1094. Determination of Plasma Protein Binding of Dalbavancin

Abstract Background Dalbavancin is a semi-synthetic glycopeptide with a long half-life, making it a promising alternative for infections requiring prolonged therapy such as complicated Staphylococcus aureus bacteremia. A critical pharmacokinetic consideration with prolonged treatment is the unbound or “free” concentration-time profile, as free antibiotic concentrations may correlate with tissue penetration and therapeutic effects better than total drug. Dalbavancin’s plasma protein binding (PB) remains poorly studied and has been reported to range between 93-99%. A reliable and validated free drug assay is needed to link dalbavancin concentrations with patient outcomes. Methods The ultracentrifugation technique was used to determine free dalbavancin concentrations in plasma at two concentrations (50 and 200 µg/mL) in duplicate. Centrifuge tubes and pipette tips were treated for 24 hours before use with Tween 80 to assess adsorption. PB centrifugation conditions: 400,000 g (106,000 RPM in TLA-120.1 rotor) for 4 hours at 37°C. Dalbavancin concentrations were analyzed from the plasma samples (total) and middle layer samples (free) by liquid chromatography – tandem mass spectrometry (LC/MS/MS) with isotopically labeled internal standard. Warfarin served as a positive control with known high protein binding. Results Measurement of free dalbavancin was sensitive to adsorption onto plastic. Treatment of tubes and pipette tips with ≥2% Tween 80 effectively prevented drug loss during PB experiments (Figure 1). Addition of 2% Tween 80 did not affect PB results of warfarin. In PB experiments with 2% Tween 80 coated tubes, the free fraction of dalbavancin was 0.96% (95% CI: 0.94-0.98) at 50 µg/mL and 1.11% (95% CI: 1.08-1.13) at 200 µg/mL. Figure 1. Percent Free Dalbavancin vs Varying Concentrations of Tween 80 for Pretreatment of Tubes Conclusion By the ultracentrifugation method, dalbavancin’s PB was estimated to be approximately 99%. Given dalbavancin’s high PB, accurate measurement of free dalbavancin concentrations should be a key consideration in future exposure-response studies, especially clinical trials. Future investigations should also determine if the active fraction is best predicted by the free or total fraction, as this remains a subject of debate. Supported by NIAID/NIH grant UM1AI104681. Content is solely the authors’ responsibility and does not represent official NIH views. Disclosures Thomas L. Holland, MD, Aridis (Consultant)Basilea Pharmaceutica (Consultant)Lysovant (Consultant) Thomas L. Holland, MD, Aridis (Individual(s) Involved: Self): Consultant; Basilea Pharmaceutica (Individual(s) Involved: Self): blinded adjudication, Consultant, Other Financial or Material Support; Genentech (Individual(s) Involved: Self): Consultant; Lysovant (Individual(s) Involved: Self): Consultant; Motif Bio (Individual(s) Involved: Self): Consultant Thomas Lodise, Jr., PharmD, PhD, Astra-Zeneca (Consultant)Bayer (Consultant)DoseMe (Consultant, Advisor or Review Panel member)ferring (Consultant)genentech (Consultant)GSK (Consultant)Melinta (Consultant)merck (Consultant, Independent Contractor)nabriva (Consultant)paratek (Consultant, Advisor or Review Panel member, Speaker’s Bureau)shionogi (Consultant, Advisor or Review Panel member, Speaker’s Bureau)Spero (Consultant)tetraphase (Consultant)Venatrox (Consultant) Thomas Lodise, Jr., PharmD, PhD, Melinta Therapeutics (Individual(s) Involved: Self): Consultant; Merck (Individual(s) Involved: Self): Consultant, Scientific Research Study Investigator; Paratek (Individual(s) Involved: Self): Consultant; Shionogi (Individual(s) Involved: Self): Consultant, Speakers’ bureau; Spero (Individual(s) Involved: Self): Consultant; Tetraphase Pharmaceuticals Inc. (Individual(s) Involved: Self): Consultant

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Effects of pronounced haemodilution on the plasma protein binding of lidocaine

Perfusion ◽

10.1177/026765919501000104 ◽

1995 ◽

Vol 10 (1) ◽

pp. 17-20 ◽

Cited By ~ 4

Author(s):

PA Lönnqvist ◽

L. Herngren

Keyword(s):

Plasma Concentration ◽

Protein Binding ◽

Plasma Protein Binding ◽

Plasma Protein ◽

Free Fraction ◽

Total Plasma ◽

Free Concentration ◽

Significant Difference ◽

Total Plasma Concentration ◽

Pharmacologically Active

The effects of pronounced haemodilution on the protein binding of lidocaine was investigated in vitro in plasma from five healthy adult volunteers. The plasma was diluted with a phosphate buffer to reach a plasma protein concentration normally seen during paediatric cardiopulmonary bypass (CPB) and protein binding was determined at a low (1.5 μg/ml) and a moderate (4 μg/ml) total plasma concentration of lidocaine. The effects of different haematocrits on plasma protein binding was also determined over the haematocrit range 20-60%. The binding of lidocaine was found to be inversely related to the degree of dilution, i.e. the free fraction increased significantly with increasing dilution (p < 0.0001). Furthermore, the binding was dependent on the total plasma concentration of lidocaine, since a significantly higher percentage of free drug was found at the higher total lidocaine level (4 μg/ml) compared with the lower level (1.5 μg/ml) (p < 0.05). No significant difference in the free fraction of lidocaine could be found over the studied haematocrit range. The results of the present study indicate that plasma protein levels commonly associated with CPB in neonates and infants are associated with a significant increase in the free, unbound and pharmacologically active fraction of lidocaine compared with normal conditions. The use of commonly recommended dosages of lidocaine might result in toxic-free concentration in this setting.

