The U.S. Department of Food and Drug Administration is being called to investigate a short-lived pilot program that sought to treat inmates with anti-addiction implants never approved by federal regulators.

The Advocate reports advocacy group Public Citizen requested the probe in a letter Wednesday.

The pilot by the Louisiana Department of Public Safety and Corrections and California-based creator BioCorRx, Inc. involved a surgical implant that released the opioid and addiction fighting drug naltrexone.

Officials said the chemical would be metabolized over several months. The FDA already approved naltrexone as daily pills and monthly shots.
BioCorRx offered the corrections department 10 free implants for volunteer recipients.

For unclear reasons, the pilot stopped after the first implant. Recipient 39-year-old Alvin Dutruch says he has been doing well in recovery since his release.