RESUMO
While an initial clinical absorption, distribution, metabolism, and excretion (ADME) study (Study 1; N = 6) with 100 mg/100 µCi [14 C]lorlatinib, radiolabeled on the carbonyl carbon, confirmed that the primary metabolic pathways for lorlatinib are oxidation (N-demethylation, N-oxidation) and N-glucuronidation, it also revealed an unanticipated, intramolecular cleavage metabolic pathway of lorlatinib, yielding a major circulating benzoic acid metabolite (M8), and an unlabeled pyrido-pyrazole substructure. Concerns regarding the fate of unknown metabolites associated with this intramolecular cleavage pathway led to conduct of a second ADME study (Study 2; N = 6) of identical design but with the radiolabel positioned on the pyrazole ring. Results were similar with respect to the overall mass balance, lorlatinib plasma exposures, and metabolic profiles in excreta for the metabolites that retained the radiolabel in both studies. Differences were observed in plasma total radioactivity exposures (2-fold area under the plasma concentration-time curve from time 0 to infinity difference) and relative ratios of the percentage of dose recovered in urine vs feces (48% vs 41% in Study 1; 28% vs 64% in Study 2). In addition, an approximately 3-fold difference in the mean molar exposure ratio of M8 to lorlatinib was observed for values derived from metabolic profiling data relative to those derived from specific bioanalytical methods (0.5 vs 1.4 for Studies 1 and 2, respectively). These interstudy differences were attributed to a combination of factors, including alteration of radiolabel position, orthogonal analytical methodologies, and intersubject variability, and illustrate that results from clinical ADME studies are not unambiguous and should be interpreted within the context of the specific study design considerations.
Assuntos
Radioisótopos de Carbono/metabolismo , Radioisótopos de Carbono/farmacocinética , Lactamas Macrocíclicas/metabolismo , Lactamas Macrocíclicas/farmacocinética , Administração Oral , Adolescente , Adulto , Aminopiridinas , Biotransformação , Radioisótopos de Carbono/administração & dosagem , Radioisótopos de Carbono/química , Vias de Eliminação de Fármacos , Fezes/química , Voluntários Saudáveis , Humanos , Lactamas , Lactamas Macrocíclicas/administração & dosagem , Lactamas Macrocíclicas/química , Masculino , Pessoa de Meia-Idade , Modelos Biológicos , Pirazóis , Soluções , Adulto JovemRESUMO
Two chemotypes were examined in vitro with CYPs 3A4 and 2C19 by molecular docking, metabolic profiles, and intrinsic clearance deuterium isotope effects with specifically deuterated form to assess the potential for enhancement of pharmacokinetic parameters. The results show the complexity of deuteration as an approach for pharmacokinetic enhancement when CYP enzymes are involved in metabolic clearance. With CYP3A4 the rate limiting step was chemotype-dependent. With one chemotype no intrinsic clearance deuterium isotope effect was observed with any deuterated form, whereas with the other chemotype the rate limiting step was isotopically sensitive, and the magnitude of the intrinsic clearance isotope effect was dependent on the position(s) and extent of deuteration. Molecular docking and metabolic profiles aided in identifying sites for deuteration and predicted the possibility for metabolic switching. However, the potential for an isotope effect on the intrinsic clearance cannot be predicted and must be established by examining select deuterated versions of the chemotypes. The results show how in a deuteration strategy molecular docking, in-vitro metabolic profiles, and intrinsic clearance assessments with select deuterated versions of new chemical entities can be applied to determine the potential for pharmacokinetic enhancement in a discovery setting. They also help explain the substantial failures reported in the literature of deuterated versions of drugs to elicit a systemic enhancement on pharmacokinetic parameters.
