Overlapping pK a of the Multiprotic Hemostyptic Eltrombopag using UV–Vis Multiwavelength Spectroscopy and Potentiometry

Eltrombopag-Induced Falsely Elevated Bilirubin Concentrations in Enzymatic and Vanadate Oxidation Assays: Involvement of High Serum Eltrombopag Concentrations

BACKGROUND

The administration of eltrombopag, used to restore low blood count, demonstrates a positive interference of blood bilirubin levels when analyzed through the diazo assay. However, research on bilirubin measurements using other methods is limited. Therefore, using an enzymatic assay, this study aimed to investigate the effect of serum eltrombopag on bilirubin measurements in patients with aplastic anemia. It further assessed the concentration-dependent effect of eltrombopag on bilirubin measurements using enzymatic and vanadate oxidation assays.

METHODS

Total and conjugated bilirubin concentrations measured using an enzymatic assay and serum eltrombopag concentrations were examined in 227 serum samples collected from 30 patients with aplastic anemia receiving eltrombopag. Eltrombopag-spiked samples were analyzed using the enzymatic and vanadate oxidation assays for total and conjugated bilirubin to determine its concentration-dependent effects.

RESULTS

A strong positive correlation was observed between total bilirubin and serum eltrombopag concentrations in patients receiving eltrombopag (r = 0.820). However, the correlation between conjugated bilirubin and serum eltrombopag concentrations was weaker (r = 0.413). In eltrombopag-spiked serum samples, the enzymatic assay showed significant false elevation of total bilirubin concentrations at ≥6.0 mcg/mL; no interference with conjugated bilirubin measurements was observed. The vanadate oxidation assay showed mild positive biases of 0.2 and 0.1 mg/dL for total and conjugated bilirubin concentrations, respectively, at a high eltrombopag concentration (50 mcg/mL).

CONCLUSIONS

Eltrombopag causes clinically significant concentration-dependent interference in total blood bilirubin, but not in conjugated bilirubin measurements through the enzymatic assay in patients with aplastic anemia. The vanadate oxidation assay may be used as an alternative to measure total blood bilirubin when the eltrombopag concentration is below 50 mcg/mL.

Extension of impurity profiling on eltrombopag olamine to in-silico predictions: An effort to exploit correlated forced degradation products and known drug-related substances in drug discovery

The recent pandemic has highlighted the impact of diseases on global health and the economy. The rapid discovery of new hit molecules remains a tough challenge. Pharmaceutical impurity profiling can be linked to drug discovery through the identification of new hits from compounds identified during the analytical profiling. The present study demonstrates this linkage through the extension of the impurity (forced degradation) profiling of eltrombopag (ELT) olamine, a thrombopoietin (TPO) receptor agonist. The drug was exposed to standard degradation and the degradation products were primarily resolved and identified by UPLC-ESI-MS. This led to the identification of five forced degradation products (FDP). Thirty-three other known related substances (RS) of ELT, identified in the literature, were also considered. Molecular similarity checks were performed using Tanimoto/Jaccard's similarity searches. A set of structurally and topologically similar molecules, including ELT and 15 RS, was established and subjected to in-silico toxicity-, absorption-, distribution-, metabolism-, and elimination (ADME) predictions. The RS, predicted with similar or lower toxicity than ELT and a comparable ADME profile, were subjected to molecular docking to trace changes in TPO receptor affinity. The results indicated that five RS had a high Jaccard's similarity with ELT and higher or comparable docking scores. These compounds, along with few other impurities were predicted to have lower toxicity, better or comparable absorption, distribution, metabolism, and also a better excretion profile than ELT. This justifies their entry as potential novel TPO receptor agonists in drug discovery.

