Validation of an HPLC method for the determination of fleroxacin and its photo-degradation products in pharmaceutical forms

HPLC determination of fleroxacin in dosage forms was carried out using either reversed-phase column YMC pack ODS-AQ or Supelco LC Hisep shielded hydrophobic phase column, with UV detection at 280 nm. The mobile phase for ODS column consisted of 50:50:0.5 v/v/v and for Hisep column 15:85:0.5 v/v/v acetonitrile-water-triethylamine. The pH of the mobile phase was adjusted to 6.30 for ODS column and to 6.85 for Hisep column, with H3PO4. Linear response was obtained in the concentration range of fleroxacin between 0.01 and 1.30 micrograms/mL. Detection limit was 4.8 ng/mL. Recovery test in the determination of fleroxacin in "Quinodis" tablets (Hoffmann La Roche, nominal mass 400 or 200 mg) was 98-101% for both columns. The effect of the composition and pH of the mobile phase on spectra, retention time and dissociation constants of fleroxacin was discussed. The proposed method could be also used for separation of the photo-degradation products of fleroxacin. Ten degradation products were separated on the ODS-AQ column, thus confirming the suitability of the proposed method for stability study of fleroxacin in pharmaceuticals.