New Mexico’s largest jail will no longer use methadone to treat inmates who are addicted to drugs, The New York Times reports. The jail’s warden cited cost concerns. He also questioned the program’s effectiveness.

The Metropolitan Detention Center in Albuquerque has been one of the small number of jails and prisons nationwide to administer methadone to inmates with drug addictions, according to the article. Hundreds of participants have gone through the New Mexico treatment program.

The program has been costing the jail about $10,000 a month, according to Ramon Rustin, the jail’s warden. He told the newspaper he did not believe the program truly worked. He said there is little evidence it reduces inmates’ return to the corrections system once they are released.

“My concern is that the courts and other authorities think that jail has become a treatment program, that it has become the community provider,” he said. “But jail is not the answer. Methadone programs belong in the community, not here.”

Advocates for the methadone program say cutting off inmates from methadone is like taking insulin from a diabetic.

In December, Rustin was ordered to extend the program for two months until its results could be further studied.