An improved long-acting delivery system for narcotic antagonists

Area of Science:

• Pharmacology and Drug Delivery
• Biomaterials Science

Background:

• Naltrexone is an opioid antagonist used to manage opioid and alcohol dependence.
• Prolonged-release formulations can improve patient compliance and therapeutic efficacy.

Purpose of the Study:

• To evaluate the feasibility of a cholesterol-glyceryltristearate matrix for sustained naltrexone delivery.
• To assess the in vivo performance and safety of implantable naltrexone pellets in rats.

Main Methods:

• Implantable cylindrical pellets containing naltrexone, cholesterol, and glyceryl tristearate were prepared.
• Pellets were implanted subcutaneously in rats to evaluate naltrexone release kinetics and antagonism of morphine's antinociceptive effects.
• Pharmacokinetic analysis and histological examination were performed.

Main Results:

• Naltrexone pellets effectively blocked morphine's antinociceptive effects for up to 3 months.
• Naltrexone release followed first-order kinetics with half-lives of 20-60 days.
• The drug delivery system demonstrated good biocompatibility with no significant adverse effects or tissue reactions observed.

Conclusions:

• Cholesterol-glyceryltristearate matrix is a feasible system for prolonged naltrexone release.
• The developed implantable pellets offer a promising long-acting delivery option for naltrexone, with potential for improved treatment outcomes.