SHERIDAN, Ill. (AP) — U.S. prisons are experimenting with a high-priced monthly injection that could help addicted inmates stay off opioids after they are released.

It’s called Vivitrol. And proponents say it could be effective in the fight against the opioid epidemic affecting 2 million Americans and a portion of the prison population.

Vivitrol isn’t habit-forming, unlike older drugs like methadone, which can be abused.

But it costs significantly more — about $1,000 a month, compared with methadone which runs about $30 a month. Skeptics question its effectiveness and say the manufacturer has pushed an unproven drug onto corrections officials.

Supporters say Vivitrol can save money by keeping people from returning to prison. It costs $25,000 a year to house an inmate at Sheridan Correctional Center in Illinois, which is starting a Vivitrol program.