Methotrexate Flashcards
What is methotrexate ?
immune system suppressant, used as a first-line treatment for certain autoimmune conditions including rheumatoid arthritis and psoriatic arthritis
At higher doses, methotrexate can also be used as an anti-neoplastic agent in certain cancer treatment regimens due to its action on cell division.
What is key to methotrexate dosing ?
Methotrexate tablets are prescribed as a once-weekly dose and are taken on the same day each week
To avoid errors with methotrexate prescriptions, it is recommended that only one strength of methotrexate tablet (usually 2.5mg) is prescribed and dispensed. It is good practice to decide with the patient which day of the week they will take their dose and write this down in full on the prescription
What is co-prescribed with methotrexate and why?
Folic acid should be co-prescribed with methotrexate. It can be taken once weekly on the day after the methotrexate dose, or it can be taken once daily every day except on the day of the methotrexate dose
Folic acid reduces the side effects of methotrexate. It can decrease mucosal and gastrointestinal side effects and may prevent liver toxicity
Folic acid should never be taken on the same day as methotrexate as it can impair the efficacy of the medication
what counselling points surround methotrexate ?
Patients should swallow the methotrexate tablets whole with a drink of water. The tablets can be taken before or after food.
Advise the patient to wash their hands after touching the tablets
they’ll be given an alert card to advise healthcare professionals that they are taking methotrexate
what should they do if they miss a dose of methotrexate ?
Advise the patient that if they forget to take a dose, to take it as soon as they remember the next day or the day after.
If the dose is more than two days late, they must contact their GP or clinic for advice. Patients should be advised to never take two doses together to make up for a missed dose.
What common medicines should be avoided with methotrexate?
When NSAIDs (e.g. ibuprofen) are taken with methotrexate there is an increased risk of toxicity.
Trimethoprim or co-trimoxazole (septrin) co-prescribed with methotrexate can be fatal. This is due to an additive effect of inhibiting dihydrofolate reductase, which increases the risk of bone marrow suppression.
How long does it usually take before it starts to have effect?
onset of action is 4-6 weeks
What are common side effects of methotrexate ?
Loss of appetite
Nausea
Indigestion
Diarrhoea
Headaches
Tiredness
Hair loss
What are some serious side effects of methotrexate ?
Liver toxicity: jaundice
Pulmonary toxicity: persistent cough, chest pain, dyspnoea
Renal toxicity: peripheral oedema, polyuria
Signs of infection: fever, chills, muscle aches, sore throat
Thrombocytopenia: bleeding gums, haematuria, unexplained bruising
Stevens-Johnson syndrome: severe skin rash or blisters on skin, mouth, eyes or genitals
What is patient monitoring like for Methotrexate?
When beginning treatment, full blood count, renal and liver function tests should be carried out every 1-2 weeks until the therapy is stabilised. Thereafter, patients should be monitored every 2-3 months
What are symptoms of bone marrow suppression?
Symptoms of a low red blood cell count may include:
- Fatigue
- Pale skin, lips, and nail beds
- Faster heart rate
- Easy tiring with exertion
- Dizziness
- Shortness of breath
Symptoms of a low white blood cell count only happen if an infection occurs because of the low count. These may include:
- Fever and chills
- Mouth sores
- Rash
- Diarrhoea
- Swelling
- Redness
- An area that is warm to touch
Symptoms of a low platelet count may include:
- Easy bruising
- Bleeding through nosebleeds, or from the gums or mouth
- Tiny red spots on the skin
- Blood in the urine
- Dark or black bowel movements
