An evaluation of the hot plate technique to study narcotic antagonists

The mouse hot plate model, with slight differences from the way it is used to study narcotic analgesics, was evaluated as a method for determining the oral effectiveness, relative potency and duration of action of two standard narcotic antagonists, naloxone and naltrexone, and a new agent, 6-desoxy-6-methylene-naltrexone (ORF 11676). Naltrexone and ORF 11676 were found to be more effective orally than naloxone. Naltrexone and ORF 11676 were equipotent by 3 routes of administration and both were more potent than naloxone. Naloxone produced a significantly shorter duration of action than the other two drugs. It was concluded that the mouse hot plate method, used to detect and characterize the activity of narcotic antagonists, provides information compatible with that obtained in other species, including man.