Degradation kinetics study of cabozantinib by a novel stability-indicating LC method and identification of its major degradation products by LC/TOF-MS and LC–MS/MS

Nano-Resveratrol Liposome: Physicochemical Stability, In Vitro Release, and Cytotoxicity

Nano-resveratrol liposome (RES-LIP) was prepared by the thin film rotary-evaporated method combined with ultrasonication and characterized by transmission electron microscopy (TEM), zeta potential, dynamic light scattering (DLS), and Fourier-transform infrared (FT-IR). The physicochemical stability, in vitro release, antioxidant activity, and cytotoxicity of RES-LIP were studied. Data showed that RES-LIP was a spherical vesicle with a diameter of less than 100 nm, the zeta potential was - 60 mV and the encapsulation efficiency was 86.78%. The physicochemical stability of RES-LIP was determined by Ea, ΔG, ΔH, and ΔS, which suggested that the process of RES-LIP degradation was spontaneous and endothermic. The in vitro release of RES-LIP was pH-dependent, belonged to the Weibull model, and was non-Fick diffusion. The antioxidant activity of RES-LIP was stronger than free resveratrol. The MTT assay and flow cytometry results suggested that resveratrol decreased cytotoxicity after being encapsulated by liposome. The prepared RES-LIP had high encapsulation efficiency, was sustained-release, had low cytotoxicity, was pH-targeted, and had potential usage in food and medicine fields.

Mini Review on Forced Degradation Studies on Anti-Epileptic Drugs and Beyond

In this review on the forced degradation studies on anti-epileptic drugs and the development of validated stability-indicating assay methods for drug substances and products at a condition more severe than accelerated condition (i.e. 40 ± 2°C, 75 ± 5% relative humidity), the drug substance and drug product undergo degradation is known as forced or stress degradation. To know about the impurities developed during the storage of drug products in various environmental conditions. The limit of degradation allowable is 5-20%. More than 20% of degradation is abnormal and must be investigated. Any regulatory guidelines do not mention the pH conditions for acid or base hydrolysis, the temperature for thermal degradation or the concentration of the oxidation agent. Only International Conference on Harmonization (ICH) guidelines Q1B photostability stability and states that light sources must be a combination of UV and visible light. The shortcomings of mentioned techniques with appreciation to regulatory necessities are highlighted. A systematic method for the forced degradation studies on anti-epileptic drugs such as "Topiramate, Vigabatrin, Lacosamide, Tiagabine, Levetiracetam and Zonisamide" is discussed. This review helps researchers to get an idea about stability-indicating methods of development and validation for newer antiepileptic drugs and the characteristics of drug products that degrade under specific degradation conditions.

Salmon sperm DNA binding study to cabozantinib, a tyrosine kinase inhibitor: Multi-spectroscopic and molecular docking approaches

In the current work, the binding interaction of cabozantinib with salmon sperm DNA (SS-DNA) was studied under simulated physiological conditions (pH 7.4) using fluorescence emission spectroscopy, UV-Vis absorption spectroscopy, viscosity measurement, ionic strength measurement, FT-IR spectroscopy, and molecular modeling methods. The obtained experimental data demonstrated an apparent binding interaction of cabozantinib with SS-DNA. The binding constant (K_b) of cabozantinib with SS-DNA evaluated from the Benesi-Hildebrand plot was equal to 5.79 × 10⁵ at 298 K. The entropy and enthalpy changes (∆S⁰ and ∆H⁰) in the binding interaction of SS-DNA with cabozantinib were 44.13 J mol^-1 K^-1 and -19.72 KJ mol^-1, respectively, demonstrating that the basic binding interaction forces are hydrophobic and hydrogen bonding interactions. Results from UV-Vis absorption spectroscopy, competitive binding interaction with rhodamine B or ethidium bromide, and viscosity measurements revealed that cabozantinib binds to SS-DNA via minor groove binding. The molecular docking results revealed that cabozantinib fits into the AT-rich region of the B-DNA minor groove and the binding site of cabozantinib was 4 base pairs long. Moreover, cabozantinib has eight active torsions, implying a high degree of flexibility in its structure, which played a significant role in the formation of a stable cabozantinib-DNA complex.

Cabozantinib for relapsed neuroblastoma: Single institution case series

Relapsed high-risk neuroblastoma has few effective therapies currently available or in development. Cabozantinib is an Food and Drug Administration approved multitargeted tyrosine kinase inhibitor for select adult malignancies with preclinical data suggesting efficacy against neuroblastoma. A safe and tolerable dose has been identified for children, but its efficacy remains unknown. We describe four children with relapsed metastatic neuroblastoma treated with cabozantinib. All four patients had extended disease control (two complete responsesfor >12 months, 2 stable disease >6 months) with manageable predictable toxicities requiring dose reduction in two patients. We discuss the potential for the use of cabozantinib in neuroblastoma.

