Is Dimethyl Fumarate safe while breastfeeding?

Effects on the breastfed infant

Twenty-six women taking dimethyl fumarate for relapsing-remitting multiple sclerosis were followed during 29 pregnancies from 2015 to 2020. Dimethyl fumarate was administered through week 24 of pregnancy and resumed 1 month after delivery. Twenty-two of 26 mothers breastfed (extent not stated) for 4 to 7 months. Infants were monitored up to the third year of life for infections and developmental disorders. All children were the 70th and 95th percentile for height and weight. The authors concluded that continuing dimethyl fumarate while breastfeeding is safe,[ 4 ] although infants were not exposed during the first month of life. One group reported two mothers with multiple sclerosis who resumed taking dimethyl fumarate 1 week after delivery while partially breastfeeding their infants. One was taking 240 mg daily and withheld breastfeeding for 4 hours after each dose. The other was taking 480 mg daily with mixed feeding continuing for 15 months. The latter patient became pregnant again and once again used mixed feeding while taking dimethyl fumarate. All 3 infants developed normally and had no serious infections.[ 5 ]

Effects on milk supply

Relevant published information was not found as of the revision date.

Levels in milk

Dimethyl fumarate is not found in the plasma because it is rapidly converted to the active drug, monomethyl fumarate, which has a half-life of about 1 hour. Maternal Levels. Two nursing mothers with relapsing-remitting multiple sclerosis began oral dimethyl fumarate 240 mg twice daily after discontinuing breastfeeding. They continued pumping milk and on day 8 of therapy, they each provided milk samples at 1, 2, 4, 8 and 12 hours after a dose. Peak monomethyl fumarate milk levels were 3.7 mcg/L in one mother and 11.2 mcg/L in the other and occurred at about 2 hours after the dose. Average milk levels were 2.7 mcg/L and 7.5 mcg/L, respectively. These values indicate that the infants would receive daily dosages of about 0.8 mcg/kg and 1.13 mcg/kg, respectively, or weight-adjusted relative infant dosages of 0.007% and 0.019% of the maternal dosage.[ 2 ] A woman with multiple sclerosis who was 3 months postpartum began dimethyl fumarate 120 mg (Polpharma SA Pharmaceutical works, Starogard Gda ski, Poland) orally twice daily after weaning her infant. Four milk samples were collected over a 24-hour period 6 days after starting therapy. The concentration of monomethyl fumarate ranged from 83.5 mcg/L just after a dose to undetectable ( 5.5 mcg/L) at 2 hours before the next dose. The authors estimated a daily dose of 5.76 mcg/kg with a daily milk intake of 150 mL/kg, which represents a relative infant dose of 0.16%.[ 3 ] Infant Levels. Relevant published information was not found as of the revision date.

Alternatives LactMed lists

• Immune Globulin
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