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Methotrexate by Pharmascience
How does this medication work? What will it do for me?
Methotrexate is used to treat certain types of cancer such as leukemia, non-Hodgkin’s lymphoma, breast cancer, head and neck cancer, stomach cancer, bladder cancer, bone cancer, and choriocarcinoma (a type of uterine cancer). It is also used to treat rheumatoid arthritis, psoriatic arthritis, and psoriasis (a chronic skin disorder that produces patchy scales) when other treatments have not provided a satisfactory result.
When used to treat cancer, methotrexate works by blocking an enzyme process in cancer cells so they cannot grow. Used for this purpose, methotrexate is known as an anti-metabolite.
For rheumatoid arthritis, it works by reducing inflammation and by suppressing the immune system. For psoriasis, methotrexate works by attacking the rapidly dividing cells that are involved in causing psoriasis. Under these circumstances, methotrexate is known as a disease-modifying antirheumatic drug (DMARD).
This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.
Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.
Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.
What form(s) does this medication come in?
Each mL of solution contains 25 mg of methotrexate sodium. Nonmedicinal ingredients: sodium chloride, water for injection, and sodium hydroxide to adjust pH.
How should I use this medication?
Cancer: The dose of methotrexate varies depending on the type of cancer being treated and body weight or size. Your doctor may recommend either the tablet or injectable form of this medication.
If your doctor recommends the injectable form of methotrexate, the appropriate dose is usually injected one or more times weekly, either in cycles (i.e., some weeks no injections are given) or on a regular basis, depending on the type of cancer being treated. The tablet form of the medication can be given twice a week or daily, depending on the type of cancer being treated.
Rheumatoid arthritis: The usual adult dose of methotrexate is 7.5 mg taken as one dose once weekly by mouth or 2.5 mg taken every 12 hours for 3 doses once weekly. Doses are sometimes adjusted gradually according to response but are usually no more than 20 mg weekly. The benefits of treatment usually appear about 3 to 6 weeks after starting the medication.
Psoriasis: The usual adult starting dose of methotrexate is 10 mg to 25 mg per week in one dose (tablet or injection) or 2.5 mg (tablet) to 5 mg taken every 12 hours for 3 doses once weekly. Doses can be adjusted gradually but are usually no more than 30 mg weekly.
Methotrexate tablets may be taken with or without food. Your doctor may want you to drink extra fluids while you are taking this medication in order to help pass the drug from the body and to prevent kidney problems.
Many things can affect the dose of medication that a person needs, such as age, body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor because there may be specific reasons why it is different.
It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and contact your doctor for advice on when to take the next dose. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.
If you miss an appointment to receive the injection form of this medication, contact your doctor as soon as possible to reschedule your appointment.
Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.
Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.
Who should NOT take this medication?
Do not use this medication if you:
- are allergic to methotrexate or any ingredients of this medication
- have severely decreased renal function
- are breast-feeding
- are pregnant
Additionally, do not use this medication for rheumatoid arthritis or psoriasis if you:
- have a history of alcohol abuse or alcoholic liver disease
- have chronic (long-term) liver disease
- have an immunodeficiency syndrome (e.g., HIV)
- have anemia or other blood diseases
- are pregnant or are planning on becoming pregnant, or your partner is
- are going to be receiving nitrous oxide anaesthesia
What side effects are possible with this medication?
Many medications can cause side effects. A side effect is an unwanted response to a medication when it is used in normal doses. Side effects can be mild or severe, temporary or permanent.
The side effects listed below are not experienced by everyone who uses this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.
The following side effects have been reported by at least 1% of people using this medication. Many of these side effects can be managed, and some may go away on their own over time.
Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.
- abdominal pain
- decreased blood pressure
- hair loss
- loss of appetite
- loss of sexual interest or ability
- muscle or joint pain
- upset stomach
Although most of the side effects listed below don’t happen very often, they could lead to serious problems if you do not seek medical attention.