Study of release kinetics and degradation thermodynamics of ferric citrate liposomes

Ferric citrate liposome (FAC-Lip) with good sustained-released property was prepared by the rotary-evaporated film-ultrasonic method, and characterized by TEM, DLS, zeta potential and encapsulation efficiency (EE%). The effects of membrane material ratios (m_PC: m_chol = 8:1, 10:1 and 12:1) and drug lipid ratios (m_FAC: m_PC = 1:4, 1:6.5 and 1:8) on the release of FAC-Lip were examined. The in vitro release kinetic models and mechanisms of FAC-Lip in artificial gastric juice (SGF) and artificial intestinal juice (SIF) compared with free-FAC were determined. The thermal degradation in PBS was also determined. The results showed that FAC-Lip with membrane material ratio (10:1) and drug lipid ratio (1:6.5) had the optimal sustained-released property, unilamellar vesicles with uniform size (178 ± 2.12 nm), negative charge (-56 ± 3.51 mV) and high encapsulation efficiency (72.77 ± 0.42%). The in vitro release kinetic models of FAC-Lip were two-phase kinetics model and the release mechanisms were non-Fick diffusion both in SGF and SIF. The thermal degradation of FAC-Lip was an endothermic and spontaneous reaction. The results may be helpful in optimizing drug-liposome design, application in food and medicine industries, and furthermore, predicting and guiding medication in vivo.

Discrimination and identification of Q-markers based on 'Spider-web' mode for quality control of traditional Chinese medicine

BACKGROUND

The safety and effectiveness of traditional Chinese medicine (TCM) in clinical practice is directly related to the quality of TCM. And, the quality control of TCM is a pivotal issue to the quality of TCM, but also an obstacle impeding the modernization of TCM.

PURPOSE

The purpose of this work is to compile and develop a strategy based on discrimination and identification of quality markers (Q-markers) for quality control of TCM.

METHODS

Mainly established by seven variables derived from four dimensions including content, stability, pharmacokinetics and pharmacology, the 'Spider-web' mode was undertaken to assess the Q-marker property of candidate compounds originated from TCM by taking regression area (A) and coefficient variation (CV) of the tested compounds into account. The importance index (ImI), ImI = A × 1/CV, was suggested to focus Q-markers.

RESULTS

The compounds with larger regression area (A) and less coefficient variation (CV) are preferentially adopted as Q-markers, which should possess the satisfactory properties of content, stability, pharmacokinetics and pharmacological activity. To the contrary, the compounds are excluded on the grounds of the unsatisfactory Q-markers' property, less regression area (A) and larger coefficient variation (CV), which cannot represent the quality of TCM.

CONCLUSIONS

The 'Spider-web' mode can filter out the redundant constituents and focus on the key indexes of quality control - Q-markers. The screened Q-markers possess the optimal integrated properties of content, stability, pharmacokinetics and pharmacology among the numerous and complicated ingredients of TCM, which can comprehensively characterize inherent quality of TCM. In summary, the novel strategy established in this work provides a valuable perspective for the quality control of TCM.

Degradation kinetics study of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) by a validated stability-indicating RP-HPLC method

The chemical stability of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG), a therapeutic agent for neutropenia, was investigated using a validated stability-indicating reversed phase high-performance liquid chromatographic (RP-HPLC) method. The forced degradation of PLAG was carried out under the stress conditions of hydrolysis (alkaline, acidic and various pH buffers), oxidation, photolysis and heat. A simple, sensitive, specific, robust, precise and accurate RP-HPLC method was developed and validated for evaluating the degradation kinetics of PLAG. The chromatographic validation of various parameters, such as system suitability, detection limit, quantification limit, linearity, accuracy, precision, specificity, robustness and stability, was achieved. The method was validated for linearity, accuracy and precision over the concentration range of 0.7813-100μg/mL (r²=0.9999). The proposed method provided excellent stability study of PLAG indicated by the resolution of degradation products from the drug. Degradation of PLAG provided first order kinetics under all experimental conditions. PLAG was catalysed more rapidly in alkaline and acidic conditions than in neutral conditions. PLAG was relatively stable in photolytic and oxidative conditions compared to hydrolysis and thermal conditions, although this drug was not also stable in these conditions. Exposed to high temperature, PLAG was more rapidly catalysed. The activation energy evaluated from the Arrhenius plot was about 110kJ/mol in the thermal conditions. Additionally, PLAG with a t_1/2 of about 400h was very stable at room temperature. Therefore, PLAG was considerably influenced by alkaline and acidic hydrolysis, and thermal degradation.

