A panel of U.S. Food and Drug Administration advisers on Wednesday unanimously voted in favor of approving Emergent BioSolutions Inc's over-the-counter version of opioid overdose reversing drug Narcan.

The favorable vote puts the treatment on track to potentially become the first naloxone-based drug to be sold OTC nationwide.

"I agree that there are some incremental improvements (needed), but the bottom line is that overwhelmingly the drug's benefit outweighs the risk," said panelist Dr. Maura McAuliffe.

Naloxone rapidly reverses or blocks the effects of opioids, restoring normal respiration, especially when given within minutes of the first signs of an overdose.

The FDA, which usually follows the recommendations of its expert panel but is not obligated to do so, is expected to make its final decision by March 29 on the prescription-free sale of Narcan.

FDA approval for OTC Narcan could increase its availability and would align the federal government's stance with that of various states that have provisions to offer Narcan or naloxone without prescriptions through a pharmacist.