PILLS - Oral methotrexate

Specific medicines

Methotrexate is used to treat a number of non-cancer indications, such as rheumatoid arthritis, psoriasis and Crohn’s disease. In these cases, it is prescribed as a single weekly dose. Since 2004, the NPSA has received 165 reports of patient safety incidents involving oral methotrexate (NPSA 2006). Dosing errors were a common cause of severe patient harm, especially when methotrexate was prescribed more frequently than once weekly. This has been so well publicised by the NPSA, that the Department of Health (2012) has classed it as a ‘never event’. When prescribing oral methotrexate, you should always include the correct:

Dose
Route
Frequency
Day of the week when methotrexate should be taken

In addition, only one strength of methotrexate tablet should be used (usually 2.5mg). When prescribing oral methotrexate on an inpatient prescription chart, you must state that it is a weekly dose and the other six days of the week should be struck out (see below). Methotrexate is a cytotoxic drug and every patient who takes it needs to be closely monitored. Serious patient harm can occur if the correct monitoring is not carried out (NPSA 2006).

Oral methotrexate

What monitoring do you think needs to take place in these patients?

Why do you think it is important to consider folic acid for patients prescribed methotrexate?

What monitoring do you think needs to take place in these patients?
For all patients prescribed methotrexate, the full blood count, liver function tests and renal function tests need to be closely reviewed. Patients also need to be monitored for signs of methotrexate toxicity/intolerance, such as breathlessness, dry persistent cough, vomiting, diarrhoea, sore throat, bruising or mouth ulcers. Were you aware that there is a patient held monitoring booklet to help with this? These should be issued to all patients taking oral methotrexate. These booklets should give details of the dose being taken and the monitoring schedule that is being followed. They should also give details about the patient’s folic acid regime.
Why do you think it is important to consider folic acid for patients prescribed methotrexate?
Methotrexate affects folate metabolism and can cause side effects that are similar to folate deficiency. Patients who experience mucosal or gastrointestinal side effects may benefit from folic acid. This is an unlicensed indication but as long as it is not taken on the same day as methotrexate, the effectiveness of methotrexate should not be reduced. Whenever you prescribe methotrexate you should make sure you are informing patients about how to take methotrexate safely. Telling them about potential side effects and how these should be managed can reduce the risk of patient harm. Patient information leaflets are available at http://www.mhra.gov.uk/spc-pil/ to help with this and should be given to patients before treatment is started.