Conference Coverage
Dimethyl Fumarate
Flushing occurs in one-third of patients taking dimethyl fumarate. This side effect is benign and typically passes in 20 minutes. Taking aspirin daily can prevent flushing or reduce its severity.
One-third of patients may experience gastrointestinal side effects, including nausea, vomiting, diarrhea, and abdominal pain. The symptoms typically improve after one month. Administering the drug with food, titrating the dose slowly, and providing symptomatic treatments may help.
Dimethyl fumarate also is associated with lymphopenia, which typically takes around 12 months to develop. It is reasonable to monitor patients for lymphopenia, particularly at 12 months, and for infections, said Dr. Fox.
The drug also may be associated with a risk of PML. Four cases of PML have been reported from a total experience of approximately 170,000 patient years. Patients with PML had been receiving a formulation of dimethyl fumarate used to treat psoriasis, and some had prior immunosuppressant use and prolonged lymphopenia. After the ECTRIMS meeting, the manufacturer reported a case of PML in a patient with MS receiving dimethyl fumarate who had low lymphocyte counts for 3.5 years. Compared with natalizumab, dimethyl fumarate is associated with a lower risk of PML. “Nonetheless, it’s something that we’re keeping in the back of our mind and watching for,” said Dr. Fox. Monitoring for severely reduced lymphocyte counts may mitigate the risk of PML, he concluded.
—Erik Greb
