Direct quantification of unencapsulated doxorubicin in liposomal doxorubicin formulations using capillary electrophoresis

An Automated Capillary Electrophoresis Based Method for Drug Release Profiling of Liposomal Doxorubicin

Liposomal doxorubicin hydrochloride is an antineoplastic agent widely used against human cancers. The data from in vitro drug release test (IVRT) is essential for quality and/or bioequivalence evaluation in drug approval and post-approval regulation of liposomal drug products. However, most of the currently available IVRT methods for liposomal doxorubicin hydrochloride have experimental deficiencies associated with liposomal rupture during the separation process which is needed for selective quantification of released drug from liposomal-bound drug. In addition, many of the methods are time consuming, requiring bulk quantities of liposomal drug product, and lack of automation. We have developed a selective, sensitive, and automated capillary electrophoresis (CE)-based IVRT method, measuring released doxorubicin without additional sampling and separation steps. This method requires a small volume of sample compared to currently available methods. The IVRT release study with liposomal doxorubicin was conducted at different temperatures and pH conditions. It was observed that the release profiles obtained for five formulations including the reference listed drug were similar at pH 6.50 and 47.0 °C. The drug release increased with the increase of media pH and temperature. Complete doxorubicin release (100 %) was obtained in 7 h at pH 6.50 and 47.0 °C, and in less than 3 h at pH 6.50 and 52.0 °C. This CE-based method can be extended for determination of the IVRT profiling of other liposomal drug products.

Liposomal doxorubicin and free doxorubicin in vivo quantitation method developed on CE-LIF and its application in pharmacokinetic analysis

As a novel drug delivery system, liposomes were used to improve pharmacokinetics/pharmacodynamics (PK/PD) characters, minimize toxicity, and enhance drug-target selectivity. However, heterogeneity of drug releasing process and liposome itself challenged traditional pharmaceutical analytical techniques, especially in vivo pharmacokinetic studies. In this study, a novel liposomal doxorubicin (L-DOX) pharmacokinetic analysis strategy was developed with capillary electrophoresis coupled with laser-induced fluorescence (CE-LIF) detector. The background electrolyte (BGE) system was composed of borate and sodium dodecyl sulfate (SDS), which was optimized to successfully achieve simultaneous online separation and quantitative analysis of free DOX and liposome-encapsulated DOX. The method was applied to the in vivo pharmacokinetic study of L-DOX in rats. The results showed that the concentration of total DOX (T-DOX) was gradually decreasing, while the concentration of L-DOX was relatively stable, with a concentration of 31.6 ± 4.8 µg/mL within 24 h. It was the first time to achieve liposomal drugs in vivo analysis with CE-LIF. CE-LIF was proved as potential rapidly real-time analytical methods for liposomal drugs in vivo occurrence monitoring.

Combining orthogonal measurements to unveil diclofenac encapsulation into polymeric and lipid nanocarriers

The quantification of the drug associated to nanoparticle carriers, often expressed in terms of encapsulation efficiency, is a regulatory requirement. The establishment of independent methods to evaluate this parameter provides a means for measurement validation, which is critical in providing confidence in the methods and enabling the robust characterization of nanomedicines. Chromatography is traditionally used to measure drug encapsulation into nanoparticles. Here, we describe an additional independent strategy based on analytical centrifugation. The encapsulation of diclofenac into nanocarriers was quantified based on the mass difference between placebo (i.e. unloaded) and loaded nanoparticles. This difference was estimated using particle densities measured by differential centrifugal sedimentation (DCS) and size and concentration values measured by particle tracking analysis (PTA). The proposed strategy was applied to two types of formulations, namely poly(lactic-co-glycolic acid) (PLGA) nanoparticles and nanostructured lipid carriers, which were analysed by DCS operated in sedimentation and flotation modes, respectively. The results were compared to those from high performance liquid chromatography (HPLC) measurements. Additionally, X-ray photoelectron spectroscopy analysis was used to elucidate the surface chemical composition of the placebo and loaded nanoparticles. The proposed approach enables the monitoring of batch-to-batch consistency and the quantification of diclofenac association to PLGA nanoparticles from 0.7 ng to 5 ng of drug per 1 μg of PLGA, with good linear correlation between DCS and HPLC results (R² = 0.975). Using the same approach, similar quantification in lipid nanocarriers was possible for a loading of diclofenac ≥1.1 ng per 1 μg of lipids, with results in agreement with the HPLC method (R² = 0.971). Hence, the strategy proposed here expands the analytical tools available for evaluating nanoparticles encapsulation efficiency, being thus significant for increasing the robustness of drug-delivery nanocarriers characterization.

