Tobramycin levels in cerebrospinal fluid of patients with slightly and severely impaired blood-cerebrospinal barrier

Abstract

Concentrations of tobramycin in cerebrospinal fluid (CSF) and serum of neurosurgical and of meningitis patients were determined following systemic application of 80-mg doses. Tobramycin was detectable only in 8 tests out of 17 in CSF of 11 neurosurgical patients. The highest drug amount in CSF in these tests was 0.47 microgram/ml. In CSF of 7 meningitis patients with CSF cell counts ranging from 173/3 to 20,500/3 cells, tobramycin was detectable in all 11 determinations. However, the tobramycin level was above 1.0 microgram/ml in only one CSF sample. These results also confirm the poor penetrability of aminoglycosides through the blood-CSF barrier for tobramycin. In proven gram-negative bacillary meningitis and tobramycin treatment, additional intraventricular aminoglycoside application is necessary to obtain effective levels in CSF. An exception may be treatment of neonatal meningitis.