metotrexato (MTX) is a medicine used in the treatment of the psoriasis, rheumatoid arthritis (AR), psoriática arthritis, the dermatomiositis and some other diseases. In the beginning this medicine was used to treat different types from cancer, but at that time a high dose of which it is used nowadays, for the treatment of the AR was used much more.

The metotrexato has been used by more than 25 years in the treatment of rheumatoid arthritis, and in 1988 by FDA was approved in EE.UU (Food And Drug Administration), for its use in the AR of the adult.

The metotrexato alters the form in which the organism uses the folic acid, that is necessary for the cellular growth. Also it has effect like anti-inflammatory. By these two actions the MTX is beneficial in the treatment of the AR. This medicine belongs to the called medicine group: therapies of 2ª line or modifiers of rheumatoid arthritis (DMAR). These medecines can diminish the activity of the AR in a degree greater than aspirina and another antiinflammatories nonsteroids (AINES). Commonly the metotrexato one in association with the AINES. Generally it begins to act to the 3 weeks, but it can sometimes delay up to 3 months to reach his maximum effectiveness.

The metotrexato benefits a high percentage from these patients and as well it is tolerated commonly is used in the therapy of the AR, in association with another antiinflammatories. It diminishes the number of painful joints and fans in Rheumatoid Arthritis.

Mechanism of Action

Also call methotrexate is Medicine that interferes with the route of acid folic, when inhibiting nothing else competitively Dihidrofolato reductasa, preventing its activation to acid folínico .


It can cause Trombocitopenia, hepatic Fibrosis, Pancitopenia, Cirrhosis, Pneumonitis

When is used the Metotrexato?

The metotrexato is used in children and adults with active or progressive rheumatoid arthritis, although the FDA has only approved their use in adults. The initial treatment of the AR is with antiinflammatories (AINES) and physical therapy. Sometimes it will be necessary to add Steroids in low doses (Prednisona, Medrol, Azacortrid). The decision to begin metotrexato or any other of drugs of second line, is an important decision in the treatment of the AR. The decision to use this medicine will be based as much on opinions of the patient as of the doctor, in relation to the progression and activity of the disease. This therapy will begin if the patient has not responded to the antiinflammatories and other medecines of second line like the antimalarials (Plaquinol) or the injections of gold salts. Other times if the activity of arthritis is very severe perhaps the metotrexato Plaquinol or gold salts begins before use with.


It serves for the treatment as reumatoide Arthritis, neoplasias, Psoriasis, Youthful Rheumatoid Arthritis, Syndrome of Reiter, rheumatic Polimialgia, intestinal inflammatory diseases.

How is taken Metotrexato (MTX)?

The MTX is taken once to the week, in oral form or injection. The tablets are of 2,5 mgs; and the usual dose of beginning is of 2 to 3 tablets (5 to 7,5 mgs) to take only a day to the week. If the doctor is necessary will be increasing the dose through time, with a maximum permissible dose of 20 mgs once per week.

The dose increases gradually in case the activity of Arthritis persists. Doses majors of 20 mgs per week are used only very rarely.

The oral MTX takes everything in a single dose generally although sometimes if it is wanted are possible to be separated the doses and to take 2 or 3 times in 24 h, but always only once for week. Example: you can in the evening take all the medicine in the days Monday, or take half from the medicine in the morning of Monday and the rest in afternoon. Other times a day is even taken two parts and the rest in the morning of the following one, in this case divides to Monday and another part Tuesday. This is made generally in Psoriática Arthritis, since in this disease this form of treatment has more effect. In the AR it seems to give the same turn out to take it everything in a single taking, whenever there are not important indirect effect, like nauseas and vomits. Also the Metotrexato can be given in subcutaneous or intramuscular injection. The injectable route in people is used who are not responding to the dose by oral route or because they present/display stomach nauseas or annoyances. The MTX is not taken more frequently than a day to the week, since if it is taken more frequently it can produce serious secondary phenomena. It is necessary to take the medicine the same day every week not to be mistaken. A good idea is to mark in the calendar when the dose has been taken thus to make sure and not to be mistaken. In case of doubt he is better not to take the medicine and to call to the doctor.

Indirect effect

As all the medecines the MTX can also have indirect effect. Most common they are buccal stomach ache, nauseas, vomits, loss of the appetite, diarrhea and ulcers. If these problems appear it contacts his doctor immediately. A change in the dose or as to take the medicine it can reduce to l problem. Occasionally they can have headaches, mareos, alterations of the way as one feels, sarpullidos or even lost of weight. Also increase of sensitivity has been observed the sun, although he is little frequent. They can appear alterations in the examinations of laboratory. Especially it can have a diminution of white blood cells, which in some cases can facilitate the infections. A diminution of plaquetas can increase the tendency to the sangramiento or to the hematomas. Also it can have a diminution of red blood cells sometimes what can cause to fatigue and headache. Some of these indirect effect are more frequent in the people who have had problems to the kidneys, a level under folic acid and also with the concominante medecine use certain like sulfas. Rarely they can have problems to the lungs, taking place a pneumonitis.

