Sensitive high-performance liquid chromatographic assay for norfloxacin utilizing fluorescence detection

Area of Science:

• Analytical Chemistry
• Pharmacokinetics
• Biomedical Analysis

Background:

• Accurate quantification of fluoroquinolone antibiotics like norfloxacin is crucial for therapeutic drug monitoring and pharmacokinetic studies.
• Existing methods may lack the sensitivity, speed, or reproducibility required for comprehensive analysis.
• Development of a robust assay is needed to assess norfloxacin's behavior in biological matrices.

Purpose of the Study:

• To develop and validate a rapid, sensitive, and reproducible reversed-phase high-performance liquid chromatographic (RP-HPLC) assay for norfloxacin determination in plasma.
• To assess the assay's suitability for pharmacokinetic investigations.
• To establish a reliable method for quantifying norfloxacin concentrations in biological samples.

Main Methods:

• Plasma samples underwent protein precipitation using 10% trichloroacetic acid.
• Norfloxacin and the internal standard (enoxacin) were extracted using chloroform.
• Chromatographic separation was performed on a C8 column with fluorescence detection (Ex: 280 nm, Em: 418 nm).

Main Results:

• The assay demonstrated excellent linearity (r² ≥ 0.998) over a concentration range of 0.025–5.0 µg/mL in plasma.
• Inter-assay variability was consistently low (≤13.6%) across tested concentrations.
• Chromatographic peaks showed adequate resolution (>1.5), indicating minimal interference.

Conclusions:

• A validated RP-HPLC method provides a rapid, sensitive, and reproducible means for quantifying norfloxacin in rat plasma.
• The assay's performance characteristics confirm its suitability for pharmacokinetic studies.
• This method facilitates accurate assessment of norfloxacin's absorption, distribution, metabolism, and excretion.