I came across an interesting methotrexate case today and thought I would post on my blog to share some of the key points that Pharmacists must look out for when dealing with patients using methotrexate. I hope that the same points will help students who are currently studying the therapeutic area(s) of rheumatoid arthritis / psoriatic arthritis.
My patient was a 30 year old female, diagnosed with psoriatic arthritis several years ago. She was initiated on oral methotrexate at a starting dose of 7.5mg per week. Over time, this dose was increased to 20mg each week. The patient couldn’t tolerate the oral dose due to gastrointestinal side effects and therefore the consultant switched her to the injectable format (Metoject) at a dose of 22.5mg per week. The dose of methotrexate was fine, no problem there - the BNF recommends a maximum dose of 25mg per week. So, I didn’t have any concerns.
My concerns lay in three key areas; namely patient safety, patient compliance and patient monitoring. With this medication patient safety is paramount. The DMARD is highly effective in the treatment of arthritis either as monotherapy or in combination with the newer biologics. However, it can be very dangerous due to the lack of target specificity once administered. In order to improve the safety aspect, folic acid 5mg each day - apart from the day of taking methotrexate - is advised. This is so as methotrexate is a reversible dihydrofolate reductase that leads to lower than normal levels of folate in the bloodstream. To counter this effect, folic acid is given and should be taken as prescribed (i.e. the compliance aspect). On review of the patient notes, it was evident that folic acid 5mg wasn’t regularly requested and therefore I made a point of informing the patient that this is a key requirement of her treatment regimen. On discussion with the patient, it was clear that she hadn’t been for regular screening whilst taking methotrexate. Because this agent can adversely affect the body, it is important to book tests including full blood count, eGFR, LFTs and as a baseline (for comparison later down the line) a chest x-ray. The date of the last blood panel was 6 months prior (perhaps due to COVID-19) and therefore I informed the patient that she must book an appointment with the nurse to have a full work up.
Further counselling points revolved around adequate contraceptive cover whilst taking methotrexate, as specified by current NHS shared care guidelines, plus the use of relevant information leaflets for up-to-date information / handheld methotrexate monitoring booklet for recording important biological indicators (e.g. ESR, CRP, LFTs and FBC). Finally, I discussed important symptoms of methotrexate toxicity and these included for instance increased breathlessness, a dry persistent cough sore throat and unexplained vomiting and diarrhoea. The conversation concluded by “safety-netting” the patient. Here, I clearly outlined the availability of a helpline that can be referred to should side effects to the medication be suspected.
The patient was grateful to receive my advice and told me that she would take all of the information on-board.
As a final note, I thought it would be worthwhile to list important points that the Pharmacist should be aware of when dealing with patients prescribed methotrexate:
Why is the patient taking methotrexate?
How long will it take for the drug to work effectively to control the disease?
What is the dose and frequency of dosing? And, does this sound sensible?
What monitoring is in place?
Which side effects would warrant referral to a practitioner?
The potential for drug interactions, including over-the-counter medicines
The need for adequate contraceptive cover
The need to ensure that the healthcare team is aware methotrexate is being used
Please get in touch with me [https://www.pharmascholar.co.uk/contact-us] if you have any queries or questions in relation to the above. I would be more than happy to speak with you and offer further information if you so wish.
