Prince died one day before an appointment with an opioid addiction specialist

Prince died one day before he was going to see a specialist about an opioid painkiller addiction, according to the Minneapolis Star Tribune.

The doctor, Howard Kornfeld, reportedly received a call from Prince's representatives the night of April 20 because Prince "was dealing with a grave medical emergency," William Mauzy, an attorney working with the Kornfeld family, told the Tribune.

Kornfeld, the founder and medical director of the California addiction treatment clinic Recovery Without Walls, couldn't meet with Prince immediately, so he sent his son, Andrew, who works at the clinic as a consultant. The elder Kornfeld planned to fly out a day later to meet with the star.

"The plan was to quickly evaluate his health and devise a treatment plan," Mauzy told the Tribune, on behalf of the Kornfelds. "The doctor was planning on a lifesaving mission."

But he was too late: Prince died at the age of 57 on April 21 in his home in Chanhassen, Minnesota. Autopsy results, which will confirm his cause of death, are expected to be released in the coming weeks.

The epidemic of opioid abuse is one of the most pressing public-health challenges in the United States today. In 2014, there were 29,000 overdose deaths linked to opioids — more than any other year on record. The drugs are extremely addictive and, over time, users build a tolerance to the drug's high more quickly than a tolerance to its effects on the respiratory system. The cause of death from opioids is typically hypoventilation, also known as respiratory depression.

According to a recent Kaiser Family Foundation survey, one in five Americans say they have a family member who has struggled with an addiction to prescription painkillers.

The details of Prince's medical history remain murky, and according to the Tribune's account, he was seeking treatment. But for many Americans, accessing treatment is a huge challenge, said Dr. Patrice Harris, the chair-elect of the American Medical Association and chair of its Task Force to Reduce Opioid Abuse.

"For every ten people who want treatment, and treatment when they want it, maybe two are three are able to get it," Harris said. "If you want to stop using and you decide, 'Today, 'I want to stop using,' and you call me looking for treatment, the unfortunate response is, 'Call back in 6 weeks.'"

There's movement afoot to try to fix the treatment gap. According to Vox's German Lopez, the Obama administration has been pushing for more funding for treatment programs, as have some states.