Assuntos
Citocromo P-450 CYP2C19/química , Citocromo P-450 CYP3A/química , Deutério/química , Farmacocinética , Citocromo P-450 CYP2C19/efeitos da radiação , Citocromo P-450 CYP3A/efeitos da radiação , Deutério/farmacologia , Heme/química , Heme/efeitos da radiação , Humanos , Inativação Metabólica , Cinética , Microssomos/efeitos da radiação , Simulação de Acoplamento Molecular , Oxirredução/efeitos da radiação , Especificidade por SubstratoRESUMO
Ertugliflozin, a sodium glucose cotransporter-2 inhibitor, is approved in the United States for treatment of type 2 diabetes mellitus. A novel two-period study design with 14 C microtracer dosing in each period was used to determine absolute oral bioavailability (F) and fraction absorbed (Fa ) of ertugliflozin. Eight healthy adult men received 100-µg i.v. 14 C-ertugliflozin (400 nCi) dose 1 h after a 15-mg oral unlabeled ertugliflozin dose (period 1), followed by 100 µg 14 C-ertugliflozin orally along with 15 mg oral unlabeled ertugliflozin (period 2). Unlabeled ertugliflozin plasma concentrations were determined using high-performance liquid-chromatography tandem mass spectrometry (HPLC-MS/MS). 14 C-ertugliflozin plasma concentrations were determined using HPLC-accelerator mass spectrometry (AMS) and 14 C urine concentrations were determined using AMS. F ((area under the curve (AUC)p.o. /14 C-AUCi.v. )*(14 C-Dosei.v. /Dosep.o. )) and Fa ((14 C_Total_Urinep.o. /14 C_Total_Urinei.v. )* (14 C-Dosei.v. /14 C-Dosep.o. )) were estimated. Estimates of F and Fa were 105% and 111%, respectively. Oral absorption of ertugliflozin was complete under fasted conditions and F was â¼100%. Ertugliflozin was well tolerated.
Assuntos
Compostos Bicíclicos Heterocíclicos com Pontes/farmacocinética , Inibidores do Transportador 2 de Sódio-Glicose/farmacocinética , Espectrometria de Massas em Tandem/métodos , Administração Oral , Adulto , Área Sob a Curva , Disponibilidade Biológica , Compostos Bicíclicos Heterocíclicos com Pontes/administração & dosagem , Compostos Bicíclicos Heterocíclicos com Pontes/efeitos adversos , Química Farmacêutica/métodos , Cromatografia Líquida de Alta Pressão/métodos , Diabetes Mellitus Tipo 2/tratamento farmacológico , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Traçadores Radioativos , Inibidores do Transportador 2 de Sódio-Glicose/administração & dosagem , Inibidores do Transportador 2 de Sódio-Glicose/efeitos adversos , Adulto JovemRESUMO
1. The metabolism, excretion and pharmacokinetics of glasdegib (PF-04449913) were investigated following administration of a single oral dose of 100 mg/100 µCi [14C]glasdegib to six healthy male volunteers (NCT02110342). 2. The peak concentrations of glasdegib (890.3 ng/mL) and total radioactivity (1043 ngEq/mL) occurred in plasma at 0.75 hours post-dose. The AUCinf were 8469 ng.h/mL and 12,230 ngEq.h/mL respectively, for glasdegib and total radioactivity. 3. Mean recovery of [14C]glasdegib-related radioactivity in excreta was 91% of the administered dose (49% in urine and 42% in feces). Glasdegib was the major circulating component accounting for 69% of the total radioactivity in plasma. An N-desmethyl metabolite and an N-glucuronide metabolite of glasdegib represented 8% and 7% of the circulating radioactivity, respectively. Glasdegib was the major excreted component in urine and feces, accounting for 17% and 20% of administered dose in the 0-120 hour pooled samples, respectively. Other metabolites with abundance <3% of the total circulating radioactivity or dose in plasma or excreta were hydroxyl metabolites, a desaturation metabolite, N-oxidation and O-glucuronide metabolites. 4. Elimination of [14C]glasdegib-derived radioactivity was essentially complete, with similar contribution from urinary and fecal routes. Oxidative metabolism appears to play a significant role in the biotransformation of glasdegib.
