ENTEROHEPATIC CIRCULATION OF ESTRIOL - STUDY OF THE EFFECTS OF AMPICILLIN ON PLASMA ESTRIOL LEVELS

Plasma total oestriol was measured daily before and during ampicillin therapy in five pregnant patients and in eight patients, four of whom were receiving ampicillin, for four days following delivery. Ampicillin caused a fall in plasma oestriol of 25 per cent during the first three days of treatment, thereafter the level remained stable with a lower day‐to‐day variability than in untreated patients. Ampicillin reduced the plasma half life of total oestriol by 60 per cent. This study illustrates how the re‐entry of oestriol from the gut leads to irregular fluctuations in plasma oestriol levels and helps to keep up the plasma concentration of the steroid when inflow from the fetoplacental unit is cut off. Copyright © 1979, Wiley Blackwell. All rights reserved