Monitoring of drugs in breast milk

With the increasing popularity of breast feeding, the secretion of drugs in breast milk would be of clinical interest. The merits of breast feeding and the composition of breast milk are outlined. The pharmacokinetics of drugs in breast milk may be described by a 3-compartment open model, with breast milk being the third compartment--a deep compartment with limited capacity. Recent clinical studies on secretion of atenolol, propranolol, propoxyphene, phenytoin, carbamazepine, and valproic acid in breast milk showed that the infant ingested dose was insignificant. Thus, nursing mothers on these drug therapies should be allowed to breast feed their infants. Owing to the lack of adequate clinical data and methodology for studying the secretion of antidepressants in breast milk, there is a need for a sensitive assay. Thus, a reversed-phase high performance liquid chromatography assay of imipramine and desipramine in breast milk was outlined, with sensitivity of 5 micrograms per liter. With the instrumentational capability of most clinical laboratories, it would be possible to perform drug levels measurement in breast milk. In collaboration with other clinicians, a useful data base could be accumulated for making rational decisions on breast feeding for mothers on drug therapy.