Anti-Biofouling Electrochemical Sensor Based on the Binary Nanocomposite of Silica Nanochannel Array and Graphene for Doxorubicin Detection in Human Serum and Urine Samples

A disposable and portable electrochemical sensor was fabricated by integrating vertically-ordered silica mesoporous films (VMSF) and electrochemically reduced graphene (ErGO) on a screen-printed carbon electrode (SPCE). Such VMSF/ErGO/SPCEs could be prepared by a simple and controllable electrochemical method. Stable growth of VMSF on SPCE could be accomplished by the introduction of an adhesive ErGO nanolayer owing to its oxygen-containing groups and two-dimensional (2D) planar structure. An outer VMSF layer acting as a protective coating is able to prevent the leakage of the inner ErGO layer from the SPCE surface. Thanks to the electrostatic permselectivity and anti-fouling capacity of VMSF and to the good electroactive activity of ErGO, binary nanocomposites of VMSF and ErGO endow the SPCE with excellent analytical performance, which could be used to quantitatively detect doxorubicin (DOX) in biological samples (human serum and urine) with high sensitivity, good long-term stability, and low sample amounts.

Liposomes: preparation and characterization with a special focus on the application of capillary electrophoresis

Liposomes are nowadays a matter of tremendous interest. Due to their amphiphilic character, various substances with different properties can be incorporated into them and they are especially suitable as a model system for controlled transport of bioactive substances and drugs to the final destination in the body; for example, COVID-19 vaccines use liposomes as a carrier of mRNA. Liposomes mimicking composition of various biological membranes can be prepared with a proper choice of the lipids used, which proved to be important tool in the early drug development. This review deals with commonly used methods for the preparation and characterization of liposomes which is essential for their later use. The alternative capillary electrophoresis methods for physico-chemical characterization such as determination of membrane permeability of liposome, its size and charge, and encapsulation efficiency are included. Two different layouts using liposomes to yield more efficient separation of various analytes are also presented, capillary electrochromatography, and liposomal electrokinetic chromatography.

A ratiometric fluorescent strategy based on copper nanoclusters/carbon dots for sensitive detection of doxorubicin

Sensitive detection of doxorubicin (DOX) is critical for clinical theranostics. A novel ratiometric fluorescence strategy based on inner filter effect (IFE) has been established for sensitive detection of DOX by designing a ratiometric fluorescence probe. In the presence of DOX, the fluorescence intensity of copper nanoclusters (CuNCs) at 485 nm decreases, and the fluorescence intensity of carbon dots (CDs) at 560 nm increases. Therefore, DOX can be quantitatively detected by measuring the ratio of the fluorescence intensities at 560 and 485 nm (F₅₆₀ /F₄₈₅ ). The F₅₆₀ /F₄₈₅ ratio exhibits a linear correlation to the DOX concentration in the range from 1.0×10^-8 M to 1.0×10^-4 M with the detection limit of 3.7 nM. Furthermore, this method is also successfully applied to analysis of DOX in human plasma samples, affording an effective platform for drug safety management.

An analytical study of lipid-oligonucleotide aggregation properties

Lipid-oligonucleotides (LON) attract great interest as supramolecular scaffolds to improve the intracellular delivery of nucleic acids. Analytical characterization of LON assemblies is critical to formulation development, understanding in-vivo performance, as well as quality control. For this study, we selected LONs featuring different modifications on both oligonucleotide (with or without a G4 prone sequence) and lipid (mono or bis-alkyl chain covalently attached to the oligonucleotide sequence). Size exclusion chromatography (SEC) and, for the first time, capillary electrophoresis (CE) were investigated to study LON supramolecular self-assemblies. Results were correlated to those obtained with conventional physico-chemical characterization techniques i.e. gel electrophoresis, dynamic light scattering, and circular dichroism. In SEC, a separation between LON monomers and micelles was achieved in 5min on a TSK-gel G3000PW column at 70°C with 100% water, as mobile phase. CE conditions were optimized using a fused-silica capillary length of 10.0cm effective length at 15°C. Different background electrolytes were tested by varying the nature and the concentration of salts added. A sodium tetraborate buffer with 75mM NaCl appeared suitable to promote LON assembly. CE offers benefits to LON micelle analysis in terms of speed of analysis, high resolution, and low quantity of sample injected. Moreover, CE provides an appropriate tool to assess the impact of media of biological relevance on LON self-assembly. In this work, the key role of lipophilic tails and the formation of tetramolecular G-quadruplexes on the stability of LON micelles was confirmed.

