INTERACTIONS BETWEEN IBOGAINE, A POTENTIAL ANTI-ADDICTIVE AGENT, AND MORPHINE - AN INVIVO MICRODIALYSIS STUDY

Ibogaine, an indolalkylamine, has been claimed to be effective in abolishing drug craving in heroin and cocaine addicts. The present study used in vivo microdialysis to determine the effects of ibogaine on extracellular levels of dopamine (DA) and its metabolites and the effects of ibogaine pretreatment on morphine stimulation of brain DA systems. Acutely, ibogaine (40 mg/kg i.p.) decreased extracellular DA levels in the striatum, increased them in the prefrontal cortex and had no significant effects in the nucleus accumbens. Nineteen hours after ibogaine injection, DA levels were still decreased in the striatum and the metabolite levels were lower in all three regions. When injected 19 h prior to a morphine challenge (5 mg/kg i.p.), ibogaine (40 mg/kg, i.p.) prevented the rise in DA levels in all three regions normally observed after a morphine injection. A high dose of morphine (30 mg/kg i.p.), administered alone, produced no increase in extracellular DA levels; it is therefore unclear whether ibogaine antagonized or potentiated the effects of the lower dose of morphine. Regardless of the nature of this interaction, it appears that ibogaine affects brain DA systems for a period of time that exceeds its elimination from the body and, during this time, alters the responses of these systems to morphine.