Simultaneous quantitation of polymyxin B1, polymyxin B2 and polymyxin B1-1 in human plasma and treated human urine using solid phase extraction and liquid chromatography–tandem mass spectrometry

Condensation methodology for quantification of Polymyxin B fluorimetrically: application to pharmaceutical formulations and greenness assessment

The appearance of multidrug-resistant Gram-negative bacterial infections, along with the lack of newly discovered antibiotics, resulted in the return to old antimicrobial medications like Polymyxins. As a result, the suggested technique aims to develop a fast, environmentally friendly, and sensitive fluorimetric method for quantifying Polymyxin B. The investigated approach depends on generating a highly fluorescent derivative by a condensation pathway between the studied drug and ninhydrin in the presence of phenylacetaldehyde and then estimated spectrofluorimetrically. After the reaction conditions were well optimized, the fluorescent product was estimated at emission wavelength (λem) = 475.5 nm (following excitation at a wavelength (λex) = 386 nm. The developed calibration plot displayed rectilinear throughout the following range (0.2-3 µg mL- 1), and the calculated limit of detection and quantification were 0.062 µg mL- 1 and 0.187 µg mL- 1, respectively. As a consequence, the drug's ophthalmic and intravenous pharmaceutical forms were both successfully quantified with an excellent degree of recovery. Finally, the methodology's greenness was assessed utilizing Analytical Eco-Scale scores.

Molecular Weights of Polyethyleneimine-Dependent Physicochemical Tuning of Gold Nanoparticles and FRET-Based Turn-On Sensing of Polymyxin B

Environmental monitoring and the detection of antibiotic contaminants require expensive and time-consuming techniques. To overcome these challenges, gold nanoparticle-mediated fluorometric "turn-on" detection of Polymyxin B (PMB) in an aqueous medium was undertaken. The molecular weight of polyethyleneimine (PEI)-dependent physicochemical tuning of gold nanoparticles (PEI@AuNPs) was achieved and employed for the same. The three variable molecular weights of branched polyethyleneimine (MW 750, 60, and 1.3 kDa) molecules controlled the nano-geometry of the gold nanoparticles along with enhanced stabilization at room temperature. The synthesized gold nanoparticles were characterized through various advanced techniques. The results revealed that polyethyleneimine-stabilized gold nanoparticles (PEI@AuNP-1-3) were 4.5, 7.0, and 52.5 nm in size with spherical shapes, and the zeta potential values were 29.9, 22.5, and 16.6 mV, respectively. Accordingly, the PEI@AuNPs probes demonstrated high sensitivity and selectivity, with a linear relationship curve over a concentration range of 1-6 μM for polymyxin B. The limit of detection (LOD) was calculated as 8.5 nM. This is the first unique report of gold nanoparticle nano-geometry-dependent FRET-based turn-on detection of PMB in an aqueous medium. We believe that this approach would offer a complementary strategy for the development of a highly sophisticated and advanced sensing system for PMB and act as a template for the development of new nanomaterial-based engineered sensors for rapid antibiotic detection in environmental as well as biological samples.

Polymyxin B complexation enhances the antimicrobial potential of graphene oxide

Introduction

The antibacterial activity of graphene oxide (GO) has been widely explored and tested against various pathogenic bacterial strains. Although antimicrobial activity of GO against planktonic bacterial cells was demonstrated, its bacteriostatic and bactericidal effect alone is not sufficient to damage sedentary and well protected bacterial cells inside biofilms. Thus, to be utilized as an effective antibacterial agent, it is necessary to improve the antibacterial activity of GO either by integration with other nanomaterials or by attachment of antimicrobial agents. In this study, antimicrobial peptide polymyxin B (PMB) was adsorbed onto the surface of pristine GO and GO functionalized with triethylene glycol.

Methods

The antibacterial effects of the resulting materials were examined by evaluating minimum inhibitory concentration, minimum bactericidal concentration, time kill assay, live/dead viability staining and scanning electron microscopy.

Results and discussion

PMB adsorption significantly enhanced the bacteriostatic and bactericidal activity of GO against both planktonic cells and bacterial cells in biofilms. Furthermore, the coatings of PMB-adsorbed GO applied to catheter tubes strongly mitigated biofilm formation, by preventing bacterial adhesion and killing the bacterial cells that managed to attach. The presented results suggest that antibacterial peptide absorption can significantly enhance the antibacterial activity of GO and the resulting material can be effectively used not only against planktonic bacteria but also against infectious biofilms.

