The pharmacokinetics and pharmacodynamics of ibogaine in opioid use disorder patients.

Ibogaine, a hallucinogenic drug being studied for opioid use disorder, shows highly variable pharmacokinetics strongly linked to CYP2D6 genotype. In 14 patients given a single 10 mg/kg dose, ibogaine clearance increased by 30.7 L/h per point of CYP2D6 activity score, from a baseline of 0.82 L/h. Higher ibogaine plasma concentrations correlated significantly with QTc prolongation and cerebellar ataxia, while noribogaine did not. Neither ibogaine nor its metabolite correlated with opioid withdrawal severity. These findings suggest that cardiac and neurological side effects are driven more by ibogaine itself, and that lower or genotype-personalized dosing may improve safety.

Study at a glance

Abstract

Ibogaine is a hallucinogenic drug that may be used to treat opioid use disorder (OUD). The relationships between pharmacokinetics (PKs) of ibogaine and its metabolites and their clinical effects on side effects and opioid withdrawal severity are unknown. We aimed to study these relationships in patients with OUD undergoing detoxification supported by ibogaine. The study was performed in 14 subjects with OUD. They received a single dose of 10mg/kg ibogaine hydrochloride. Plasma PKs of ibogaine, noribogaine, and noribogaine glucuronide were obtained during 24 h. Cytochrome P450 isoenzyme 2D6 (CYP2D6) genotyping was performed. The PKs were analyzed by means of nonlinear mixed effects modeling and related with corrected QT interval (QTc) prolongation, cerebellar ataxia, and opioid withdrawal severity. The PK of ibogaine were highly variable and significantly correlated to CYP2D6 genotype (p < 0.001). The basic clearance of ibogaine (at a CYP2D6 activity score (AS) of 0) was 0.82 L/h. This increased with 30.7 L/h for every point of AS. The relation between ibogaine plasma concentrations and QTc was best described by a sigmoid Emax model. Spearman correlations were significant (p < 0.03) for ibogaine but not noribogaine with QTc (p = 0.109) and cerebellar effects (p = 0.668); neither correlated with the severity of opioid withdrawal symptoms. The clearance of ibogaine is strongly related to CYPD2D6 genotype. Ibogaine cardiac side effects (QTc time) and cerebellar effects are most likely more driven by ibogaine rather than noribogaine. Future studies should aim at exploring lower doses and/or applying individualized dosing based on CYP2D6 genotype.