A simple dilute and shoot methodology for the identification and quantification of illegal insulin

Quantification of Ephedrine Substances in Human Urine by Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry

An accurate quantitative method for four prohibited ephedrine substances in human urine has been established, based on ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The quantitative bias caused by pretreatment operations and matrix effects was reduced by the dilute and shoot pretreatment method. The good separation of isomers was achieved with the advantages of the UPLC instrument and Agilent Poroshell 120 EC-C8 UPLC column. Stable quantitative ions were selected during the analysis with MS/MS. The result of the method validation experiment showed an excellent linearity between 50% and 200% threshold concentration with a correlation coefficient (r2) greater than 0.999. The coefficient of variation at the limit of quantification and threshold was <20% and 10%, respectively. The uncertainty was below the maximum uncertainty specified in the technical document of the World Anti-Doping Agency (WADA). The analytical result using this method has passed the WADA-external quality assessment scheme. The anti-doping laboratory has applied the method in routine tests and reported adverse analytical finding.

Quantification of Insulin Analogs by Liquid Chromatography-High-Resolution Mass Spectrometry

Administration of exogenous insulin or insulin analogs is a common cause of hypoglycemia. The etiology of hypoglycemic episodes can be investigated by the measurement of insulin. However, frequently used synthetic insulin analogs show variable reactivity with immunoassays designed for the quantification of human insulin and may produce misleading results. To overcome this challenge, mass spectrometric methods can be applied to differentiate and accurately quantify insulin and its analogs. Here we describe a liquid chromatography-tandem high-resolution accurate mass (LC-HRAM) for the highly specific and independent quantification of insulin and its synthetic analogs including aspart, detemir, glargine, glulisine, and lispro. This method utilizes antibody affinity extraction followed by analysis on a high-resolution accurate mass spectrometer.

Determination of human insulin and its six therapeutic analogues by capillary electrophoresis - mass spectrometry

In this work, human insulin and its 6 analogues were separated and determined using CZE-MS. Three different capillaries (bare fused silica, successive multiple ionic-polymer layer (SMIL) and static linear polyacrylamide (LPA) coated) were compared based on their separation performances in their optimal operating conditions. Coated capillaries demonstrated slightly better separation of the components, although some components showed wide, distorted peaks. The highest plate number could be obtained in the SMIL capillary (192 000/m). For UV and ESI-MS detection relatively similar LOD values were obtained (0.3-1.2 mg/L and 1.0-3.4 mg/L, respectively). The application of MS detection provided useful structural information and unambiguous identification for insulins having similar or the same molecular mass. This work is considered to be important not only for the investigation of insulins but also for its potential contribution to the top-down analysis of proteins using CE-MS.

Simultaneous quantitative determination of insulin aspart and insulin degludec in human plasma using simple shoot LC method

Combining short-acting and long-acting insulin analogs was a real challenge that was overcome by NovoNordisk through the co-formulation of insulin aspart and insulin degludec in single-dosage form. The proposed study provides a simple, short, and reliable HPLC method with diode array detection that is developed and validated for the simultaneous determination of insulin aspart and insulin degludec in human plasma. The proposed method achieved good separation between the two analytes utilizing a C8 column at 35°C in a very short run time (6 min), with a simple, low-cost, and reliable extraction method through precipitation of plasma protein. Gradient elution was applied using a mobile phase consisting of 0.1 M sodium sulfate (pH 3.4) and acetonitrile. The method was validated according to EMA Guideline on Bioanalytical Validation. The proposed method had a linear range from 3.0 to 300 μg/mL for insulin aspart and from 3.5 to 300 μg/mL for insulin degludec. The intra- and inter-day precision of insulin aspart were 0.36-3.33% and 1.59-8.84%, respectively, and accuracy was between 10.06 and 3.09% The intra- and inter-day precision of insulin degludec were 0.29-1.93% and 0.89-5.14%, respectively, and accuracy was between -5.29 and 3.91%.

