DEVELOPMENT OF AN IMPROVED NALTREXONE DEPOT FORMULATION

Naltrexone is a well known opioid antagonist with established properties but clinical usefulness in oral formulations is limited by high patient attrition. Research at Unit for Addiction Medicine points to implant formulations as promising, but implant p rocedures hamper clinical applicability and slow absorption of implant is by some patients found bothersome. An injectable depot formulation would increase therapeutic feasibility. A depot developed in US has been tested, but found to have too short durat ion. The Polymer Research Group at the Department of Chemistry, University of Oslo judges that recent advances in polymer technology makes it is realistic to produce slow release depot formulations that attain naltrexone plasmalevel above 2 ng/ml for 5-6 months based on thermo-responsive polymer systems that can be injected as solutions and then form gel at body temperature. Naltrexone will be physically or chemically entrapped in the polymer network and released slowly over an extended period of time. On this basis an interdisciplinary project is suggested with collaboration between Unit of Addiction Medicine Institute of Psychiatry, the SiteDel research group at the School of Pharmacy, the Polymer Research Group in the Department of Chemistry and the Norwegian Institute of Public Health. In a first stage the Polymer Research Group together with the School of Pharmacy will develop a polymer system with sufficient slow release properties of naltrexone. In a second stage preliminary studies in animals, t esting the in vivo feasibility of promising polymer formulations, will be performed in cooperation with the Norwegian Institute of Public Health.