The primary objective of this study is to evaluate the pharmacokinetic profile of vonoprazan in adolescent participants with symptomatic gastroesophageal reflux disease (GERD).

This clinical trial information was submitted voluntarily under the applicable law and, therefore, certain submission deadlines may not apply. (That is, clinical trial information for this applicable clinical trial was submitted under section 402(j)(4)(A) of the Public Health Service Act and 42 CFR 11.60 and is not subject to the deadlines established by sections 402(j)(2) and (3) of the Public Health Service Act or 42 CFR 11.24 and 11.44.).

Inclusion Criteria:

• The participant is 12 to 17 years of age, inclusive, at the time of informed consent signing and throughout study participation.
• The participant has a body weight within the 5th through 95th percentile by age, inclusive, as determined by the National Center for Health Statistics.
• The participant has a medical history of symptoms of GERD for at least 3 months prior to screening, based on physical examination, current symptoms (eg, heartburn), or diagnostic tests (eg, pH or endoscopy). Notes in the medical records and/or other source documents such as prior endoscopies can be used to support the diagnosis.
• The participant has symptoms of at least moderate heartburn severity based on the GERD Symptom Assessment-Investigator scale performed at screening.
• The participant must be able to swallow study drug.
• Parent or legal guardian (ie, legally authorized representative [LAR]) is willing and able to complete the informed consent process and comply with study procedures and visit schedule. The participant will provide assent as applicable.
• A female participant of childbearing potential who is or may be sexually active with a nonsterilized male partner agrees to routinely use adequate contraception from the signing of informed consent until 2 weeks after the last dose of study drug.

Exclusion Criteria:

• The participant has used prescription or non-prescription proton pump inhibitors (PPIs) or histamine-2 receptor antagonists (H2RAs) within 7 days prior to randomization or requires their use during the Treatment Period.
• The participant has used sucralfate or antacids within 1 day prior to randomization or requires their use during the Treatment Period.
• The participant has received other agents affecting digestive organs, including muscarinic antagonists (eg, hyoscyamine), prokinetics, oral anticholinergic agents, prostaglandins, bismuth from 30 days prior to Day 1 or requires their use during the course of the study.
• The participant has received atazanavir sulfate or rilpivirine hydrochloride from 5 days prior to Day 1 or requires their use during the course of the study.
• The participant has received any investigational compound (including vonoprazan) within 30 days prior to the start of the Screening Period.
• The participant is an immediate family member or is in a dependent relationship with a study site employee who is involved in the conduct of this study (eg, child, sibling) or who may have consented under duress.
• The participant requires hospitalization or has surgery scheduled during the course of the study or has undergone major surgical procedures within 30 days prior to the Screening Period.
• The participant has undergone prior gastrointestinal surgeries such as fundoplication.
• The participant has any abnormal laboratory test values at the start of the Screening Period.
• The participant has a history of hypersensitivity or allergies to vonoprazan (including the formulation excipients: D-mannitol, microcrystalline cellulose, hydroxypropyl cellulose, fumaric acid, croscarmellose sodium, magnesium stearate, hypromellose, macrogol 8000, and titanium oxide, or red or yellow ferric oxide).
• The participant used any prescription (excluding hormonal birth control) or over-the-counter medications (including CYP3A4 inducers), including herbal or nutritional supplements, within 14 days (or 5 half-lives) before the first dose of study drug or throughout the study. NOTE: Acid suppressive therapies are considered separately under exclusion criteria 1 and 2.
• The participant has consumed grapefruit or grapefruit juice, Seville orange or Seville orange-containing products (eg, marmalade), or other food products that may be CYP3A4 inhibitors (eg, vegetables from the mustard green family [kale, broccoli, watercress, collard greens, kohlrabi, Brussels sprouts, mustard] and charbroiled meats) within 7 days (or 5 half-lives) before the first dose of study drug or throughout the study.
• Female participant has a positive pregnancy test at screening or check in or is lactating.
• The participant has a positive urine drug or alcohol result at screening.
• The participant has positive results at screening for human immunodeficiency virus, hepatitis B surface antigen, or hepatitis C virus.
• In the opinion of the investigator, the participant is not suitable for entry into the study.