CONCENTRATIONS OF ACTIVE ISONIAZID IN SERUM AND CEREBROSPINAL FLUID OF PATIENTS WITH TUBERCULOSIS TREATED WITH ISONIAZID

Microbiologic assay for antimicrobially active isoniazid was performed on the serum of 57 children with tuberculosis. Comparisons were made with similar assays of serum from 344 adult tuberculous patients. Regardless of the basis for calculating equivalent dosage, the relative proportion of children and adults who were rapid inactivators of isoniazid was roughly the same. Six hours after administration of isoniazid the concentrations in cerebrospinal fluid were equal to or greater than those of the serum. The value of determining the concentrations of isoniazid in serum for individualization of dosage in children was discussed.