Can you take belimumab while breastfeeding?

How much belimumab gets into breastmilk

Maternal Levels. A postpartum woman with mixed connective tissue disease was started on intravenous belimumab 520 mg (10 mg/kg) every 2 weeks for 2 doses, then 520 mg monthly as well as hydroxychloroquine 200 to 400 mg daily. Belimumab milk concentrations were 0.12 mg/L at 2 weeks after the first dose and prior to the second dose, 0.17 mg/L on the following day, and 0.12 mg/L at 7 weeks after the second dose.

Two lactating women with systemic lupus erythematosus who were receiving belimumab 200 mg subcutaneously every 2 weeks donated milk samples postpartum at starting at 3 to 4 days postpartum. Milk concentrations were highest at about 3 days after the dose at about 75 mcg/L in one woman and about 125 mcg/L in the other. At 7 days after the dose, milk levels remained relatively constant in the first woman and decreased to about 90 mcg/L in the second.

A woman with systemic lupus erythematosus was started on belimumab 200 mg subcutaneously every two weeks and discontinued breastfeeding at 3 months postpartum. She continued to pump milk to avoid engorgement. Two milk samples were analyzed for belimumab. On day 14 after 2 doses of the drug, an evening milk sample contained 0.264 mg/L of belimumab and a second sample taken on day 28 before the fifth dose contained 0.885 mg/L.

A woman with relapsing-remitting small-fiber neuropathy had a remission at two months postpartum. She resumed weekly subcutaneous belimumab injections of 1800 mg. Breastfeeding and normal infant development continued through 19 months postpartum at the time of the report.

Three women were receiving belimumab for systemic lupus erythematosus. Two were receiving a dose of 200 mg subcutaneously every 2 weeks, with the previous dose 1 day prior to delivery. In one woman, breastmilk samples were collected at five different time points from 2 to 5 days postpartum and the concentrations ranged from 0.2 to 0.6 mg/L. In the second woman, breast milk samples were collected at six different time points from 1 to 30 days postpartum with concentrations ranging from 0.12 to 0.17 mg/L. A third woman was receiving a dose of 400 mg intravenously once a month, with doses 3 weeks prior to delivery and 5 days postpartum. Milk levels ranged from 0.49 to 1.14 mg/L at seven time points from 4 to 27 days postpartum.

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

What has been seen in breastfed infants

A woman with systemic lupus erythematosus was taking belimumab (dose not stated) for 1 year when she became pregnant. She received monthly belimumab infusions during pregnancy and continued postpartum, starting at 2 weeks postpartum. She breastfed her infant (extent not stated). No infant effects were mentioned.

Three women with systemic lupus erythematosus were taking belimumab, in doses of 200 mg subcutaneously every 2 weeks in two women and 400 mg intravenously once a month in the other. One infant was hospitalized for surgical treatment of left vesicoureteral reflux, but peripheral T and B lymphocyte counts, and gamma globulin were normal at 20 months of age. The infant received all required vaccinations, both live and inactivated, with no adverse reactions, and adequate antibody levels against hepatitis B, measles, and rubella at 18 months of age. The second infant had low peripheral B and transitional B cell counts at birth, but the infants’ T cell counts, and serum IgG levels were within normal range. The infant received all the required live and inactivated vaccines with no adverse events following vaccination. Follow-up of these infants at 2 years revealed no adverse developmental outcomes. The infant of the mother receiving 400 mg monthly had decreased peripheral B, transitional B, and NK cell counts at birth, but a normal T cell count and serum IgG level. The infant was monitored for 6 months, with no adverse developmental outcomes.

Effects on milk supply

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