Naltrexone for Opioid Use Disorder

(iSTEP-N Trial)

This trial tests a new implant, iSTEP-N, designed to release naltrexone over several months to block opioid effects. It compares blood levels of naltrexone from the implant with those from monthly Vivitrol injections (extended-release naltrexone injection), which the FDA has already approved. Healthy adults with no history of opioid use or substance abuse in the past year and who can maintain consistent follow-up visits are suitable candidates for this study. The goal is to determine if the implant can maintain steady naltrexone levels, potentially offering a longer-lasting option for those recovering from opioid use. Participants will receive either a low-dose implant, high-dose implant, or monthly injections for about a year and will be monitored for safety and effectiveness. As a Phase 1 trial, the research focuses on understanding how the treatment works in people, offering participants the opportunity to be among the first to receive this innovative implant.

Previous studies have found that extended-release naltrexone injections, such as Vivitrol, are safe and well-tolerated for treating opioid use disorder. Research shows that Vivitrol lacks abuse potential and is the only non-controlled substance approved for this purpose. It reduces cravings and helps prevent relapse. Most users experience mild to moderate side effects, like nausea and headaches, which are generally manageable.

Researchers are excited about these treatments for opioid use disorder because they offer innovative delivery methods of naltrexone, aiming to improve patient adherence and outcomes. The Vivitrol injection provides an extended-release formulation administered every four weeks, ensuring consistent medication levels and reducing the need for daily dosing. The iSTEP-N implants, available in high and low doses, are particularly unique because they deliver naltrexone continuously over a long period with just a single administration, potentially increasing convenience and compliance. These approaches could significantly enhance the effectiveness of naltrexone therapy compared to current oral and injectable forms.

Studies have shown that naltrexone effectively blocks the effects of opioids. In this trial, participants may receive Vivitrol, an injectable form already approved to reduce cravings and prevent relapse by maintaining steady naltrexone levels in the body. Alternatively, participants may receive the new iSTEP-N implant, which is still under testing and might offer a longer-lasting option by releasing the medication over several months. Early results indicate that the iSTEP-N implant, at a 9.6 g dose, maintains effective levels for up to 12 weeks. This could lead to fewer treatments and better adherence for people managing opioid use disorder.⁶⁷⁸⁹¹⁰