Methotrexate

Administration

• Type: Immunosuppressant/antineoplastic
• Dosage Forms:
• Routes of Administration: IV/IM, oral
• Common Trade Names:

Adult Dosing

• Ectopic pregnancy: Single-dose regimen: Methotrexate 50 mg/m2

Special Populations

• Pregnancy Rating: X
• Lactation risk: Infant risk has been determined (risk of serious adverse effects for infant)

Renal Dosing

• Adult:
• Pediatric:

Hepatic Dosing

• Adult:
• Pediatric:

Contraindications

• Allergy to class/drug
• Breastfeeding, pregnant, or possibility of impregnating someone
• Blood dyscrasias
• Chronic liver disease

Adverse Reactions

Serious

• Hepatotoxicity
• Nephrotoxicity
• Myelosuppression, aplastic anemia, pancytopenia
• Infectious disease
• Tumor lysis syndrome
• GI bleed
• Neurotoxicity, seizure
• Pericardial effusion
• TEN

Common

• Nausea/vomiting, diarrhea
• Stomatitis
• Leukopenia, thrombocytopenia
• Alopecia, photosensitivity, rash
• Dizziness

Pharmacology

• Half-life: 8-15hr
• Metabolism: Extensive hepatic and intracellular
• Excretion: Mostly renal. Dialyzable.

Mechanism of Action

• Inhibits dihydrofolate reductase--> blocks DNA synthesis and thus, cellular replication/repair