Buprenorphine, a drug used to treat opioid addiction, is increasingly being abused, The New York Times reports. Some for-profit buprenorphine clinics are run by doctors with troubled records, according to the newspaper.

The drug was developed as a safer alternative to methadone for treating addiction to heroin and painkillers. It can be prescribed by doctors in offices, rather than dispensed daily in a clinic. The newspaper tracked patients of two large buprenorphine programs. In one program in suburban Pittsburgh, requirements for obtaining the drug are minimal, and there is a high tolerance for patient missteps, the article notes. Another center at West Virginia University in Morgantown is located in a hospital complex, and run by an addiction medicine specialist.

The doctor who runs the Pittsburgh clinic, Allan W. Clark, is in recovery. He prescribed himself Adderall in the late 1990s, and found his mood improved and he focused better. He took more and more of the drug to get the same effect. In 1999, he checked himself into a rehabilitation program. He lost his Ohio medical license and was put on probation in Pennsylvania for eight years. He now runs a buprenorphine clinic with five doctors working for him, and treats 600 patients.

Dr. Carl R. Sullivan III, who runs the West Virginia University program, primarily treated alcoholism until he saw a “spectacular explosion of prescription opioid drugs” starting around 2000. He saw many patients leave rehab and relapse. Some died. When he started prescribing Suboxone, the brand-name drug whose main ingredient is buprenorphine, he saw a big change. He became a paid treatment advocate for the drug’s maker, Reckitt Benckiser. He noted, “If the company didn’t pay me a nickel, I’d still promote Suboxone because in 2013, it’s the best thing that’s happened for the opioid addict.”