It calls immediately to his doctor if it develops cough, progressive difficulty to breathe or fever. One of the problems most frequent is the possibility of hepatic damage, that it is detected with blood examinations. This is little frequent when low doses like the used ones for rheumatoid arthritis are used, unless the person drinks alcohol. By this it is necessary to avoid the consumption to regulate of spirits while the treatment with Metotrexato lasts.

How are monitored the indirect effect?

In order to avoid the indirect effect he is absolutely essential to make examinations of laboratory with the frequency that indicates its doctor to him. Before beginning the MTX use examinations become of blood of routine including examinations of the hepatic function. He is recommendable to make a x-ray of thorax. During the therapy with MTX examinations will become of blood in routine form. These will be more frequent in the beginning, but later 2 or 3 months will be made at least every, or before if there is some important secondary phenomenon. These examinations are made to evaluate the hepatic function and if there is some problem in the bony marrow that is reflected by the hemogram. If there are important toxic phenomena of the liver will be due to make a biopsy hepatic, which is very infrequent. If discútalo with its doctor has questions about this medicine.

Note: it is essential to become the examinations of laboratory in the dates that to him his doctor indicates and to return to consult the doctor in regular form, since many of these indirect effect can be detected precociously before serious and sometimes mortal complications are developed. The indirect effect indicate that it is necessary to change the dose or to suspend the medicine.

Can the women in age procreate to take Metotrexato?

The MTX can cause congenital effects if this medicine has been taken during the conception or the pregnancy. The women in age to procreate must use control systems of the natality and they do not have to be pregnant while they are taking MTX. After finishing taking this medicine the woman must at least wait for a menstrual cycle before trying to be pregnant. If it is possible, is recommendable to wait for a longer time. The Metotrexato does not have effects in the fertility, so it is possible to be pregnant while this medicine is being taken which would be serious, since the boy can be born with congenital defects. The lactancia must be avoided while Metotrexato is taken. In the man the number of espermios can fall, but these return to the normal thing once east medicine has been suspended. He is advisable that the man at least suspends to the MTX three months before planning the pregnancy of the wife.

Can the children with youthful rheumatoid arthritis take MTX?

The children with similar youthful rheumatoid (ARJ) arthritis or another arthritis can be dealt with MTX. The indirect effect are similar to those of the adults, although the added problem is that in high doses they can diminish the growth. The doses in the children calculate in relation to the weight of the body or with the corporal surface and the doses they are increased as the boy grows. The use of MTX in children with rheumatoid Arthritis causes that they feel better and than they have one better quality of life. They allow him to attend the school and to participate in the scholastic functions. Although in the United States the FDA has not tried the use of the Metotrexato in the ARJ this is used by the great majority of the rheumatologists of children.

How can be obtained the greater benefit with the use of the MTX?

To take any medicine in incorrect form can be in important indirect effect. In order to obtain the majors benefits with this medicine the following advice are due to follow:

. He learns more on the Metotrexato. He discusses east medicine with his doctor. He takes only the amount prescribed by his doctor. It remembers that this medicine is taken only once per week. It does not stop becoming the examinations of laboratory in the indicated date and it does not lack to the appointments with his doctor. It does not take other medecines when it is taking Metotrexato without asking his doctor to see if there are contraindications. If another doctor prescribes another medicine to him adviértale that is taking MTX. They do not have to take Sulfas when Metotrexato is taken. The Sulfas is used generally for the urinary infections and generally they have other names of fantasy (like Bactrimel) and so sometimes it is difficult to identify them.

She knows that she can have a folic acid deficit when You this taking MTX, are by this your doctor perhaps suggests to him to take folic acid every day. The folic acid can diminish the occurrence of buccal ulcers, annoyances gastrointestinal, diarrhea, headaches and even problems in the hemogram that can appear with the MTX. It does not drink alcohol. It communicates the doctor to him if You have: - Allergies to other medicines. - If it is taking other medicines including vitamins or other medecines bought without prescription. - If it has other medical problems, especially of the kidney, liver or lung. Any vaccine without being in agreement with its doctor is not put. The MTX can diminish the resistance of their organism and perhaps You have problems with the vaccine.

If You have influenza or if she has other infections she calls to his doctor quickly to see if she must continue taking Metotrexato during this disease. The dehydration (loss of flowed) can increase the risk of indirect effect.

Like other medecines, the use of MTX in rheumatoid Arthritis is not guarantee of which he will be effective for all the people. In spite of this, the majority of the Rheumatologists agrees in which when the MTX is used in appropriate form the benefits surpass greatly to the possible indirect effect. Conver with his doctor and it discusses the different alternatives from treatment of his disease. The communication between UD and its doctor is extremely important.

Loa cases that do not respond to a taken good treatment with MTX can be dealt now with new medecines that are excellent, but more expensive. Between these they are Leflunomide (ARAVA) and the Etanercept that is Anti-Factor de Necrosis Tumoral (ENBREL). Another medicine with mechanism similar to the Enbrel is Infliximab (REMICADE). This it is by endovenosa route and it is necessary to use it in association with MTX.

In experimental form in EE.UU a procedure similar to the called dialysis is used in some refractory cases to all other type of treatment (PROSORBA). This it allows to remove of the blood compound the antigen-antibody harmful to the organism.

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