Study finds certain drugs used to treat eye diseases excreted into breast milk, posing potential risks for infant development

By Anna Wassermann

Certain drugs used to treat retinal diseases are excreted into breast milk, raising possible safety concerns for developing infants, suggests a first-of-its-kind study led by St. Michael’s Hospital in Toronto and published in Ophthalmology.

Ranibizumab and aflibercept are medications used to treat several retinal diseases. They contain an agent called anti-vascular endothelial growth factor (anti-VEGF), which blocks the eye’s production of vascular endothelial growth factor (VEGF). VEGF is a protein that stimulates the development of blood vessels but is associated with retinal diseases in high quantities.

VEGF is present in breast milk and plays an important role in the development of an infant’s digestive system. As a result, anti-VEGF drugs in a nursing mother raise concerns about possible adverse events in a developing infant if the drugs were to pass into breast milk and suppress VEGF.

“As retina specialists, we often tell our pregnant or nursing patients that there’s a risk of a small amount of these drugs making its way into the breast milk, but we can’t be sure,” said Dr. Rajeev Muni, co-lead author, a vitreoretinal surgeon at St. Michael’s and a project investigator at the hospital’s Li Ka Shing Knowledge Institute.

“We don’t want these patients to lose their vision so we make a decision, despite limited information.”

Hoping to change this, Dr. Muni and Dr. Verena Juncal, co-lead author and a retinal fellow at St. Michael’s, measured the concentrations of retinal medications in the breast milk of three lactating patients following injection of anti-VEGF therapy. Each patient represented a different scenario – one continued to breastfeed while receiving therapy, one discontinued breastfeeding, and one never started.

The team found that the drugs were excreted into the breast milk within the first couple days following injection, with a corresponding reduction in VEGF levels.

They also found that the amount of medication detected in the patient who continued to breastfeed was significantly lower than the other two patients, suggesting that the medication was constantly excreted and ingested by the infant.

“These results definitively show us that the drug reaches the breast milk,” said Dr. Juncal. “We realize that some readers may question the small sample size, but if the drug reaches the breast milk in three patients, it’ll reach in 30 patients because it’s the same biological process.”

As the first study to evaluate the presence of Health Canada approved anti-VEGF therapy in human breast milk, these results provide a resource for ophthalmologists and retina specialists counselling pregnant and nursing patients.

“I’m comforted knowing that other pregnant or nursing mothers with retinal diseases will have the information needed to make an educated decision about whether to consider nursing while receiving these medications,” said Lisa, one of the three study participants, who didn’t want to reveal her surname.

Next, the researchers hope to collaborate with a team of paediatricians to find out whether the drug passes from the breast milk through the infant’s digestive system and into the blood stream.

“If we can measure the levels of these drugs in the infant’s blood, we can figure out the exposure over a long period of time,” said Dr. Muni. “That’s what’s really important here – the possible effect of these drugs on the infant over a long period of time.”

Drs. Muni and Juncal would like to acknowledge their collaborators in the Department of Ophthalmology at the University of Calgary.

This paper is an example of how St. Michael’s Hospital is making Ontario Healthier, Wealthier, Smarter.

About St. Michael’s Hospital

St. Michael’s Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in more than 27 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the Hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael’s Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.

About Unity Health Toronto

Unity Health Toronto, comprised of Providence Healthcare, St. Joseph’s Health Centre and St. Michael’s Hospital, works to advance the health of everyone in our urban communities and beyond. Our health network serves patients, residents and clients across the full spectrum of care, spanning primary care, secondary community care, tertiary and quaternary care services to post-acute through rehabilitation, palliative care and long-term care, while investing in world-class research and education. For more information, visit www.unityhealth.to.

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Media contacts

For more information, or to arrange an interview with one of the authors, please contact:

Leslie Shepherd

Manager, Media Strategy, St. Michael’s Hospital

416-864-6094 or 416-200-4087

shepherdl@smh.ca

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