The effects of noribogaine and harmaline in rats trained with ibogaine as a discriminative stimulus

In the present investigation, Fischer-344 rats were trained to discriminate 10.0 mg/kg of ibogaine from water using a pretreatment time of 60 minutes. Analysis of dose response data generated and ED₅₀ of 4.6 mg/kg. The time course of the ibogaine (10.0 mg/kg) cue was also determined. The stimulus reached a maximum level of 94% ibogaine-appropriate responding at the 60-min pretreatment time. This was followed by a time-dependent decrease in ibogaine-appropriate responding. At a pretreatment time of 8 hrs only 6.4% drug-appropriate responding was observed. In substitution experiments, intermediate generalization was observed with a metabolite of ibogaine, 12-hydroxyibogamine [noribogaine] (71.6%) whereas complete generalization was seen with harmaline (83.5%).