Development and validation of a liquid chromatography-tandem mass spectrometry method for topotecan determination in beagle dog plasma and its application in a bioequivalence study

Self-assembled ordered AuNRs-modified electrodes for simultaneous determination of dopamine and topotecan with improved data reproducibility

Gold nanomaterials have been widely explored in electrochemical sensors due to their high catalytic property and good stability in multi-medium. In this paper, the reproducibility of the signal among batches of gold nanorods (AuNRs)-modified electrodes was investigated to improve the data stabilization and repeatability. Ordered and random self-assembled AuNRs-modified electrodes were used as electrochemical sensors for the simultaneous determination of dopamine (DA) and topotecan (TPC), with the aim of obtaining an improved signal stability in batches of electrodes and realizing the simultaneous determination of both substances. The morphology and structure of the assemblies were analyzed and characterized by UV-Vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray powder diffraction (XRD). Electrochemical studies showed that the ordered AuNRs/ITO electrodes have excellent signal reproducibility among several individuals due to the homogeneous mass transfer in the ordered arrangement of the AuNRs. Under the optimized conditions, the simultaneous detection results of DA and TPC showed good linearity in the ranges 1.75-45 μM and 1.5-40 μM, and the detection limits of DA and TPC were 0.06 μM and 0.17 μM, respectively. The results showed that the prepared ordered AuNR/ITO electrode had high sensitivity, long-term stability, and reproducibility for the simultaneous determination of DA and TPC, and it was expected to be applicable for real sample testing.

An electrochemical sensing platform with a molecularly imprinted polymer based on chitosan-stabilized metal@metal-organic frameworks for topotecan detection

The present study aims to develop an electroanalytical method to determine one of the most significant antineoplastic agents, topotecan (TPT), using a novel and selective molecular imprinted polymer (MIP) method for the first time. The MIP was synthesized using the electropolymerization method using TPT as a template molecule and pyrrole (Pyr) as the functional monomer on a metal-organic framework decorated with chitosan-stabilized gold nanoparticles (Au-CH@MOF-5). The materials' morphological and physical characteristics were characterized using various physical techniques. The analytical characteristics of the obtained sensors were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). After all characterizations and optimizing the experimental conditions, MIP-Au-CH@MOF-5 and NIP-Au-CH@MOF-5 were evaluated on the glassy carbon electrode (GCE). MIP-Au-CH@MOF-5/GCE indicated a wide linear response of 0.4-70.0 nM and a low detection limit (LOD) of 0.298 nM. The developed sensor also showed excellent recovery in human plasma and nasal samples with recoveries of 94.41-106.16 % and 95.1-107.0 %, respectively, confirming its potential for future on-site monitoring of TPT in real samples. This methodology offers a different approach to electroanalytical procedures using MIP methods. Moreover, the high sensitivity and selectivity of the developed sensor were illustrated by the ability to recognize TPT over potentially interfering agents. Hence, it can be speculated that the fabricated MIP-Au-CH@MOF-5/GCE may be utilized in a multitude of areas, including public health and food quality.

Development and Validation of an HPLC Method for Analysis of Topotecan in Human Cerebrospinal Fluid and Its Application in Elimination Evaluation of Topotecan after Intraventricular Injection

Intrathecal administration of anticancer drugs is an effective dosage strategy, but the elimination of intraventricular drugs is not uniform in all patients. For safety, a system to evaluate local pharmacokinetics in the ventricles after administration is desired. In this study, we developed a simple and reproducible method to measure topotecan concentration in the cerebrospinal fluid (CSF) and confirmed its clinical applicability. High-performance liquid chromatography (HPLC) analysis was performed using a C18 column to measure the total topotecan concentration in the CSF. Clinical CSF samples were obtained from a 1-year old child with poor CSF absorption and stagnation. The patient received topotecan via an intraventricular subcutaneous reservoir. The HPLC method complied with the validation criteria. The lower limit of quantitation of this method was 0.04 µM. Using the developed method, we could determine the difference in topotecan CSF concentrations at 24 and 48 h after administration. The patient's topotecan elimination rate was extremely low, and signs of adverse effects were observed at high CSF concentration of topotecan. The developed method could detect the delay in topotecan elimination after intrathecal injection. The findings of this study are valuable for the development of personalized treatments for the intrathecal administration of anticancer drugs.

Pharmacokinetic Comparison of Three Different Administration Routes for Topotecan Hydrochloride in Rats

Topotecan is actively used in clinic, with its primary use being in treatment of various types of cancer. The approved administration routes are oral and intravenous. The purpose of this study was to investigate and identify pharmacokinetic profiles of different administration routes. We conducted pharmacokinetic studies on three different routes of administration in rats. Five rats in each group received a single dose of 4 mg/kg of topotecan hydrochloride intravenously, orally, or subcutaneously, and the concentrations of lactone and total forms of the drug in plasma, urine, and feces were quantified. Various pharmacokinetic parameters were compared statistically. Plasma concentrations of both the lactone and total forms at elimination phase following subcutaneous administration, were two times higher than was seen with oral administration and 10 times higher than with intravenous administration. Subcutaneous administration of topotecan showed pharmacokinetic profiles similar to sustained release. In addition, subcutaneous administration showed bioavailability from 88.05% (for lactone form) to 99.75% (for total form), and these values were four–five times greater than those of oral administration. The results of this non-clinical study will not only provide greater understanding of the in vivo pharmacokinetics of topotecan, but also be useful for development of additional formulations and/or administration routes.

