Noribogaine (12-hydroxyibogamine): a biologically active metabolite of the antiaddictive drug ibogaine.

Ibogaine, a plant-derived alkaloid being studied for substance use disorders, is rapidly converted in the body to its metabolite noribogaine. In rats, noribogaine reaches higher blood levels than ibogaine and persists for at least 24 hours. Noribogaine did not cause tremors or forepaw treading, unlike ibogaine, but both drugs elevated stress hormones corticosterone and prolactin, with ibogaine more potent for corticosterone. Neither drug affected dopamine levels in the nucleus accumbens, but both increased serotonin levels, with noribogaine more potent. Noribogaine is biologically active and likely contributes to ibogaine's effects but may be safer, producing fewer adverse effects like tremors and stress-axis activation.

Study at a glance

Abstract

Ibogaine (IBO) is a plant-derived alkaloid that is being evaluated as a possible medication for substance use disorders. When administered peripherally to monkeys and humans, IBO is rapidly converted to an o-demethylated metabolite, 12-hydroxyibogamine (NORIBO). We have found in rats that peak blood levels of NORIBO can exceed those of the parent compound, and NORIBO persists in the bloodstream for at least 24 h. Surprisingly few studies have examined the in vivo biological activity of NORIBO. In the present series of experiments, we compared the effects of intravenous (i.v.) administration of IBO and NORIBO (1 and 10 mg/kg) on unconditioned behaviors, circulating stress hormones, and extracellular levels of dopamine (DA) and serotonin (5-HT) in the nucleus accumbens of male rats. IBO caused dose-related increases in tremors and forepaw treading, whereas NORIBO did not. Both IBO and NORIBO produced significant elevations in plasma corticosterone and prolactin, but IBO was more potent as a stimulator of corticosterone secretion. Neither drug affected extracellular DA levels in the nucleus accumbens. However, both IBO and NORIBO increased extracellular 5-HT levels, and NORIBO was more potent in this regard. The present data demonstrate that NORIBO is biologically active and undoubtedly contributes to the in vivo pharmacological profile of IBO in rats. Most importantly, NORIBO appears less likely to produce the adverse effects associated with IBO (i.e., tremors and stress-axis activation), suggesting that the metabolite may be a safer alternative for medication development.