Assuntos
Benzimidazóis/farmacocinética , Compostos de Fenilureia/farmacocinética , Administração Oral , Adulto , Biotransformação , Glucuronídeos/metabolismo , Voluntários Saudáveis , Humanos , Masculino , Adulto JovemRESUMO
RATIONALE: The covalent modification of proteins by toxicants, new chemical entities or drug molecules, either by metabolic activation or the presence of inherently reactive functional groups, is commonly implicated in organ toxicity and idiosyncratic reactions. In efforts to better prosecute protein modifications, we investigated a tag-free technique capable of detecting protein-small molecule adducts based solely on the collision-induced dissociation (CID) of the protein-small molecule complex. Detection of proteins using unique CID small molecule (SM) product ions would mitigate common issues associated with tagging technologies (e.g., altered reactivity/affinity of the protein-SM complex). METHODS: A Waters SYNAPT G2 mass spectrometer (MS) was operated in MS(e) mode with appropriate collision energy conditions during the MS(2) acquisition for fragmentation of protein-small molecule adducts to generate characteristic small molecule product ions. RESULTS: Ibrutinib, an acrylamide-containing small molecule drug, was shown to form adducts with rat serum albumin in ex vivo experiments and these adducts were detected by relying solely on the CID product ions generated from ibrutinib. Additionally, ibrutinib produced three CID product ions, one of which was a selective protein-ibrutinib fragment ion not produced by the compound alone. CONCLUSIONS: Herein we describe a tag-free mass spectral detection technique for protein-small molecule conjugates that relies on the unique product ion fragmentation profile of the small molecule. This technique allows the detection of macromolecular ions containing the adducted small molecule from complex protein matrices through mass range selection for the unique product ions in the CID spectra.
Assuntos
Íons/química , Espectrometria de Massas/métodos , Preparações Farmacêuticas/química , Proteínas/química , Adenina/análogos & derivados , Animais , Cromatografia Líquida de Alta Pressão , Humanos , Íons/análise , Íons/metabolismo , Modelos Químicos , Preparações Farmacêuticas/metabolismo , Piperidinas , Proteínas/análise , Proteínas/metabolismo , Pirazóis , Pirimidinas , RatosRESUMO
Drug-drug interaction is an important element of modern drug development. In the case of antituberculosis drugs, which are frequently administered as combinations of multiple therapeutic agents, the potential for interactions between coadministered drugs and between new and existing drugs should be considered during the development of new antituberculosis drugs and combination regimens. The current understanding of drug-drug interactions involving the first-line antituberculosis drugs is reviewed in this article, along with the approaches that are used to prospectively delineate potential interactions during development of new therapies. In addition, current knowledge gaps are identified, and future directions for enhancing the understanding of drug-drug interactions that will further facilitate the development of novel antituberculosis therapies are discussed.
Assuntos
Antituberculosos/metabolismo , Antituberculosos/uso terapêutico , Interações Medicamentosas/fisiologia , Tuberculose/tratamento farmacológico , Quimioterapia Combinada/métodos , Humanos , Tuberculose/metabolismoRESUMO
The bioavailability of aromatic azaheterocyclic drugs can be affected by the activity of aldehyde oxidase (AO). Susceptibility to AO metabolism is difficult to predict computationally and can be complicated in vivo by differences between species. Here we report the use of bis(((difluoromethyl)sulfinyl)oxy)zinc (DFMS) as a source of CF2H radical for a rapid and inexpensive chemical "litmus test" for the early identification of heteroaromatic drug candidates that have a high probability of metabolism by AO.
Assuntos
Aldeído Oxidase/metabolismo , Hidrocarbonetos/metabolismoRESUMO
Tofacitinib is a novel, oral Janus kinase inhibitor. The objectives of this study were to summarize the pharmacokinetics and metabolism of tofacitinib in humans, including clearance mechanisms. Following administration of a single 50-mg (14)C-labeled tofacitinib dose to healthy male subjects, the mean (standard deviation) total percentage of administered radioactive dose recovered was 93.9% (±3.6), with 80.1% (±3.6) in the urine (28.8% parent), and 13.8% (±1.9) in feces (0.9% parent). Tofacitinib was rapidly absorbed, with plasma concentrations and total radioactivity peaking at around 1 hour after oral administration. The mean terminal phase half-life was approximately 3.2 hours for both parent drug and total radioactivity. Most (69.4%) circulating radioactivity in plasma was parent drug, with all metabolites representing less than 10% each of total circulating radioactivity. Hepatic clearance made up around 70% of total clearance, while renal clearance made up the remaining 30%. The predominant metabolic pathways of tofacitinib included oxidation of the pyrrolopyrimidine and piperidine rings, oxidation of the piperidine ring side-chain, N-demethylation and glucuronidation. Cytochrome P450 (P450) profiling indicated that tofacitinib was mainly metabolized by CYP3A4, with a smaller contribution from CYP2C19. This pharmacokinetic characterization of tofacitinib has been consistent with its clinical experience in drug-drug interaction studies.
