Canis ISSN: 2398-2942

Methotrexate

Contributor(s): William Brewer Jr

Introduction

Name

  • Methotrexate.

Class of drug

  • Antimetabolite antineoplastic agent.

Description

Storage requirements

  • Room temperature.
  • Reconstituted powder stable for 4 weeks at room temperature and for 3 months under refrigeration when diluted to 2-25 mg/ml.

Uses

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Indications

  • Lymphomas Lymphoma and some solid tumors.
  • This may be limited by its toxicity when used in a high dose regimen.
  • In human medicine it is also used to treat refractory rheumatoid arthritis.

Administration

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Pharmocokinetics

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Precautions

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Interactions

with other drugs

Chloramphenicol Chloramphenicol, oral anticoagulants, phenylbutazone, phenytoin Phenytoin, salicylates, sulphonamides and tetracycline Tetracycline
  • Methotrexate is highly bound to serum albumin and thus may be displaced, resulting in increased blood levels and toxicity.
Folic acid supplements
  • May inhibit the response to methotrexate.
Pyrimethamine Pyrimethamine
  • A similar folic acid antagonist, may increase methotrexate toxicity.
Cytarabine Cytarabine
  • Increased cytotoxicity.
Hydrocortisone Hydrocortisone, hydroxyurea Hydroxycarbamide, methylprednisolone Methylprednisolone
  • Cellular uptake of methotrexate decreased.
Amphotericin B Amphotericin B, vincristine Vincristine
  • Cellular uptake of methotrexate increased.
NSAIDs
  • Increased risk of hematologic, renal and hepatic toxicity.

Adverse Reactions

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Further Reading

Publications

Other sources of information

  • Fischer D S, Knobf M Tet al(2003)The Cancer Chemotherapy Handbook.6th edn. Philadelphia, PA, Mosby. pp 167-171.
  • Based onSmall Animal Formulary.Tennant, Bryn (1999) 3rd edn. Cheltenham: BSAVA.
  • Fraizier D L & Hahn K A (1995)Commonly Used Drugs.In: Hahn K A & Richardson R C (eds)Cancer Chemotherapy A Veterinary Handbook. Philadelphia, PA. Williams & Wilkins. pp 112-113.

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