The population PK of oxycodone and its metabolites has not been fully established for oral oxycodone in pediatric patients. In addition, there is a group of ultra-rapid metabolizers (approximately 4.5% of the population, but as high as 20% in some particular ethnic groups; East African and Saudi Arabian populations) which may be at risk for serious side effects in the commonly prescribed dose (which is extrapolated from adult recommendations). Given that BCH has switched (from codeine) to oxycodone as the most common opioid prescribed for all postoperative patients and the recent concerns of serious side effects from codeine. It is important to further investigate oral oxycodone to optimize dosing recommendations.