A panel of outside advisers to the U.S. Food and Drug Administration on Thursday voted against approving Purdue Pharma's opioid painkiller over concerns of overdosing. 

The recommendation follows comments from the health regulator's staff on Tuesday on likely errors in administering the experimental drug.

The agency's staff on Wednesday had also highlighted that a rival opioid painkiller from Collegium Pharmaceuticals Inc could be wrongly used.

Collegium's shares were down 18 percent at $11.06 in extended trading.

An FDA panel is expected to review Collegium's experimental drug on Friday.

Purdue Pharma's experimental drug, to be called Avridi on approval, was designed as an abuse-deterrent fast-acting form of opioid painkiller oxycodone.

The FDA panel voted 23 to 1 against the approval.

Avridi is among the first few drugs to be evaluated by the FDA for the efficacy of such formulations' abuse-deterrent properties.

An estimated 46 people die everyday in the United States from opioid painkiller overdose, according to The Centers for Disease Control and Prevention.

Avridi is designed to be taken every 4-6 hours on an empty stomach and the presence of food could cause inadequate pain control. Inadequate pain control could lead to patients taking more of the drug, the FDA staff had said.

Most painkillers can be administered irrespective of food intake.