Vonoprazan Study of Investigating the Effect on Sleep Disturbance Associated With Reflux Esophagitis- Exploratory Evaluation

The purpose of this study is to exploratorily evaluate the effect of vonoprazan 20 mg on sleep disturbance of patients with reflux esophagitis, who have heartburn and/or regurgitation and ≥ 6.0 in the Pittsburgh Sleep Quality Index (PSQI) global score despite the maintenance treatment with PPI other than vonoprazan.

The purpose of this study is to evaluate the effect of vonoprazan on sleep disturbance in the participants under maintenance treatment for reflux esophagitis with proton pump inhibitor (PPI) other than vonoprazan after initial treatment.

Participants who have been diagnosed as reflux esophagitis based on Los Angeles (LA) Classification Grades A to D, undergoing maintenance treatment with PPI other than vonoprazan after initial treatment, and with Pittsburgh Sleep Quality Index (PSQI) global score \>= 6.0 at enrolment (VISIT 1) will be eligible for study entry and will be administered vonoprazan 20 mg once daily for 8 weeks.

Planned number of participants is 25. The study period is 9 weeks. The number of visits is 6visits.

Eligibility Criteria:
Inclusion Criteria:

1. Participants who completed the initial treatment with PPIs (esomeprazole, omeprazole, rabeprazole, or lansoprazole) and have received high dose PPIs (esomeprazole 20 mg, omeprazole 20 mg, rabeprazole 10 mg, or lansoprazole 30 mg) for more than 8 weeks at the time of informed consent as maintenance treatment for LA Classification Grades A to D reflux esophagitis.
2. Participants who have heartburn and/or regurgitation.
3. Participants with reflux esophagitis related sleep disturbance, fulfilling at least one of following in a week before the baseline/start of administration.

   * Difficulty in falling asleep for \> = 3 nights
   * Nocturnal awaking or early morning awaking for \> = 3 nights
4. Participants whose heartburn and/or regurgitation at the time of informed consent were alleviated from initial treatment.
5. Participants with PSQI global score \> = 6.0
6. Participants who, in the opinion of the investigator, are capable of understanding the content of the study and complying with the protocol requirements.
7. Participants who can sign and date an informed consent form and information sheet prior to the initiation of the study procedures.
8. Male or female participants aged 20 years or older at the time of informed consent.
9. Therapeutic category: Ambulatory

Exclusion Criteria:

1. Participants with Zollinger-Ellison syndrome.
2. Participants with diseases that affect sleep (chronic obstructive pulmonary disease, bronchitis asthma, sleep apnea syndrome, mental disorder, etc.)
3. Nightshift workers.
4. Participants who have a plan to travel beyond three time zones during the study.
5. Participants with a history of, concurrent, or suspicious functional dyspepsia or functional heartburn based on Rome IV criteria.
6. Participants with history of surgery or treatment affecting gastroesophageal reflux (fundoplication or dilation for esophageal stenosis \[except for Schatzki's ring\], etc.).
7. Participants with an esophagus-related complication (eosinophilic esophagitis, esophageal varices, scleroderma, viral or fungal infection, esophageal stenosis, etc.), a history of radiotherapy or cryotherapy of the esophagus, a caustic or physiochemical trauma (esophageal sclerotherapy, etc.). However, participants with Schatzki's ring (mucosal tissue ring around inferior esophageal sphincter) or Barrett's esophagus are allowed to be included.
8. Participants with a history of gastrectomy, gastrointestinal resection, or vagotomy.
9. Participants who took antidepressant agents or anti-anxiety agents within 8 weeks before the time of informed consent.
10. Participants who took H2 receptor antagonist within 8 weeks before the time of informed consent.
11. Participants planning to take prohibited concomitant medications during the study period.
12. Participants who have any of the following abnormal clinical laboratory test values at the screening (VISIT 1):

    * Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \> upper limit of normal (ULN)
    * Bilirubin (Total bilirubin) \> ULN
13. Participants with a malignant tumor.
14. Participants who are pregnant, breast-feeding, possibly pregnant, or planning to become pregnant.
15. Participants who have serious renal diseases.
16. Participants with the conditions listed under administration contraindication in the vonoprazan package insert.
17. Participants participating in other clinical studies.
18. Participants who have been determined as inappropriate participants by the investigator.