Change to methotrexate pack sizes due to safety concerns

Published in NPS RADAR

Date published: About this date

Clinical content may change after this date. This information is not intended as a substitute for medical advice from a qualified health professional. Health professionals should rely on their own expertise and enquiries when providing medical advice or treatment.

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

References

  1. 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).
  2. 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).
  3. 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).
  4. Kanagarajah S. Perils and pitfalls of methotrexate prescription. Australian Prescriber 2000;23. http://www.australianprescriber.com/upload/pdf/articles/368.pdf