The purpose of this research study is to evaluate how much of repeated once daily intravenous (IV, meaning through a vein) doses of esomeprazole gets into the bloodstream of hospitalized children aged 0-17 years old that require acid suppression therapy.

Inclusion Criteria:

• parent/guardian must sign consent form and the child will be asked to sign and Assent Form if he/she is old enough and is able to sign
• verbal assent will be acceptable if the child is old enough to understand, but unable to write
• female and/or male hospitalized patients aged 0-17 years old who should be considered for treatment with acid suppressive therapy.

Exclusion Criteria:

• female patients that are pregnant, or plan to become pregnant during the study period or is breast-feeding a child
• patients with a history of multiple drug allergies
• any illness, medical history, abnormal laboratory values, abnormal physical examination findings or abnormal vitals signs that could put the patient at risk when participating in the study