A review on analytical methods with special reference to electroanalytical methods for the determination of some anticancer drugs in pharmaceutical and biological samples

It is widely accepted that cancer, the second leading cause of death, is a morbidity with big impacts on the global health. In the last few years, chemo-therapeutic treatment continually induces alone most lengthy consequents, which is extremely harmful for the physiological and psychological health of the patients. In the present research, we discuss the recent techniques for employed for extraction, and quantitative determination of such compounds in pharmaceutical, and biological specimens. In the frame of this information, this review aims to provide basic principles of chromatography, spectroscopy, and electroanalytical methods for the analysis of anticancer drugs published in the last three years. The review also describes the recent developments regarding enhancing the limit of detection (LOD), the linear dynamic range, and so forth. The results show that the LOD for the chromatographic techniques with the UV detector was obtained equaled over the range 2.0 ng mL^-1-0.2 μg mL^-1, whereas the LOD values for analysis by chromatographic technique with the mass spectrometry (MS) detector was found between 10.0 pg mL^-1-0.002 μg mL^-1. The biological fluids could be directly injected to capillary electrophoresis (CE) in cases where the medicine concentration is at the contents greater than mg L^-1 or g L^-1. Additionally, electrochemical detection of the anticancer drugs has been mainly conducted by the voltammetry techniques with diverse modified electrodes, and lower LODs were estimated between 3.0 ng mL^-1-0.3 μg mL^-1. It is safe to say that the analyses of anticancer drugs can be achieved by employing a plethora of techniques such as electroanalytical, spectroscopy, and chromatography techniques.

Sensitive analysis of doxorubicin and curcumin by micellar electromagnetic chromatography with a double wavelength excitation source

Doxorubicin has been extensively used to treat cancers, and there are recent findings that the anticancer activities can be enhanced by curcumin. Although the two compounds have native fluorescence, they can hardly be quantified directly simultaneously using the laser-induced fluorescence (LIF) detection method. To avoid complex fluorescence derivatization and introduction of interfering components, a highly sensitive double wavelength excitation source LIF (D-W-Ex-LIF) detector composed of a 445-nm and 488-nm commercial laser diode was constructed to detect them simultaneously. Rhodamine 6G was selected as an internal standard, because its fluorescence can be excited at 445 nm and 488 nm. The native fluorescence of doxorubicin and curcumin and their resolution were enhanced by introducing mixed micelles. The optimal electrophoretic separation buffer was 10 mM borate buffer containing 20 mM Triton X-100, 5 mM sodium dodecyl sulfate, and 30% (v/v) methanol at pH 9.00. Therefore, the developed method was specific, accurate, and easily operable. Its limits of detection for doxorubicin and curcumin in human urine samples were 4.00 × 10^-3 and 1.00 × 10^-2 μg/mL, respectively, and the limits of quantification were 1.00 × 10^-2 and 3.00 × 10^-2 μg/mL, respectively. The recoveries were 94.9-109.1%. Graphical abstract.

Capillary electrophoretic methods for quality control analyses of pharmaceuticals: A review

Capillary electrophoresis represents a promising technique in the field of pharmaceutical analysis. The presented review provides a summary of capillary electrophoretic methods suitable for routine quality control analyses of small molecule drugs published since 2015. In total, more than 80 discussed methods are sorted into three main sections according to the applied electroseparation modes (capillary zone electrophoresis, electrokinetic chromatography, and micellar, microemulsion, and liposome-electrokinetic chromatography) and further subsections according to the applied detection techniques (UV, capacitively coupled contactless conductivity detection, and mass spectrometry). Key parameters of the procedures are summarized in four concise tables. The presented applications cover analyses of active pharmaceutical ingredients and their related substances such as degradation products or enantiomeric impurities. The contribution of reported results to the current knowledge of separation science and general aspects of the practical applications of capillary electrophoretic methods are also discussed.

Analytical characterization of liposomes and other lipid nanoparticles for drug delivery

Lipid nanoparticles, especially liposomes and lipid/nucleic acid complexed nanoparticles have shown great success in the pharmaceutical industry. Their success is attributed to stable drug loading, extended pharmacokinetics, reduced off-target side effects, and enhanced delivery efficiency to disease targets with formidable blood-brain or plasma membrane barriers. Therefore, they offer promising formulation options for drugs limited by low therapeutic indexes in traditional dosage forms and current "undruggable" targets. Recent development of siRNA, antisense oligonucleotide, or the CRISPR complex-loaded lipid nanoparticles and liposomal vaccines also shed light on their potential in enabling versatile formulation platforms for new pharmaceutical modalities. Analytical characterization of these nanoparticles is critical to drug design, formulation development, understanding in vivo performance, as well as quality control. The multi-lipid excipients, unique core-bilayer structure, and nanoscale size all underscore their complicated critical quality attributes, including lipid species, drug encapsulation efficiency, nanoparticle characteristics, product stability, and drug release. To address these challenges and facilitate future applications of lipid nanoparticles in drug development, we summarize available analytical approaches for physicochemical characterizations of lipid nanoparticle-based pharmaceutical modalities. Furthermore, we compare advantages and challenges of different techniques, and highlight the promise of new strategies for automated high-throughput screening and future development.

