A Retrospective Review of Patients Prescribed Low Dose Naltrexone for Chronic Pain (Abstract)

A Retrospective Review of Patients Prescribed Low Dose Naltrexone for Chronic Pain at a Single Institution

The Anesthesiology Annual Meeting
20 October 2019

Introduction: Safe and effective alternatives are needed to long-term opioids for the treatment of chronic pain.(1) Low dose naltrexone (LDN) has unique analgesic properties with few side effects. LDN temporarily blocks intrinsic opioid receptors with rebound increase in beta endorphin and methionine enkephalin (Met-Enkephalin) receptors. LDN is also an immune modulator, working at the level of the glial cell as a toll like receptor 4 (TLR4) antagonist.(2) The most commonly reported dose related side effects attributed to LDN include difficulty sleeping and vivid dreams.(2) We reviewed patients who had been prescribed LDN from April 1, 2008 to April 1, 2018. We examined the characteristics of patients who benefitted from LDN and those who did not.

Methods: After IRB approval, we reviewed the charts of all of our patients for whom we had documentation of a low-dose naltrexone prescription. LDN is not commercially available; prescriptions are filled at compounding pharmacies and rarely covered by insurance. We looked at insurance coverage of each of the patients. We reviewed primary and secondary pain diagnoses, noted responses, frequency and dose of LDN in addition to side effects.

Results: 60 patients were prescribed LDN. Out of these 60 patients, 26 patients never took LDN or did not return to clinic and 34 patients took LDN. Of the 34 who took LDN, 18 reported no benefit and 16 reported at least ‘some benefit’. We termed those who reported at least ‘some benefit’ as ‘responders’, those who took LDN and did not report any benefit as ‘nonresponders’ and those who did not take LDN or never returned to clinic as ‘noncompliant’. The responders were more likely to have neuropathic pain, complex regional pain syndrome (CRPS) or multiple sclerosis as either a primary or secondary diagnosis. They took LDN for a longer time period and at a higher dose than the nonresponders. (Fig1.; Fig 2) Most of the responders took LDN dose of 3 to 4.5mg/day vs. nonresponders who took 3mg or less daily. (Fig 2) The nonresponders were more likely to have spondylosis or CRPS as a primary or secondary diagnosis. Few nonresponders took LDN for more than 3 months.

Side Effects: 3 of the responders and 1 of the nonresponders reported vivid dreams. Two nonresponders had nightmares, 1 had night sweats. 3 patients cited the cost of the medications as a reason for not taking the medications. 1 responder stopped due to medication cost, despite benefit.

Discussion: Responders were more likely to have taken LDN for over 6 months; it may be that LDN takes months for full effect. Among those who took LDN, most had commercial insurance. The retrospective nature of data collection made specific responses to LDN difficult to obtain. There were reports of improvement, often without percentage pain relief or specific reduction in pain scores.