Can Low-Dose Naltrexone Work For Pain Relief?

By Kelly Burch 09/27/19

Chronic Pain

Some chronic pain patients say that naltrexone has offered them much-needed relief.

Naltrexone has changed Lori Pinkley’s life. But unlike most people who have benefited from the drug, she’s not using it to treat alcohol or opioid use disorder. Pinkley uses naltrexone to treat chronic pain. 

“I can go from having days that I really don’t want to get out of bed because I hurt so bad, to within a half-hour of taking it, I’m up and running, moving around, on the computer, able to do stuff,” Pinkley told NPR

Jumpstarting Endorphins

Pinkley’s physician, Dr. Andrea Nicol, is a pain specialist at the University of Kansas. She started prescribing naltrexone to Pinkley about a year ago. For people living with substance use disorder, she said, 50 milligrams of naltrexone blocks the brain’s opioid receptors.

However, Nicol said that in her pain patients, a much lower dose of about 4.5 milligrams helps their malfunctioning nervous systems reset and work optimally, and jumpstart the production of endorphins, which contribute to natural pain relief. 

“What it’s felt to do is not shut down the system, but restore some balance to the opioid system,” she said. 

There have not been any wide-scale studies of low-dose naltrexone, which is sold under the brand names Revia and Vivitrol to treat addiction. However, a review recently published in the journal Medical Sciences found that naltrexone has entirely different effects at low doses. 

Different Dynamics In Low Doses

“In substantially lower than standard doses, they exert different pharmacodynamics,” the review authors wrote of naltrexone and a related drug, naloxone. This makes them potentially useful in treating pain, and keeping patients off high-dose opioids, said Dr. Bruce Vrooman, the study author. He added that patients on low-dose naltrexone report fewer side effects than patients on opioids. 

“Those patients may report that this is indeed a game changer. It may truly help them with their activities, help them feel better,” he said. 

Doctors Are Unaware Of Its Off-Label Use

However, naltrexone faces barriers to becoming a widely-used pain reliever. First, many doctors don’t know that it can be prescribed for pain relief, or may not be comfortable prescribing it “off label.” In addition, pharmacies don’t sell such small doses, so people using low-dose naltrexone need to use compounding pharmacies, and insurance often won’t cover the medicine. 

Finally, there is little interest from companies in producing naltrexone products. Since it’s already available as a generic, there’s less profit to be derived from it. 

“Bringing a new drug to market requires getting FDA approval and that requires doing clinical trials,” said Patricia Danzon, a professor of health care management at the Wharton School at the University of Pennsylvania. “That’s a significant investment, and companies—unsurprisingly—are not willing to do that unless they can get a patent and be the sole supplier of that drug for at least some period of time.”