RESUMO
1. In vitro clearance in liver microsomes is routinely measured in drug discovery and development for new chemical entities. Literature reports indicate that long chain fatty acids such as arachidonic, linoleic and oleic acids may be released over a period of time during microsomal incubations. Some fatty acids have been shown to interfere with oxidative and conjugative reactions in microsomes, thus potentially inhibiting microsomal clearance of compounds. 2. The present study was aimed at deciphering the fatty acids present or released from microsomes. Analytical methods were developed to characterize and quantitatively assess the fatty acids without chemical derivatization in rat, monkey and human liver microsomes. Additionally, incubations with uridine-5'-diphosphoglucuronic acid (UDPGA) were utilized to trap the released fatty acids as their glucuronate esters, which were characterized and confirmed by high-resolution LC-MS/MS. 3. Our results indicate for the first time that timnodonic, trans-eicosenoic, gondoic, behenic, and nervonic acid were released during microsomal incubations. Additionally, α- and γ-linolenic, timnodonic, palmitoleic, linoleic, arachidonic, palmitic, oleic, and stearic acid were identified as their corresponding acyl-glucuronides in rat, monkey and human liver microsomes, providing the first direct evidence that the released fatty acids are capable of forming glucuronides under incubation conditions.
Assuntos
Ácidos Graxos Insaturados/metabolismo , Microssomos Hepáticos/metabolismo , Animais , Feminino , Glucuronídeos/metabolismo , Humanos , Macaca fascicularis , Masculino , Ratos Sprague-Dawley , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
The authors present a comprehensive analysis on the estimation of volume of distribution at steady state (VD(ss) ) in human based on rat, dog, and monkey data on nearly 400 compounds for which there are also associated human data. This data set, to the authors- knowledge, is the largest publicly available, has been carefully compiled from literature reports, and was expanded with some in-house determinations such as plasma protein binding data. This work offers a good statistical basis for the evaluation of applicable prediction methods, their accuracy, and some methods-dependent diagnostic tools. The authors also grouped the compounds according to their charge classes and show the applicability of each method considered to each class, offering further insight into the probability of a successful prediction. Furthermore, they found that the use of fraction unbound in plasma, to obtain unbound volume of distribution, is generally detrimental to accuracy of several methods, and they discuss possible reasons. Overall, the approach using dog and monkey data in the íie-Tozer equation offers the highest probability of success, with an intrinsic diagnostic tool based on aberrant values (<0 or >1) for the calculated fraction unbound in tissue. Alternatively, methods based on dog data (single-species scaling) and rat and dog data (íie-Tozer equation with 2 species or multiple regression methods) may be considered reasonable approaches while not requiring data in nonhuman primates.
Assuntos
Avaliação Pré-Clínica de Medicamentos , Farmacocinética , Animais , Cães , Haplorrinos , Humanos , Ratos , Especificidade da Espécie , Distribuição TecidualRESUMO
A comprehensive analysis on the prediction of human clearance based on intravenous pharmacokinetic data from rat, dog, and monkey for approximately 400 compounds was undertaken. This data set has been carefully compiled from literature reports and expanded with some in-house determinations for plasma protein binding and rat clearance. To the authors- knowledge, this is the largest publicly available data set. The present examination offers a comparison of 37 different methods for prediction of human clearance across compounds of diverse physicochemical properties. Furthermore, this work demonstrates the application of each prediction method to each charge class of the compounds, thus presenting an additional dimension to prediction of human pharmacokinetics. In general, the observations suggest that methods employing monkey clearance values and a method incorporating differences in plasma protein binding between rat and human yield the best overall predictions as suggested by approximately 60% compounds within 2-fold geometric mean-fold error. Other single-species scaling or proportionality methods incorporating the fraction unbound in the corresponding preclinical species for prediction of free clearance in human were generally unsuccessful.
Assuntos
Avaliação Pré-Clínica de Medicamentos , Farmacocinética , Animais , Cães , Haplorrinos , Humanos , Taxa de Depuração Metabólica , Ratos , Especificidade da EspécieRESUMO
Metabolic activation of new chemical entities to reactive intermediates is routinely monitored in drug discovery and development. Reactive intermediates may bind to cellular macromolecules such as proteins, DNA and may eventually lead to cell death via necrosis, apoptosis or oxidative stress. The evidence that the ultimate outcome of metabolic activation is an adverse drug reaction manifested as in vivo toxicity, is at best circumstantial. However, understanding the process of bioactivation of structural alerts by trapping the reactive intermediates is critical to guide medicinal chemistry efforts in quest for safer and potent molecules. This commentary provides a brief introduction to adverse drug reactions and mechanisms of reactive intermediate formation for various functional groups, followed by a review of chemical design approaches, examples of such strategies, possible isosteric replacements for structural alerts and rationalization of laboratory approaches to determine reactive intermediates, as a guide to today's medicinal chemist.
