Methotrexate

Generic name: methotrexate (oral) [ meth-oh-TREX-ate ]
Brand names: Trexall, Xatmep

Drug class: Antineoplastics, Antirheumatics (Disease-modifying antirheumatic drugs – DMARDs)

Dosage form: Tablet, Injection

Route of administration: Oral, Intramuscular (IM), Subcutaneous (SC), Intravenous (IV), Intrathecal

Dose: Tablet: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 15 mg; Injection: 25 mg/mL, 50 mg/2 mL, 100 mg/4 mL

Mechanism of action: Methotrexate inhibits dihydrofolate reductase, an enzyme necessary for the conversion of dihydrofolate to tetrahydrofolate, which is crucial for DNA synthesis and cell replication. By inhibiting this enzyme, methotrexate decreases the synthesis of DNA, RNA, and proteins, leading to reduced cell proliferation, especially in rapidly dividing cells.

Drug usage cases: Methotrexate is used to treat various types of cancer, including acute lymphoblastic leukemia, non-Hodgkin’s lymphoma, breast cancer, and osteosarcoma. It is also used for the treatment of severe rheumatoid arthritis, juvenile idiopathic arthritis, and severe psoriasis.

Drug contra indications: Methotrexate should not be used in patients with known hypersensitivity to the drug, severe renal or hepatic impairment, bone marrow suppression, or in pregnant or breastfeeding women.

Side effects: Common side effects include nausea, vomiting, stomatitis, and fatigue. Serious side effects may include:

• Bone marrow suppression: Risk of severe leukopenia, thrombocytopenia, and anemia.
• Hepatotoxicity: Potential for liver enzyme elevation, fibrosis, and cirrhosis.
• Pulmonary toxicity: Risk of interstitial pneumonitis and pulmonary fibrosis.
• Gastrointestinal toxicity: Potential for severe mucositis, diarrhea, and gastrointestinal bleeding.

Warnings: Methotrexate can cause severe bone marrow suppression, hepatotoxicity, pulmonary toxicity, and gastrointestinal toxicity. Regular monitoring of blood counts, liver function tests, and pulmonary function is required. Patients should be advised to report any signs of infection, liver dysfunction, or respiratory issues promptly.

Use during pregnancy or breastfeeding: Methotrexate is contraindicated during pregnancy due to its teratogenic effects and potential to cause fetal harm. Women of childbearing potential should use effective contraception during treatment and for at least six months after discontinuation. Methotrexate is excreted in human milk and can harm a nursing infant, so breastfeeding should be avoided during treatment.