Background: Celecoxib is effective for reducing postoperative pain in adults. Children use celecoxib more rapidly than adults and require higher doses. Celecoxib is partially metabolized in the liver by a certain enzyme. A person's genetic variation of this enzyme can influence how well their body uses Celecoxib. Understanding the blood and cerebrospinal fluid (CSF) profile of celecoxib in children and the influence of genetics on metabolism would help to develop appropriate celecoxib dosing in children for various treatment options.