Longer durations of bismuth-based therapy appear to be more efficacious. A study of a bismuth–omeprazole–amoxycillin and clarithromycin regimen showed superior eradication of 94% in a group treated for 14 days compared with 80% for a group treated for 7 days [19]. Bismuth also appears to be a viable option when standard first-line triple therapy has failed. In one study of patients unsuccessfully treated Selleckchem MG132 with triple therapy, eradication rates of 77% were obtained for 1 week of bismuth-based quadruple

therapy and 94% for 2 weeks (per-protocol) [20]. This study showed, though, that adverse events were more than twice as common in the 14-day group, although no decrease in compliance was seen. The primary goal of the sequential regimen is to overcome clarithromycin resistance. During the first 5 days of therapy, amoxycillin is taken with proton pump inhibitors (PPI) with the intention to weaken the bacterial cell wall, which prevents the formation of the channels that block clarithromycin from binding to the bacterium and hence cause resistance to the antibiotic. Then, in the second phase of therapy, amoxycillin is discontinued and clarithromycin and a nitroimidazole are added for a further 5 days. Proton pump inhibitor is continued throughout treatment. Although this regimen was largely heralded as being able to overcome clarithromycin resistance, recent studies

have shown in fact that it can be influenced by clarithromycin learn more resistance and that when the clarithromycin resistance mutation exists, eradication rates are lower (65% vs 98%) [21]. Evidence for the efficacy of sequential therapy had previously been heavily weighted toward

studies carried out on Italian patients [22]. The last year has seen a greater number of studies carried out in other parts of the MCE公司 world. One study from Thailand reported a 95% eradication rate for 10-day sequential therapy [23]. Another study from Turkey where eradication rates are low showed 78% eradication for sequential therapy versus 53% for standard triple therapy based on a per-protocol analysis [24]. In China, a comparative study showed eradication rates of 83% for bismuth-based quadruple therapy and 81% for standard triple therapy with the most impressive eradication rate of 89% for sequential therapy [25]. Further study showed that continuing amoxycillin for the entire duration of the sequential therapy did not increase the eradication rate [26]. Furthermore, extending the duration of sequential therapy from 10 to 14 days was not associated with an increased eradication rate [27]. “Concomitant” or quadruple therapy has also been proposed. It is intended to reduce the complexity associated with sequential therapy by having the patient take all three antibiotics for the entire 10-day duration of therapy.