Two U.S. senators this week urged federal officials to expand access to buprenorphine to treat heroin and painkiller addiction.

Buprenorphine helps control drug cravings and withdrawal symptoms, but remains underused a decade after it was approved, the Associated Press reports. It can be prescribed as a take-home medicine, unlike methadone, which must be administered in a clinic. Buprenorphine has a lower risk of overdose and milder side effects, the article notes.

Federal law restricts buprenorphine prescribing, and insurance coverage of the treatment is inconsistent, according to the AP.

“We’ve heard remarkable stories of success with buprenorphine treatment, of lives saved and families rebuilt from the ravages of addiction,” Senator Carl Levin of Michigan said in a news release. “But we have also heard stories of frustration at the fact that many patients want this treatment but can’t get it, and we need to remove those hurdles.”

In 2000, Levin and Senator Orrin Hatch of Utah sponsored the Drug Addiction Treatment Act (DATA 2000), which made it legal for doctors to prescribe buprenorphine for up to 30 patients at a time in their offices. The Food and Drug Administration approved the drug’s use in 2002. Subsequently, the patient limit was raised to 100.

Senators Levin and Hatch hosted a forum Wednesday to examine impediments that prevent greater access to buprenorphine, and to explore changes that could help expand access. The American Society of Addiction Medicine has proposed raising the patient limit to as high as 500 for doctors who complete 40 hours of training, the article notes.

Some federal officials said they do not want to raise the patient limit because buprenorphine can be abused. Dr. Nora Volkow, Director of the National Institute on Drug Abuse, said buprenorphine overdoses are common in Europe, where the drug is more available. Raising the patient limit could lead to buprenorphine “pill mills,” some officials noted at the forum.