A temperature-sensitive phase-change hydrogel of topotecan achieves a long-term sustained antitumor effect on retinoblastoma cells

Background

Retinoblastoma (Rb) is one of the most common malignancies among children. Following early diagnosis and prompt treatment, the clinical outcome or prognosis of Rb is promising. However, the prognosis or survival rates of patients with late-stage Rb remain poor. Current therapeutic strategies for advanced Rb mainly involve the use of advanced chemotherapeutic options. However, the efficacy of these strategies is not satisfactory. Therefore, the development of novel strategies to achieve a more effective antitumor effect on late-stage Rb is of crucial importance.

Methods and materials

Topotecan was dissolved in phosphate-buffered saline and prepared into a temperature-sensitive phase-change hydrogel (termed Topo-Gel). Moreover, Topo-Gel was injected into tumor tissues formed by Y79 cells (an Rb cell line) in nude mice to examine the long-term release and long-acting antitumor effect of Topo-Gel on Rb tumors.

Results

Topo-Gel transforms from liquid to a hydrogel at near body temperatures (phase-change temperature [T_1/2] was 37.23±0.473 °C), and maintains the slow release of topotecan in Rb tumor tissues. Following the subcutaneous injection of Topo-Gel, the treatment induced long-acting inhibition of tumor growth and relieved the adverse effects associated with topotecan. Topo-Gel, a temperature-sensitive phase-change hydrogel, is a slow-release system that prolongs the presence of topotecan in Rb tissues, and preserves the efficacy of topotecan in the long term.

Conclusion

Preparation of topotecan into a temperature-sensitive phase-change hydrogel achieves a long-term sustained antitumor effect on Rb cells, and may be a useful strategy for the treatment of intraocular Rb.

Development of a Ternary Solid Dispersion Formulation of LW6 to Improve the In Vivo Activity as a BCRP Inhibitor: Preparation and In Vitro/In Vivo Characterization

LW6 (3-[2-(4-adamantan-1-yl-phenoxy)-acetylamino]-4-hydroxy-benzoic acid methyl ester) is a potent inhibitor of drug efflux by the breast cancer resistance protein (BCRP). However, its poor aqueous solubility leads to low bioavailability, which currently limits in vivo applications. Therefore, the present study aimed to develop ternary solid dispersion (SD) formulations in order to enhance the aqueous solubility and dissolution rate of LW6. Various SDs of LW6 were prepared using a solvent evaporation method with different drug/excipient ratios. The solubility and dissolution profiles of LW6 in different SDs were examined, and F8-SD which is composed of LW6, poloxamer 407, and povidone K30 at a weight ratio of 1:5:8 was selected as the optimal SD. The structural characteristics of F8-SD were also examined using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), and scanning electron microscopy (SEM). In the acidic to neutral pH range, F8-SD achieved rapid dissolution with a drug release of 76–81% within 20 min, while the dissolution of pure LW6 was negligible. The XRPD patterns indicated that F8-SD probably enhanced the solubility and dissolution of LW6 by changing the drug crystallinity to an amorphous state, in addition to the solubilizing effect of the hydrophilic carriers. Furthermore, F8-SD significantly improved the oral bioavailability of topotecan, which is a BCRP substrate, in rats. The systemic exposure of topotecan was enhanced approximately 10-fold by the concurrent use of F8-SD. In conclusion, the ternary SD formulation of LW6 with povidone K30 and poloxamer 407 appeared to be effective at improving the dissolution and in vivo effects of LW6 as a BCRP inhibitor.

Mass spectrometry in the pharmacokinetic studies of anticancer natural products

In the history of medicine, nature has represented the main source of medical products. Indeed, the therapeutic use of plants certainly goes back to the Sumerian and Hippocrates and nowadays nature still represents the major source for new drugs discovery. Moreover, in the cancer treatment, drugs are either natural compounds or have been developed from naturally occurring parent compounds firstly isolated from plants and microbes from terrestrial and marine environment. A critical element of an anticancer drug is represented by its severe toxicities and, after administration, the drug concentrations have to remain in an appropriate range to be effective. Anyway, the drug dosage defined during the clinical studies could be inappropriate for an individual patient due to differences in drug absorption, metabolism and excretion. For this reason, personalized medicine, based on therapeutic drug monitoring (TDM), represents one of most important challenges in cancer therapy. Mass spectrometry sensitivity, specificity and fastness lead to elect this technique as the Golden Standard for pharmacokinetics and drug metabolism studies therefore for TDM. This review focuses on the mass spectrometry-based methods developed for pharmacokinetic quantification in human plasma of anticancer drugs derived from natural sources and already used in clinical practice. Particular emphasis was placed both on the pre-analytical and analytical steps, such as: sample preparation procedures, sample size required by the analysis and the limit of quantification of drugs and metabolites to give some insights on the clinical practice applicability. © 2015 Wiley Periodicals, Inc. Mass Spec Rev. 36:213-251, 2017.