What is Methotrexate?
Methotrexate (pronounced meth-oh-trex-ate) is a prescription medicine used to treat several medical conditions, including certain cancers and autoimmune diseases. It belongs to a class of drugs called antimetabolites — medicines that stop or slow down the growth of cells.
Originally developed as a cancer treatment, Methotrexate is now widely used in lower doses for conditions like rheumatoid arthritis, psoriasis, and Crohn’s disease.
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Methotrexate Class and Mechanism of Action
Methotrexate belongs to the antimetabolite and antifolate class of drugs. It works by blocking the action of folic acid, a vitamin that helps cells grow and divide.
Mechanism of Action:
Methotrexate inhibits an enzyme called dihydrofolate reductase (DHFR). This enzyme helps in producing DNA, RNA, and proteins that are essential for cell survival and replication. By blocking DHFR, Methotrexate stops the growth of rapidly dividing cells — such as cancer cells or overactive immune cells that cause inflammation in diseases like arthritis.
In simple terms, Methotrexate controls cell growth and reduces the immune system’s overreaction, which helps in managing autoimmune and inflammatory diseases.
Methotrexate Uses: What is Methotrexate Mainly Used For?
Methotrexate is a versatile medication with a wide range of medical uses. Let’s explore its main applications:
1. Cancer Treatment
Methotrexate is used in high doses to treat various cancers such as:
- Leukemia (blood cancer)
- Lymphoma
- Breast cancer
- Head and neck cancers
- Osteosarcoma (bone cancer)
It helps slow down the growth of cancer cells and is often given as part of chemotherapy combinations.
2. Rheumatoid Arthritis (RA)
Methotrexate is one of the most effective Disease-Modifying Anti-Rheumatic Drugs (DMARDs). It helps reduce joint inflammation, stiffness, pain, and long-term damage by suppressing the overactive immune system.
3. Psoriasis
Methotrexate helps control severe psoriasis, a skin condition where cells build up quickly causing itchy, scaly patches. It slows the rapid growth of skin cells and improves skin texture.
4. Crohn’s Disease
In patients with Crohn’s disease (a type of inflammatory bowel disease), Methotrexate helps reduce inflammation in the digestive tract and maintain remission.
5. Ectopic Pregnancy
In certain cases, Methotrexate is used to end an ectopic pregnancy — a condition where the fertilized egg grows outside the uterus, usually in the fallopian tube. It prevents further growth of the embryo and avoids surgery in some cases.
Methotrexate Forms and How It’s Given
Methotrexate comes in several forms depending on your condition and doctor’s advice:
- Methotrexate Tablets (Oral Form)
- Methotrexate Injection (Intramuscular, Intravenous, or Subcutaneous)
- Methotrexate Solution for Injection
- Methotrexate Auto-Injectors or Prefilled Pens
Common Brand Names:
- Trexall
- Rheumatrex
- Otrexup
- Rasuvo
Methotrexate Dosage
The Methotrexate dose depends on your medical condition, age, and how your body responds to treatment. It is very important to take Methotrexate exactly as prescribed by your doctor.
Typical Dosage Guidelines:
| Condition | Typical Adult Dose | Frequency |
|---|---|---|
| Rheumatoid Arthritis | 7.5–25 mg | Once a week |
| Psoriasis | 10–25 mg | Once a week |
| Cancer (chemotherapy) | 40–500 mg/m² | Varies (hospital use) |
| Crohn’s Disease | 15–25 mg | Once a week |
| Ectopic Pregnancy | 50 mg/m² | Single dose (under supervision) |
Important: Methotrexate is usually taken once a week, not daily. Taking it daily by mistake can cause serious side effects or even death.
Methotrexate Injection vs Tablets
Methotrexate Tablets:
- Taken orally with water.
- Easy to use but may cause more stomach-related side effects.
- Works best for mild to moderate conditions.
