Placenta Acts as Gateway: New Study Shows Drug Levels in Fetus

Scientists wanted to understand how a COVID treatment called nirmatrelvir moves from a pregnant mom's blood into the baby. They used a special lab setup that mimics the placenta to measure this transfer.

The team set up a dual closed-closed perfusion system using a single human placenta lobule. They added the drug at two different levels - 2.21 micrograms per milliliter and 22.1 micrograms per milliliter - which is ten times the first level. Each placenta was perfused for one hour before exposure for three hours. They collected samples throughout to track drug levels and check placental health.

The study found that fetal-maternal drug ratios were 0.34 at the lower concentration and 0.42 at the higher one after 180 minutes. When they adjusted for things like protein binding and ionization, the ratios ranged from 0.26 to 0.35 at the lower dose and 0.33 to 0.47 at the higher dose. The drug moved across the placenta in a concentration-dependent way.

These findings give a solid basis for building better computer models of drug movement in pregnancy. They could help doctors figure out the right dose of nirmatrelvir for each pregnant person based on their unique situation.