STUDY OF THE DISPOSITION OF ALPHA-METHYLDOPA IN NEWBORN-INFANTS FOLLOWING ITS ADMINISTRATION TO THE MOTHER FOR THE TREATMENT OF HYPERTENSION DURING PREGNANCY

1 The nine infants participating in this study were born to mothers who received continuous therapy with alpha‐methyldopa (0.75‐2.0 g/day) for several weeks extending to the time of delivery. 2 The concentration of free and total (free plus conjugated) alpha‐methyldopa was determined by gas chromatography‐mass spectrometry in amniotic fluid, umbilical cord plasma and maternal plasma at delivery; also in urine collected over time intervals from neonates during the first days after birth. 3 The results indicate that alpha‐methyldopa administered to the mother is present in the infant at birth at a level comparable to the maternal level and persists for some days. The ratio of conjugated to free drug increases with time after birth. 4 The excretion of free and conjugated alpha‐methyldopa in the urine indicated that the drug is slowly eliminated in the neonate by excretion in the urine and apparently by metabolism, mainly to the sulphate conjugate. 5 The concentration of free and conjugated alpha‐methyldopa in amniotic fluid tended to be higher than in umbilical cord plasma but lower than in neonatal urine, conjugated drug predominated. 1979 The British Pharmacological Society