Radioligand-binding study of noribogaine, a likely metabolite of ibogaine.
Brain research – March 27, 1995
Source: PubMed
Summary
Noribogaine exhibits significantly higher affinity for opioid receptors compared to ibogaine, with binding affinities of 0.96 µM for kappa and 2.66 µM for mu receptors, versus ibogaine’s 3.77 µM and 11.04 µM, respectively. Notably, noribogaine also binds to delta receptors (Ki = 24.72 µM), where ibogaine shows no affinity. With these findings from radioligand-binding studies involving precise measurements, noribogaine's role in contributing to the pharmacological effects of ibogaine becomes increasingly evident, suggesting its potential therapeutic significance.
Abstract
Radioligand-binding studies were performed to ascertain the actions of noribogaine, a suspected metabolite of ibogaine, on opioid receptors. Consistent with previous results, ibogaine showed highest affinity for kappa opioid receptors (Ki = 3.77 +/- 0.81 microM), less affinity for mu receptors (Ki = 11.04 +/- 0.66 microM) and no affinity for delta receptors (Ki > 100 microM). Noribogaine showed a higher affinity than ibogaine for all of the opioid receptors: kappa Ki = 0.96 +/- 0.08 microM, mu Ki = 2.66 +/- 0.62 microM and delta Ki = 24.72 +/- 2.26 microM. These data suggest that noribogaine is active in vivo and that it may contribute to ibogaine's pharmacological effects.