The interactions between chloramphenicol, penicillin and phenobarbitone were investigated in 383 children (premature and neonate children, infants and small children). As expected, the chloramphenicol concentrations in the serum of the newborns was considerably higher than that of infants and small children with the same dosage of chloramphenicol. In the age group of the premature and newborn children and infants there were significantly higher total chloramphenicol concentrations with the chloramphenicol-penicillin combination than with chloramphenicol monotherapy. Addition of phenobarbitone to the combination significantly reduced the chloramphenicol concentrations in the neonates. Lowering of the serum chloramphenicol concentrations by phenobarbitone could not be statistically confirmed in the infant age group.
Combinations of chloramphenicol with ampicillin, gentamycin or cephalosporin derivatives showed no influence on serum chloramphenicol concentrations.
Transference of chloramphenicol from the serum to the cerebrospinal fluid was about twice as high in the acute inflammatory stage as when the meninges were no longer acutely diseased (60 and 30% respectively of the serum concentrations). The passage of chloramphenicol to the cerebrospinal fluid showed no dependence on age.