Methotrexate (Drugs used in immune diseases)

Question 1

What tablet strength should be prescribed in methotrexate patients?

Answer 1

Only 2.5mg tablets should be prescribed for patients

Question 2

What is the frequency that methotrexate should be given?

Answer 2

Methotrexate should be given ONCE A WEEK on the same day each week

Question 3

What is the recommended methotrexate dose in rheumatoid arthritis patients?

Answer 3

• Start at 7.5mg once a week and then gradually increase by 2.5-5mg every 1-3 weeks
• The optimal dose should be reached within 4-6 weeks

Question 4

What baseline assessments should be carried out before the commencement of Methotrexate treatment and how frequently afterwards?

Answer 4

Full blood count
Liver function test
Urea and electrolytes
Renal function- neGFR or Creatinine function- as over 80% of methotrexate is excreted unchanged in the urine

Chest x-ray- to monitor pulmonary toxicity
- this is not routine only if symptoms of pulmonary toxicity develop e.g. shortness of breath, tiredness, chronic cough

These factors should be monitored every 1-2 weeks until therapy has been stabilised, then every 2-3 months thereafter

Question 5

What signs should patients self-monitor for while on methotrexate?

Answer 5

• Signs of infection- e.g. sore throat, bleeding, bruising- could be a sign of a blood disorder
• Nausea and vomiting, abdominal discomfort, dark urine colour- could be a sign of liver toxicity
• Shortness of breath, chronic cough- pulmonary toxicity

Question 6

What are the side effects of Methotrexate?

Answer 6

• Bone marrow suppresssion- low WBC, low platelet count, anaemia, easy bleeding and bruising- can cause bone marrow suppression.
• GI effects- GI ulcers and bleeding, stomatitis, mucositis
  Pulmonary toxicity- dry cough, breathlessness
  Liver toxicity- jaundice, N+v, yellowing of eyes
• N&V, sickness, diarrhoea- should improve gradually, if not increase folic acid dosage. If still bad, consider addition of an anti-emetic. if still bad, consider oral to subcutaneous switch
• Mouth ulcers

Question 7

What are the steps to improving methotrexate-induced GI side effects?

Answer 7

These side effects e.g. N+V, diarrhoea will usually gradually improve on their own
- If not, can increase the dose of Folic acid or give an oral anti-emetic
- if the symptoms are still not improved, consider an oral to subcutaneous switch

Question 8

What are the contra-indications for Methotrexate use?

Answer 8

• Active infection- Methotrexate can cause bone marrow suppression so the patient wouldn’t be able to fight this infection adequately
• Renal impairment- Methotrexate is mostly renal excreted, so if patient is renal impaired, this could leas to dose accumulation and therefore increased toxicity
• Hepatic impairment- risk of hepatotoxicity
• Bone marrow suppression
• Immunodeficiency
• Pregnancy or breastfeeding- both male and female patients should. not try to conceive while on methotrexate as it is teratogenic (harmful to unborn foetus). Therefore, patients should be on effective contraception while on and for 3-6 months after stopping methotrexate.

Question 9

What is the importance in methotrexate and chicken pox?

Answer 9

If a patient on methotrexate has never had chicken pox before, they are at risk of severe infection from the varicella-zoster virus that causes chicken pox.

• If the patient comes into contact with someone who has chicken pox or shingles, they should contact their doctor immediately

Question 10

What is the procedure for taking methotrexate while on antibiotics/suffering from an infection?

Answer 10

• Usually Methotrexate is temporarily withheld in these patients

Question 11

What drug should be co-prescribed with methotrexate?

Answer 11

• Folic acid should be co-prescribed with methotrexate
• Usual dose is 5mg OW- but not on the same day as methotrexate
• This dose can be increased to up to 6 days of the week ( still not on the day of methotrexate)

This decreases the risk of hepatotoxicity and GI side effects

Question 12

What should a patient do if they miss a dose of Methotrexate?

Answer 12

The missed dose can be taken within two days of the regular dose e.g. if normally taken on Monday, the dose can be taken up until Wednesday. If it is after this however, miss the dose as methotrexate is a longterm treatment and so will have little effect

Question 13

What are some drugs that interact with methotrexate?

Answer 13

• Anti-folates e.g. Trimethoprim, Co-trimoxazole
• NSAIDs- should not be self-administered, may be prescribed
• Live vaccinations
• Ciclosporin

Question 14

What are some important counselling points for methotrexate?

Answer 14

• Recommend flu and pneumococcal vaccines, NO live vaccines
• Report to dr if come across anyone with chicken pox or shingles
• No-self prescribing of NSAIDs as they decrease the excretion of methotrexate so it is accumulated.
• Reduce alcohol intake- as both can effect the liver
• Should always carry an alert card

Question 15

What drug class is methorexate?

Answer 15

A dihydrofolate reductase inhibitor- prevents production of purine nucleotides needed for DNA synthesis
is a DMARD