The number of people filling prescriptions for buprenorphine to treat opioid use disorder barely increased despite the federal government making it easier for doctors to prescribe the medication last year, AP reports.

Researchers at the University of Michigan Medical School analyzed buprenorphine prescriptions filled by pharmacies. They reported in the New England Journal of Medicine that there was a 27% increase in the number of prescribers at the end of 2023 compared with a year earlier, while the number of people filling prescriptions increased about 2%.

Experts say there are many barriers to patients taking buprenorphine. These include insurance hurdles, price, pharmacies that don’t stock buprenorphine and doctors who treating patients with substance use disorder takes up too much time.

“There’s a lot of stigma about this medication, and just in general about patients with opioid addiction,” study co-author Kao-Ping Chua said.