Sustained release of naltrexone from glyceride implants

Area of Science:

• Pharmacology and Drug Delivery
• Biomaterials Science

Background:

• Naltrexone is a potent narcotic antagonist.
• Continuous delivery systems are needed for long-term therapeutic effects.

Purpose of the Study:

• To develop and evaluate injectable implants for sustained in vivo release of naltrexone.
• To control naltrexone release rates and assess implant biocompatibility.

Main Methods:

• Formulation of solid dispersions of naltrexone in natural glycerides into pellets and microparticles.
• In vivo testing in mice to assess naltrexone delivery and blockade of morphine's anti-nociceptive effects.
• Evaluation of implant degradation, absorption, and tissue compatibility in various animal models.

Main Results:

• Both implant forms delivered naltrexone effectively for over one month in mice.
• Naltrexone release rates were tunable by adjusting drug concentration and glyceride composition.
• Implant degradation and absorption varied with composition, size, and anatomical location.
• No significant tissue incompatibility was observed across multiple species.

Conclusions:

• Injectable naltrexone implants in natural glycerides provide a viable long-term delivery system.
• The system allows for controlled release and demonstrates excellent biocompatibility in preclinical models.
• This technology holds promise for sustained blockade of opioid effects.