Methotrexate: Uses, Dosage, Side Effects, Interactions

Methotrexate is a medication prescribed for certain types of cancers and is also used in treating conditions like rheumatoid arthritis, psoriasis, and also polyarticular juvenile arthritis. This medication comes under the category of Antimetabolites. It lowers immune system activity and inhibits progression of malignant cells. Methotrexate is also used for treatment of dermatological conditions like psoriasis. It does this by inhibiting skin cell growth to prevent development of scales on the skin surface. By inhibiting immune system activity, it may treat Rheumatoid arthritis. This medicine is available in the form of a tablet and also in powdered form which is to be mixed with liquid to be injected intramuscularly, intravenously, intra-arterially or intrathecally. Methotrexate can be found in under the brand names like Folex PFS, Rasuvo, Otrexup, Rheumatrex, Trexall, Xatmep, etc.

Read below to know about the uses, side effects and dosage of Methotrexate.

As mentioned above, methotrexate is a prescription medication that is used for treating the following conditions.

• Rheumatoid arthritis.
• Polyarticular juvenile idiopathic arthritis or PJIA.
• Severe psoriasis.
• Breast cancer.
• Lung cancer.
• Specific types of cancers of the neck and head.
• Non-Hodgkin lymphoma which is advanced.
• A variant of cutaneous T-cell lymphoma known as Advanced Mycosis fungoides.

This medication is also used to treat osteosarcoma which is still in the primary stage and has not spread to surrounding areas after surgery to remove the primary tumor. Methotrexate is used also in treating the following types of gestational trophoblastic tumors.

• Chorioadenoma destruens.
• Choiocarcinoma.
• Hydatidiform mole.

There are also other conditions which might require you to use Methotrexate. Ask your doctor or pharmacists to know more about it.

Oral or injectable dosage of Methotrexate must be taken as prescribed by your doctor. You must follow the directions on your prescription labels very carefully. Your doctor recommends you the doses of Methotrexate based on factors like the medical condition that is being treated, your age, gender, heigh and weight, any other medical condition you have, other medications that you are taking and how you respond to methotrexate medication, etc.

The dosage of Methotrexate for some of the conditions, includes the following.

• Dosage of Methotrexate For Rheumatoid Arthritis. Oral formulation at 7.5 mg once a week or 2.5 mg at 12 hour intervals for 3 doses, given as a course, once in a week.
• Dosage of Methotrexate For PJIA. Once a week at 10 mg/m2.
• Dosage of Methotrexate For Psoriasis. once a week at 10 to 25 mg orally or as an injection in to the muscle, just under the skin or in to the vein; or 2.5 mg at 12 hour intervals for 3 doses.
• Dosage of Methotrexate For Leukemia. When used for induction, the recommended tablet dose is 3.3 mg/m2 given regularly. Maintenance therapy is methotrexate tablets taken twice weekly orally, in total weekly doses of 30 mg/m2.
• Dosage of Methotrexate For Lymphoma. The recommended dosage is 10 mg to 25 mg/day orally for 4 to 8 days. Lymphosarcomas in stage III, may respond to combined drug therapy with methotrexate when given in doses of 0.625 to 2.5 mg/kg regularly.
• Dosage of Methotrexate For Choriocarcinoma and Similar Trophoblastic Diseases. 15 mg to 30 mg orally on a daily basis, for a, 5 days of course. Such courses are usually repeated 3-5 times as required.
• Dosage of Methotrexate For Mycosis fungoides or cutaneous T cell lymphoma. Dosage in early stages is usually 5 mg to 50 mg, once in a week. Methotrexate has also been administered two times in a week in doses ranging from 15 mg to 37.5 mg, in those who have poorly responded to the weekly therapy.

Note. In case of methotrexate overdose, or if you take too much of this medication, then call your healthcare provider or local poison control center or seek emergency medical attention on an immediate basis.

Below are some of the side effects of methotrexate. Consult your doctor in case you notice any of the symptoms because of the medication.

• Dizziness, drowsiness.
• Headache.
• Swollen and tender gums.
• Reddened eyes.
• Reduced appetite.
• Hair loss.

