Cerebrospinal fluid and serum ampicillin levels in bacterial meningitis patients after intravenous and intramuscular administration.

Abstract28 patients with bacterial meningitis received ampicillin by the intramuscular (IM) route and 16 patients by the intravenous (IV) route. The mean cerebrospinal fluid (CSF) ampicillin levels were similar in the two groups 1 h after a dose given on the first or second day of treatment, but they were higher in the IM group on both days 4 h after a dose. CSF/serum ratios were similar in both groups but considerably higher at 4 h than at 1 h.