Screening for benfluorex and its major urinary metabolites in routine doping controls

Benfluorex metabolism complemented by electrochemistry-mass spectrometry

The hypolipidemic and hypoglycemic drug benfluorex was widely applied to treat type 2 diabetes mellitus and metabolic syndrome in overweight patients since 1976. However, benfluorex was connected to multiple cases of valvular heart disease and pulmonary arterial hypertension later on. Similar adverse drug reactions were previously found to be associated to the structurally related drug fenfluramine, which was attributed to the formation of its N-deethylated metabolite norfenfluramine. Even though norfenfluramine was known to be a common metabolite of fenfluramine and benfluorex, only fenfluramine was withdrawn from European and United States markets in 1997 while benfluorex remained available until 2009. In this work, the metabolism of benfluorex is simulated by an online hyphenation of electrochemistry and mass spectrometry and the observed transformation products are further characterized using liquid chromatography and high-resolution tandem mass spectrometry. Using this approach, norfenfluramine is found to be the main electrochemical transformation product of benfluorex. Considering the knowledge about norfenfluramine toxicity, rapid metabolite screening using electrochemistry hyphenated to mass spectrometry could have been used to predict the potential of benfluorex for adverse drug reactions early on, showcasing the value of electrochemical metabolism mimicry for rapid drug safety evaluation.

Angiogenin-loaded fibrin/bone powder composite scaffold for vascularized bone regeneration

Background

Angiogenin (ANG) is a potent stimulator of angiogenesis. The aim of this study was to fabricate an ANG-loaded scaffold and to evaluate its angiogenic and osteogenic effects. In this study, we fabricated an ANG-loaded scaffold using bovine bone powder and fibrin glue. We then evaluated the structural, morphological, and mechanical properties of the scaffold and the in vitro release profile of ANG. Cell proliferation, viability, and adhesion were evaluated using endothelial cells in vitro, and angiogenesis and new bone formation were evaluated using a rabbit calvarial defect model in vivo.

Results

Micro-computed tomography imaging showed that the bone powder was uniformly distributed in the scaffold, and scanning electron microscopy showed that the bone powder was bridged by polymerized fibrin. The porosity and compressive strength of the scaffolds were ~60 % and ~0.9 MPa, respectively, and were not significantly altered by ANG loading. In vitro, at 7 days, approximately 0.4 μg and 1.3 μg of the ANG were released from the FB/ANG 0.5 and FB/ANG 2.0, respectively and sustained slow release was observed until 25 days. The released ANG stimulated cell proliferation and adherence and was not cytotoxic. Furthermore, in vivo implantation resulted in enhanced angiogenesis, and new bone formation depended on the amount of loaded ANG.

Conclusions

These studies demonstrate that a fibrin and bone powder scaffold loaded with ANG might be useful to promote bone regeneration by enhanced angiogenesis.

From the mobile proton to wandering hydride ion: mechanistic aspects of gas-phase ion chemistry

Structural characterization of molecular species by mass spectrometry supposes the knowledge of the type of ions generated and the mechanism by which they dissociate. In this context, a need for a rationalization of electrospray ionization(+)(-) mass spectra of small molecules has been recently expressed. Similarly, at the other end of the mass scale, efforts are currently made to interpret the major fragmentation processes of protonated and deprotonated peptides and their reduced forms produced in electron capture or electron transfer experiments. Most fragmentation processes of molecular and pseudo-molecular ions produced in the ion source of a mass spectrometer may be described by a combination of several key mechanistic steps: simple bond dissociation, formation of ion-neutral complex intermediates, hydrogen atom, hydride ion or proton migrations and nucleophilic attack. Selected crucial aspects of these elementary reactions, occurring inside positively charged ions, will be recalled and illustrated by examples taken in recent mass spectrometry literature. Emphasis will be given on the protonation process and its consequence in terms of structure and energetic.

Echocardiographic evidence for valvular toxicity of benfluorex: a double-blind randomised trial in patients with type 2 diabetes mellitus

Objectives

REGULATE trial was designed to compare the efficacy and safety of benfluorex versus pioglitazone in type 2 diabetes mellitus (DM) patients.

Methods

Double-blind, parallel-group, international, randomised, non-inferiority trial. More than half of the 196 participating centres were primary care centres. Patients eligible had type 2 DM uncontrolled on sulfonylurea. 846 were randomised. They received study treatment for 1 year. 423 patients were allocated to benfluorex (150 to 450 mg/day) and 423 were allocated to pioglitazone (30 to 45 mg/day). Primary efficacy criterion was HbA_1c. Safety assessment included blinded echocardiographic evaluation of cardiac and valvular status.

Results

At baseline, patients were 59.1±10.5 years old with HbA1c 8.3±0.8%, and DM duration 7.1±6.0 years. During the study, mean HbA1c significantly decreased in both groups (benfluorex: from 8.30±0.80 to 7.77±1.31 versus pioglitazone: from 8.30±0.80 to 7.45±1.30%). The last HbA1c value was significantly lower with pioglitazone than with benfluorex (p<0.001) and non-inferiority of benfluorex was not confirmed (p = 0.19). Among the 615 patients with assessable paired echocardiography (310 benfluorex, 305 pioglitazone), 314 (51%) had at least one morphological valvular abnormality and 515 (84%) at least one functional valvular abnormality at baseline. Emergent morphological abnormalities occurred in 8 patients with benfluorex versus 4 with pioglitazone (OR 1.99), 95% CI (0.59 to 6.69). Emergent regurgitation (new or increased by one grade or more) occurred more frequently with benfluorex (82 patients, 27%) than with pioglitazone (33 patients, 11%) (OR 2.97), 95% CI (1.91 to 4.63) and were mainly rated grade 1; grade 2 (mild) was detected in 2 patients with benfluorex and 3 with pioglitazone. There was no moderate or severe regurgitation.

Conclusion

After 1 year of exposure, our results show a 2.97 fold increase in the incidence of valvular regurgitation with benfluorex and provide evidence for the valvular toxicity of this drug.

Trial registration

www.controlled-trials.com ISRCTN 27354239. isrctn27354239