Combining direct urinary injection with automated filtration and nanoflow LC-MS for the confirmatory analysis of doping-relevant small peptide hormones

Nano-liquid chromatography (nanoLC) has proven itself as a powerful tool and its scope entails various applications in (bio)analytical fields. Operation at low (nL/min) flow rates in combination with reduced inner dimensions (ID < 100 µm), leads to significantly enhanced sensitivity when coupled with electrospray ionization-mass spectrometry (ESI-MS). Challenges that remain for the routine implementation of such miniaturized setups are related to clogging of the system and robustness in general, and thus the application of tedious sample preparation steps. To improve ruggedness, a filter placed upstream in the LC prevents particles from entering and clogging the system. This so-called online automatic filtration and filter back-flush (AFFL) system was combined with nanoLC and the direct injection principle for the sensitive confirmatory analysis of fifty different doping-relevant peptides in urine. The presented assay was fully validated for routine purposes according to selectivity and matrix interference, limit of identification (LOI), carryover, matrix effect, sample extract stability, analysis of educational external quality assessment (EQAS) samples, robustness of the online AFFL-setup and retention time stability. It was also fully compliant with the most recent minimum required performance levels (MRPL) and chromatographic/mass spectrometric identification criteria (IDCR), as imposed by the World Anti-Doping Agency (WADA). In the absence of labor-intensive sample preparation, the application of AFFL allowed for the injection of diluted urine samples without any noticeable pressure buildup in the nanoLC system. Contrary to earlier observations by our group and others, the addition of dimethylsulfoxide (DMSO) to the mobile phase did not enhance sensitivity in the presented nanoflow setup, yet was beneficial to reduce carry over. Although the robustness of the presented setup was evaluated only for the analysis of diluted urine samples, it is entirely conceivable that routine applications employing other matrices and currently running on analytical scale LC instruments could be transferred to micro/nanoLC scale systems to reach lower detection limits.

A comprehensive stability assessment of insulin degludec using New customized validated RP-HPLC and SEC-HPLC methods in an orthogonal testing protocol

Stress testing of biopharmaceuticals plays an important role in preparation of their stability profiles through investigation of possible degradation pathways and identification of degradation products, so in this study Insulin Degludec which is a new generation ultra-long-acting basal insulin is subjected to stress conditions as different temperatures, different pH, oxidation, mechanical agitation, and repeated freeze and thaw cycles to generate possible degradation products and aggregation that are investigated by two new validated RP-HPLC and SEC-HPLC methods in addition to dynamic light scattering (DLS) and native polyacrylamide gel electrophoresis (Nu-PAGE). SEC-HPLC was used to investigate formation of aggregates whose results were correlated with those obtained from DLS and Nu-PAGE, while RP-HPLC was used to investigate any possible chemical modifications. The Proposed RP-method had limit of detection (LOD) and limit of quantitation (LOQ) of 0.012 mg/mL and 0.045 mg/mL respectively and accuracy of 99.22 ± 1.07 %, while the SEC methods had limit of detection (LOD) and limit of quantitation (LOQ) of 0.012 mg/mL and 0.031 mg/mL, respectively. The degradation pattern due to high temperature effect and oxidation is investigated by LC- tandem mass spectrometry. Results showed that Insulin degludec is highly stable under low temperature, mechanical agitation and repeated freeze and thaw stress conditions but elevated temperature and high acidic condition lead to formation of aggregates and also chemical modifications including deamidation, isomerization and oxidation. Such different chemical degradation pathways are due to presence of variable reactive moieties in Insulin degludec structure. Insulin degludec is highly vulnerable to oxidation at the sulfur containing cysteine residue in B chain in position B7 forming trioxidation derivative when exposed to hydrogen peroxide. Formation of A21-Asp and A18-Asp deamidated variants as well as B3-Asp and B3-isoAsp deamidated variants are prominent degradation pathways at neutral pH but at elevated temperature.

Commercially Available Insulin Products Demonstrate Stability Throughout the Cold Supply Chain Across the U.S

OBJECTIVE

A recent publication questioned the integrity of insulin purchased from U.S. retail pharmacies. We sought to independently validate the method used, isotope dilution solid-phase extraction (SPE) liquid chromatography mass spectrometry (LC-MS), and expand analysis to two U.S. Pharmacopeia (USP) methods (high-performance LC with ultraviolet detection and LC-MS).

