Effect of Ibogaine on the Development of Tolerance to the Analgesic Effect of Morphine

The results of 3 experiments demonstrated that (a) 20 mg/kg ibogaine (but not 10 mg/kg), administered 30 min before morphine, attenuates the development of tolerance to the analgesic effect of morphine in rats; (b) this 20 mg/kg dose of ibogaine, if administered 5 hr before morphine, has no effect on tolerance development; and (c) a high dose of ibogaine (40 mg/kg), administered 24 hr before morphine, does not affect analgesic tolerance (despite reports that this dose of ibogaine, administered 1 day before morphine, modulates the neurochemical and reinforcing effect of the opiate, see P. Popik, R. T. Layer, & P. Skolnick, 1995). The findings are discussed in the context of suggestions that ibogaine be evaluated as a treatment for opiate dependence, and recent research indicating that ibogaine is an N-methyl-d-aspartate antagonist.