An improved HPLC assay for ciprofloxacin in biological samples

Area of Science:

• Analytical Chemistry
• Pharmacokinetics
• Biomedical Science

Background:

• Ciprofloxacin is a widely used antibiotic.
• Accurate quantification of ciprofloxacin in biological fluids is essential for therapeutic drug monitoring and pharmacokinetic studies.
• Existing methods may lack sensitivity or require larger sample volumes.

Purpose of the Study:

• To develop and validate a simple, sensitive, and rapid high-performance liquid chromatographic (HPLC) method for determining ciprofloxacin concentrations.
• To quantify ciprofloxacin in small volumes of serum and cerebrospinal fluid (CSF) from rabbits and humans.
• To apply the developed method for pharmacokinetic profiling of ciprofloxacin.

Main Methods:

• High-performance liquid chromatography (HPLC) with fluorescence detection.
• Separation on a Nucleosil C18 column.
• Mobile phase: acetonitrile and phosphate buffer (pH 2.7) with tetrabutylammonium hydrogen sulfate.
• Internal standard: pipemidic acid.
• Detection wavelengths: excitation 274 nm, emission 418 nm.

Main Results:

• The method achieved good separation of ciprofloxacin and pipemidic acid with retention times of 5.9 min and 4.0 min, respectively.
• High precision was demonstrated with inter-day coefficients of variation < 6.97% and intra-day < 3.33%.
• Sensitive detection limits were achieved: 3 ng/mL in serum and 5 ng/mL in CSF, with high linearity (r >= 0.9996).

Conclusions:

• A robust and sensitive HPLC-fluorescence method was successfully developed for ciprofloxacin determination in serum and CSF.
• The method's simplicity and sensitivity make it suitable for analyzing small biological sample volumes.
• The validated method was effectively applied to generate concentration-time profiles of ciprofloxacin in rabbits during intravenous infusions.