Development and validation of a sensitive LC-MS/MS method with electrospray ionization for quantitation of rhein in human plasma: application to a pharmacokinetic study

RP-HPLC METHOD DEVELOPMENT, VALIDATION, AND ITS PHARMACOKINETIC APPLICABILITY IN PRECLINICAL EVALUATION OF RHEIN TREATED WITH NOVEL DIACEREIN EUTECTICS

The current study represents the bio-analytical method for the estimation of Rhein (Rh, an active metabolite of Diacerein (DIA)) in rats treated with novel DIA eutectics to investigate the pharmacokinetics of DIA. A simple protein precipitation technique was used to extract Rh and internal standard (IS), p-aminobenzoic acid, and injected into a Phenomenex Gemini C18 column. The separation was achieved by gradient elution comprising of ammonium acetate (10 mM; pH 3.0) and acetonitrile in 18 min of run time at a flow rate of 0.8 mL/min with the retention time of 11.8 min (Rh) and 5.9 min (IS). The results revealed that the proposed method was linear over the range of 200-20,000 ng/mL (r² > 0.9988) of Rh and proved to be precise and accurate. The method was fully validated as per the USFDA guideline and the pharmacokinetic study in rats was performed for Rh following oral administration of the pure DIA and newly developed eutectics. Therefore, the present method could be used to estimate DIA to illustrate the comparative pharmacokinetic analysis. This can be also applied to its related multi-component formulations for future study.

Basal pharmacokinetic parameters of topically applied diacerein in pediatric patients with generalized severe epidermolysis bullosa simplex

Abstract

Generalized severe epidermolysis bullosa simplex (EBS-gen sev) is caused by mutations within either the KRT5 or KRT14 gene, phenotypically resulting in blistering and wounding of the skin and mucous membranes after minor mechanical friction. In a clinical phase 2/3 trial, diacerein has recently been shown to significantly reduce blister numbers upon topical application. In this study we addressed basic pharmacokinetic parameters of locally applied diacerein in vitro and in vivo.

Ex vivo experiments using a Franz diffusion cell confirmed the uptake and bio-transformation of diacerein to rhein in a porcine skin model. Rhein, the active metabolite of diacerein, was also detected in both urine and serum samples of two EBS-gen sev patients who topically applied a 1% diacerein ointment over a period of 4 weeks. The accumulated systemic levels of rhein in EBS-gen sev patients were lower than reported levels after oral application.

These preliminary findings point towards the uptake and prolonged persistance of diacerein / rhein within the intended target organ - the skin. Further, they imply an acceptable safety profile at the systemic level.

Trial registration

DRKS. DRKS00005412. Registered 6 November 2013.

Quantum dot-based lateral-flow immunoassay for rapid detection of rhein using specific egg yolk antibodies

The lateral-flow immunoassays based on novel fluorescent labels have been receiving increasing attention. Here, we developed a rapid, quantitative, lateral-flow immunoassay for rapid and accurate detection of rhein (RHE). The competitive immunoassay used anti-RHE IgY (immunoglobulin of yolk) probe conjugated with QDs as reporter. Our results showed that the immunochromatographic strip can be applied for qualitative and quantitative analysis of RHE in samples. For quantitative analysis, the strips were scanned by a membrane-strip reader, and a detection curve (y = -0.128ln(x) + 1.7627, correlation coefficient = 0.9792) representing the averages of the scanned data was obtained. The detection range was 80-5000 ng mL^-1 and the qualitative-detection limit for RHE was 98.2 ng mL^-1. To our knowledge, this is the first report of the quantitative detection of a natural product by QDs-IgY immunochromatography, which creates a new strategy to detect the harmful or index component of TCM and may be applied as a supplement or alternative to instrument detection.

