A simple, robust HPLC method was developed to measure simultaneously the plasma concentrations of amoxycillin and
metronidazole in order to assess their disposition in the eradication of Helicobacter pylori. Plasma samples were protein
precipitated, pH adjusted and the supernatant injected onto the HPLC system which used a C column, paired-ion aqueous 18
mobile phase and photodiode array detection of amoxycillin at 230 nm and metronidazole at 313 nm. Intra- and inter-day
precision and inaccuracy were less than 10% for concentrations between 5 and 20 mg/ l. The limit of quantification was 1
mg/ l. Samples were stable on the HPLC injector for 48 h at room temperature and multiple freeze–thaw cycles led to no
decomposition. Ó 1999 Elsevier Science B.V. All rights reserved.
Keywords: Amoxycillin; Metronidazole; Antibiotics