Phase 1 Dexlansoprazole Delayed-Release Capsules for Acid-Related Disorders in Infants Aged 1 to 11 Months

The drug being tested in this study is called dexlansoprazole. Dexlansoprazole is being tested to find a safe and well-tolerated dose and to assess how dexlansoprazole is processed by the body in infants aged 1 to 11 months. This study will look at side effects and lab results in infants who take dexlansoprazole. The study will enroll approximately 24 participants. Participants will be randomly assigned to 1 of the 4 treatment groups based on body weight and age: * Dexlansoprazole 10 mg * Dexlansoprazole 15 mg * Dexlansoprazole 20 mg * Dexlansoprazole 30 mg Participants who weigh \<3.4 kg will not be enrolled. Participants ≤ 10 weeks of age with a body weight of ≥ 3.4 kg will initially receive Regimen A (dexlansoprazole delayed-release 10 mg capsules). Randomization for participants \> 10 weeks of age will be stratified by weight group. Participants whose baseline weight is ≥ 3.4 kg but \< 4.1 kg will be assigned to receive Regimen A or Regimen B (dexlansoprazole delayed-release 10 or 15 mg capsules as an initial dose) in a ratio of 1:1. Participants whose weight is ≥ 4.1 kg but \< 6.2 kg will be assigned to receive Regimens B or C (dexlansoprazole delayed-release 15 or 20 mg capsules as an initial dose) in a ratio of 1:1. Participants whose weight is ≥ 6.2 kg will be assigned to receive Regimen B, C, or D (dexlansoprazole delayed-release 15, 20, or 30 mg capsules as an initial dose) in a ratio of 1:1:2. All participants will be administered 1 capsule of dexlansoprazole in the morning at the same time each day throughout the study. The study medication may be administered to the participants by opening a capsule and sprinkling the granules on 1 tablespoon of applesauce or pureed apples, or mixing the capsule granules with about 20 mL of water. The food-granule mixture should be administered immediately. The water mixed with the granules will be administered via an oral syringe into the mouth immediately. The granules should not be chewed in mouth. The food or liquid used for administering the study medication should be recorded for Days 1 through Confinement Day 1. The parents of all participants will be asked to record dosing information, the food or liquid used for administering the study medication (Day 1 through Confinement Day 1), food intake, and episodes of vomiting in a diary from Day 2 until the day before Confinement Day 1 (Day 5 to 9). This multicenter trial will be conducted worldwide. The overall time to participate in this study is up to 114 days. Participants will make multiple visits to the clinic, including two 2-day visits that may require confinement to the clinic, and will be contacted by telephone 30 days after last dose of study drug for a follow-up assessment.