BACKGROUND: Lansoprazole (LAN) is a proton pump inhibitor drug (PPI) metabolized by the P-450 liver cytochrome (CYP-450) system. LAN is used in association with antimicrobial agents in Helicobacter pylori (HP) eradication therapy. The 13C-Aminopyrine breath test (ABT) is a non-invasive tool exploring liver CYP-450 metabolic activity. Since pharmacological interactions may occur during PPI administration, we attempted to evaluate possible interference with liver CYP-450 activity during HP eradication therapy. MATERIAL/ METHODS: Fourteen HP positive patients received LAN (30 mg b.i.d.), clarithromycin (500 mg b.i.d.) and metronidazole (500 mg b.i.d.) for one week. Prior to therapy, and at day 8, each patient underwent 13C-ABT. The 13CO2 concentration in breath samples was measured every 15 minutes from t0 to t120. Results are expressed as cumulative percentage of the administered dose of 13C recovered over time (% 13C dose cum), and as a percentage of the administered dose of 13C recovered per hour (% l3C dose/h). Comparisons were carried out by the Wilcoxon test. Data are presented as mean +/- SD. RESULTS:At day 8, mean ABT was no different from baseline values, both considering % 13C dose cum and% 13C dose/h at each sampling time (e.g.,% 13C dose cum120 which is the most expressive value of the parameters taken into consideration, baseline vs day 8: 10.88 +/- 3.81 vs 10.13 +/- 3.57). CONCLUSIONS: These results show that LAN administration and the concomitant use of antimicrobial drugs during HP eradication therapy do not seem to be associated with significant modifications in liver CYP-450 activity.

Keywords: Aminopyrine - chemistry, 2-Pyridinylmethylsulfinylbenzimidazoles, Aminopyrine - metabolism, Breath Tests, Carbon Isotopes, Clarithromycin - therapeutic use, Helicobacter Infections - microbiology, Helicobacter pylori - physiology, lansoprazole, Metronidazole - therapeutic use, Omeprazole - therapeutic use, Sex Characteristics