(Reuters) - Collegium Pharmaceutical Inc's experimental opioid painkiller moved one step closer to approval after a panel of outside advisers to the U.S. Food and Drug Administration unanimously voted in favor of the drug.

The FDA panel's vote also was contrary to a recommendation by FDA staff, which on Wednesday expressed concerns that the oral painkiller could be wrongly used, leading to an overdose.

The panel voted 23 to 0 in favor of approving the drug.

The FDA is not obliged to follow the advice of its advisory panels, but usually does.

Collegium's long-acting experimental oxycodone pill, to be sold as Xtampza if approved, is meant to be taken after a meal to provide maximum pain relief.

The FDA staff had said if the drug was taken without food, it could lead to insufficient pain control, which in turn could contribute to overdosing and misuse.

The abuse of opioids – a class of drugs that include heroin and prescription painkillers – has long been a concern. An overdose of such drugs can produce euphoric highs, and even disrupt parts of the brain that control breathing.

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

Collegium has proposed to make clear on the label that Xtampza, its lead drug in development, should only be taken after eating.

The FDA panel's vote of approval for Xtampza is also a positive for other companies developing abuse-deterrent version of painkillers.

Pernix Therapeutics Holdings Inc, Egalet Corp, KemPharm Inc, IntelliPharmaCeutics International Inc, Pain Therapeutics Inc and Acura Pharmaceuticals Inc are among the drugmakers developing abuse-deterrent painkillers.

However, another FDA panel on Thursday voted against approving Purdue Pharma's fast-acting opioid painkiller due to concerns of overdosing.

Trading in Collegium's shares were halted through Friday, ahead of the vote. They closed at $13.45 on Thursday.

(Reporting by Vidya L Nathan in Bengaluru; Editing by Savio D'Souza)