New tool helps practitioners identify what medications are safe to use while breastfeeding

Researchers from the University of Waterloo’s School of Pharmacy have created a new tool that helps identify what medications are safe to take while breastfeeding.

Called the Upper Area Under the Curve Ratio (UAR) metric, it’s a modelling system that helps healthcare providers determine if a medication is safe for breastfeeding people to take. 

The research, published in Frontiers in Pediatrics, was led by Cindy Yeung, a recent PhD graduate from the school. “We developed the novel Upper Area Under the Curve Ratio metric using physiologically based pharmacokinetic modelling to help a population that is often left out of scientific research,” she said in a press release.

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It allows the researchers to simulate how a drug moves through a person mathematically, which tells them how much of the drug will be present in breast milk and go through to the baby. It calculates the risk to the infant by taking into account their anatomy and physiology; variability in the baby’s exposure, through things like pharmacogenotype; and the amount of breastmilk that would be consumed. 

“The UAR metric uses an estimated drug dose from breastmilk that is then given to virtual infants to assess likely drug exposures and to identify characteristics of those infants that may be at increased risk to high exposures. This brings researchers one step closer to understanding the response or the adverse effects you might see in infants,” Yeung said.

The UAR metric could be added to informational resources that already exist to help healthcare providers be able to offer accurate advice on whether medications pose a risk to infants. Right now, healthcare providers often err on the side of caution and advise breastfeeding mothers against using medications, though that might be detrimental to the lactating person or result in them discontinuing breastfeeding so they can take needed medications. 

“The limited information on medication use during lactation has created a significant knowledge gap that directly impacts a vulnerable population due to the exclusion of lactating persons and infants from the drug development process,” Yeung said. 

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