Summary Safety Review - Dimethyl Fumarate - Assessing the Potential Risk of Fanconi Syndrome

Dimethyl fumarate-containing products

Fanconi syndrome, a serious disorder that affects how the kidneys reabsorb certain essential substances

• Dimethyl fumarate is authorized for sale in Canada for the treatment of adult patients with a form of multiple sclerosis in which symptoms intensify and decrease over a certain period of time (relapsing remitting multiple sclerosis).

• Health Canada reviewed the potential risk of Fanconi syndrome with the use of dimethyl fumarate. The safety review was triggered by a labelling update for dimethyl fumarate-containing products by the European Medicines Agency (EMA).

• Health Canada's review of the available information did not find sufficient evidence to support a link between the risk of Fanconi syndrome and the use of dimethyl fumarate for the treatment of multiple sclerosis.

• Health Canada will continue to monitor the safety of dimethyl fumarate.

Health Canada reviewed the potential risk of Fanconi syndrome with the use of dimethyl fumarate. This safety review was triggered by a labelling update for dimethyl fumarate-containing products by the EMA. Fanconi Syndrome has been reported in Europe for a product containing dimethyl fumarate in combination with other fumaric acid esters (a mixture that contains chemical substances along with dimethyl fumarate), used to treat psoriasis. Dimethyl fumarate is not authorized in Canada for the treatment of psoriasis. In addition, only single ingredient dimethyl fumarate, and not fumaric acid ester compounds, is authorized for sale in Canada.

• Dimethyl fumarate is a prescription drug authorized for sale in Canada for the treatment of adult patients with relapsing remitting multiple sclerosis. Dimethyl fumarate helps to reduce the number of flare-ups (relapses) and delay physical problems due to multiple sclerosis.

• Dimethyl fumarate has been marketed in Canada since 2013. It is currently available as 120 mg and 240 mg delayed-release capsules, under the brand name Tecfidera, and as generics.

• There were 236,000 prescriptions for dimethyl fumarate dispensed by Canadian retail pharmacies between 2018 and 2022, with an average of 47,000 prescriptions dispensed yearly.

• Health Canada reviewed the available information from searches of the Canada Vigilance database^a, international databases, and scientific literature.

• At the time of the review, Health Canada had not received any Canadian or international reports of Fanconi syndrome related to the use of dimethyl fumarate. Therefore, Health Canada requested a search of the manufacturer’s international databases.

• A review of the manufacturer’s international databases did not identify any cases of Fanconi syndrome related to the use of dimethyl fumarate for the treatment of multiple sclerosis.

• Health Canada’s review of the scientific literature did not identify any cases of Fanconi syndrome associated with single ingredient dimethyl fumarate for the treatment of multiple sclerosis.

• Health Canada’s review of the available information did not find sufficient evidence to support a link between the risk of Fanconi syndrome and the use of dimethyl fumarate for the treatment of multiple sclerosis.

• Health Canada encourages consumers and healthcare professionals to report any side effects related to the use of dimethyl fumarate and other health products to the Canada Vigilance Program.

• Health Canada will continue to monitor safety information involving dimethyl fumarate, as it does for all health products on the Canadian market, to identify and assess potential harms. Health Canada will take appropriate and timely action should new health risks be identified.

The analysis that contributed to this safety review included scientific and medical literature, Canadian and international information, and what is known about the use of dimethyl fumarate both in Canada and internationally.

For additional information, contact the Marketed Health Products Directorate.

1. Canadian reports can be accessed through the Canada Vigilance Online Database.