Metformin accumulation and chronic kidney disease
Metformin may accumulate in people with kidney disease causing an increase in the risk of lactic acidosis, a rare but potentially fatal adverse drug reaction. When metformin is appropriately prescribed, lactic acidosis occurs in less than 1 in 10 000 patients.1
Avoiding metformin accumulation
Australian guidelines recommend a maximum daily dose of 2 g for patients with a glomerular filtration rate (GFR) of 60–90 mL/min, and 1 g for patients with a GFR of 30–60 mL/min. Metformin is not recommended for patients with a GFR less than 30 mL/min 2
Product Information may not be up to date
Some manufacturers have not updated their Product Information to reflect the latest guidelines and may recommend a higher GFR cut-off as a contraindication for metformin.3,4
- Endocrinology Writing Group. Therapeutic guidelines: endocrinology, version 4. Melbourne: Therapeutic Guidelines Ltd, 2009.
- Australian medicines handbook. Adelaide: Australian Medicines Handbook Pty Ltd, 2013.
- Alphapharm Pty Limited. Diaformin product information. 2011. https://www.ebs.tga.gov.au/ebs/picmi/picmirepository.nsf/pdf?OpenAgent&id=CP-2010-PI-04546-3 (accessed 4 June 2013).
- Symbion Pharmacy Services Pty Ltd. Chemmart metformin product information. 2010. https://www.ebs.tga.gov.au/ebs/picmi/picmirepository.nsf/pdf?OpenAgent&id=CP-2010-PI-05805-3 (accessed 4 June 2013).