Methotrexate Flashcards Preview

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Flashcards in Methotrexate Deck (15)
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1
Q

What are indications for the use of methotrexate?

A
  • Rheumatoid arthritis
  • Chemotherapy
  • Psoriasis
2
Q

What is the mechanism of action of methotrexate?

A

Inhibits dihydrofolate reductase, which converts dietary folic acid to tetrahydrofolate. This is required for DNA and protein synthesis, so lack of it prevents cellular replication. Actively dividing cells are particularly sensitive to the effects of methotrexate, accounting for its efficacy in cancer. It also has anti-inflammatory and immunosuppressive effects

3
Q

What are adverse effects of methotrexate?

A
  • Gastrointestinal upset
  • Rash
  • Myelosuppression
  • Alopecia
  • Cirrhosis
  • Pulmonary fibrosis
  • Renal impairment (high dose therapy)
4
Q

What are contraindications you would check for before starting someone on methotrexate?

A
  • Hepatic impairment
  • Pregnancy and breast feeding
  • Active infection
  • Immunodeficiency
5
Q

When should cuation be used when prescribing methotrexate?

A
  • Peptic ulceration
  • Pleural effusion or ascites
  • Renal impairment
  • Porphyria
6
Q

What drugs interact with methotrexate?

A
  • Aspirin
  • NSAIDs
  • Folate antagonists - trimethoprim, co-trimoxazole
  • Ciclosporin
7
Q

How often should methotrexate be given?

A

Once weekly tablets, same day each week unless used as chemo

8
Q

Is methotrexate teratogenic?

A

YEs

9
Q

What monitoring would you want to do for someone on methotrexate?

A

Regular FBC, U+E’s and LFTs

  1. Before starting treatment
  2. 1-2 weekly until treatment established
  3. 2-3 montlhy once established
10
Q

What effects does methotrexate overdose cause?

A
  • Renal impairment
  • Hepatotoxicity
  • Headache
  • Seizures
  • Coma
11
Q

What would you administer to treat methotrexate toxicity?

A

Folinic acid

12
Q

What should be prescribed with methotrexate?

A

Folic acid for 6 days that methotrexate is not taken - limits adverse effects

13
Q

How long does it take for methotrexate to be effective?

A

3-12 weeks

14
Q

What features would you want to warn someone about who is on methotrexate?

A
  • Infection
  • Unexplained bruising
15
Q

What should you prescribe with methotrexate?

A

Folic acid 5mg - another day of the week