Naloxone and naltrexone antagonism of various central effects of morphine
Piccinelli, D.; de Feo, G.; Mazzanti, G.
Bollettino della Societa Italiana di Biologia Sperimentale 62(10): 1213-1220
1986
ISSN/ISBN: 0037-8771 PMID: 3828119 Document Number: 280406
Naloxone and Naltrexone block analgesic activity of morphine, evaluated with the hot plate test; the first product is active at 0,25-1 mg/kg s.c. and the second at 0,5- 1 m/kg s.c. Naltrexone and naloxone, at 2 mg/kg s.c, inhibit morphine induced Straub's tail in mice; the effect of the former drug lasts for six hours and that of the latter for four hours. Naltrexone induces abstinence syndrome in mice dependent on morphine, starting from 0,5 mg/kg s.c., whereas naloxone is active at 1 mg/kg s.c. The above reported data show that naltrexone is twice as active as naltrexone in blocking central effect of morphine; moreover its effects are more prolonged than those of naloxone.