Low dose naltrexone (LDN) may be effective in treating chronic refractory pain, early research suggests.
Preliminary data from a retrospective review of patients with chronic pain showed that those who received LDN experienced a significant improvement in both pain and disability.
“Naltrexone has been studied especially in the context of the opioid and alcohol abuse, but we see that, at low doses, it has a paradoxical effect in that it has anti-inflammatory properties and may be beneficial for patients with fibromyalgia or low back pain, ”said study researcher Kaivalya Deshpande, MD, a resident at the University of Pittsburgh Medical Center (UPMC) Medscape Medical News.
The results showed that, with proper patient selection, “LDN could be an additional treatment option within the pain doctor’s toolkit,” Deshpande said.
Also, because the dose of naltrexone used to treat pain is so low at only one-tenth of the actual dose. addiction, the potential for addiction is low, he noted.
“With high-dose naltrexone, you definitely have some of these addiction risks, but so far there has been no documented potential for abuse with low-dose naltrexone,” he added.
The results were presented at the 2021 annual meeting of the American American Academy of Pain Medicine (AAPM) virtual.
The researchers wanted to understand the effects of low-dose naltrexone as a complementary treatment in their patients with chronic pain, many of whom are refractory to first-line treatments.
The study included 65 patients who attended the UPMC pain clinic. All had experienced pain for more than 3 months, either from low back pain with radiculopathy or fibromyalgia. They had also failed in traditional treatment strategies, such as physical therapy, anti-inflammatory and neuropathic pain medications, and epidural steroid injections.
All patients completed standardized pain inventories to measure pain, disability, and the impact of naltrexone on their ability to perform daily activities. Deshpande noted that these surveys are useful for monitoring patients’ progress.
“Pain is such a subjective modality, so it’s very important to evaluate the results, especially the function, to be able to say that a particular intervention has been effective,” he said.
“While there are many variables that cannot be controlled within a retrospective study, we were able to track the longitudinal outcomes of patients with low-dose naltrexone to assess whether medication contributes to some of the benefits we were seeing,” he added. . .
Patients received low doses of naltrexone for a minimum period of 1 month and were followed longitudinally.
Outcome measures included pain scores, disability percentage improvement, Oswestry Disability Index (ODI), pain catastrophe scale, and Outcome Measurement Information System (PROMIS) metrics reported by the patient.
Viable treatment option?
Preliminary analysis of the data showed a statistically significant improvement in pain scores, improvement in disability percentage, and ODI scores in patients receiving naltrexone at low doses. These improvements were found at 3 and 6 months after the start of treatment.
Patients also reported improved sleep and decreased pain interference using the PROMIS metric. Numerical pain scale scores improved from an average of 7.5 to 4.9 at 3 months after the start of naltrexone at low doses.
In addition, the researchers found a 40% improvement in disability at 3 months and this improvement increased to 50% at 12 months. ODI scores improved from 50.3 to 43.4 at 3 months after the start of treatment.
Adverse events included dry mouth, headache, dizziness, gastrointestinal disorders and living dreams. However, these “were transient and generally mild,” Deshpande said.
Overall, “we definitely saw positive results in our clinic with low-dose naltrexone with pain and disability scores,” he noted.
Deshpande reported that the researchers ’next step is to review other metrics to examine potential improvement in psychosocial or physical outcomes.
“Ultimately, it will be important to do a randomized control trial to eliminate possible confounding variables and increase the generalization of the study, in order to be able to say that LDN is useful. But we can use this study as a basis for this essay, “” He said.
“I definitely think this is promising data that can be used to guide further studies,” Deshpande said. “At the moment, we can say that low-dose naltrexone has potential. It has a fascinating mechanism of action, a safe side effect profile, and, for the right patient, may be a viable treatment option.”
Preliminary critical data
Commenting on the findings of Medscape Medical News, W. Michael Hooten, MD, professor of anesthesiology at the Mayo Clinic, Rochester, Minnesota, noted that naltrexone “is generally considered to have no potential for abuse.”
Hooten, who is also president-elect of the AAPM, did not participate in the current investigation. He added that the results may help expand the potential number of patients who could be candidates for low-dose naltrexone therapy.
“It provides the critical preliminary data needed to conduct a randomized, placebo-controlled prospective trial,” Hooten said.
Deshpande and Hooten have not revealed any relevant financial relationship.
2021 Annual Meeting of the American Academy of Pain Medicine (AAPM). Presented from April 23 to 25, 2021.