Assuntos
Hidrocarboneto de Aril Hidroxilases/metabolismo , Citocromo P-450 CYP3A/metabolismo , Janus Quinases/antagonistas & inibidores , Fígado/metabolismo , Piperidinas/farmacocinética , Inibidores de Proteínas Quinases/farmacocinética , Pirimidinas/farmacocinética , Pirróis/farmacocinética , Biotransformação , Cromatografia Líquida de Alta Pressão , Citocromo P-450 CYP2C19 , Fezes/química , Feminino , Humanos , Fígado/enzimologia , Espectroscopia de Ressonância Magnética , Masculino , Taxa de Depuração Metabólica , Microssomos Hepáticos/enzimologia , Microssomos Hepáticos/metabolismo , Piperidinas/sangue , Piperidinas/metabolismo , Piperidinas/urina , Inibidores de Proteínas Quinases/sangue , Inibidores de Proteínas Quinases/metabolismo , Inibidores de Proteínas Quinases/urina , Pirimidinas/sangue , Pirimidinas/metabolismo , Pirimidinas/urina , Pirróis/sangue , Pirróis/metabolismo , Pirróis/urina , Espectrometria de Massas em TandemRESUMO
The disposition of ertugliflozin (PF-04971729), an orally active selective inhibitor of the sodium-dependent glucose cotransporter 2, was studied after a single 25-mg oral dose of [(14)C]-ertugliflozin to healthy human subjects. Mass balance was achieved with approximately 91% of the administered dose recovered in urine and feces. The total administered radioactivity excreted in feces and urine was 40.9% and 50.2%, respectively. The absorption of ertugliflozin in humans was rapid with a T(max) at â¼1.0 hour. Of the total radioactivity excreted in feces and urine, unchanged ertugliflozin collectively accounted for â¼35.3% of the dose, suggestive of moderate metabolic elimination in humans. The principal biotransformation pathway involved glucuronidation of the glycoside hydroxyl groups to yield three regioisomeric metabolites, M4a, M4b, and M4c (â¼39.3% of the dose in urine), of which M4c was the major regioisomer (â¼31.7% of the dose). The structure of M4a and M4c were confirmed to be ertugliflozin -4-O-ß- and -3-O-ß-glucuronide, respectively, via comparison of the HPLC retention time and mass spectra with authentic standards. A minor metabolic fate involved oxidation by cytochrome P450 to yield monohydroxylated metabolites M1 and M3 and des-ethyl ertugliflozin (M2), which accounted for â¼5.2% of the dose in excreta. In plasma, unchanged ertugliflozin and the corresponding 4-O-ß- (M4a) and 3-O-ß- (M4c) glucuronides were the principal components, which accounted for 49.9, 12.2, and 24.1% of the circulating radioactivity. Overall, these data suggest that ertugliflozin is well absorbed in humans, and eliminated largely via glucuronidation.
