Injexate (Methotrexate)

Methotrexate is used across several disease families, primarily oncology and autoimmune disorders, where it modulates cell proliferation and immune activity.

• Rheumatoid arthritis: reduces joint inflammation and slows structural damage in adult patients.
• Psoriasis: limits skin cell proliferation and improves plaque lesions.
• Acute lymphoblastic leukemia: induces remission by targeting rapidly dividing lymphoblasts.
• Non‑Hodgkin lymphoma: interferes with malignant B‑cell growth.
• Breast cancer: used in combination regimens to inhibit tumor cell replication.
• Ectopic pregnancy: terminates trophoblastic tissue when surgery is not indicated.

• Methotrexate inhibits the enzyme dihydrofolate reductase, preventing the conversion of dihydrofolate to tetrahydrofolate. This blockade reduces the availability of folate cofactors required for synthesis of purine nucleotides and thymidylate, thereby impairing DNA, RNA and protein synthesis in rapidly dividing cells and activated immune cells.

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

Common Side Effects

• Nausea or vomiting.
• Fatigue or malaise.
• Mild mouth sores.
• Transient elevation of liver enzymes.
• Low white‑blood cell count.
• Skin rash or itching.

Serious or Rare Side Effects

• Severe liver toxicity or fibrosis.
• Pulmonary fibrosis or interstitial pneumonitis.
• Bone marrow suppression leading to pancytopenia.
• Renal impairment or failure.
• Life‑threatening infections due to immunosuppression.
• Rare anaphylactic reactions on injection.

When using Injexate, careful monitoring and patient education are essential.

• Pregnancy: contraindicated; teratogenic risk is high (Category X).
• Renal function: assess creatinine clearance before initiation and periodically thereafter.
• Hepatic health: perform baseline liver function tests and monitor regularly.
• Hematology: obtain complete blood counts before each dose to detect marrow suppression.
• Concomitant drugs: avoid known major interacting agents without specialist advice.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake the vial.

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

Major Interactions (Avoid)

• Non‑steroidal anti‑inflammatory drugs (NSAIDs): increase methotrexate plasma levels and risk of toxicity.
• Proton pump inhibitors (e.g., omeprazole): may reduce renal clearance and heighten adverse effects.
• High‑dose folic acid supplements: can diminish therapeutic effect.

Moderate Interactions (Monitor Closely)

• Azathioprine or other immunosuppressants: additive bone‑marrow suppression.
• Penicillins (e.g., ampicillin): may increase methotrexate concentrations.
• Sulfonamides: potential for enhanced hematologic toxicity.