Quality by design-aided acid-free synthesis of self P, N, S-doped black seed-derived carbon quantum dots for application as a nanosensor for eltrombopag environmental and bioanalysis and pharmacokinetic assay

Herein, we developed a rapid, one-step, and cost-effective methodology based on the fabrication of water-soluble self-nitrogen, sulfur, and phosphorus co-doped black seed carbon quantum dots (BSQDs) via microwaveirradiation in six minutes. Our synthesis approach is superior to those in the literature as they involved long-time heating (12 h) with sulfuric acid and sodium hydroxide and/or high temperatures (200 °C). A full factorial design was applied to obtain the most efficient synthesis conditions.BSQDs displayed excitation-independent emissions, demonstrating the purity of the synthesized BSQDs, with a maximum fluorescence at 425 nm after excitation at 310 nm. Eltrombopag olamine is an anti-thrombocytopenia drug that is also reported to cause toxicity in river water based on its Persistence, Bioaccumulation, and Toxicity (PBT). The synthesized BSQDs were employed as the first fluorometric sensor for environmental and bioanalysis of eltrombopag. The fluorescence of BSQDs decreased with increasing concentrations of eltrombopag, with excellent selectivity and sensitivity down to 30 ppb. BSQDs were successfully applied as sensing probes for the detection of eltrombopag in medical tablets, spiked and real human plasma samples, and river water samples, with an overall recovery of at least 97 %. The good tolerance to high levels of foreign components and co-administered drugs indicates good selectivity and versatility of the proposed methodology. Plasma pharmacokinetic parameters such as t1/2, Cmax, and t max of eltrombopag were evaluated to be 9.91 h, 16.0 μg mL-1, and 5 h, respectively. Moreover, the green character of the BSQDs as a sensor was proved by various analytical greenness scales.

Comprehensive characterization and resolution of discrepant spectrophotometric bilirubin results in patients on eltrombopag therapy

Background

Eltrombopag is a thrombopoietin receptor agonist used for the treatment of thrombocytopenic conditions. It can cause pH-dependent discoloration of plasma/serum. Eltrombopag is potentially hepatotoxic. It can affect the assessment of hyperbilirubinemia because of its (i) absorbance at ~450 nm (bilirubin), (ii) absorbance at ~550 nm (diazo-bilirubin) and (iii) it can cause yellowish discoloration of the eyes at normal circulating bilirubin levels.

Methods

We collected 66 samples from patients on a range of eltrombopag dosages up to 150 mg daily. Bilirubin was measured using multiple routine spectrophotometric analyzers, the Doumas reference method and high-performance liquid chromatography (HPLC). Plasma/serum eltrombopag concentrations were determined using liquid chromatography tandem mass spectrometry (LC-MS/MS). Spike-in and admixture experiments delineated the effects of eltrombopag and its metabolites.

Results

Forty-nine of 52 samples from patients on ≥50 mg daily eltrombopag therapy showed significantly discrepant inter-analyzer total bilirubin results, a difference up to 64 μmol/L (3.7 mg/dL). In one sample, total bilirubin varied from 8 to 65 μmol/L (0.4–3.8 mg/dL) by different routine analyzers, with direct bilirubin ≤4 μmol/L (0.2 mg/dL). There was a positive correlation between total bilirubin difference and plasma eltrombopag concentration (r = 0.679), and spike-in experiments demonstrated that Beckman AU and Doumas reference methods were susceptible to positive interference. HPLC can quantify bilirubin after separating eltrombopag, and results suggest different analyzers are affected to varying degrees by eltrombopag and its metabolites.

Conclusions

Eltrombopag and its metabolites can cause positive interference to the spectrophotometric measurements of total bilirubin. Accurate measurements of total bilirubin may improve our understanding of the prevalence of hyperbilirubinemia in patients on eltrombopag therapy.

Phytate–molybdate(vi) interactions in NaCl(aq)at different ionic strengths: unusual behaviour of the protonated species

Stepwise stability constants of phytate/molybdate(vi) complexes regularly increase with the number of protons in the species, affecting their speciation and sequestration.