Effect of methotrexate
Methotrexate belongs to the group of so-called cytostatics and inhibits cell division in the body in the following way: In order for a cell to be able to divide, it needs folic acid. The chemical structure of methotrexate is very similar to folic acid. As a result, methotrexate “fits” into an enzyme that normally provides the cell with folic acid in the form it needs and blocks it. As a result, the cell does not have enough folic acid available and cell division is prevented.
On the one hand, methotrexate is effective against cancer because it prevents the growth of tumor cells. On the other hand, it can be used against chronic inflammatory diseases, because in these so-called autoimmune diseases, the immune system fights cells of its own body. Here, methotrexate prevents the immune cells from multiplying as much and thus slows down the course of the disease. However, the division of other cells in the human body is also slowed down, which is why numerous side effects can occur while taking it.
application and dosage
In rheumatism therapy, the dosage ranges from 7.5 to 20 milligrams per week. In the treatment of psoriasis, the maximum dose is 30 milligrams, which is taken as a tablet once a week . If methotrexate is used against the chronic inflammatory bowel disease Crohn’s disease, 15-25 milligrams are administered as an injection once a week. To simplify the injection, MTX pens are now available as an alternative to the syringe.
The prescribed dose or the frequency of intake should not be exceeded under any circumstances, as otherwise serious to life-threatening health effects are possible.
In cancer therapy, methotrexate slows down the growth of tumor cells. Considerably higher doses are used here, which are calculated per square meter of body surface. Depending on the type of disease, the maximum dose is up to 12,000 mg/m² (per square meter of body surface). A so-called rescue therapy must be carried out: an infusion of folic acid is administered to alleviate the side effects.
Taking folic acid supplements is also often prescribed for the treatment of other diseases in order to prevent a deficiency caused by taking methotrexate. However, folic acid should be taken at different times (usually 24 hours after taking MTX) so as not to reduce the effect.
Side effects of MTX
Methotrexate acts primarily on cancer cells and cells of the immune system, as these divide particularly quickly. Nevertheless, the reproduction of other cells in the body is also impaired to a small extent, which is why it can sometimes lead to severe side effects while taking it.
Very common side effects are:
- headache
- Cough
- dizziness
- diarrhea , abdominal pain, nausea or vomiting
- Ulcers in the throat and mouth
- Decrease in leukocytes (white blood cells) and/or thrombocytes (blood platelets)
- Higher liver function values
- hair loss
- Decreased excretion of creatinine by the kidneys
- feeling weak
The long-standing suspicion of a possible connection between methotrexate and the development of pulmonary fibrosis and inflammatory changes in the lungs (pneumonitis) has now been disproved. Nevertheless, lung problems such as coughing and shortness of breath can occur during therapy with MTX. In rare cases, a pulmonary embolism can also occur.
In addition, due to the suppression of the immune system, the susceptibility to infections and the risk of benign and malignant tumor formation increases. Kidneys and liver can be damaged, especially with high doses in cancer therapy. For a full list of methotrexate side effects, see the package leaflet or seek medical advice.
MTX: side effects on the psyche?
Taking MTX can lead to so-called central nervous side effects. These include feeling exhausted, tired, or light-headed . On the other hand, depression is also a possible side effect of methotrexate. This side effect on the psyche occurs in up to one in 100 people.
If the affected person develops depressive moods, a doctor should check to what extent other triggers, such as the stress caused by the illness, can be the cause or whether a direct connection between the intake of MTX and the occurrence of the symptoms is possible.
Contraindications for methotrexate
As with other active ingredients, methotrexate has a number of contraindications. For example, it must not be used if there is hypersensitivity to the active ingredient, or if you have the following pre-existing conditions:
- renal dysfunction
- liver diseases
- Bone Marrow Diseases
- immune deficiency (AIDS)
- Gastrointestinal ulcers
- infections
- alcohol addiction
Likewise, treatment with methotrexate must not be carried out during pregnancy and breastfeeding.
Possible interactions
Methotrexate can interact with many other medications. If you take anti-inflammatory painkillers (nonsteroidal anti-inflammatory drugs, NSAIDs) such as ASA , ibuprofen or diclofenac at the same time, the risk of kidney damage can be increased, since these active ingredients are also excreted via the kidneys. If these painkillers are combined with methotrexate in rheumatism therapy, for example, close medical monitoring is required.
Some drugs, such as the gout drug probenecid, and some antibiotics , such as penicillins, sulfonamides, tetracyclines, and chloramphenicol, affect the absorption, metabolism, or excretion of methotrexate and can thus unintentionally alter the levels of the drug in the blood. Therefore, always inform your doctor about all medications you are taking before starting treatment! For a full list of all interactions, please see the package leaflet.
methotrexate and alcohol
Alcohol consumption during methotrexate therapy increases the risk of liver damage and other adverse effects. As with many other active ingredients, you should therefore avoid drinking alcohol during treatment with methotrexate. Excessive consumption of caffeinated beverages such as coffee , cola and black tea should also be avoided.
In addition to alcohol, excessive consumption of drinks with caffeine or theophylline should also be avoided. These include caffeinated soft drinks , coffee, or black tea.
Methotrexate in pregnancy
Methotrexate must not be used during pregnancy as it damages the genetic material and can lead to miscarriage and serious developmental disorders in the unborn child. During the treatment and six months afterwards, women and men of sexual maturity should therefore ensure that they use reliable contraception. If you wish to have children, inform your doctor before the treatment.
Since the active ingredient passes into breast milk, methotrexate should not be taken while breastfeeding.
MTX in ectopic pregnancy
Methotrexate is also used to treat ectopic pregnancy. If the fertilized egg is implanted in the fallopian tube instead of the uterus, MTX acts on and kills the tissue surrounding the embryo. As a result, the embryo is also lost.
This treatment is an alternative to surgery and offers the advantage that the fallopian tube is not injured. However, it can only be used in a relatively early stage of pregnancy when the concentration of the pregnancy hormone HCG is not too high, the embryo and the tissue surrounding it are less than four centimeters and the affected person has not yet experienced any symptoms from the ectopic pregnancy. Whether therapy with MTX is possible will be clarified in consultation with the doctor treating you.