A UHPLC-UV-QTOF study on the stability of carfilzomib, a novel proteasome inhibitor

This study addresses the lack of data on the stability of carfilzomib, a newly approved proteasome-inhibiting anticancer drug. A new stability-indicating UHPLC-UV method for analysis of carfilzomib was developed and validated within the concentrations of 10-250 μg/mL. The aforementioned method was utilized to evaluate the effects of forced degradation and to investigate the degradation kinetics, as well as to examine drug stability in a pharmaceutical formulation. A UHPLC-QTOF method was utilized to identify the principal degradation products. It was found that carfilzomib: (1) is stable at neutral and slightly acidic pH, but prone to degradation at both high and low pH; (2) is acceptably stable in the pharmaceutical formulation; but (3) is prone to oxidation and photodegradation. Carfilzomib degradation followed first-order kinetics. The decomposition products resulted from peptide bond hydrolysis, epoxide hydrolysis, hydrogen chloride addition, base-catalyzed Robinson-Gabriel reaction, tertiary amine oxidation and isomerization. Our results document, for the first time, the inherent stability of carfilzomib and provide information about the identity of its degradation products. These results highlight the stability issues that need to be kept in mind for handling and storage of carfilzomib.

Chemical stability and in vitro and clinical efficacy of a novel hybrid retinoid derivative, bis-retinamido methylpentane

The anti-aging agent, retinol, has fewer side effects and similar biological activity compared to retinoic acid. However, retinol becomes unstable when exposed to light and heat. A novel hybrid retinoid derivative, bis-retinamido methylpentane (RS-2A), was newly developed to overcome the limitations. This study evaluated the chemical stability of RS-2A under thermal and light conditions by examining degradation profiles, and assessed the in vitro biological activity, cytotoxicity, and clinical efficacy. Chemical stability and degradation profiles were investigated with HPLC and LC-MS. Especially, photo-stability of RS-2A was analyzed under various conditions, such as change of physical state and concentration, different solvents, and various excipients. For analyses of cellular activity and cytotoxicity, human dermal fibroblasts were cultured with RS-2A. To evaluate the safety and efficacy of the compound with the cellular results, RS-2A was applied to women who had moderate to severe wrinkles at the periorbital region. All of the experiments were conducted with retinol as a reference. RS-2A was more stable than retinol to thermal conditions, especially in solution. Both RS-2A and retinol were unstable to light, but RS-2A showed enhanced photo-stability with regard to concentration, more polar solvent, and addition of proper excipients. RS-2A exhibited decreased cytotoxicity and enhanced effects on collagen synthesis compared with retinol. In a clinical study, a 4-week treatment with RS-2A significantly improved the appearance of periorbital wrinkles without any side effects. The results indicate that RS-2A might have potential as an anti-aging agent for cosmeceutical preparations because of its enhanced chemical stability, biological activity, safety, and clinical efficacy.

Stability and solubility of trans-resveratrol are strongly influenced by pH and temperature

Recently trans-resveratrol (trans-RSV) has received great attention due to its prophylactic and therapeutic properties. Its limited bioavailability provides compelling evidence of the need for more suitable formulations in order to attain better clinical effectiveness. Some physicochemical properties of trans-RSV are still unknown or research findings are contradictory. Therefore, this paper presents newly determined trans-RSV solubility and stability at various pH and temperatures, and the importance of such data for the studies of novel trans-RSV-loaded nanofibers. In acidic pH trans-RSV was stable, whereas its degradation started to increase exponentially above pH 6.8. Consequently, it is worthwhile to note that special consideration has to be dedicated to long dissolution testing or biological assays on cell lines in order to obtain relevant data. Measurements were done by validated UV/VIS spectroscopy, HPLC, and newly developed UPLC methods. Specificity was confirmed for HPLC and UPLC method, whereas UV/VIS spectroscopy resulted in false higher trans-RSV concentrations in conditions under which it was not stable (alkaline pH, light, increased temperature). The study is of interest because it draws attention to the importance of careful selected experimental conditions, their influence on the trans-RSV stability and the implications this has for formulation development, storage, and maintenance of therapeutic doses.

A new method to determine the new C-Met inhibitor “Cabozantinib” in dosage form and human plasma via micelle-enhanced spectrofluorimetry

A highly sensitive and simple micelle-enhanced spectrofluorimetric method was developed for the determination of cabozantinib (CBZ) in its pharmaceutical formulation and spiked human plasma without any derivatization.