Check with your doctor as soon as possible if any of the following side effects occur:
- blurred vision
- cough or hoarseness
- fever or chills
- mood changes
- mouth sores
- pinpoint-sized red spots on skin
- ringing in the ears
- sensitivity to sunlight
- signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
- signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don’t stop bleeding)
- signs of infection (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
- signs of heart problems (e.g., fast, irregular heartbeat or pulse; chest pain; sudden weight gain; difficulty breathing; leg swelling)
- signs of kidney problems (e.g., decreased urination, nausea, vomiting, swelling of the feet and ankles, blood in the urine)
- signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
- signs of lung damage (e.g., difficulty breathing, fatigue, persistent dry cough)
- skin rash
- sore eyes
- stomach pain
- weight loss
Stop taking the medication and seek immediate medical attention if any of the following occur:
- severe headaches
- signs of bleeding in the stomach (e.g., bloody, black, or tarry stools; spitting up of blood; vomiting blood or material that looks like coffee grounds)
- signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort
- symptoms of leukencephalopathy (e.g., seizures, vision loss, trouble thinking clearly, difficulty walking)
- symptoms of a severe allergic reaction (e.g., hives; difficulty breathing; swelling of the face, mouth, tongue, or throat)
Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.
Are there any other precautions or warnings for this medication?
Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Anemia: Methotrexate may cause low levels of red blood cells. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, feeling unusually tired, or pale skin, contact your doctor as soon as possible.
Bleeding: Methotrexate may cause a reduced number of platelets in the blood, which can make it difficult to stop cuts from bleeding. If you notice any signs of bleeding, such as frequent nosebleeds, unexplained bruising, or black and tarry stools, notify your doctor as soon as possible. Your doctor will order routine blood tests to make sure potential problems are caught early.
Blood counts: Methotrexate can cause a decrease in the number of white blood cells, red blood cells, and platelets in your blood, especially when higher doses are used to treat cancer. This may increase your risk of bleeding or infections. Your doctor will monitor your blood counts with regular blood tests.
If you are using this medication to treat cancer and already have a blood disorder such as anemia, reduced white blood cell counts, or reduced platelet counts, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Cancer: This medication may cause lymphoma (cancer of the immune cells) that may resolve when the medication is stopped. Your doctor will monitor for this.
Dizziness/fatigue: This medication may cause dizziness and fatigue. Do not drive or operate machinery until you are certain that taking this medication does not impair your ability to safely perform these tasks.
Hepatitis B and C infection: Methotrexate can cause reactivation of hepatitis B and C infections or worsening of existing infections. If you have a history of infection with hepatitis B or C virus, let your doctor know before starting this medication.
Infection: As well as killing cancer cells, methotrexate can reduce the number of cells that fight infection in the body (white blood cells). If possible, avoid contact with people with contagious infections. Tell your doctor immediately if you notice signs of an infection, such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness.
If you are using this medication to treat rheumatoid arthritis and have an infection, talk to your doctor about whether you need to temporarily stop this medication until the infection resolves.
Kidney function: Reduced kidney function or kidney disease may cause this medication to build up in the body. If you have reduced kidney function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. If you are using this medication to treat cancer, your doctor may want you to drink extra fluids to help prevent kidney problems.
Liver problems: Methotrexate can cause liver problems. Your doctor will check your liver function with blood tests before starting this medication and regularly during treatment. If you have liver problems or reduced liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Do not drink alcohol while you are taking this medication as this can increase the chance of liver problems.
If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.
Lung problems: Lung inflammation (interstitial lung disease), causing difficulty breathing has occurred in some people taking this medication. This complication can be serious and sometimes fatal. If you experience new or worsening shortness of breath or non-productive cough (with or without fever) at any time while you are taking methotrexate, contact your doctor immediately.
Nausea: Methotrexate may sometimes cause nausea. If you feel ill after taking methotrexate, do not stop taking the medication without first talking with your doctor. Your doctor or pharmacist may be able to help you with ways to reduce the nausea associated with taking this medication.