Direct quantitation of free, encapsulated, total doxorubicin and doxorubicinol in stabilized frozen human plasma to support a BE study of liposomal doxorubicin

Regulatory guidance requires the quantification of encapsulated and free doxorubicin for a liposomal doxorubicin injection bioequivalence study. Due to the instability of liposome formulations in plasma samples, the release of free drug from the liposomal encapsulated doxorubicin during sample handling would result in elevation of measured free doxorubicin concentration. To prevent the potential release of free drug, stabilizer reagents and procedures were successfully developed and validated to adequately stabilize liposomal drugs in plasma samples during sample collection, storage and extraction. Three LC-MS/MS methods were developed and fully validated for direct quantitation of free, encapsulated and total doxorubicin concentrations in human plasma according to relevant regulatory guidance: Method 1: Quantitation of free doxorubicin and doxorubicinol at a linear range of 1-400 ng/mL and 0.5-10 ng/mL, respectively, from stabilizer treated plasma samples using solid phase extraction (SPE); Method 2: Quantitation of encapsulated doxorubicin at a linear range of 50-50,000 ng/mL from the stabilizer treated plasma sample using SPE followed by PPE extraction method; Method 3: Quantitation of total concentration of doxorubicin from untreated plasma samples at a linear range of 50-50,000 ng/mL using PPE. All three methods were successfully used to support a bioequivalence study between Caelyx® and Duomeisu® (Doxorubicin Hydrochloride Liposomal injection, generic doxorubicin formulation produced by CSPC). Incurred sample reanalysis (ISR) passing rate for total doxorubicin, free doxorubicin/doxorubicinol, and encapsulated doxorubicin methods were 100 %, 84.7 %/100 %, and 98.5 %, respectively. The measured total doxorubicin concentrations matched the sum of free and encapsulated doxorubicin concentrations.

Evaluation of size-based distribution of drug and excipient in amphotericin B liposomal formulation

Conventional quantitation of drug content in the liposome formulation involves the breakdown of bulk liposomes, which ignores details on the distribution of the active pharmaceutical ingredient (API) and excipients in liposomes of different sizes. The objective of this study is to develop an analytical method which can separate the liposomes into different sizes and obtain information of the drug and excipient distribution in the different sized liposomes. We developed an asymmetric flow field-flow fractionation (AF4) method for size-based separation of AmBisome, an amphotericin B liposomal formulation, and a high-performance liquid chromatography ultraviolet-visible and charged aerosol detection (HPLC-UV-CAD) method for simultaneous quantitation of the API (Amphotericin B) and the lipid excipients [1,2-Distearoyl-sn-glycero-3-phosphoglycerol (DSPG), hydrogenated soy phosphatidylcholine (HSPC), and cholesterol]. The measured drug content in the bulk liposome formulation was consistent with the drug product labeling. Liposomes were separated using AF4 into eleven size fractions and the liposomes particles sizes of each fraction were measured with nanoparticle tracking analysis. The drug to total lipid ratios in fractionated liposomes increased from 0.1 to 0.45 when the liposome size increased from 75 nm to 124 nm, while the lipid composition remained constant throughout the fractioned size range (cholesterol:DSPG, 0.7 and HSPC:DSPG, 0.3). These study results suggest that, for liposomal formulations of Amphotericin B in liposomes, the drug to lipid ratio increases with the size of the liposomes. This new analytical method provided a more in-depth characterization of liposomes, i.e., determining drug and excipient distributions in different sizes of liposomes, in a more efficient manner with more specific size-based composition information.

Innovation for Generic Drugs: Science and Research Under the Generic Drug User Fee Amendments of 2012

Regulatory science is science and research intended to improve decision making in a regulatory framework. Improvements in decision making can be in both accuracy (making better decisions) and in efficiency (making faster decisions). Science and research supported by the Generic Drug User Fee Amendments of 2012 (GDUFA) have focused on two innovative methodologies that work together to enable new approaches to development and review of generic drugs: quantitative models and advanced in vitro product characterization. Quantitative models faithfully represent current scientific understanding. They are tools pharmaceutical scientists and clinical pharmacologists use for making better and faster product development decisions. Advances in the in vitro product comparisons provide the measurements of product differences that are the critical input into the models. This paper outlines four areas where science and research funded by GDUFA support synergistic use of models and characterization at critical decision points during generic drug product development and review.