Drug Concentrations in Breast Milk and Prediction of Blood Levels of the Breastfed Infants

Drugs in Breast Milk

There is a significant lack of information on drug secretion into milk and infant exposure. As a first step to address this issue, the investigators examine milk concentrations of selected drugs prescribed to breastfeeding women, which lack milk excretion data. Milk data will be analyzed using population pharmacokinetic approaches, when possible, and acquired data of drug concentration profiles in milk will be combined with infant physiologically-based pharmacokinetic (PBPK) models to predict infant exposure levels.

In this study the investigators measure drug concentrations in breast milk (and optional blood) samples collected through sparse and flexible sampling strategy mitigating intense approaches of conventional PK study. Whenever possible, population PK method is used to characterize milk concentration profiles of the selected drugs. The obtained data is further processed through a PBPK model of infant to predict infant drug exposure levels.

The study also includes an optional pharmacogenetic part. This will allow the investigators to understand how variations in genetic composition plays role in breaking down drugs and how it affects the drug transfer into breast milk.

This study is conducted at three sites: Hospital for Sick Children (leading site), CHU Sainte Justine Hospital, Montreal (Study Lab: for drug measurement), and University of Waterloo (Modelling Core: to create computer model).

Inclusion Criteria for breastfeeding women

• Age of 18 years or older
• Lactating women taking at least one of the study target drugs per Standard of Care
• Obtained informed consent
• Ability to communicate in English

Exclusion Criteria for breastfeeding women

• Any concomitant medication
• Known pregnancy during PK sampling

Inclusion criteria for their infant

• Older than 1 week
• Healthy

Exclusion criteria for their infant

• Concomitant medical treatment