New mathematical model assesses drug exposure for breastfed infants

A new mathematical model developed at the University of Waterloo can determine a baby's overall drug exposure when their mother is taking medication. This is the first study to include drug transfer from the umbilical cord and through breastfeeding in determining the baby's total drug levels.

The research team from the School of Pharmacy at Waterloo looked specifically at Levetiracetam. It is a drug commonly prescribed long term for women with epilepsy, yet there was minimal data on the risk of adverse effects on breastfed infants.

Breastfeeding mothers often face the hard choice of continuing to take their medication and risking harm to their babies due to exposure during feeding, or stopping potentially life-saving treatments. The World Health Organization and UNICEF recommend that infants breastfeed within an hour of birth and do so exclusively for six months.

A mother can be at serious risk if Levetiracetam is stopped, affecting her ability to care for her infant. Our research shows that the probability of negative effects on a breastfeeding infant is very low for typically prescribed doses of Levetiracetam."

Shirley Wang, a PhD student in the School of Pharmacy at Waterloo

The team built the mathematical model using physiologically based pharmacokinetic (PBPK) modeling, to determine the overall infant exposure to the drug.

"We included both womb and breast milk exposure in our newborn-infant model, which we've coined the cord-coupled model (CCM), to gain a more accurate picture of drug exposure to infants during their most vulnerable time in the first weeks of life," Wang said.

"We also included in the PBPK model infant anatomy and physiology, the volume of breast milk consumed and the drug concentrations in breast milk for more accurate results," said Dr. Santosh Suryavanshi, research associate at the School of Pharmacy.

Clinical data for infants is still lacking for many drugs. The study's model can help in the assessment of other commonly prescribed drugs that breastfeeding mothers might take.

"There has always been limited data in specific populations due to the risks associated with clinical trials," Suryavanshi said. "This mathematical modelling is a tool researchers can use to determine drug exposures to improve the quality of life for both mother and infant."