Population pharmacokinetic analysis and dosing optimization of polymyxin B in critically ill patients

Objectives: Since the global broadcast of multidrug-resistant gram-negative bacteria is accelerating, the use of Polymyxin B is sharply increasing, especially in critically ill patients. Unsatisfactory therapeutic effects were obtained because of the abnormal physiological function in critically ill patients. Therefore, the determination of optimal polymyxin B dosage becomes highly urgent. This study aimed to illustrate the polymyxin B pharmacokinetic characteristics by defining the influencing factors and optimizing the dosing regimens to achieve clinical effectiveness.

Methods: Steady-state concentrations of polymyxin B from twenty-two critically ill patients were detected by a verified liquid chromatography-tandem mass spectrometry approach. The information on age, weight, serum creatinine, albumin levels, and Acute Physiology and Chronic Health Evaluation-II (APACHE-II) score was also collected. The population PK parameters were calculated by the non-parametric adaptive grid method in Pmetrics software, and the pharmacokinetic/pharmacodynamics target attainment rate was determined by the Monte Carlo simulation method.

Results: The central clearance and apparent volume of distribution for polymyxin B were lower in critically ill patients (1.24 ± 0.38 L h-1 and 16.64 ± 12.74 L, respectively). Moreover, albumin (ALB) levels can be used to explain the variability in clearance, and age can be used to describe the variability in the apparent volume of distribution. For maintaining clinical effectiveness and lowering toxicity, 75 mg q12 h is the recommended dosing regimen for most patients suffering from severe infections.

Conclusion: This study has clearly defined that in critically ill patients, age and ALB levels are potentially important factors for the PK parameters of polymyxin B. Since older critically ill patients tend to have lower ALB levels, so higher dosages of polymyxin B are necessary for efficacy.

Ratiometric detection of polymyxin B based on the disaggregation of pyrenyl nanoassemblies in 100% aqueous media

Polymyxin B (PMB) was an antibiotic with highly effective antibacterial effect but narrow safety interval, and its residues in food had attracted widespread attention. It was important to develop an accurate method for the rapid detection of PMB in animal foods. In this work, we had established a ratiometric sensing system based on the formation of supramolecular assemblies of pyrenyl probes, which were driven by the synergy of noncovalent forces such as multiple-electrostatic and π-π stacking interactions. Compared with the traditional fluorescence detection based on the single wavelength change, the present approach showing two-wavelength fluorescence response could reduce the interference of other factors making the experimental results more accurate. The sensor exhibited high sensitivity and selectivity with a low detection limit (28.3 nM). This method could be used to realize visual detection and had a visual detection limit of 1 μM. As we had learned yet, this was the first ratiometric sensor for PMB detection in aqueous solution. We believed all our preliminary would not only provide a complementary strategy for the detection of PMB, but also develop some new ideas for the construction of sensors for rapid antibiotic detection.

The Determination of Polymyxin B in Critically Ill Patients by the HPLC-MS/MS Method

Polymyxin B (PB) is a dose-dependent drug used to treat multidrug-resistantgram-negative bacteria, for which a suitable method is needed to determine clinical samples. A simple, economical, and efficient high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS) method was developed and validated for polymyxin B1 (PB1), polymyxin B1-Ile (PB1-I), polymyxin B2 (PB2), and polymyxin B3 (PB3) in human plasma. Chromatographic column was Waters BEH C18 column (2.1 × 50 mm, 1.7 μm). Phase A was water with 0.2% formic acid (FA), and phase B was acetonitrile containing 0.2% FA. The elution method is gradient elutio. The total analysis time was 5 min. The pretreatment method involved protein precipitation using acetonitrile containing 0.2% trifluoroacetic acid and 0.1% FA as the precipitant. The recovery rate was 92-99%. The total quantity of PB1 and PB1-I was measured in the linear range of 100-8000 ng/mL. Simultaneously, the total amounts of PB2 and PB3 were measured in the linear range of 11.9-948.5 ng/mL. This validated method was successfully applied to the pharmacokinetics of PB in critically ill patients.