Assuntos
Desenho de Fármacos , Preparações Farmacêuticas/química , Preparações Farmacêuticas/metabolismo , Animais , Química Farmacêutica , HumanosRESUMO
A novel class of potent and selective inhibitors of KDR incorporating an indazole moiety 1 is reported. The discovery, synthesis, and structure-activity relationships of this series of inhibitors have been investigated. The most promising compounds were also profiled to determine their pharmacokinetic properties and evaluated in a VEGF-induced vascular permeability assay.
Assuntos
Indazóis/farmacologia , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/antagonistas & inibidores , Animais , Permeabilidade Capilar/efeitos dos fármacos , Células Cultivadas , Cristalografia por Raios X , Avaliação Pré-Clínica de Medicamentos , Humanos , Indazóis/síntese química , Indazóis/química , Indazóis/metabolismo , Masculino , Camundongos , Camundongos Nus , Ligação Proteica/fisiologia , Inibidores de Proteínas Quinases/classificação , Ratos , Ratos Sprague-Dawley , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismoRESUMO
Angiogenesis is vital for solid tumor growth, and its prevention is a proven strategy for the treatment of disease states such as cancer. The vascular endothelial growth factor (VEGF) pathway provides several opportunities by which small molecules can act as inhibitors of endothelial proliferation and migration. Critical to these processes is signaling through VEGFR-2 or the kinase insert domain receptor (KDR) upon stimulation by its ligand VEGF. Herein, we report the discovery of 2,3-dihydro-1,4-benzoxazines as inhibitors of intrinsic KDR activity (IC 50 < 0.1 microM) and human umbilical vein endothelial cell (HUVEC) proliferation with IC 50 < 0.1 microM. More specifically, compound 16 was identified as a potent (KDR: < 1 nM and HUVEC: 4 nM) and selective inhibitor that exhibited efficacy in angiogenic in vivo models. In addition, this series of molecules is typically well-absorbed orally, further demonstrating the 2,3-dihydro-1,4-benzoxazine moiety as a promising platform for generating kinase-based antiangiogenic therapeutic agents.
Assuntos
Inibidores da Angiogênese/administração & dosagem , Benzoxazinas/administração & dosagem , Neoplasias/irrigação sanguínea , Neovascularização Patológica/prevenção & controle , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/antagonistas & inibidores , Administração Oral , Inibidores da Angiogênese/síntese química , Inibidores da Angiogênese/química , Animais , Benzoxazinas/síntese química , Benzoxazinas/química , Disponibilidade Biológica , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Neovascularização da Córnea/sangue , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Células Endoteliais/efeitos dos fármacos , Feminino , Humanos , Injeções Subcutâneas , Ligantes , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Modelos Animais , Modelos Moleculares , Estrutura Molecular , Ratos , Ratos Sprague-Dawley , Estereoisomerismo , Relação Estrutura-Atividade , Fator A de Crescimento do Endotélio Vascular/metabolismo , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismoRESUMO
We have previously shown N-arylnaphthamides can be potent inhibitors of vascular endothelial growth factor receptors (VEGFRs). N-Alkyl and N-unsubstituted naphthamides were prepared and found to yield nanomolar inhibitors of VEGFR-2 (KDR) with an improved selectivity profile against a panel of tyrosine and serine/threonine kinases. The inhibitory activity of this series was retained at the cellular level. Naphthamides 3, 20, and 22 exhibited good pharmacokinetics following oral dosing and showed potent inhibition of VEGF-induced angiogenesis in the rat corneal model. Once-daily oral administration of 22 for 14 days led to 85% inhibition of established HT29 colon cancer and Calu-6 lung cancer xenografts at doses of 10 and 20 mg/kg, respectively.
Assuntos
Antineoplásicos/farmacologia , Células Endoteliais/efeitos dos fármacos , Naftalenos/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/antagonistas & inibidores , Administração Oral , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Neovascularização da Córnea/sangue , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos , Feminino , Humanos , Concentração Inibidora 50 , Injeções Intravenosas , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Microssomos Hepáticos/efeitos dos fármacos , Modelos Moleculares , Estrutura Molecular , Naftalenos/síntese química , Naftalenos/química , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/química , Ratos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
A series of naphthyl-based compounds were synthesized as potential inhibitors of vascular endothelial growth factor (VEGF) receptors. Investigations of structure-activity relationships led to the identification of a series of naphthamides that are potent inhibitors of the VEGF receptor tyrosine kinase family. Numerous analogues demonstrated low nanomolar inhibition of VEGF-dependent human umbilical vein endothelial cell (HUVEC) proliferation, and of these several compounds possessed favorable pharmacokinetic (PK) profiles. In particular, compound 48 demonstrated significant antitumor efficacy against established HT29 human colon adenocarcinoma xenografts implanted in athymic mice. A full account of the preparation, structure-activity relationships, pharmacokinetic properties, and pharmacology of analogues within this series is presented.
