Tolerance to and physical dependence on N-allylnormetazocine (NANM) in chronic spinal dogs.

Six female chronic spinal dogs were administered N-allylnormetazocine (NANM) chronically by the intravenous route starting at 0.3 mg/kg/day. The dose was escalated to a stabilization dose of 10 mg/kg/day. The dogs became tolerant to NANM's ability to produce canine delirium and its anorexigenic and respiratory stimulant effects. Naltrexone increased the amplitude of the flexor reflex and pulse rate in the body temperature, pupillary constriction, bradycardia and tachypnea. Appetite was decreased and weight was lost. These data indicate that chronic administration of NANM produces tolerance and a unique type of physical dependence. Some changes produced by chronically administered NANM were naltrexone antagonizable, others were not suggesting that NANM may have several mechanisms of action.