Absence of Nitrofurantoin From Human Milk

To the Editor:— Concern has been expressed frequently regarding the excretion in human milk of drugs administered to the mother, and the effects of these drugs on the nursing infant. Knowles in a recent review 1 cited findings to the effect that several antibacterial drugs can be found in milk, in pharmacologically significant concentrations, when these substances are administered to lactating women. We obtained samples of milk from women during postpartum hospitalization and had them analyzed for nitrofurantoin (Furadantin) by the method of Conklin and Hollifield. 2 The subjects were normal, healthy women, aged 16 to 25, para 0 to para 2, who received nitrofurantoin at the usual therapeutic dosage: 100 mg four times a day, by mouth, during the period of observation (three or four days). All mothers had spontaneous deliveries. The infants were bottle-fed, and the milk samples were collected by means of a breast pump, beginning on