Toxicokinetics of ibogaine and noribogaine in a patient with prolonged multiple cardiac arrhythmias after ingestion of internet purchased ibogaine

Background: Ibogaine is an agent that has been evaluated as an unapproved anti-addictive agent for the management of drug dependence. Sudden cardiac death has been described to occur secondary to its use. We describe the clinical effects and toxicokinetics of ibogaine and noribogaine in a single patient. For this purpose, we developed a LC-MS/MS-method to measure ibogaine and noribogaine plasma-concentrations. We used two compartments with first order absorption. Case details: The maximum concentration of ibogaine was 1.45 mg/L. Our patient developed markedly prolonged QTc interval of 647ms maximum, several multiple cardiac arrhythmias (i.e., atrial tachycardia and ventricular tachycardia and Torsades des Pointes). QTc-prolongation remained present until 12 days after ingestion, several days after ibogaine plasma-levels were low, implicating clinically relevant noribogaine concentrations long after ibogaine had been cleared from the plasma. The ratio k12/k21 for noribogaine was 21.5 and 4.28 for ibogaine, implicating a lower distribution of noribogaine from the peripheral compartment into the central compartment compared to ibogaine. Conclusions: We demonstrated a linear relationship between the concentration of the metabolite and long duration of action, rather than with parent ibogaine. Therefore, after (prolonged) ibogaine ingestion, clinicians should beware of long-term effects due to its metabolite

Switchability of gabapentin formulations : a randomized trial to assess bioequivalence between Neurontin and Gabasandoz on the individual subject level

Generic substitution of antiepileptic drugs is generally not advised by neurologists. The present study investigated the switchability of gabapentin 800 mg tablets (Neurontin and Gabasandoz) using an individual bioequivalence (IBE) study design with two batches of each product and assessed whether between-batch and between-formulation variability in exposure play a significant role in the within-subject variability. The trial was analyzed according to the US Food and Drug Administration (FDA) framework to establish IBE. The IBE was shown between both products with the 95% upper confidence bound of the IBE criterion being -2.01 and -2.31 for area under the concentration-time curve from zero to infinity (AUC(0-inf)) and peak plasma concentration (C-max), respectively. Subject-by-formulation variability (1.35%) was negligible compared with the within-subject variability of AUC(0-inf) with Neurontin (19.0%) and Gabasandoz (23.6%). Inclusion of an additional batch did not significantly change this within-subject variability (20.2% and 23.6%, respectively). This study shows that substitution of gabapentin 800 mg tablets of Neurontin and Gabasandoz should be possible without affecting clinical outcomes

Dried blood spot sampling of nilotinib in patients with chronic myeloid leukaemia: a comparison with venous blood sampling

Objectives: To compare nilotinib concentrations obtained by venous blood sampling and dried blood spot (DBS) in patients with chronic myeloid leukaemia (CML). It was investigated how to predict nilotinib plasma levels on the basis of DBS. Methods: Forty duplicate DBS and venous blood samples were collected from 20 patients. Capillary blood was obtained by finger prick and spotted on DMPK-C Whatman sampling paper, simultaneously with venous blood sampling. Plasma concentrations were predicted from DBS concentrations using three methods: (1) individual and (2) mean haematocrit correction and (3) the bias between plasma and DBS concentrations. Results were compared using Deming regression and Bland–Altman analysis. Key findings: Nilotinib plasma concentrations ranged from 376 to 2663 μg/l. DBS concentrations ranged from 144 to 1518 μg/l. The slope was 0.56 (95% CI, 0.51 to 0.61) with an intercept of −41.68 μg/l (95% CI, −93.78 to 10.42). Mean differences between calculated and measured plasma concentrations were −14.3% (method 1), −14.0% (method 2) and −0.6% (method 3); differences were within 20% of the mean in 73%, 85% and 80% of the samples, respectively. The slopes were respectively 0.96 (95% CI, 0.86 to 1.06), 0.95 (95% CI, 0.86 to 1.03) and 1.00 (95% CI, 0.91 to 1.09). Conclusions: Plasma concentrations of nilotinib could be predicted on the basis of DBS. DBS sampling to assess nilotinib concentrations in CML patients seems a suitable alternative for venous sampling