Assuntos
Compostos Bicíclicos Heterocíclicos com Pontes/farmacocinética , Hipoglicemiantes/farmacocinética , Administração Oral , Adulto , Biotransformação , Compostos Bicíclicos Heterocíclicos com Pontes/administração & dosagem , Compostos Bicíclicos Heterocíclicos com Pontes/sangue , Compostos Bicíclicos Heterocíclicos com Pontes/química , Compostos Bicíclicos Heterocíclicos com Pontes/urina , Cromatografia Líquida de Alta Pressão , Fezes/química , Glucuronídeos/metabolismo , Humanos , Hidroxilação , Hipoglicemiantes/administração & dosagem , Hipoglicemiantes/sangue , Hipoglicemiantes/química , Hipoglicemiantes/urina , Absorção Intestinal , Masculino , Pessoa de Meia-Idade , Estrutura Molecular , Transportador 2 de Glucose-Sódio/metabolismo , Inibidores do Transportador 2 de Sódio-Glicose , Espectrometria de Massas em Tandem , Adulto JovemRESUMO
BACKGROUND: Atherosclerosis starts by lipid accumulation in the arterial intima and progresses into a chronic vascular inflammatory disease. A major atherogenic process is the formation of lipid-loaded macrophages in which a breakdown of the endolysomal pathway results in irreversible accumulation of cargo in the late endocytic compartments with a phenotype similar to several forms of lipidosis. Macrophages exposed to oxidized LDL exihibit this phenomenon in vitro and manifest an impaired degradation of internalized lipids and enhanced inflammatory stimulation. Identification of the specific chemical component(s) causing this phenotype has been elusive because of the chemical complexity of oxidized LDL. METHODOLOGY/PRINCIPAL FINDINGS: Lipid "core aldehydes" are formed in oxidized LDL and exist in atherosclerotic plaques. These aldehydes are slowly oxidized in situ and (much faster) by intracellular aldehyde oxidizing systems to cholesteryl hemiesters. We show that a single cholesteryl hemiester incorporated into native, non-oxidized LDL induces a lipidosis phenotype with subsequent cell death in macrophages. Internalization of the cholesteryl hemiester via the native LDL vehicle induced lipid accumulation in a time- and concentration-dependent manner in "frozen" endolysosomes. Quantitative shotgun lipidomics analysis showed that internalized lipid in cholesteryl hemiester-intoxicated cells remained largely unprocessed in those lipid-rich organelles. CONCLUSIONS/SIGNIFICANCE: The principle elucidated with the present cholesteryl hemiester-containing native-LDL model, extended to other molecular components of oxidized LDL, will help in defining the molecular etiology and etiological hierarchy of atherogenic agents.
Assuntos
Aterosclerose/etiologia , Aterosclerose/metabolismo , Lipidoses/induzido quimicamente , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Eletroforese em Gel de Ágar , Imunofluorescência , Lipoproteínas LDL/farmacologia , Camundongos , Microscopia ConfocalRESUMO
The synthesis and biological activity of a new series of LpxC inhibitors represented by pyridone methylsulfone hydroxamate 2a is presented. Members of this series have improved solubility and free fraction when compared to compounds in the previously described biphenyl methylsulfone hydroxamate series, and they maintain superior Gram-negative antibacterial activity to comparator agents.
Assuntos
Amidoidrolases/antagonistas & inibidores , Antibacterianos/síntese química , Bactérias Gram-Negativas/efeitos dos fármacos , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Ácidos Hidroxâmicos/síntese química , Piridonas/síntese química , Ácidos Sulfônicos/síntese química , Animais , Antibacterianos/farmacocinética , Antibacterianos/farmacologia , Cristalografia por Raios X , Humanos , Ácidos Hidroxâmicos/farmacocinética , Ácidos Hidroxâmicos/farmacologia , Testes de Sensibilidade Microbiana , Modelos Moleculares , Estrutura Molecular , Conformação Proteica , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/enzimologia , Piridonas/farmacocinética , Piridonas/farmacologia , Ratos , Estereoisomerismo , Relação Estrutura-Atividade , Ácidos Sulfônicos/farmacocinética , Ácidos Sulfônicos/farmacologiaRESUMO
The pharmacokinetic properties of drugs may be altered by kinetic deuterium isotope effects. With specifically deuterated model substrates and drugs metabolized by aldehyde oxidase, we demonstrate how knowledge of the enzyme's reaction mechanism, species differences in the role played by other enzymes in a drug's metabolic clearance, and differences in systemic clearance mechanisms are critically important for the pharmacokinetic application of deuterium isotope effects. Ex vivo methods to project the in vivo outcome using deuterated carbazeran and zoniporide with hepatic systems demonstrate the importance of establishing the extent to which other metabolic enzymes contribute to the metabolic clearance mechanism. Differences in pharmacokinetic outcomes in guinea pig and rat, with the same metabolic clearance mechanism, show how species differences in the systemic clearance mechanism can affect the in vivo outcome. Overall, to gain from the application of deuteration as a strategy to alter drug pharmacokinetics, these studies demonstrate the importance of understanding the systemic clearance mechanism and knowing the identity of the metabolic enzymes involved, the extent to which they contribute to metabolic clearance, and the extent to which metabolism contributes to the systemic clearance.