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Solid-phase microextraction for assessment of plasma protein binding, a complement to rapid equilibrium dialysis

Bioanalysis ◽

10.4155/bio-2021-0109 ◽

2021 ◽

Author(s):

Sheelan Ahmad ◽

Daniel Baker ◽

Darragh Murnane ◽

Neil Spooner ◽

Ute Gerhard

Keyword(s):

Protein Binding ◽

Plasma Protein Binding ◽

Plasma Protein ◽

Solid Phase Microextraction ◽

Solid Phase ◽

Equilibrium Dialysis ◽

Free Concentration ◽

Rapid Equilibrium

Aim: Determination of plasma protein binding ( PPB) is considered vital for better understanding of pharmacokinetic and pharmacodynamic activities of drugs due to the role of free concentration in pharmacological response. Methodology & results: Solid-phase microextraction (SPME) was investigated for measurement of PPB from biological matrices and compared with a gold standard approach (rapid equilibrium dialysis [RED]). Discussion & conclusion: SPME-derived values of PPB correlated well with literature values, and those determined by RED. Respectively, average protein binding across three concentrations by RED and SPME was 33.1 and 31.7% for metoprolol, 89.0 and 86.6% for propranolol and 99.2 and 99.0% for diclofenac. This study generates some evidence for SPME as an alternative platform for the determination of PPB.

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Faculty Opinions recommendation of Matched molecular pairs as a guide in the optimization of pharmaceutical properties; a study of aqueous solubility, plasma protein binding and oral exposure.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1046889.496914 ◽

2006 ◽

Author(s):

Michael Gelb

Keyword(s):

Protein Binding ◽

Plasma Protein Binding ◽

Plasma Protein ◽

Aqueous Solubility ◽

Oral Exposure ◽

Matched Molecular Pairs ◽

Pharmaceutical Properties

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Possible therapeutic interventions in COVID-19 induced ARDS by cotinine as an ACE-2 promoter and AT-1R blocker

Infectious Disorders - Drug Targets ◽

10.2174/1871526520666201218153554 ◽

2020 ◽

Vol 20 ◽

Author(s):

Tarun Sharma ◽

Sidharth Mehan

Keyword(s):

Protein Binding ◽

Plasma Protein Binding ◽

Plasma Protein ◽

Distress Syndrome ◽

Therapeutic Interventions ◽

Promising Candidate ◽

Angiotensin Converting Enzyme 2 ◽

Proinflammatory Effect ◽

Pulmonary Permeability

: In these challenging times of the pandemic, as coronavirus disease 2019 (COVID-19) has taken over the planet, its complications such as acute respiratory distress syndrome (ARDS) have the potential to wipe out a large portion of our population. Whereas a serious lack of ventilators, vaccine being months away makes the condition even worse. That's why promising drug therapy is required. One of them was suggested in this article. It is the angiotensin-converting enzyme-2 (ACE-2) to which the COVID-19 virus binds and upon downregulation of which the pulmonary permeability increases and results in the filling of alveoli by proteinaceous fluids, which finally results in ARDS. ARDS can be assisted by angiotensinII type-1 receptor (AT-1R) blocker and ACE-2 upregulator. AT-1R blocker will prevent vasoconstriction, the proinflammatory effect seen otherwise upon its activation. ACE-2 upregulation will ensure less formation of angiotensin II, vasodilatory effects due to the formation of angiotensin (1-7), increased breakdown of bradykinin at lung level. Overall, decreased vasoconstriction of vessels supplying lungs and decreased vasodilation of lung tissues will ensure decreased pulmonary permeability and eventually relieve ARDS. It should also be considered that all components of the reninangiotensin-aldosterone system (RAAS) are located in the lung tissues. A drug with the least plasma protein binding is required to ensure its distribution across these lung tissues. Cotinine appears to be a promising candidate for COVID-19- induced ARDS. It acts across the board and acts as both an AT-1R blocker, ACE-2 upregulator. It also has a weak plasma protein binding that helps to spread through the lung tissues. In this review, we summarized that cotinine, along with COVID-19 virus replication blocker anti-virals, may prove to be a promising therapy for the treatment of COVID-19 induced ARDS.

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Ultrafiltration Method for Plasma Protein Binding Studies and Its Limitations

Processes ◽

10.3390/pr9020382 ◽

2021 ◽

Vol 9 (2) ◽

pp. 382

Author(s):

Camelia-Maria Toma ◽

Silvia Imre ◽

Camil-Eugen Vari ◽

Daniela-Lucia Muntean ◽

Amelia Tero-Vescan

Keyword(s):

Protein Binding ◽

Plasma Protein Binding ◽

Plasma Protein ◽

Specific Binding ◽

Critical Role ◽

Volume Ratio ◽

Binding Studies ◽

Experimental Conditions ◽

Key Aspects

Plasma protein binding plays a critical role in drug therapy, being a key part in the characterization of any compound. Among other methods, this process is largely studied by ultrafiltration based on its advantages. However, the method also has some limitations that could negatively influence the experimental results. The aim of this study was to underline key aspects regarding the limitations of the ultrafiltration method, and the potential ways to overcome them. The main limitations are given by the non-specific binding of the substances, the effect of the volume ratio obtained, and the need of a rigorous control of the experimental conditions, especially pH and temperature. This review presents a variety of methods that can hypothetically reduce the limitations, and concludes that ultrafiltration remains a reliable method for the study of protein binding. However, the methodology of the study should be carefully chosen.

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