Rhein: A Review of Pharmacological Activities

Rhein (4, 5-dihydroxyanthraquinone-2-carboxylic acid) is a lipophilic anthraquinone extensively found in medicinal herbs, such as Rheum palmatum L., Cassia tora L., Polygonum multiflorum Thunb., and Aloe barbadensis Miller, which have been used medicinally in China for more than 1,000 years. Its biological activities related to human health are being explored actively. Emerging evidence suggests that rhein has many pharmacological effects, including hepatoprotective, nephroprotective, anti-inflammatory, antioxidant, anticancer, and antimicrobial activities. The present review provides a comprehensive summary and analysis of the pharmacological properties of rhein, supporting the potential uses of rhein as a medicinal agent.

Determination of bioactive components in Chinese herbal formulae and pharmacokinetics of rhein in rats by UPLC-MS/MS

Rhein (4,5-dihydroxy-9,10-dioxoanthracene-2-carboxylic acid, cassic acid) is a pharmacological active component found in Rheum palmatum L. the major herb of San-Huang-Xie-Xin-Tang (SHXXT), a medicinal herbal product used as a remedy for constipation. Here we have determined multiple bioactive components in SHXXT and investigated the comparative pharmacokinetics of rhein in rats. A sensitive and specific method combining liquid chromatography with electrospray ionization tandem mass spectrometry has been developed and validated to simultaneously quantify six active compounds in the pharmaceutical herbal product SHXXT to further study their pharmacokinetics in rats. Multiple reaction monitoring (MRM) was employed for quantification with switching electrospray ion source polarity between positive and negative modes in a single run. There were no significant matrix effects in the quantitative analysis and the mean recovery for rhein in rat plasma was 91.6%±3.4%. The pharmacokinetic data of rhein demonstrate that the herbal formulae or the single herbal extract provide significantly higher absorption rate than the pure compound. This phenomenon suggests that the other herbal ingredients of SHXXT and rhubarb extract significantly enhance the absorption of rhein in rats. In conclusion, the herbal formulae (SHXXT) are more efficient than the single herb (rhubarb) or the pure compound (rhein) in rhein absorption.

Recent developments in the field of the determination of constituents of TCMs in body fluids of animals and human

Although traditional Chinese medicines (TCMs) play important role in drug discovery and human health, the actual value of TCMs has not been fully recognized worldwide due to its complex components and uncontrollable quality. For the modernization and globalization of TCMs, it is important to establish selective, sensitive and feasible analytical methods for determination and quantification of bioactive components of TCMs in body fluids primarily due to the low concentration, the complex nature of the biological matrices, and multi-components and their metabolites present in biological fluids. The present review summarizes the current extraction techniques, chromatographic separation and spectroscopic (especially mass spectrometric) analysis methods and new trends on the analysis of bioactive components and metabolites of TCMs in biological fluids. In addition, the importance of establishment of pharmacokinetics and bioavailability profiles and simultaneous determination of multi-active components in TCMs is discussed to provide proper examples of analytical methods for pharmacological and clinical studies of TCMs.

Simultaneous Determination of Celecoxib, Erlotinib, and its Metabolite Desmethyl-Erlotinib (OSI-420) in Rat Plasma by Liquid chromatography/Tandem Mass Spectrometry with Positive/Negative Ion-Switching Electrospray Ionisation

A new method for the simultaneous determination of celecoxib, erlotinib, and its active metabolite desmethyl-erlotinib (OSI-420) in rat plasma, by liquid chromatography/tandem mass spectrometry with positive/negative ion-switching electrospray ionization mode, was developed and validated. Protein precipitation with methanol was selected as the method for preparing the samples. The analytes were separated on a reverse-phase C₁₈ column (50mm×4.6mm i.d., 3μ) using methanol: 2 mM ammonium acetate buffer, and pH 4.0 as the mobile phase at a flow rate 0.8 mL/min. Sitagliptin and Efervirenz were used as the internal standards for quantification. The determination was carried out on a Theremo Finnigan Quantam ultra triple-quadrupole mass spectrometer, operated in selected reaction monitoring (SRM) mode using the following transitions monitored simultaneously: positive m/z 394.5→278.1 for erlotinib, m/z 380.3→278.1 for desmethyl erlotinib (OSI-420), and negative m/z −380.1→ −316.3 for celecoxib. The limits of quantification (LOQs) were 1.5 ng/mL for Celecoxib, erlotinib, and OSI-420. Within- and between-day accuracy and precision of the validated method were within the acceptable limits of < 15% at all concentrations. The quantitation method was successfully applied for the simultaneous estimation of celecoxib, erlotinib, and desmethyl erlotinib in a pharmacokinetic study in Wistar rats.

