Oxycontin is highly addictive painkiller and giving it to kids is highly controversial, but Purdue Pharma, the maker of Oxycontin, needs the study to extend the drug's patent which is due to expire next year.
Purdue insists the study is not for financial gain, but to give more information on how the drug acts in children.
Oxycontin earned nearly $3 billion for Purdue last year.