The drug being tested in this study is called TAK-438. TAK-438 is being tested to treat people who have duodenal ulcers and also may or may not have Helicobacter pylori (HP) infection. This study will look at duodenal ulcer healing and also the elimination of HP in people who take TAK-438 versus lansoprazole. The study will enroll approximately 530 patients.~Participants were randomly assigned (by chance, like flipping a coin) to one of the two treatment groups-which remained undisclosed to the participant and study doctor during the study (unless there is an urgent medical need):~TAK-438 20 mg~Lansoprazole 30 mg~HP+ participants will be asked to take a TAK- 438 tablet and a lansoprazole capsule twice daily in conjunction with bismuth-containing quadruple therapy for 2 weeks, followed up by a TAK-438 tablet and a lansoprazole capsule once daily for up to 4 weeks. HP negative (HP-) participants will be asked to take a TAK-438 tablet and a lansoprazole capsule once daily for up to 6 weeks.~This multi-center trial will be conducted China, Korea and Taiwan. The overall time to participate in this study is up to 10 weeks. Participants will make multiple visits plus final visit at 2 weeks or 4 weeks after last dose of study drug for a follow-up assessment.
The purpose of this study is to demonstrate the non-inferior efficacy of TAK-438 versus lansoprazole in the treatment of participants with duodenal ulcer.