[Circulatory failure after bupropion overdose]

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.

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.

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.

Population pharmacokinetics of mefloquine in military personnel for prophylaxis against malaria infection during field deployment

OBJECTIVE

The purpose of this study was to determine the population pharmacokinetics of mefloquine in healthy military personnel during prophylaxis for malaria infections.

METHODS

The subjects were 1,111 Australian soldiers participating in two studies: a randomised double-blinded study (group A, 161 subjects) and an open-label study (group B, 950 subjects). Following a loading dose (250 mg mefloquine base daily, 3 days), subjects received an oral weekly maintenance dose of 250 mg over 6 months. Blood was collected after the last split loading dose then at weeks 4, 8 and 16 for group A, and at weeks 13 and 26 for group B. Plasma mefloquine concentrations were measured by high-performance liquid chromatography (HPLC). Pharmacokinetic modelling was performed using NONMEM.

RESULTS

A two-compartment model with inter-occasion variability (IOV) for clearance satisfactorily described the pharmacokinetics. Typical values were clearance (CL/F, 2.09 l/h), central volume of distribution (V1/F, 528 l), absorption rate constant (KA, 0.24 h(-1)), inter-compartmental clearance (Q/F, 12.5 l/h), peripheral volume of distribution (V2/F, 483 l) and elimination half-life (t (1/2), 14.0 days). Weight had a positive influence on central volume but was insufficient to warrant dosage adjustments. The inter-individual variability (coefficient of variation, CV%) for CL/F and V1/F was 24.4% and 29.6%, respectively. The IOV for CL/F was 17.8%. The proportional residual error (CV%) for groups A and B was 11.5% and 19.5%, respectively, and the additive error standard deviation (SD) was 57 ng/ml and 149 ng/ml, respectively.

CONCLUSION

The typical parameter values were comparable with those estimated in much smaller cohorts of healthy subjects and in malaria patients treated with single-dose mefloquine. The lower unexplained variability in the blinded study suggested these subjects may have been more compliant in taking their medication than soldiers in the open-label study.

Relative systemic dose potency and tolerability of inhaled formoterol and salbutamol in healthy subjects and asthmatics

OBJECTIVES

To compare the relative systemic dose potency and tolerability of inhaled formoterol and salbutamol and to describe elimination of formoterol, particularly any enantioselectivity.

METHODS

Twelve healthy subjects, aged 18-28 years, completed three open study days, and eleven asthmatic patients, aged 20-56 years, completed four double-blind study days in randomised, placebo-controlled and crossover fashions. The healthy subjects inhaled 13.5 + 13.5 + 27 microg formoterol (Oxis) via Turbuhaler and 300 + 300 + 600 microg salbutamol (Ventoline) via a pressurised metered dose inhaler (pMDI). The asthmatics, being on formoterol 9 microg twice daily via Turbuhaler during the study, inhaled the same single doses as the healthy subjects plus 900 + 900 + 1800 microg salbutamol via pMDI. Doses were given cumulatively 30 min apart on separate study days. Placebo was a day of no treatment in the healthy subjects. Double dummies were used for the asthmatics. Cardiovascular and metabolic effects were evaluated. Elimination of formoterol was addressed in the healthy subjects.

RESULTS

Formoterol was estimated to be 28-109 times as potent as salbutamol, depending on the systemic effect variable. The duration of systemic action seemed to differ marginally at approximately equieffective doses of formoterol and salbutamol. Systemic effects were well tolerated and tended to be more pronounced in the healthy subjects than in the asthmatic patients. The half-life of the pharmacologically more active (R;R)-formoterol was longer than that of (S;S)-formoterol.

CONCLUSIONS

Systemically, formoterol was shown to be 28-109 times as potent as salbutamol. Equieffective doses seemed to have a similar duration of effect. Formoterol and salbutamol were well tolerated by healthy subjects up to the tested total doses of 54 microg and 1200 microg, respectively, and by asthmatic patients up to the tested total doses of 54 microg and 3600 microg, respectively. Elimination of formoterol was enantioselective.