Methotrexate Injection:
- Given under the skin, into a muscle, or vein.
- Works faster and better absorbed.
- Ideal for patients who don’t respond to tablets or have severe symptoms.
Methotrexate Warnings and Precautions
Methotrexate is a powerful medicine and must be used carefully. Here are some important warnings to know before starting it:
Do NOT Use Methotrexate If:
- You are pregnant or planning to become pregnant
- You are breastfeeding
- You have liver disease
- You have weakened immune system
- You consume excessive alcohol
Key Warnings:
- Pregnancy Warning: Methotrexate can cause serious birth defects and miscarriage. Effective birth control is a must during treatment.
- Liver and Kidney Damage: Regular blood tests are needed to monitor liver enzymes and kidney function.
- Infection Risk: Methotrexate weakens the immune system, making you more prone to infections.
- Lung Problems: Rarely, it can cause lung inflammation or scarring.
- Sun Sensitivity: Avoid prolonged sun exposure as Methotrexate can increase sunburn risk.
Methotrexate Side Effects
Like any medicine, Methotrexate can cause side effects. However, not everyone experiences them, and many are mild when monitored properly.
Common Methotrexate Side Effects:
- Nausea or vomiting
- Loss of appetite
- Mouth sores
- Fatigue
- Dizziness
- Diarrhea
Serious Side Effects (Seek medical help immediately):
- Yellowing of skin or eyes (liver problem)
- Shortness of breath or persistent cough (lung issue)
- Severe skin rash
- Unusual bleeding or bruising
- Signs of infection (fever, sore throat)
- Extreme tiredness
Tip: To reduce side effects, doctors often prescribe Folic Acid along with Methotrexate.
Methotrexate and Folic Acid: Why Both Are Important
Methotrexate blocks folate metabolism, which can lead to side effects like mouth sores and fatigue. That’s why doctors recommend taking Folic Acid (Vitamin B9) supplements — to reduce toxicity without affecting the drug’s benefits.
Typically, folic acid is taken daily (except on the day Methotrexate is taken).
Methotrexate: Before and After Tips
Before Taking Methotrexate:
- Inform your doctor about all medicines you’re taking.
- Avoid alcohol completely.
- Discuss pregnancy prevention options.
After Taking Methotrexate:
- Drink plenty of water to help flush the drug from your body.
- Go for regular blood tests.
- Report any unusual symptoms immediately.
Drug Interactions: Medicines to Avoid with Methotrexate
Methotrexate interacts with several other medications. Always inform your doctor if you are using any of these:
- NSAIDs (like ibuprofen, naproxen)
- Antibiotics (penicillin, sulfa drugs)
- Diuretics (water pills)
- Proton pump inhibitors (omeprazole)
- Other chemotherapy drugs
These combinations can increase Methotrexate toxicity or reduce its effectiveness.
Frequently Asked Questions (FAQs)
What is Methotrexate mainly used for?
Methotrexate is used for rheumatoid arthritis, psoriasis, Crohn’s disease, certain cancers, and ectopic pregnancy.
What are the main side effects of Methotrexate?
Common side effects include nausea, fatigue, mouth sores, and liver problems. Regular monitoring helps prevent severe complications.
What is the mechanism of action of Methotrexate?
Methotrexate blocks dihydrofolate reductase (DHFR), preventing DNA synthesis and reducing the growth of rapidly dividing cells.
Can Methotrexate cause hair loss?
Yes, mild hair thinning can occur, but it’s usually reversible once the medication is stopped or dose is adjusted.
Can I drink alcohol while taking Methotrexate?
No. Alcohol increases the risk of liver damage. Avoid it completely during treatment.
Is Methotrexate safe for long-term use?
Yes, when monitored regularly with blood tests and under a doctor’s care, Methotrexate can be safely used long-term.
How should Methotrexate be stored?
Keep it in a cool, dry place, away from sunlight and out of reach of children.