Enhancement of sensitivity and quantification quality in the LC-MS/MS measurement of large biomolecules with sum of MRM (SMRM)

Liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS) provides a simple and efficient means for the measurement of analytes in biological matrices with high selectivity and specificity. LC-MS/MS plays an important role in the pharmaceutical industry and biomedical research, but it requires analytes to be in an ionized form in order to be detected. This can pose a challenge for large molecules such as proteins and peptides, because they can exist in multiple charged forms, and this will reduce the total analyte signal by distributing it into multiple ion peaks with a different number of charges in a mass spectrum. In conventional LC-MS/MS analysis of such macromolecules, one charged form is selected as the precursor ion which is then fragmented by collision-induced dissociation (CID) in MS/MS to generate product ions, a process referred to as multiple-reaction monitoring (MRM). The MRM method minimizes interference from endogenous molecules within biological matrices that share the same molecular weight of the precursor ion, but at the expense of signal intensity as compared to precursor ion intensity. We describe here an approach to boost detection sensitivity and expand dynamic range in the quantitation of large molecules while maintaining analytical specificity using summation of MRM (SMRM) transitions and LC separation technique. Protein image from PDB-101 (PDB101.rscb.org).

A Simple and Robust Liquid Chromatography With Tandem Mass Spectrometry Analytical Method for Therapeutic Drug Monitoring of Plasma and Cerebrospinal Fluid Polymyxin B1 and B2

BACKGROUND

Polymyxin B is used as the last treatment resort for multidrug-resistant gram-negative bacterial infections. This study aimed to develop and validate a simple and robust liquid chromatography with tandem mass spectrometry analytical method for therapeutic drug monitoring of plasma and cerebrospinal fluid (CSF) polymyxin B1 and B2.

METHODS

Plasma and CSF polymyxin B1 and B2 were chromatographically separated on a Thermo Hypersil GOLD aQ C18 column and detected using electrospray ionization mode coupled with multiple reaction monitoring. Blood and CSF samples for pharmacokinetic analysis were collected from 15 polymyxin B-treated patients.

RESULTS

The calibration curve showed acceptable linearity over 0.2-10 mcg/mL for polymyxin B1 and 0.05-2.5 mcg/mL for B2 in the plasma and CSF, respectively. After validation, according to the Food and Drug Administration (FDA) method validation guideline, this method was applied for polymyxin B1 and B2 quantification in over 100 samples in a clinical study.

CONCLUSIONS

A simple and robust method to measure polymyxin B1 and B2 in human CSF was first exploited and validated with good sensitivity and specificity, and successfully applied in polymyxin B pharmacokinetic analysis and therapeutic monitoring in Chinese patients.

Population pharmacokinetic and optimization of polymyxin B dosing in adult patients with various renal functions

AIMS

Current FDA-approved label recommends that the dosage of polymyxin B should be adjusted according to renal function. However, the correlation between polymyxin B pharmacokinetics (PK) and creatinine clearance (CrCL) is poor. This study aimed to develop a population PK model of polymyxin B in adult patients with various renal functions and to identify a dosing strategy.

METHODS

A retrospective PK study was performed in 32 adult patients with various renal function. Nonlinear mixed effects modelling was applied to build a population PK model of polymyxin B followed by Monte Carlo simulations which designed polymyxin B dosing regimens across various renal function.

RESULTS

Polymyxin B PK analyses included 112 polymyxin B concentrations at steady state from 32 adult patients, in which 71.9% of them were critically ill. In the final PK model, CrCL was the significant covariate on CL (typical value 1.59 L/h; between-subject variability 13%). The mean (SD) individual empirical Bayesian estimate of CL was 1.75 (0.43) L/h. In addition, a new dosing strategy combining the PK/pharmacodynamic (PD) targets and Monte Carlo simulation indicated that the reduction of polymyxin B dose in patients with renal insufficiency improved the probability of achieving optimal exposure. For severe infections caused by organisms with minimum inhibitory concentration (MIC) ≥ 2 mg/L, a high daily dose of polymyxin B might be possible for bacterial eradication, but the risk of nephrotoxicity is increased.

CONCLUSIONS

Renal function plays a significant role in polymyxin B PK, and the dose of polymyxin B should be adjusted according to CrCL in patients with renal insufficiency.

TDM-guided medication of polymyxin B in a patient with CRKP-induced bloodstream infection: a case report

The narrow therapeutic window of polymyxin B constrains its clinical use against the multidrug-resistant organisms (MDRO). A 45-year-old patient was suffering with bloodstream infection with high fever and received a combined treatment with polymyxin B and tigecycline. Therapeutic drug monitoring (TDM) was applied to polymyxin B to develop a personalized medication against MDRO. The dose adjustment of polymyxin B with TDM successfully alleviated the infection and reduced the incident of acute kidney injury as caused in case of the original doses of polymyxin B. TDM of polymyxin B represents a valid treatment to ensure the efficiency and safety.

