Comparison of high-performance liquid chromatography and microbiological assay for the determination of ofloxacin in serum and urine in humans

Ofloxacin is one of the new carboxylic acid derivatives showing a broad antibacterial spectrum active against most Gram negative bacteria, many Gram positive bacteria and some anaerobes. The metabolism of ofloxacin produced 3 metabolites that could interfere with some analytical procedures. In fact, we have compared the HPLC results with a microbiological activity assay showing considerable differences in mean urine levels for the two methods. When measured by bioassay, an increase of urinary recovery between the 4 and 24 hr ofloxacin levels was observed. These differences could suggest a persisting antibacterial activity of some of the metabolic derivatives of ofloxacin.