biology

Methotrexate

Methotrexate is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Methotrexate rather than just read about it. In short: Methotrexate, formerly known as amethopterin, is a chemotherapy agent and immune-system suppressant. It is used to treat cancer, autoimmune diseases, and ectopic pregnancies.

Key takeaways

Methotrexate belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Methotrexate to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Methotrexate from memory before moving on to harder problems.

Reference excerpt

Methotrexate, formerly known as amethopterin, is a chemotherapy agent and immune-system suppressant. It is used to treat cancer, autoimmune diseases, and ectopic pregnancies. It is used for cancers such as breast cancer, leukemia, lung cancer, lymphoma, gestational trophoblastic disease, and osteosarcoma, as well as autoimmune diseases such as psoriasis, rheumatoid arthritis, and Crohn's disease. It can be given by mouth or by injection. Common side effects include nausea, feeling tired, fever, increased risk of infection, low white blood cell counts, and breakdown of the skin inside the mouth. Other side effects may include liver disease, lung disease, lymphoma, and severe skin rashes. People on long-term treatment should be regularly checked for side effects. It is not safe during breastfeeding. In those with kidney problems, lower doses may be needed. It acts by blocking the body's use of folic acid, so taking folic acid supplements can reduce its effectiveness. Folinic acid (leucovorin) is used to reduce the side effects of methotrexate (rescue therapy). Methotrexate was first made in 1947 and initially was used to treat cancer, as it was less toxic than the then-current treatments. In 1956 it provided the first cures of a metastatic cancer. It is on the World Health Organization's List of Essential Medicines. Methotrexate is available as a generic medication. In 2023, it was the 130th most commonly prescribed medication in the United States, with more than 4 million prescriptions.

Medical uses

Chemotherapy Methotrexate was originally developed and continues to be used for chemotherapy, either alone or in combination with other agents. It is effective for the treatment of several cancers, including solid tumours of breast, head and neck, lung, bladder, as well as acute lymphocytic leukemias, non-Hodgkin's lymphoma, osteosarcoma, and choriocarcinoma and other trophoblastic neoplasms. It is also used in the treatment of aggressive fibromatosis (desmoid tumor).

Autoimmune disorders Although originally designed as a chemotherapy drug, in lower doses methotrexate is a generally safe and well-tolerated drug in the treatment of certain autoimmune diseases. Methotrexate is used as a disease-modifying treatment for several autoimmune diseases in adults, including rheumatoid arthritis, psoriasis and psoriatic arthritis, reactive arthritis, enteropathic arthritis, myositis, systemic sclerosis, lupus, sarcoidosis, Crohn's disease, and many forms of vasculitis. In children, it can be used for juvenile dermatomyositis, juvenile idiopathic arthritis, uveitis and localised scleroderma. Methotrexate is one of the first-line therapies for the treatment of rheumatoid arthritis. Weekly doses of 5–25 mg were found by a Cochrane review to be beneficial for 12–52 weeks duration of therapy, though it is used longer-term in clinical practice. Discontinuation rates are as high as 16% due to adverse effects. Use of low doses of methotrexate together with NSAIDs such as aspirin or analgesics such as paracetamol is relatively safe in people being treated for rheumatoid arthritis, with appropriate monitoring. Methotrexate is also sometimes used in combination with other conventional DMARDs, such as sulfasalazine and hydroxychloroquine. X-rays showed that the progress of the disease slowed or stopped in many people receiving methotrexate, with the progression being completely halted in about 30% of those receiving the drug. Those individuals with rheumatoid arthritis treated with methotrexate have been found to have a lower risk of cardiovascular events such as myocardial infarctions and strokes. Results of a systematic review exploring the comparative effectiveness of treatments of early rheumatoid arthritis show that treatment efficacy can be improved with combination therapy with anti-TNF or other biologic medications, compared with methotrexate monotherapy. Likewise, a 2016 study found the use of methotrexate, in combination with anti-TNF agents, is effective for the treatment of ulcerative colitis. Methotrexate has also been used for multiple sclerosis and is used occasionally in systemic lupus erythematosus, with tentative evidence to support such use.

Atopic dermatitis Along with other immunosuppressants, methotrexate is used to treat severe atopic dermatitis (eczema).

During pregnancy Methotrexate is an abortifacient and is used to treat ectopic pregnancies, provided the fallopian tube has not ruptured. Methotrexate with dilation and curettage is used to treat molar pregnancy. Rarely, it is used in combination with misoprostol to abort intrauterine pregnancies.

Administration Methotrexate can be given by mouth or by injection (intramuscular, intravenous, subcutaneous, or intrathecal). Doses are usually taken weekly, not daily, to limit toxicity. Routine monitoring of the complete blood count, liver function tests, and creatinine are recommended. Measurements of creatinine are recommended at least every two months. Folic acid is commonly co-prescribed with methotrexate to minimise the risk of adverse effects.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Methotrexate

Start with the simplest possible case. Write down what Methotrexate claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Methotrexate before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Methotrexate ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Methotrexate

In research: Methotrexate appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Methotrexate in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Methotrexate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Abortifacients, Antifolates, Antineoplastic and immunomodulating drugs, so understanding it makes those chapters shorter.
In everyday life: Look for Methotrexate outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Methotrexate in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Methotrexate means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Methotrexate out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Methotrexate in simple terms?

Methotrexate, formerly known as amethopterin, is a chemotherapy agent and immune-system suppressant. It is used to treat cancer, autoimmune diseases, and ectopic pregnancies.

Why does Methotrexate matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Methotrexate?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Methotrexate.