A study of conjugation and drug elimination in the human neonate.

1 An investigation has been made of the excretion of alpha-methyldopa, alpha-methyldopa sulphate, lorazepam and lorazepam glucuronide in the urine of neonates. 2 The rate of elimination of both the drugs in the newborn is slow compared with the adult rate, and apparent half-life being 3 to 4 times longer than the reported adult values. 3 The newborn appear able to readily metabolise alpha-methyldopa to alpha-methyldopa sulphate and to slowly conjugate lorazepam with glucuronic acid. alpha-Methyldopa tends to be conjugated to a greater extent and lorazepam to about the same or slightly lesser extent in the newborn than in adults. 4 It is postulated that elimination in the neonate is mainly controlled by the rate of renal excretion in the case of alpha-methyldopa and by the rate of conjugation in the case of lorazepam.