There may also be some serious side effects of Methotrexate. Below are some of them.

• Vomiting.
• Sudden fevere, severe headache and stiff neck.
• Blurred vision or sudden vision loss.
• Seizures.
• Difficulty walking or unsteady walking.
• Confusion or memory loss.
• Weakness or difficulty moving one or both the sides of the body.
• Loss of consciousness.
• Decreased urination.
• Impaired speech.
• Hives, itching, skin rashes.
• Swelling of the face, hands, arms, feet, ankles or lower legs.
• Difficulty breathing or swallowing.

Make sure you need to consult your doctor in case of any such side effects of methotrexate.

Let your doctor know about all the medicines that you are taking with methotrexate for your condition. Tell your doctor if you take NSAIDs like aspirin, ibuprofen, naproxen or salsalate etc, acitretin, azathioprine, tretinoin, isotretinoin, sulfasalazine, chloramphenical, penincillin, tetracycline, folic acid, sulfadiazine, probenecid, phenytoin, co-trimoxazole, sulfisoxazole, theophylline etc. It must be noted that this is not the list of complete methotrexate drug interactions. Do ask you doctor for more information on this.

Medciaitons can also interact with certain types of foods. In some cases, it may be harmful and your doctor may advice you to avoid specific foods. However, in case of methotrexate, there are no specific foods that you must avoid while taking the medication.

Tell your doctor in case you are pregnant or planning to become pregnant before starting methotrexate. Methotrexate may cause death or serious harm to your unborn baby in the womb. Apart from this, you should also not breastfeed your baby while taking methotrexate, as it is excreted into human breast milk and can harm your lactating baby.

• Do not take alcohol while taking this methotrexate. Alcohol can increase the risk of liver problems with methotrexate.
• Do not take NSAIDS like aspirin, naproxen or ibuprofen with methotrexate without first checking with your doctor.
• Talk to your doctor before receiving vaccinations when taking methotrexate.
• Methotrexate may lower the number of WBCs in your blood and this may increase the risk of getting an infection. Avoid people with any known infections. Avoid touching your nose or eyes and wash your hands often.
• Methotrexate may increase your risk of bleeding by lowering the number of platelets in your blood. Tell your doctor immediately in case you notice any unusual bleeding or bruising.
• Methotrexate may cause dizziness or also may make you feel drowsy. So, do not drive or operate machinery until you know how methotrexate affects your body.
• Methotrexate may make your skin sensitive to sunlight or UV light. In case you have psoriasis, your sores may get worse if you expose your skin to sunlight while you are taking the methotrexate medication. So, avoid prolonged exposure to sunlight or UV light or wear protective clothing and sunglasses while you are outside.
• Do not take methotrexate in case you are pregnant or are breastfeeding.
• In case you have immunodeficiency syndromes along with RA or psoriasis, then avoid taking methotrexate.
• Do not take methotrexate if you have alcoholic liver disease or any other chronic liver disease
• Do avoid this if you have a known hypersensitivity to Methotrexate.

In case you have pre-existing blood dyscrasias like bone marrow hypoplasia, leucopenia, thrombocytopenia along with psoriasis or RA, then do avoid methotrexate.

Inform your medical professional in case you have medical conditions like allergy to the drug or any of its ingredient, if you have low blood folate levels, or in case you are having surgery that includes dental surgery.

Note. Before taking Methotrexate, tell your doctor about all the medicines you are taking including the prescription medicines, OTC, vitamins and herbal supplements.

Below are some other precautions you must follow.

• Store the oral methotrexate medication at room temperature, protect it from light, and keep out of reach of children.
• The injectable methotrexate medication must also be stored at room temperature; excursions permitted to 15 degrees to 30 degree c. They are also required to be protected from light.
• Retain the injectable methotrexate in carton until the time of use and discard the unused portion.

Now that we know about some of the uses, side effects and dosages of methotrexate; you must keep in mind while taking this medicine and also take effective precautions while using methotrexate. Let your doctor know about all other medicines you are taking including vitamins, herbal supplements that you are prescribed with the methotrexate medication for your condition.