In their article, Cairns and colleagues1 raised a pertinent issue regarding the incorrect dosing and administration of low dose methotrexate, which may result in potentially serious adverse outcomes. In 2014, the Australasian Psoriasis Collaboration recommended a specified day dosing regimen for methotrexate and folic acid, with the instructions written on the script: methotrexate on Mondays and folate on Fridays.2 Even if the patient mistook one for the other, they would still take the medication once a week even if it was on the wrong day. This does not prevent the incorrect tablet size (2.5 mg or 10 mg) from being dispensed, but it should reduce the risk of taking methotrexate more than once a week. Moreover, the Australasian Psoriasis Collaboration also recommended a greater use of weekly subcutaneous methotrexate as a way of reducing adverse gastrointestinal effects, improving compliance and reducing medication error.
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