Therapeutic drug monitoring of polymyxin B by LC-MS/MS in plasma and urine

Background: A robust and rapid method for therapeutic drug monitoring (TDM) is urgently needed for polymyxin B, which is a last-line antibiotic for multidrug-resistant gram-negative bacteria infection. Methodology: A 3-min run of LC-MS/MS method was established to determine the main components of polymyxin B (polymyxin B1 and B2) in human plasma or urine. Solid-phase extraction was employed to eliminate the matrix effect from complicated samples from patients. Results: The calibration range was 0.050-5.00 and 0.0110-0.549 μg/ml for polymyxin B1 and B2, respectively, in plasma and urine. The precision and accuracy of quality controls, matrix effect, extraction recovery and stability were all validated and satisfied with the ICH requirements. The method was successfully applied to a pharmacokinetic study in healthy subjects and TDM in patients. Conclusion: The rapid LC-MS/MS method was validated for polymyxin B in plasma and urine, and robust for TDM.

A Review of the Clinical Pharmacokinetics of Polymyxin B

Polymyxin B remains an antibiotic of last resort because of its toxicities. Although newer therapies are becoming available, it is anticipated that resistance to these agents will continue to emerge, and understanding the safest and most efficacious manner to deliver polymyxin B will remain highly important. Recent data have demonstrated that polymyxin B may be less nephrotoxic than colistin. Pharmacokinetically, polymyxin B is primarily eliminated via non-renal pathways, and most do not recommend adjusting the dose for renal impairment. However, some recent studies suggest a weak relationship between polymyxin B clearance and patient creatinine clearance. This review article will describe the clinical pharmacokinetics of polymyxin B and address relevant issues in chemistry and assays available.

Comparison of the composition and in vitro activity of polymyxin B products

A number of companies manufacture polymyxin B using United States Pharmacopeia (USP) metrics, rather than chemical composition, to report biological activity. Given that polymyxin B contains several different components, it is unknown whether pharmacokinetic and pharmacodynamic variability exists between the different brands and whether USP metrics capture this variability. Here we investigated the composition of polymyxin B obtained from four manufacturers (Sigma-Aldrich, AK Scientific, USP and MP Biomedicals) and evaluated their rate and extent of killing against multidrug-resistant Acinetobacter baumannii and Klebsiella pneumoniae using in vitro static time-kill experiments. Ultraviolet (UV) fingerprinting and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis revealed similarities and differences between component distributions. The significant differences between products, based on UV fingerprinting and LC-MS/MS, did not translate into pharmacodynamic differences at the three concentrations evaluated. The aggregate polymyxin B concentration, rather than that of the individual components, influences overall bacterial killing.

A Rapid and Semi-Quantitative Gold Nanoparticles Based Strip Sensor for Polymyxin B Sulfate Residues

Increasing attention is now being directed to the utilization of polymyxin B (PMB) as a last-line treatment for life-threatening infections caused by multidrug resistant Gram-negative bacteria. Unfortunately, polymyxins resistance is also increasingly reported, leaving a serious threat to human health. Therefore, the establishment of rapid detection methods for PMB residues is highly essential to ensure public health. In this study, two monoclonal antibodies (mAb; 2A2 and 3C6) were obtained using PMB-bovine serum albumin as the immunogen and PMB-ovalbumin as the coating antigen, which were prepared with N-(γ-maleimidobutyryloxy) succinimide ester and glutaraldehyde as cross-linking agents, respectively. Through an indirect competitive enzyme-linked immunosorbent assay, resultant two mAbs were compared and the results indicated that 3C6 showed higher sensitivity with a half maximum inhibition concentration of 13.13 ng/mL. Based on 3C6, a gold nanoparticles (AuNPs)-based immunochromatographic test (ICT) strip was then established, the mechanism of which is that free PMB competes with the fixed coating antigen to combine with mAb labeled by AuNPs. Using ICT strip to detect milk and animal feed samples revealed the visible detection limits were 25 ng/mL and 500 μg/kg, respectively and the cutoff limits were 100 ng/mL and 1000 μg/kg, respectively. The ICT strip provides results within 15 min, facilitating rapid and semi-quantitative analysis of PMB residues in milk and animal feed.