Antibiotic drug therapy in the newborn

The use of antimicrobial agents in newborn infants has always been fraught with uncertainty. Because of the immature excretory and/or metabolic process of infants, it was recognized that detailed pharmacokinetic studies were necessary before these drugs could be used safely and effectively in young infants, but it was only with experience that it became obvious that toxicity remained relatively unpredictable. Babies were found to be more resistant to certain types of adverse reactions (eg, renal damage by aminoglycosides, bacitracin, methicillin, etc) but more susceptible to others (sulfonamides, chloramphenicol, tetracyclines, nitrofurantoin, and so forth). In many instances, the toxic effects encountered could have been predicted on the basis of experimental data in animals, but in other cases, this was not possible. Thus, the use of new antimicrobial agents in babies may expose them to unpredictable dangers. For that reason, new drugs should only be administered to young infants if they clearly have a therapeutic advantage over older ones. Therapeutic trials must await adequate pharmacokinetic studies, and the investigator must be prepared to follow the treated infants (along with a group of matched control patients) for a sufficient length of time to be certain that any organ damage caused by the drug would have become clinically detectable. In some cases this requires a period of several years.