[Circulatory failure after bupropion overdose]. / Allt fler allvarliga förgiftningar med preparatet bupropion.

A case of massive overdose of sustained release bupropion tablets is described. The patient presented with GCS 3, tachycardic and in vasoplegic shock. ECHO and EKG were initially normal. The hemodynamic situation was stabilised with vasopressors, but 18 h after presentation the patient deteriorated with wide complex arrhythmias rapidly progressing to cardiac arrest. The patient was put on VA-ECMO after 35 minutes of CPR. Circulation could be stabilized and ECMO was discontinued after 36 h. The patient was extubated on day 6 and made a complete recovery on discharge two weeks after presentation. At 34h, with ongoing ECMO, 236 tablets (with visible print identifying them as bupropion) were evacuated from the patient's stomach by gastroscopy. The tablets were analysed by NMR (nuclear magnetic resonance) but no longer contained any active substance. Blood levels of bupropion and hydroxybupropion at 36h were 790 and 1300 µg/l. The case illustrates a worrying surge in serious bupropion poisonings as noted by the Swedish Poisons Information Centre during the last 5 years.

Survey of peptide quantification methods and comparison of their reproducibility: A case study using oxytocin.

USP's peptide reference standards content is typically determined using an HPLC assay against an external standard for which the purity was determined by a mass balance approach. To explore the use of other analytical methods, the USP Biologics Department conducted a multi-laboratory collaborative study. The study determined the inter-laboratory variability for peptide quantitation using the following methods: HPLC assay, quantitative nuclear magnetic resonance (qNMR) spectroscopy, or amino acid analysis (AAA). The three methods were compared with regard to their suitability for quantitation of the nonapeptide oxytocin. In this study, the HPLC assay method using the same peptide bulk material as the standard showed the lowest inter-lab variability. The coefficient of variation (%CV) was calculated without counting the uncertainty associated with the purity assignment of the standard with mass balance. The proton qNMR method is a direct measurement of the peptide against an internal standard, which is not difficult to perform under common laboratory conditions. Because of the simpler operation and shorter analytical time, qNMR as a primary method for peptide reference standard value assignment deserves further exploration.

Enabling adoption of 2D-NMR for the higher order structure assessment of monoclonal antibody therapeutics.

The increased interest in using monoclonal antibodies (mAbs) as a platform for biopharmaceuticals has led to the need for new analytical techniques that can precisely assess physicochemical properties of these large and very complex drugs for the purpose of correctly identifying quality attributes (QA). One QA, higher order structure (HOS), is unique to biopharmaceuticals and essential for establishing consistency in biopharmaceutical manufacturing, detecting process-related variations from manufacturing changes and establishing comparability between biologic products. To address this measurement challenge, two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR) methods were introduced that allow for the precise atomic-level comparison of the HOS between two proteins, including mAbs. Here, an inter-laboratory comparison involving 26 industrial, government and academic laboratories worldwide was performed as a benchmark using the NISTmAb, from the National Institute of Standards and Technology (NIST), to facilitate the translation of the 2D-NMR method into routine use for biopharmaceutical product development. Two-dimensional 1H,15N and 1H,13C NMR spectra were acquired with harmonized experimental protocols on the unlabeled Fab domain and a uniformly enriched-15N, 20%-13C-enriched system suitability sample derived from the NISTmAb. Chemometric analyses from over 400 spectral maps acquired on 39 different NMR spectrometers ranging from 500 MHz to 900 MHz demonstrate spectral fingerprints that are fit-for-purpose for the assessment of HOS. The 2D-NMR method is shown to provide the measurement reliability needed to move the technique from an emerging technology to a harmonized, routine measurement that can be generally applied with great confidence to high precision assessments of the HOS of mAb-based biotherapeutics.

Synthesis and labeling of a piperazine-based library of ¹¹C-labeled ligands for imaging of the vesicular acetylcholine transporter.

The cholinergic system is involved in neurodegenerative diseases, and visualization of cholinergic innervations with positron emission tomography (PET) would be a useful tool in understanding these diseases. A ligand for the vesicular acetylcholine transporter (VAChT), acknowledged as a marker for cholinergic neurons, could serve as such a PET tracer. The aim was to find a VAChT PET tracer using a library concept to create a small but diverse library of labeled compounds. From the same precursor and commercially available aryl iodides 6a-f, six potential VAChT PET tracers, [(11)C]-(±)5a-f, were (11)C-labeled by a palladium (0)-mediated aminocarbonylation, utilizing a standard protocol. The labeled compounds [(11)C]-(±)5a-f were obtained in radiochemical purities >95% with decay-corrected radiochemical yields and specific radioactivities between 4-25% and 124-597 GBq/µmol, respectively. Autoradiography studies were then conducted to assess the compounds binding selectivity for VAChT. Labeled compounds [(11)C]-(±)5d and [(11)C]-(±)5e showed specific binding but not enough to permit further preclinical studies. To conclude, a general method for a facile synthesis and labeling of a small piperazine-based library of potential PET tracers for imaging of VAChT was shown, and in upcoming work, another scaffold will be explored using this approach.