Stomach and intestinal problems: If you have stomach or intestinal ulcers or ulcerative colitis, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Seizures: Methotrexate has been reported to cause a condition called leukoencephalopathy that often causes seizures. Leukoencephalopathy is a rare disorder that causes nerve damage in the brain. Other symptoms of this disorder include memory loss, vision loss, trouble thinking, or difficulty walking. If you experience any of these, contact your doctor immediately.
Sun sensitivity: You may be more sensitive to the sun while using this medication. Avoid excessive sun exposure and do not use sunlamps or sun beds until you know how this medication affects your skin.
Tumour lysis syndrome: Methotrexate, like many other cancer medications, causes many cancer cells to be suddenly killed when treatment is first started. This can overwhelm the body with waste products from the cells. As a result, the body may not be able to keep up with getting rid of all the waste. When this happens, you may experience nausea, shortness of breath, cloudy urine, or joint pain. This is called tumour lysis syndrome. Your doctor may prescribe medications to help your body get rid of the waste products. Make sure you understand how to use these medications and report any of these signs or symptoms to your doctor immediately.
Vaccines: Vaccines may be ineffective if given during treatment with methotrexate. Live virus vaccines (e.g., smallpox, measles, mumps, rubella, chickenpox, shingles) are not recommended during treatment with methotrexate.
Pregnancy: There is a possibility of birth defects if either partner is using methotrexate at the time of conception. If it is used during pregnancy, methotrexate may also cause birth defects or harm the baby.
Effective birth control should be practiced if either partner is using this medication, including for a period of time after the medication is stopped. Talk to your doctor about how long you should wait to become pregnant after you or your partner stop taking methotrexate. If you become pregnant while taking this medication, contact your doctor immediately.
If you have rheumatoid arthritis or psoriasis, you should not use this medication if you are pregnant. If you might be pregnant, do not start methotrexate until you know for sure that you are not pregnant.
Breast-feeding: Methotrexate passes into breast milk. Due to the potential for serious harm to a baby if they are exposed to this medication, women who are using methotrexate should not breast-feed.
Children: Methotrexate has been used to treat cancer in children. Methotrexate has also been used under close supervision of a doctor to treat other conditions in children, although the safety and effectiveness have not been clearly determined. This medication should not be used for infants less than 1 month old.
Seniors: If you are a senior, you may be more at risk of experiencing side effects (including serious ones) and your doctor will monitor you very closely while you are using this medication.
What other drugs could interact with this medication?
There may be an interaction between methotrexate and any of the following:
- aminoglycosides (e.g., gentamicin, tobramycin)
- amphotericin B
- "azole" antifungals (e.g., itraconazole, ketoconazole, voriconazole)
- chloral hydrate
- folic acid
- HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
- live vaccines (e.g., BCG, yellow fever, measles, mumps, rubella)
- macrolide antibiotics (e.g., clarithromycin, erythromycin)
- nonsteroidal anti-inflammatory medications (NSAIDs; e.g., diclofenac, ibuprofen, ketoprofen, naproxen)
- other cancer medications (e.g., cytarabine, doxorubicin, vinblastine)
- penicillins (e.g., amoxicillin, ampicillin, penicillin, cloxacillin)
- protein kinase inhibitors (e.g., lapatinib, nilotinib, sunitinib)
- proton pump inhibitors (e.g., lansoprazole, omeprazole)
- retinoids (e.g., tretinoin, retinol)
- St. John’s wort
- salicylates (e.g., ASA, salsalate)
- sulfonamide antibiotics (e.g., sulfasalazine, sulfamethoxazole, sulfadiazine)
- tetracyclines (e.g., doxycycline, minocycline, tetracycline)
- theophyllines (e.g., aminophylline, oxtriphylline, theophylline)
If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:
- stop taking one of the medications,
- change one of the medications to another,
- change how you are taking one or both of the medications, or
- leave everything as is
An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.
Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.
All material copyright MediResource Inc. 1996 – 2021. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/drug/getdrug/Methotrexate-by-Pharmascience