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
- Australian Government Department of Health and Ageing. Positive recommendations made by the PBAC — March 2008. http://www.health.gov.au/internet/main/publishing.nsf/Content/pbacrec-mar08-positive (accessed 4 July 2008).
- Adverse Drug Reactions Advisory Committee (ADRAC). Methotrexate — name the day. Australian Adverse Drugs Reaction Bulletin 1998;17.http://www.tga.gov.au/adr/aadrb/aadr9805.pdf (accessed 4 July 2008).
- New South Wales Government Department of Health. Methotrexate — safe use of oral methotrexate. 2005. http://www.health.nsw.gov.au/policies/pd/2005/PD2005_624.html (accessed 4 July 2008).
- Kanagarajah S. Perils and pitfalls of methotrexate prescription. Australian Prescriber 2000;23. http://www.australianprescriber.com/upload/pdf/articles/368.pdf