Development of drug delivery systems for use in treatment of narcotic addiction

The long term goal of the NIDA narcotic antagonist program of developing an implantable, biodegradable, naltrexone/PLGA matrix system which will sustain the delivery of naltrexone to biological systems for one month has been achieved. The dosage forms which provide the desired delivery characteristics are 1.5 mm diameter beads composed of 70% by weight naltrexone base in 40,000 molecular weight, 90L/10G poly (L(+)-lactic-co-glycolic acid). Other dosage forms, including 1.5 mm diameter rods which provide 6 months' naltrexone release, finely divided injectable powders which provide up to 30 days' naltrexone release, and 1.5 mm diameter rods which provide 2 weeks' sustained delivery of morphine, have also been investigated. In vitro and in vivo release rates have been determined by measuring chemical concentrations in pH 7 buffer solution and urine, respectively. In vivo efficacy of naltrexone sustained delivery devices has been measured by direct challenge with morphine (Dewey-Harris mouse tail-flick test) and inhibition of morphine self-administration in monkeys. Good Manufacturing Practices documentation has been developed and used to produce a large batch of the 1.5 mm diameter naltrexone bead dosage forms at an FDA-registered pharmaceutical manufacturer. These beads, produced at the University of North Carolina School of Pharmacy, are awaiting use in human clinical trials.