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Amethopterin, MTX
Folex PFS, Rheumatrex Dose Pak (treatment of psoriasis or rheumatoid arthritis)

Pregnancy Category X

Drug classes


Mechanism of action

Inhibits folic acid reductase, leading to inhibition of DNA synthesis and inhibition of cellular replication; selectively affects the most rapidly dividing cells (neoplastic and psoriatic cells).


  • Treatment of gestational choriocarcinoma, chorioadenoma destruens, hydatidiform mole
  • Treatment and prophylaxis of meningeal leukemia
  • Symptomatic control of severe, recalcitrant, disabling psoriasis
  • Management of severe, active, classical, or definite rheumatoid arthritis

Unlabeled uses: high-dose regimen followed by leucovorin rescue for adjuvant therapy of nonmetastatic osteosarcoma (orphan drug designation); to reduce corticosteriod requirements in patients with severe corticosteroid-dependent asthma.


  • Allergy to methotrexate
  • Lactation
  • Proriasis with renal or hepatic disorders
  • Pregnancy or childbearing age

Use caution in the presence of hematopoietic depression; leukopenia, thrombocytopenia, anemia, severe hepatic or renal disease, infection, peptic ulcer, ulcerative colitis, debility.

Adverse effects

  • CNS: Headache, drowsiness, blurred vision, aphasia, hemiparesis, paresis, seizures, fatigue, malaise, dizziness
  • GI: Ulcerative stomatitis, gingivitis, pharyngitis, anorexia, nausea, vomiting, diarrhea, hematemesis, melena, GI ulceration and bleeding, enteritis, hepatic toxicity
  • Respiratory: Interstitial pneumonitis, chronic interstitial obstructive pulmonary disease
  • Hematologic: Bone marrow depression, increased susceptibility to infection
  • GU: Renal failure, effects on fertility (defective oogenesis, defective spermatogenesis, transient oligospermia, menstrual dysfunction, infertility, abortion, fetal defects)
  • Dermatologic: Erythematous rashes, pruritus, urticaria, photosensitivity, depigmentation, alopecia, ecchymosis, telangiectasia, ance, furunculosi
  • Hypersensitivity: Anaphylaxis, sudden death
  • Other: Chills and fever, metabolic changes (diabetes, osteoporosis), cancer

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