RESEARCH DESIGN AND METHODS

Each method was used to evaluate nine insulin formulations, purchased at four pharmacies, within five geographic locations in the U.S.

RESULTS

All human and analog insulins measured by the USP methods (n = 174) contained the expected quantity of active insulin (100 ± 5 units/mL). When using isotope dilution SPE-LC-MS, units-per-milliliter values were well below product labeling due to unequal recovery of the internal standard compared with target insulin.

CONCLUSIONS

Insulin purchased from U.S. pharmacies is consistent with product labeling.

Quality of medical products for diabetes management: a systematic review

Background

The global prevalence of diabetes mellitus is increasing alarmingly. However, the quality of vital medicines and medical products used to treat and monitor diabetes remains uncertain but of potential great public health significance. Here, we review the available evidence on the quality of antidiabetic medicines and supplies for self-monitoring of blood glucose (SMBG) and discuss their potential impact for the patients and society.

Methods

Searches were conducted in PubMed, Embase, Google Scholar, Google and relevant websites in English and French. The Medicine Quality Assessment Reporting Guideline (MEDQUARG) was used to assess the quality of medicine quality surveys.

Results

52 publications on the quality of antidiabetic medicines, including 5 medicine quality prevalence surveys and 20 equivalence studies, were analysed. The prevalence surveys and equivalence studies included 674 samples of which 73 (10.8%) were of poor quality. The median (Q1-Q3) concordance with MEDQUARG items was 30.8% (19.2%-42.3%). No prevalence surveys on SMBG supplies' quality were found, but 29 publications, including falsified products and incorrect results due to strip degradation or contamination, were identified.

Conclusion

There is little accessible evidence on the quality of antidiabetic medicines and SMBG supplies. Surveys were poorly designed and reported, making data aggregation and interpretation problematic. Despite these caveats, these results suggest that there are important issues with the quality of medical products for diabetes that need focused monitoring. There is an urgent need to achieve consensus protocols for designing, conducting and reporting medical product quality surveys.

PROSPERO registration number

CRD42016039841.

Identification of recombinant human insulin and biosynthetic insulin analogues by multiplexed targeted unlabeled mass spectrometry of proteotypic tryptic peptides

Direct qualitative methods that allow the rapid screening and identification of insulin products during early stages of the drug development process and those already in the market can be of great utility for manufacturers and regulatory agencies and the recent scientific literature describes several methods. Herein, a qualitative proteomic method is presented for the identification of recombinant human insulin and all marketed biosynthetic analogues -insulin lispro, aspart, glulisine, glargine, detemir and degludec- via tryptic digestion and identification of proteotypic peptides for each insulin. Individual insulins were first denatured under reducing conditions and the cysteine residues blocked by iodoacetamide. The proteins were then digested with trypsin and the peptide products separated by reversed phase liquid chromatography on an Ascentis® Express ES-C18 column and detected by positive polarity ESI-MS/MS. The digestion peptides were characterized using a multiplexed MRM approach that monitors the fragmentation of the doubly charged unlabeled precursor ion of each peptide into a collection of signature y and b ions. The MRM transitions for the individual peptides were optimized to allow maximal ionization on a standard triple quadrupole mass spectrometer. All products of the digestion procedure for all insulins were detected with adequate signal intensity except for the C-terminal B30Thr whenever it was present and cleaved and the tryptic B1-3 tripeptide of insulin glulisine. The unique proteotypic peptides identified for each of the insulin analogues coupled with their signature y and b ions permitted the unambiguous verification of all sequence variations and chemical modifications. The elution of the A polypeptide chain for all insulins and the tryptic peptides of the B chain, with the exception of a very few, occurred around the same time point. This underscores the close similarity in the physicochemical properties between the digestion peptides and is consistent with the subtle variations in amino acid sequence among the various insulins. Therefore, the identification and distinction of the different types of insulin based solely on the chromatographic retention time of their respective proteolytic products can be deceptive without proper mass spectrometric analysis and may result in false positives.