Methotrexate Remedica (Methotrexate)

Methotrexate is an antimetabolite used in several autoimmune and oncologic disease pathways.

• Rheumatoid arthritis: reduces joint inflammation and slows disease progression.
• Psoriasis: limits skin cell proliferation and improves plaque lesions.
• Acute lymphoblastic leukemia: impedes malignant cell replication as part of chemotherapy protocols.
• Osteosarcoma: contributes to tumor growth inhibition in combination regimens.
• Gestational trophoblastic disease: induces remission by targeting rapidly dividing trophoblastic tissue.

• Methotrexate inhibits dihydrofolate reductase, blocking the conversion of dihydrofolate to tetrahydrofolate. This reduction limits the synthesis of purine nucleotides and thymidylate, leading to decreased DNA synthesis, impaired cell replication, and ultimately apoptosis of rapidly dividing cells in both inflammatory and malignant tissues.

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

Common Side Effects

• Nausea and vomiting: gastrointestinal upset often occurring shortly after dosing.
• Fatigue: persistent tiredness that may affect daily activities.
• Mouth ulcers: painful sores in the oral cavity.
• Elevated liver enzymes: mild hepatic irritation detectable on lab tests.
• Low blood counts: mild reductions in white cells, red cells, or platelets.
• Hair thinning: temporary loss of scalp hair.

Serious or Rare Side Effects

• Severe liver toxicity: risk of hepatitis or fibrosis with prolonged use.
• Pulmonary fibrosis: interstitial lung disease presenting with cough and dyspnea.
• Myelosuppression: profound bone marrow suppression leading to infection risk.
• Renal impairment: decreased kidney function affecting drug clearance.
• Severe skin reactions: such as Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Teratogenic effects: high risk of fetal malformations if exposure occurs during pregnancy.

Methotrexate requires careful monitoring and patient education to minimize risks.

• Monitor liver function: baseline and periodic liver enzyme tests are recommended.
• Assess renal function: evaluate creatinine clearance before initiation and during therapy.
• Perform blood counts: regular complete blood counts to detect myelosuppression.
• Avoid alcohol: concurrent alcohol use can increase hepatotoxicity.
• Use contraception: pregnancy must be avoided due to teratogenicity.
• Store at ambient temperature: keep in the original container, protect from moisture and heat.

Methotrexate can interact with several drugs, altering its efficacy or toxicity.

Major Interactions (Avoid)

• Non‑steroidal anti‑inflammatory drugs (NSAIDs): increase methotrexate plasma levels and risk of toxicity.
• Proton pump inhibitors: may reduce renal clearance and raise systemic exposure.
• Penicillins (e.g., ampicillin): can decrease renal elimination, leading to higher concentrations.

Moderate Interactions (Monitor Closely)

• Sulfonamides: may enhance bone marrow suppression.
• Trimethoprim‑sulfamethoxazole: can increase risk of myelosuppression.
• Live vaccines: immunosuppression may reduce vaccine efficacy and increase infection risk.