Clinical and experimental evidence of an opiate-like activity of lefetamine.

A case of lefetamine abuse (0.9-1.8 g/day in 15-30 i.m. divided doses) is reported. In this patient, the administration of naloxone precipitated a mild opiate-like withdrawal syndrome, characterized by mydriasis, piloerection, yawning and a slight increase of blood pressure. The complete withdrawal of lefetamine, substituted by a placebo regimen, aggravated these symptoms. Furthermore, experimental results showed that lefetamine induced a naloxone-reversible inhibition of the guinea-pig ileum contractile response to electric field stimulation, and that naloxone pretreatment of mice prevented lefetamine antinociceptive activity in the hot-plate test. The clinical and experimental findings suggest that lefetamine has an opiate-like activity.