Antagonist Models for Relapse Prevention and Reducing HIV Risk

Area of Science:

• Pharmacology
• Addiction Medicine
• Infectious Disease Prevention

Background:

• Naltrexone, an opioid receptor antagonist, was initially developed in the 1970s but faced challenges with patient compliance and relapse rates.
• Renewed interest in naltrexone emerged in the late 1990s due to the convergence of injecting opioid use, HIV spread in the Russian Federation, and international HIV prevention efforts.
• Discussions involving the U.S. National Institute on Drug Abuse (NIDA) highlighted naltrexone's potential role in addiction treatment, particularly in contexts where agonist treatments are restricted.

Purpose of the Study:

• To review findings from studies on naltrexone for opioid dependence treatment and HIV risk reduction.
• To evaluate the role of extended-release injectable naltrexone in preventing relapse to opioid dependence.
• To comment on the potential of extended-release naltrexone as an addition to current pharmacotherapies for opioid dependence.

Main Methods:

• Review of previous studies on oral naltrexone compliance and HIV risk reduction.
• Examination of the development pathway leading to FDA approval of extended-release injectable naltrexone.
• Analysis of pharmacological data on naltrexone's efficacy as an opioid antagonist.

Main Results:

• Naltrexone effectively blocks subjective and analgesic effects of opioids without causing physiological dependence.
• Early studies with oral naltrexone showed disappointing results due to low patient interest and high dropout rates.
• NIDA-sponsored studies in the Russian Federation demonstrated improved compliance with oral naltrexone and reduced HIV injecting risk among participants who completed treatment.

Conclusions:

• Extended-release injectable naltrexone has been approved by the FDA for preventing relapse in opioid dependence.
• Improved compliance with extended-release formulations may enhance treatment effectiveness compared to oral naltrexone.
• Extended-release naltrexone represents a potentially meaningful advancement in pharmacotherapies for opioid dependence and HIV risk reduction.