranges from 7.5 to 20 milligrams per week. In the treatment of psoriasis, the maximum dose is 30 milligrams, taking once a week as a tablet. When methotrexate is used to treat the chronic inflammatory bowel disease Crohn's disease, 15-25 milligrams are given as a syringe once a week.
In cancer therapy, methotrexate slows the growth of tumor cells. Considerably higher doses are used, which are calculated per square meter body surface. Depending on the type of disease, the maximum dose is up to 12,000 mg / m². A so-called rescue therapy must be carried out: an infusion with folic acid is added to alleviate the side effects.
Side effects of methotrexate
Methotrexate mainly affects cancer cells and cells of the immune system, as they divide very quickly. Nevertheless, other cells of the body are affected to a slight extent in the propagation, so it can sometimes come to strong side effects during ingestion.
The most common problems with taking Methotrexate include gastrointestinal complaints such as nausea, vomiting and diarrhea. In addition, inflammation of the mucous membranes in the mouth and throat as well as skin rashes, itching and light hypersensitivity may occur. Occasionally there is an increase in connective tissue (pulmonary fibrosis) or inflammatory changes (pneumonitis) in the lungs.
In addition, due to the suppression of the immune system, the susceptibility to infections and the risk of benign and malignant tumors increase. Especially at high dosages in cancer therapy kidney and liver can be damaged. For a complete list of the side effects of methotrexate, please refer to the package leaflet.
Contraindications to methotrexate
As with other drugs, methotrexate has a number of contraindications. For example, it may not be used if there is a hypersensitivity to the active substance, as well as in the following pre-existing conditions:
- Renal dysfunction
- liver disease
- Diseases of the bone marrow
- Immunodeficiency (AIDS)
- Ulcers in the gastrointestinal area
- alcohol addiction
Likewise, treatment with methotrexate should not take place during pregnancy and lactation.
Methotrexate may interact with many other medications. For example, concomitant use of anti-inflammatory analgesics (non-steroidal anti-inflammatory drugs, NSAIDs) such as ASA, ibuprofen or diclofenac may increase the risk of kidney damage as these agents are also eliminated via the kidney. If these painkillers are combined with methotrexate, for example, in rheumatism therapy, close medical supervision must therefore take place.
Some medicines such as the ointment Probenecid and some antibiotics such as penicillins, sulfonamides, tetracyclines and chloramphenicol affect the uptake, metabolism or excretion of methotrexate and may thus unintentionally alter the level of active ingredient in the blood. Therefore, always inform your doctor about all medications you are taking before beginning treatment! For a complete list of all interactions, please refer to the package leaflet.
Methotrexate and alcohol
Alcohol consumption during therapy with methotrexate increases the risk of liver damage and other adverse effects. As with many other active substances, you should therefore refrain from consuming alcohol during treatment with methotrexate. Excessive consumption of caffeine-containing beverages such as coffee, cola and black tea should also be avoided.
Methotrexate in pregnancy
Methotrexate should not be used during pregnancy as it damages the genome and can lead to miscarriage and severe developmental disorders in the unborn baby. During treatment, and six months thereafter, women and men of adult age should therefore pay attention to reliable contraception. If you have a desire to have children, tell your doctor about it before treatment.
As the active substance passes into breast milk, methotrexate must not be taken while breastfeeding.