An in vivo analysis of the therapeutic and synergistic properties of Chinese medicinal formula Yin-Chen-Hao-Tang based on its active constituents

6,7-Dimethylesculetin (D), geniposide (G) and rhein (R) are the three major active ingredients of Yin-Chen-Hao-Tang (YCHT), a famous Chinese herbal formula, which has been shown to be clinically effective for treating hepatic injury (HI) syndrome. The present study was conducted to investigate the therapeutic and synergistic effects of COC (combination of D, G and R) on HI rats by combining pharmacokinetic with biochemical analysis strategy. Plasma was analyzed by using reversed-phase high performance liquid chromatography (RP-HPLC). Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) models were built to evaluate the therapeutic and synergistic effects of COC at the biochemical level. Here, we report that the COC combination could increase the plasma level, slow elimination rate, exert a more robust therapeutic effect than any one or two of the three individual compounds by hitting multiple targets in a rat model of HI. Overall, this beneficially accounts for the popular view that traditional Chinese medicine (TCM) formula usually takes multi-component to exert their therapeutic effects. We suggest that dissecting the mode of action of clinically effective formula to be capable of producing a sufficient effect at low doses.

Visible spectrophotometric estimation of diacerein in bulk and pharmaceutical dosage forms

Two simple, sensitive, accurate, rapid, and economical spectrophotometric methods have been developed for the estimation of diacerein in Pharmaceutical dosage forms. Method A is based on the reaction of diacerein with Folin-Ciocalteu reagent, in the presence of 0.5 N sodium hydroxide solution, giving a pink-colored chromogen, which shows maximum absorbance at 512 nm against reagent blank, while method B is based on the oxidation of diacerein with potassium permanganate in an alkaline medium giving a pink-colored chromogen, which shows maximum absorption at 497.5 nm. Beer’s law was obeyed in the concentration range of 4 – 20 µg/ml for both methods A and B. Results of the analysis were validated statistically, and by recovery studies.

Torcetrapib for animal and human pharmacokinetic studies: applicability of chiral and achiral methodologies

The emergence of bioanalysis as a key tool in the drug-discovery and -development process has enabled the development of sensitive, precise and specific bioanalytical methods in recent years. These methods have enabled the progress of novel chemical entities through the life cycle of drug discovery and development. The focus of this review article is on a well-known cholesteryl ester transfer protein (CETP) inhibitor known as torcetrapib. Although torcetrapib was withdrawn from clinical development, it is important to understand the various bioanalytical methodologies (chiral and achiral) that are readily available for the pharmacokinetic/pharmacodynamic characterization of the drug. Additionally, these methodologies may be applicable to the bioanalysis of the next-generation CETP inhibitors. This review covers the development and validation of assay methods that were used to obtain preclinical and clinical pharmacokinetic parameters of torcetrapib. Accordingly, methods are available for the determination of torcetrapib in various species, namely dogs, hamsters, rats, mice, monkeys and humans. Since torcetrapib is a chiral compound, methods have been developed for stereoselective bioanalysis to evaluate in vivo chiral inversion phenomena. Interestingly, torcetrapib can be analyzed by various bioanalytical options (e.g., HPLC–UV, LC–MS, LC–MS/MS and GC–MS assays) depending on the type of species under consideration with the associated sensitivity requirements. This review covers all the available methodologies for torcetrapib, providing both assay-development and -optimization strategies. It also tabulates validation parameters and enumerates the difficulties, challenges and nuances of the various published assays for torcetrapib.