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The Pharmaceutical Journal
Medicines in use
From Mr M. F. Hannon, MRPharmS
I read with interest the letter regarding the confusion between folic acid and methotrexate tablets (PJ, 16 November, p712). Within our hospital we have had similar anxieties about this type of confusion occurring in one of our dermatology outpatients clinics and we have had two near misses of which we are aware. Our analysis suggested that although the colours and shape of the two agents are similar, we need to pay much more attention to the strength of the methotrexate tablets prescribed (dispensed) and their dosing frequency.
Therefore, about 15 years ago, we took action to stock only one strength of oral methotrexate (2.5mg tablets) in the hospital pharmacy. This decision was driven by a consultant dermatologist and myself and we organised it such that all our dermatology outpatients on oral methotrexate would, for reasons of safety and continuity, always get their drug from the hospital pharmacy. The consultant argued forcefully that with the drive by the Government to encourage generic prescribing and dispensing, changes in tablet presentation, colour, etc, happen so frequently that patients often "miss" the obvious warning signs when something is dispensed wrongly. He reasoned that for a drug such as methotrexate where the therapeutic index is so low, we needed to ensure that the patient was trained adequately and that the supply and the identity of the drug could be guaranteed. Therefore we purchased only branded, identifiable methotrexate tablets 2.5mg and patients in the clinic knew what to expect. This initiative soon spread to patients in other clinics and so far we have had no problems.
One of my colleagues in another trust asked me whether our patients and pharmacy staff eventually become "desensitised" to the risks of oral methotrexate. I hope that this never happens but given the growth in the use of oral methotrexate in other specialties (immunology, oncology, rheumatology), it is possible that methotrexate could become "just another drug". Patients, for instance, expect to take their tablets every day and weekly dosing is relatively infrequent in pharmacy practice so complacency can creep in. However, anyone who read the recent report on the fatality with methotrexate (see www.cambs-ha.nhs.uk/publications/pdf/methotrexate-toxicity.pdf) can be left in no doubt as to its potential toxicity.
The pharmaceutical industry could, with better packaging, do much more to help eliminate the hazard. But given the range of doses that we dispense in our hospital (from 2.5mg up to 22.5mg once weekly), it could prove to be difficult to get a standard pack. Until there are further controls on oral methotrexate (see Pharmacy in Practice, September 2002, p277), perhaps the only safeguard for patients and pharmacists is more information and better education. As pharmacists we must remain acutely aware of the risk posed by this drug if it is taken daily instead of weekly.
M. F. Hannon
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