Metex (Methotrexate Disodium)

Methotrexate acts on rapidly dividing cells and immune pathways, making it useful across several disease families.

• Rheumatoid arthritis: reduces disease activity and joint inflammation.
• Psoriasis: slows skin cell proliferation and improves lesions.
• Acute lymphoblastic leukemia: interferes with malignant cell DNA synthesis.
• Non‑Hodgkin lymphoma: contributes to tumor cell death.
• Breast cancer: used as part of combination chemotherapy regimens.
• Ectopic pregnancy: provides medical termination of early tubal gestation.

• Methotrexate inhibits the enzyme dihydrofolate reductase, decreasing tetrahydrofolate levels and thereby limiting the synthesis of purines and thymidylate. This impairs DNA, RNA and protein production, leading to reduced proliferation of immune cells and malignant cells, while also affecting folate‑dependent metabolic pathways.

Methotrexate may cause a range of adverse reactions that vary in frequency and severity.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Fatigue: persistent tiredness not relieved by rest.
• Mouth sores: ulceration of oral mucosa.
• Low blood counts: mild anemia or leukopenia.

Serious or Rare Side Effects

• Severe liver toxicity: marked elevation of liver enzymes or hepatitis.
• Pulmonary fibrosis: progressive scarring of lung tissue.
• Severe infection: opportunistic infections due to immunosuppression.

Methotrexate requires careful monitoring and specific safety measures.

• Liver monitoring: perform regular liver function tests.
• Blood count monitoring: check complete blood count before and during therapy.
• Pregnancy avoidance: contraindicated in pregnancy; use effective contraception.
• Renal function assessment: evaluate kidney function prior to initiation.
• Contraception counseling: advise both male and female patients on reliable methods.
• Store at below 25°C: keep in the original packaging, protect from moisture and heat.

Methotrexate interacts with several medicines that can alter its efficacy or toxicity.

Major Interactions (Avoid)

• Non‑steroidal anti‑inflammatory drugs (NSAIDs): increase methotrexate toxicity.
• Penicillins: may reduce renal clearance of methotrexate.
• Live vaccines: heightened risk of infection.

Moderate Interactions (Monitor Closely)

• Proton pump inhibitors: may affect absorption.
• Oral contraceptives: reduced effectiveness, consider alternative contraception.
• Allopurinol: may increase hematologic toxicity.