Assuntos
Aldeído Oxidase/metabolismo , Carbamatos/farmacocinética , Deutério/metabolismo , Guanidinas/farmacocinética , Pirazóis/farmacocinética , Animais , Carbamatos/metabolismo , Citosol/metabolismo , Guanidinas/metabolismo , Cobaias , Hepatócitos/metabolismo , Humanos , Cinética , Fígado/metabolismo , Masculino , Pirazóis/metabolismo , Ratos , Ratos Sprague-DawleyRESUMO
Multiple crystal structures of CYP3A4 bound with various substrates or inhibitors have been used as templates for docking of new chemical entities to predict sites of metabolism and molecular interactions for drug design. Herein, modeling studies with dirlotapide, a CYP3A4 substrate, indicated that a substantial conformational change of CYP3A4 was necessary to accommodate it within the active site cavity, which is in good agreement with a new published CYP3A4 ritonavir co-crystal structure. Thus, the importance of considering the substrate-induced conformational change in CYP3A4, thermochemical properties of reaction centers, and essential in vitro experimental data support were analyzed for the refinement of computational models.
Assuntos
Carbamatos/síntese química , Carbamatos/farmacologia , Química Farmacêutica/métodos , Citocromo P-450 CYP3A/química , Indóis/síntese química , Indóis/farmacologia , Catálise , Domínio Catalítico , Simulação por Computador , Cristalização , Cristalografia por Raios X/métodos , Desenho de Fármacos , Ligantes , Espectrometria de Massas/métodos , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/metabolismo , Modelos Químicos , Modelos Moleculares , Conformação Molecular , Conformação Proteica , TemperaturaRESUMO
Analogues related to dirlotapide (1), a gut-selective inhibitor of microsomal triglyceride transfer protein (MTP) were prepared with the goal of further reducing the potential for unwanted liver MTP inhibition and associated side-effects. Compounds were designed to decrease active metabolite load: reducing MTP activity of likely human metabolites and increasing metabolite clearance to reduce exposure. Introduction of 4'-alkyl and 4'-alkoxy substituents afforded compounds exhibiting improved therapeutic index in rats with respect to liver triglyceride accumulation and enzyme elevation. Likely human metabolites of select compounds were prepared and characterized for their potential to inhibit MTP in vivo. Based on preclinical efficacy and safety data and its potential for producing short-lived, weakly active metabolites, compound 13 (PF-02575799) advanced into phase 1 clinical studies.
Assuntos
Aminoquinolinas/química , Benzamidas/química , Carbamatos/metabolismo , Proteínas de Transporte/antagonistas & inibidores , Indóis/metabolismo , Aminoquinolinas/síntese química , Aminoquinolinas/farmacocinética , Animais , Benzamidas/síntese química , Benzamidas/farmacocinética , Carbamatos/síntese química , Carbamatos/farmacocinética , Proteínas de Transporte/metabolismo , Cães , Avaliação Pré-Clínica de Medicamentos , Humanos , Indóis/síntese química , Indóis/farmacocinética , Microssomos Hepáticos/metabolismo , Ratos , Triglicerídeos/metabolismoRESUMO
Oxidation of N-alkyl-substituted amides is a common transformation observed in metabolism studies of drugs and other chemicals. Metabolism at the alpha carbon atom can produce stable carbinolamide compounds, which may be abundant enough to require complete confidence in structural assignments. In a drug discovery setting, rapid structural elucidation of test compounds is critical to inform the compound selection process. Traditional approaches to the analysis of carbinolamides have relied upon the time-consuming synthesis of authentic standards or purification of large enough quantities for characterization by nuclear magnetic resonance (NMR). We describe a simple technique used in conjunction with liquid chromatography/tandem mass spectrometry (LC/MS/MS) which demonstrates the chemical identity of a carbinolamide by its distinctive ability to reversibly exchange [(18)O]water through an imine intermediate. A key advantage of the technique is that the chromatographic retention times of metabolites are preserved, allowing direct comparisons of mass chromatograms from non-treated and [(18)O]water-treated samples. Metabolites susceptible to the treatment are clearly indicated by the addition of 2 mass units to their original mass. An additional test which can be used in conjunction with (18)O-exchange is base-catalyzed N-dealkylation of N-(alpha-hydroxy)alkyl compounds. The use of the technique is described for carbinolamide metabolites of dirlotapide, loperamide, and a proprietary compound.
