Metotrexato Teva (Methotrexate)

Methotrexate acts on rapidly dividing cells and immune pathways, providing therapeutic benefit across several disease families.

• Rheumatoid arthritis: reduces disease activity, joint inflammation and structural damage.
• Psoriasis: improves skin lesions and decreases severity scores.
• Acute lymphoblastic leukemia: induces remission by inhibiting malignant cell proliferation.
• Non‑Hodgkin lymphoma: contributes to tumor control as part of combination regimens.
• Ectopic pregnancy: terminates trophoblastic tissue when surgical options are not chosen.

• Methotrexate inhibits the enzyme dihydrofolate reductase, leading to reduced tetrahydrofolate levels. This impairs synthesis of purine nucleotides and thymidylate, thereby blocking DNA replication and cell division in rapidly proliferating tissues and immune cells.

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

Common Side Effects

• Nausea or vomiting: gastrointestinal upset often occurring after dosing.
• Fatigue: persistent tiredness not explained by disease activity.
• Oral mucositis: painful sores or ulceration of the mouth lining.
• Cytopenias: mild reductions in white blood cells, neutrophils or platelets.
• Elevated liver enzymes: transient increase in hepatic transaminases.

Serious or Rare Side Effects

• Severe hepatic toxicity: potential for fibrosis or cirrhosis with prolonged use.
• Pulmonary fibrosis: interstitial lung disease presenting with cough and dyspnea.
• Life‑threatening infection: due to profound bone‑marrow suppression.
• Renal failure: acute kidney injury from precipitation of drug crystals.
• Severe cutaneous reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis.

Methotrexate requires careful monitoring and specific safety measures.

• Baseline assessment: obtain complete blood count, liver and renal function tests before initiating therapy.
• Regular monitoring: repeat hematology and biochemistry at intervals recommended by the prescriber.
• Pregnancy avoidance: contraindicated in pregnancy (Category X); effective contraception must be used.
• Breastfeeding restriction: drug is excreted in milk; breastfeeding is not advised.
• Drug interactions: review concomitant medications for agents that may increase toxicity.
• Store at ambient temperature: keep below 25 °C, in the original container, protected from moisture and light.

Methotrexate can interact with several medicines, altering its safety profile.

Major Interactions (Avoid)

• Non‑steroidal anti‑inflammatory drugs (NSAIDs): increase methotrexate plasma levels and toxicity.
• Penicillins and other β‑lactam antibiotics: may reduce renal clearance, raising exposure.
• Live vaccines: heightened risk of infection due to immunosuppression.

Moderate Interactions (Monitor Closely)

• Azathioprine or other immunosuppressants: additive bone‑marrow suppression.
• Proton‑pump inhibitors: may modestly increase methotrexate concentrations.