title: Development and validation of a quantification method for cucurbitacins E and I in rat plasma: Application to population pharmacokinetic studies.
abstract: Cucurbitacin E is a potential drug candidate due to its anticancer activity, recognition of its molecular targets, and synergism with other drugs used for cancer treatment. However, the use of cucurbitacin E in clinical practice is not possible because of important knowledge gaps in its preclinical and clinical pharmacokinetic characteristics. Cucurbitacin E is hydrolyzed to cucurbitacin I in plasma and in human liver microsomes. The aim of this study was to evaluate the population pharmacokinetics of cucurbitacin E and of its metabolite cucurbitacin I in rats. The method for the sequential analysis of cucurbitacins E and I in rat plasma was developed using LC-MS/MS. Plasma aliquots of 50μL were deproteinized with acetonitrile and clobazam was added as internal standard. The extracts were injected into an RP-18 column and eluted with a mobile phase consisting of a mixture of acetonitrile:water:methanol (32:35:33, v/v/v). The method was precise and accurate, showing linearity in the range of 1-100ng cucurbitacin E/mL plasma and of 0.4-200ng cucurbitacin I/mL plasma. The method was applied to the pharmacokinetic evaluation of cucurbitacin E administered intravenously to male Wistar rats (1mg/kg). Serial blood samples were collected up to 24h after administration. The plasma concentrations of cucurbitacin E were quantified up to 16h, while the plasma concentrations of cucurbitacin I remained below the limit of quantification. A population pharmacokinetic model was developed for cucurbitacin E using the NONMEM program, with adequate goodness of fit and predictive performance. The following pharmacokinetic parameters were obtained: release time of 0.45h, volume of distribution of 27.22L, clearance of 4.13L/h, and elimination half-life of 4.57h.
authors.affiliation: Department of Physics and Chemistry, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, CEP 14049-900, Brazil.
authors.forename: Giovana Maria Lanchoti
authors.initials: GML
authors.lastname: Fiori
authors.affiliation: Clinical Pharmacology & Therapeutics, University College London, London, UK.
authors.forename: Salvatore
authors.initials: S
authors.lastname: D'Agate
authors.affiliation: Department of Clinical Analyses, Toxicology and Food Sciences, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, CEP 14049-900, Brazil.
authors.forename: Adriana
authors.initials: A
authors.lastname: Rocha
authors.affiliation: Department of Biotechnology, University of Ribeirão Preto (UNAERP), Ribeirão Preto, SP, 14096-900, Brazil.
authors.forename: Ana Maria Soares
authors.initials: AMS
authors.lastname: Pereira
authors.affiliation: Clinical Pharmacology & Therapeutics, University College London, London, UK.
authors.forename: O
authors.initials: O
authors.lastname: Della Pasqua
authors.affiliation: Department of Physics and Chemistry, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, CEP 14049-900, Brazil. Electronic address: npelopes@fcfrp.usp.br.
authors.forename: Norberto Peporine
authors.initials: NP
authors.lastname: Lopes
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid; D054728:Cucurbitacins / Q000097:blood*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D053719:Tandem Mass Spectrometry
chemical_list: D054728:Cucurbitacins
keywords: Cucurbitacin E; Cucurbitacin I; LC–MS/MS; Population pharmacokinetics; Rats