Naltrexone Implant for Opioid Use Disorder

Abstract

The continued rise in the availability of illicit opioids and opioid-related deaths in the United States has left physicians, researchers, and lawmakers desperate for solutions to this ongoing epidemic. The research into therapeutic options for the treatment of opioid use disorder (OUD) began with the introduction of methadone in the 1960s. The approval of oral naltrexone initially showed much promise, as the drug was observed to be highly potent in antagonizing the effects of opioids while producing no opioid agonist effects of its own and having a favorable side effect profile. Patients that routinely take their naltrexone reported fewer days of heroin use and had more negative drug tests than those without treatment. Poor outcomes in OUD patients treated with naltrexone have been directly tied to short treatment time. Studies have shown that naltrexone given orally vs. as an implant at the 6-month interval showed a higher non-compliance rate among those who used oral medications at the 6-month mark and a slower return to use rate. There were concerns that naltrexone could possibly worsen negative symptoms seen in opiate use disorder related to blockade of endogenous opioids that are important for pleasurable stimuli. Studies have shown that naltrexone demonstrated no increase in levels of anxiety, depression and anhedonia in participants and another study found that those treated with naltrexone had a significant reduction in mental health-related hospitalizations. The latter study also concluded that there was no increased risk for mental health-related incidents in patients taking naltrexone via a long-acting implant. Although not yet FDA approved in the United States, naltrexone implant has shown promising results in Europe and Australia and may provide a novel treatment option for opioid addiction.

Comparative Evaluation of Naltrexone Implants Placed in Different Anatomical Regions According to the Suitability for Opioid Treatment and Wound Placement: A Plastic Surgery Perspective

“…The fact that the abdominal region is the most preferred region in the literature has also been another factor affecting the change of the implantation site. [19][20][21][22][23][24] The data obtained were evaluated statistically to compare the implants placed in the back and the abdominal region.…”

“…18 In the studies in the literature, although it is reported that the abdominal region is the preferred implantation site in cases of opioid addiction due to its easy accessibility, there is no study on an ideal implantation site. [19][20][21][22][23][24] In our study, we aimed to evaluate and compare whether the back or abdominal region is most ideal for implantation by evaluating treatment compliance, surgical wound site, and complications in these patient groups.…”

Fentanyl‐induced respiratory depression in rodents is inhibited by bioabsorbable, subcutaneous naltrexone implants at 3.5 months

“…The rising number of opioid‐related fatalities in the United States is a growing national crisis, with reported deaths escalating from 9496 in 2001 to 80 411 in 2021 1,2 . This upsurge is attributed to the prevalence of illicitly produced fentanyl, which exhibits an estimated 50–100 times greater potency than morphine and has displayed resistance to usual doses of naloxone, a commonly employed medication for opioid overdose management 3–6 …”

Commentary on “Antiseizure activity by opioid receptor antagonism, new evidence”

“…Naltrexone is presently used in the clinic for treating alcohol use disorder and manage opioid abuse. 11,12 The compound is considered a nonselective opioid receptor antagonist, although there is a significantly higher affinity for μ-receptors than for κ-and δ-receptors (Ki: 0.89 nM, 20.2 nM and 64.1 nM, respectively). 13 As a result, naltrexone has been found to produce a nearly complete blockade of μ-receptors in humans at a dose of 50 mg/ day, compared with 20% to 35% blockage of δ-receptors.…”

“…The results of the current study therefore confirm the possibility of using certain opioids as ASMs, at least in specific conditions. Naltrexone is presently used in the clinic for treating alcohol use disorder and manage opioid abuse 11,12 . The compound is considered a nonselective opioid receptor antagonist, although there is a significantly higher affinity for μ‐receptors than for κ‐ and δ‐receptors (Ki: 0.89 nM, 20.2 nM and 64.1 nM, respectively) 13 .…”