Novatrex (Methotrexate)

Methotrexate is used across several disease categories, primarily targeting inflammatory and neoplastic pathways.

• Rheumatoid arthritis: reduces joint inflammation and slows structural damage.
• Psoriasis: decreases skin cell proliferation and improves plaque severity.
• Acute lymphoblastic leukemia: interferes with malignant cell replication to achieve remission.
• Non‑Hodgkin lymphoma: suppresses tumor growth as part of combination chemotherapy.
• Ectopic pregnancy: halts trophoblastic tissue development to allow non‑surgical resolution.

• Methotrexate competitively inhibits dihydrofolate reductase, preventing the conversion of dihydrofolate to tetrahydrofolate, a cofactor required for purine and pyrimidine synthesis. The resulting depletion of nucleotides impairs DNA, RNA and protein synthesis, leading to reduced proliferation of rapidly dividing cells such as immune‑mediated inflammatory cells and malignant lymphocytes. Additional anti‑inflammatory actions arise from increased extracellular adenosine release.

Methotrexate may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Nausea and vomiting
• Fatigue or weakness
• Mouth sores (stomatitis)
• Diarrhea or abdominal discomfort
• Elevated liver enzymes
• Mild hair thinning

Serious or Rare Side Effects

• Bone marrow suppression leading to anemia or infection
• Severe liver injury or fibrosis
• Pulmonary toxicity (interstitial pneumonitis)
• Renal impairment or failure
• Cutaneous ulceration or severe skin reactions

When prescribing methotrexate, clinicians should observe several safety precautions to minimize risk.

• Monitor liver function: perform baseline and periodic LFTs.
• Check blood counts: regular CBC to detect marrow suppression.
• Avoid in pregnancy: contraindicated; require effective contraception for both sexes.
• Adjust for renal impairment: dose reduction or increased monitoring may be needed.
• Review concomitant NSAID or sulfonamide use: may increase toxicity.
• Store at room temperature: keep tablets in original container, protect from moisture and light.

Methotrexate interacts with several drug classes, necessitating careful review of a patient’s medication regimen.

Major Interactions (Avoid)

• Non‑steroidal anti‑inflammatory drugs (NSAIDs): can increase methotrexate plasma levels and toxicity.
• Proton pump inhibitors (PPIs): may reduce renal clearance and raise systemic exposure.
• Live vaccines: immunosuppression may lead to uncontrolled infection.

Moderate Interactions (Monitor Closely)

• Sulfonamide antibiotics: additive bone marrow suppression risk.
• Azathioprine or other immunosuppressants: may enhance myelosuppression.
• Trimethoprim‑sulfamethoxazole: can increase hepatotoxicity.
• Antifungal agents (e.g., ketoconazole): may affect methotrexate metabolism.