Assuntos
Carbamatos/química , Carbamatos/metabolismo , Cromatografia Líquida/métodos , Indóis/química , Indóis/metabolismo , Isótopos de Oxigênio/análise , Espectrometria de Massas em Tandem/métodos , Animais , Carbamatos/administração & dosagem , Catálise , Remoção de Radical Alquila , Feminino , Indóis/administração & dosagem , Masculino , Estrutura Molecular , Ratos , Ratos Sprague-DawleyRESUMO
A simple procedure is described to identify acyl-glucuronides by coupled liquid chromatography/mass spectrometry after derivatization to a hydroxamic acid with hydroxylamine. The reaction specificity obviates the need for isolation of the acyl-glucuronide from an extract. Glucuronides derived from carbamic acids, and alkyl- and aromatic amines, are inert to the derivatization reaction conditions, making the hydroxamic acid derivative a fingerprint for acyl-glucuronides.
Assuntos
Glucuronídeos/química , Espectrometria de Massas/métodos , Carbamatos/química , Ácidos Hidroxâmicos/química , Hidroxilamina/químicaRESUMO
Respiratory tract bacterial strains are becoming increasingly resistant to currently marketed macrolide antibiotics. The current alternative telithromycin (1) from the newer ketolide class of macrolides addresses resistance but is hampered by serious safety concerns, hepatotoxicity in particular. We have discovered a novel series of azetidinyl ketolides that focus on mitigation of hepatotoxicity by minimizing hepatic turnover and time-dependent inactivation of CYP3A isoforms in the liver without compromising the potency and efficacy of 1.
Assuntos
Azetidinas/química , Resistência a Múltiplos Medicamentos/efeitos dos fármacos , Cetolídeos/química , Cetolídeos/farmacologia , Infecções Respiratórias/tratamento farmacológico , Animais , Bactérias/efeitos dos fármacos , Infecções Comunitárias Adquiridas/tratamento farmacológico , Suscetibilidade a Doenças , Descoberta de Drogas , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Humanos , Cetolídeos/efeitos adversos , Cetolídeos/síntese química , Cetolídeos/uso terapêutico , Camundongos , Testes de Sensibilidade MicrobianaRESUMO
The pharmacokinetics, metabolism, and excretion of torcetrapib, a selective inhibitor of human cholesteryl ester transfer protein, were investigated in healthy human male volunteers after oral administration of [(14)C]torcetrapib (120-mg dose). The total mean recovery of radiolabeled dose after 21 days was 75.7%, and most of the dose (63%) was excreted in the urine. The total circulating radioactivity and unchanged torcetrapib plasma concentrations increased over the first 6 h and then declined slowly with mean terminal elimination half-lives of 373 and 211 h. Metabolism of torcetrapib was extensive in humans. Only 5.2% of the total dose constituted unchanged torcetrapib in the feces, whereas no parent was excreted unchanged in the urine. Similarly, pharmacokinetic analysis of total radioactivity and unchanged torcetrapib revealed that the area under the concentration versus time curve from zero to infinity of torcetrapib accounted for approximately 7.0% of the circulating radioactivity. Torcetrapib was metabolized to numerous metabolites via oxidation. The primary metabolic pathway involved initial oxidative decarbamoylation followed by extensive further oxidation, resulting in the formation of bistrifluoromethylbenzoic acid (M1) and quinaldic acid (M4) metabolites. A mean 40% of the total dose was excreted in the urine as M4 (and its glucuronide and urea conjugates), whereas 7.0% of the total dose was excreted as M1. In vitro studies using human subcellular fractions suggested that the initial metabolism of torcetrapib proceeds via CYP3A-mediated decarbamoylation. Subsequent oxidations lead to the major circulating and excretory metabolites M1 and M4.
