IngentaConnect Effectiveness of repeated administration of a new oral naltrexone...

Authors: Álvarez-Fuentes J.¹; Rojas-Corrales M.O.²; Holgado M.A.¹; Sánchez-Lafuente C.¹; Micó J.A.²; Fernández-Arévalo M.¹

Source: Journal of Pharmacy and Pharmacology, Volume 53, Number 9, 1 September 2001 , pp. 1201-1205(5)

Publisher: Pharmaceutical Press

Abstract:

Naltrexone hydrochloride, an opioid antagonist used as an adjunct to the maintenance of the opioid-free state for detoxified individuals, was introduced into the polymeric structure of Eudragit L30D, an anionic copolymer based on polymethacrylic acid and ethylacrylate. From the results of a preclinical study, this complexation technique can be considered as a useful tool in the design of oral controlled-release systems (naltrexone–Eudragit L) capable of inducing long-lasting effects in-vivo. The biopharmaceutical characterization of the naltrexone–Eudragit L complex in comparison with naltrexone hydrochloride using the mouse hot-plate model has been previously carried out. The results showed a longer effect, an enhancement of 23.47% of the area under the curve of the inhibition of analgesic activity vs time, and a delay of 51.80% in the t value induced by the complex, compared with those induced by conventional naltrexone. In this study, a regimen of chronic administration of naltrexone–Eudragit L was established. Thus, in an 8-day treatment (4 doses in alternate days) this oral controlled-release system effectively antagonized the analgesic effect of morphine for 8h, whereas naltrexone hydrochloride has to be administered over 16 days (8 doses in alternate days) to induce the same effect. In the 16-day schedule the complex-induced antagonism lasted over 14h after administration.

Document Type: Research article

DOI: 10.1211/0022357011776649

Affiliations: 1: Department of Pharmacy and Pharmaceutical Technology, Faculty of Pharmacy, University of Seville, Spain 2: Department of Neuroscience, Faculty of Medicine, University of Cádiz, Spain

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Effectiveness of repeated administration of a new oral naltrexone controlled-release system on morphine analgesia