The chromatographic approach to kinetic studies of tebipenem pivoxil.

A validated high-performance liquid chromatography-diode array detector (HPLC-DAD) method for stability studies of tebipenem pivoxil was developed. The separation of tebipenem pivoxil in the presence of main degradation product—tebipenem—was achieved by using a LiChrospher C-18 column (5 µm, 250 × 4.6 mm) with the mobile phase containing a mixture of 50 mmol L(-1) ammonium acetate-acetonitrile-triethylamine (68 : 30 : 2, v/v/v) adjusted to pH 3.5 with concentrated phosphoric acid (V). The column effluent was monitored by a photodiode array detector at 330 nm. The flow rate was 0.8 mL min(-1). Tebipenem pivoxil was subjected to degradation in aqueous solutions (acid-base hydrolysis, oxidation) and in the solid state (photolysis, thermolysis at an increased relative humidity and in dry air). The validated HPLC method was successfully applied to investigate the kinetics of conversion of tebipenem pivoxil to tebipenem (main metabolite). The other degradation products of tebipenem pivoxil were also monitored.