Assuntos
Anticolesterolemiantes/farmacocinética , Proteínas de Transferência de Ésteres de Colesterol/farmacocinética , Proteínas de Transferência de Ésteres de Colesterol/urina , Quinolinas/metabolismo , Adolescente , Adulto , Anticolesterolemiantes/metabolismo , Proteínas de Transferência de Ésteres de Colesterol/antagonistas & inibidores , Fezes/química , Humanos , Masculino , Pessoa de Meia-Idade , Quinolinas/farmacocinética , Quinolinas/urina , Fatores de Tempo , Adulto JovemRESUMO
The metabolism and disposition of N-[3-fluoro-4-[2-(propylamino)ethoxy]phenyl]-4,5,6,7-tetrahydro-4-oxo-1H-indole-3-carboxamide (1), a potent subtype-selective partial agonist at the gamma-aminobutyric acid type A receptor complex, were elucidated in humans following a p.o. dose of N-[3-fluoro-4-[2-(propylamino)ethoxy]phenyl]-4,5,6,7-tetrahydro-4-oxo-1H-[3-(14)C]indole-3-carboxamide monomethane-sulfonate ([(14)C]1). Overall, 1 was well tolerated, with approximately twice as much radioactivity excreted in feces (64.8 +/- 13.3%) as in urine (28.4 +/- 8.8%). Across subjects, the oral clearance of 1 was composed of both renal (10%) and metabolic (< or =90%) components, with the biotransformation of 1 happening predominately via oxidative deamination to either 2-fluoro-4-[(4-oxo-4,5,6,7-tetrahydro-1H-indole-3-carbonyl)-amino]-phenoxy acetic acid (2) or 4-oxo-4,5,6,7-tetrahydro-1H-indole-3-carboxylic acid [3-fluoro-4-(2-hydroxy-ethoxy)-phenyl]-amide (3) and minimally by aliphatic hydroxylation and carbamate formation. Active renal secretion of 1 was observed as its unbound renal clearance was 6-fold greater than the glomerular filtration rate. Experiments using human hepatic in vitro systems were undertaken to better understand the enzyme(s) involved in the clinically observed oxidative biotransformation pathways. N-Dealkylation of 1, the principal metabolic route observed in vivo, was found to be predominately monoamine oxidase-B-mediated with the resulting putative aldehyde intermediate undergoing subsequent oxidation to 2 or reduction to 3.
Assuntos
Agonistas GABAérgicos/química , Agonistas GABAérgicos/metabolismo , Agonistas de Receptores de GABA-A , Receptores de GABA-A/metabolismo , Adolescente , Adulto , Humanos , Masculino , Redes e Vias Metabólicas/fisiologia , Microssomos Hepáticos/metabolismo , Pessoa de Meia-Idade , Distribuição Tecidual/fisiologiaRESUMO
Therapy with the antidepressant trazodone has been associated with several cases of idiosyncratic hepatotoxicity. While the mechanism of hepatotoxicity remains unknown, it is possible that reactive metabolites of trazodone play a causative role. Studies were initiated to determine whether trazodone undergoes bioactivation in human liver microsomes to electrophilic intermediates. LC/MS/MS analysis of incubations containing trazodone and NADPH-supplemented microsomes or recombinant P4503A4 in the presence of glutathione revealed the formation of conjugates derived from the addition of the sulfydryl nucleophile to mono-hydroxylated- and hydrated-trazodone metabolites. Product ion spectra suggested that mono-hydroxylation and sulfydryl conjugation occurred on the 3-chlorophenyl-ring, whereas hydration and subsequent sulfydryl conjugation had occurred on the triazolopyridinone ring system. These findings are consistent with bioactivation sequences involving: (1) aromatic hydroxylation of the 3-chlorophenyl-ring in trazodone followed by the two-electron oxidation of this metabolite to a reactive quinone-imine intermediate, which reacts with glutathione in a 1,4-Michael fashion and (2) oxidation of the pyridinone ring to an electrophilic epoxide, ring opening of which, by glutathione or water generates the corresponding hydrated-trazodone-thiol conjugate or the stable diol metabolite, respectively. The pathway involving trazodone bioactivation to the quinone-imine has also been observed with many para-hydroxyanilines including the structurally related antidepressant nefazodone. It is proposed that the quinone-imine and/or the epoxide intermediate(s) may represent a rate-limiting step in the initiation of trazodone-mediated hepatotoxicity.