From 1 April 2008 a smaller pack size of methotrexate 10 mg tablets (15 tablets with maximum of 1 repeat) was made available on the PBS as an unrestricted benefit. The new PBS listing is to help reduce the chance of accidental overdose and potentially fatal toxicity.1 As a result of this change, the currently listed larger pack size of methotrexate 10 mg tablets (50 tablets with a maximum of 2 repeats) has received a restricted benefit listing, for patients requiring doses exceeding 20 mg weekly.1
Methotrexate can cause severe toxicity and death when the recommended dosage (dose and/or dose frequency) is exceeded.2
When prescribing or dispensing methotrexate to patients or carers:
-
stress the importance of taking methotrexate only as prescribed
-
provide clear written and verbal instructions to ensure the dosage regimen is understood (for example, the Methoblastin Consumer Medicine Information [CMI] leaflet contains instructions about safe use and may be a useful counselling aid)
-
for weekly regimens agree on a specific day of the week for taking methotrexate (preferably one of significance for the individual) and make sure once-weekly dosing is not confused with once-daily dosing.2–4
-
emphasise the importance of regular monitoring (blood tests)
-
warn about possible signs and symptoms of toxicity and explain what to do if these develop.3
