The Food and Drug Administration on Thursday approved the powerful painkiller OxyContin for a new use in children 11 to 16 who are suffering from severe, long-term pain.

OxyContin is an extended-release opioid that has long been used to treat around-the-clock pain in adults. But most pain medications are not approved for use in children.

The FDA says it asked drugmaker Purdue Pharma to study how to safely use OxyContin in children.

"This program was intended to fill a knowledge gap and provide experienced health care practitioners with the specific information they need to use OxyContin safely in pediatric patients," Sharon Hertz, an FDA drug division director, wrote in an online post.

Under the new approval, doctors are directed to only prescribe OxyContin to children who can already tolerate a minimum dose of 20 milligrams of oxycodone, the drug ingredient in OxyContin. Taking a sudden dose of an opioid can lead to overdose and death if patients haven't previously been exposed to the drug type.

The FDA notes that the Duragesic patch, which releases fentanyl, is the only other opioid approved for children.

OxyContin was re-formulated in 2010 to discourage patients from crushing the tablets for snorting or injection. Purdue Pharma discontinued the older version of its blockbuster drug, which was long associated with problems of addiction, overdose and death.

The FDA notes that the same health warnings that apply to adults apply to children taking OxyContin. Physicians should not combine the drug with any other medications that can add to its sedating effects, which could lead to breathing difficulties.

As a condition of approval, the FDA is requiring Stamford, Connecticut-based Purdue to conduct a follow-up study examining rates of injury, overdose, accidents and medication errors in patients ages 11 to 17. The final study is due April 2019.

Doctors prescribe opioids for a wide range of ailments, from post-surgical pain to arthritis and migraines. Medical experts continue to disagree over the appropriate role of the drugs, with some arguing that they should be reserved for the most severe cases, such as cancer pain or end-of-life care.

The FDA mentions severe pain due to trauma, surgery or cancer as potential uses for opioids in children.

OxyContin was the first in a class of long-acting opioids designed to deliver powerful, around-the-clock pain relief. The pills and tablets are formulated to slowly release their drug contents over 12 or more hours. But abusers often try to get a massive, heroin-like high by releasing the entire dose at once via chewing, snorting or injecting crushed tablets' contents.