Methotrexat Medac (Methotrexate)

Methotrexate is employed across several disease families, primarily as a disease‑modifying agent in autoimmune disorders and as a cytotoxic agent in malignancies.

• Rheumatoid arthritis: reduces joint inflammation and slows structural damage.
• Psoriasis: decreases skin plaque formation and severity.
• Acute lymphoblastic leukemia: inhibits leukemic cell proliferation.
• Osteosarcoma: impedes tumor growth and metastasis.
• Other malignancies: provides antineoplastic activity in various solid tumours.

• Methotrexate inhibits dihydrofolate reductase, preventing the conversion of dihydrofolate to tetrahydrofolate. This blockade reduces the synthesis of purine nucleotides and thymidylate, leading to impaired DNA replication and cell division, particularly in rapidly proliferating cells such as immune cells and cancer cells.

Methotrexate may cause a range of adverse reactions, from mild to severe, depending on dose, route and patient factors.

Common Side Effects

• Nausea and vomiting: gastrointestinal upset common after administration.
• Fatigue: persistent tiredness reported by many patients.
• Mucositis: inflammation and ulceration of the oral mucosa.
• Elevated liver enzymes: mild transaminitis detectable on labs.
• Alopecia: temporary hair thinning or loss.
• Cytopenias: mild reductions in white blood cells or platelets.

Serious or Rare Side Effects

• Severe liver toxicity: potential for fibrosis or cirrhosis.
• Pulmonary fibrosis: interstitial lung disease with dyspnea.
• Bone marrow suppression: profound pancytopenia increasing infection risk.
• Renal failure: impaired clearance leading to toxicity.
• Life‑threatening infections: due to immunosuppression.
• Secondary malignancies: rare development of new cancers.

Methotrexate requires careful monitoring and specific safety measures before and during therapy.

• Pregnancy contraindication: avoid use in pregnancy (Category X).
• Renal function monitoring: assess creatinine clearance prior to each dose.
• Liver function monitoring: perform baseline and periodic liver enzyme tests.
• Hematologic monitoring: regular complete blood counts to detect cytopenias.
• Concomitant NSAID caution: avoid or limit NSAIDs due to increased toxicity risk.
• Store at ambient temperature: keep in original container, protect from moisture and light.

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

Major Interactions (Avoid)

• Non‑steroidal anti‑inflammatory drugs (NSAIDs): increase methotrexate plasma levels.
• Penicillins and other β‑lactam antibiotics: may reduce renal clearance.
• Sulfonamides: potentiate bone marrow suppression.
• Live vaccines: heightened risk of infection due to immunosuppression.

Moderate Interactions (Monitor Closely)

• Proton pump inhibitors: may affect renal excretion.
• Trimethoprim‑sulfamethoxazole: increased risk of hematologic toxicity.
• High‑dose folic acid supplementation: may diminish therapeutic effect.