Assuntos
Antineoplásicos/farmacologia , Células Endoteliais/efeitos dos fármacos , Naftalenos/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Proteínas Tirosina Quinases/antagonistas & inibidores , Receptores de Fatores de Crescimento do Endotélio Vascular/antagonistas & inibidores , Administração Oral , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Neovascularização da Córnea/sangue , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos , Feminino , Humanos , Concentração Inibidora 50 , Injeções Intravenosas , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Microssomos Hepáticos/efeitos dos fármacos , Modelos Moleculares , Estrutura Molecular , Naftalenos/síntese química , Naftalenos/química , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/química , Ratos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
The occurrence of idiosyncratic adverse drug reactions during late clinical trials or after a drug has been released can lead to a severe restriction in its use and even in its withdrawal. Metabolic activation of relatively inert functional groups to reactive electrophilic intermediates is considered to be an obligatory event in the etiology of many drug-induced adverse reactions. Therefore, a thorough examination of the biochemical reactivity of functional groups/structural motifs in all new drug candidates is essential from a safety standpoint. A major theme attempted in this review is the comprehensive cataloging of all of the known bioactivation pathways of functional groups or structural motifs commonly utilized in drug design efforts. Potential strategies in the detection of reactive intermediates in biochemical systems are also discussed. The intention of this review is not to "black list" functional groups or to immediately discard compounds based on their potential to form reactive metabolites, but rather to serve as a resource describing the structural diversity of these functionalities as well as experimental approaches that could be taken to evaluate whether a "structural alert" in a new drug candidate undergoes bioactivation to reactive metabolites.
Assuntos
Preparações Farmacêuticas/química , Preparações Farmacêuticas/metabolismo , Animais , Biotransformação/fisiologia , Humanos , Microssomos Hepáticos/metabolismo , Compostos Orgânicos/química , Compostos Orgânicos/metabolismo , Relação Estrutura-AtividadeRESUMO
An in vitro reactive intermediate screening assay, incorporating the use of the close analog of glutathione, glutathione ethyl ester (GSH-EE) as a conjugating agent, was developed to identify compounds that form reactive intermediates in an in vitro metabolite generating system. The biological assay consisted of substrate [s] = 10 microM, human liver microsomes, an NADPH generating system and glutathione ethyl ester. Conjugates were extracted from the biological matrix using a combination of protein precipitation and a semi-automated 96-well plate solid phase extraction (SPE) procedure. A micro-bore liquid chromatography-micro-electrospray ionization-tandem mass spectrometry (microLC-microESI-MS/MS) method detected glutathione ethyl ester conjugates using selected reaction monitoring (SRM) to simultaneously monitor for multiple MH+ to [MH - 129]+ transitions, where the 129 mass unit (Da) represents the neutral loss of the pyroglutamate moiety from GSH-EE. The multiple MH+ to [MH - 129]+ transitions (SRM mass table) were generated for potential reactive intermediates of each compound. Glutathione (GSH) and GSH-EE conjugate standards were used to evaluate MS detection sensitivity. Based on direct comparison of standard curve data, an approximate 10-fold increase in sensitivity was observed for conjugates containing GSH-EE moiety versus GSH. In vitro experiments were conducted using literature substrates acetaminophen, rosiglitazone, clozapine, diclofenac and either GSH-EE or GSH as a reactive intermediate conjugating agent. An increase in detection sensitivity was observed for each GSH-EE conjugate and in the case of acetaminophen-GSH-EE the peak area increase was approximately 80-fold. Twelve drug compounds, each having known biotransformation mechanisms, were used to further test the detection capabilities of the assay and establish a concordance to literature data. When GSH was used in the assay, conjugates were detected for 4 out of the 12 test compounds (33%). When GSH-EE was used in the assay, conjugates were detected for 10 out of the 12 test compounds (83%).
Assuntos
Avaliação Pré-Clínica de Medicamentos/métodos , Glutationa/análogos & derivados , Glutationa/metabolismo , Microssomos Hepáticos/metabolismo , Preparações Farmacêuticas/análise , Bioensaio , Biotransformação , Cromatografia Líquida , Humanos , Preparações Farmacêuticas/metabolismo , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
We describe here apparatus and methods for direct analysis of (14)C in biological specimens by accelerator mass spectrometry (AMS). Liquid samples, including plasma and urine, are deposited by pipet into a bed of CuO powder that fills a space within a rigid, refractory support. Volatile components are removed under reduced pressure prior to analysis. The CuO matrix is locally heated with an infrared laser while it is contained within a sealed chamber that is swept with He carrier gas. Heating induces combustion of the applied sample, and the carrier gas transports the CO(2) that is formed to the AMS instrument's ion source, which is appropriately modified for use with CO(2). A rodent study of drug clearance with [(14)C]-acetaminophen was performed to provide plasma and urine specimens, which were analyzed with this overall approach and by liquid scintillation counting for comparison. Results presented here confirm the potential utility of laser-induced sample combustion as an alternative to graphite production for AMS analysis of (14)C. Anticipated benefits of the present approach include reduced risk of sample cross-contamination, decreased analysis time, and greater compatibility with robotics.