Naltrexone-buprenorphine interactions: effects on cocaine self-administration

Area of Science:

• Pharmacology
• Neuroscience
• Addiction Research

Background:

• Buprenorphine, an opioid mixed agonist-antagonist, effectively reduces cocaine self-administration in rhesus monkeys.
• The specific contributions of buprenorphine's agonist and antagonist properties to its anti-cocaine effects remain unclear.
• Understanding these properties is crucial for optimizing addiction treatment strategies.

Purpose of the Study:

• To investigate the role of naltrexone, a mu opioid antagonist, in modulating buprenorphine's effects on cocaine and food self-administration.
• To determine if naltrexone's timing of administration influences its interaction with buprenorphine.
• To elucidate the pharmacological mechanisms underlying buprenorphine's efficacy in reducing cocaine use.

Main Methods:

• Rhesus monkeys self-administered cocaine or food under a fixed-ratio/variable-ratio schedule.
• Monkeys received buprenorphine alone, buprenorphine with varying doses of naltrexone (simultaneously or pre-administered), or naltrexone alone.
• Behavioral effects on self-administration were compared across different treatment conditions.

Main Results:

• Buprenorphine alone significantly reduced cocaine self-administration by 53%.
• Concurrent naltrexone administration attenuated buprenorphine's cocaine-reducing effects.
• Pre-administration of naltrexone resulted in a dose-dependent decrease in buprenorphine's efficacy against cocaine self-administration.

Conclusions:

• Naltrexone appears to antagonize the partial mu-opioid agonist component of buprenorphine, which is critical for its anti-cocaine effects.
• Combining buprenorphine with opioid antagonists may compromise its effectiveness for treating dual opioid and cocaine dependence.
• These findings have implications for the development of combination therapies for substance use disorders.