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1.
Drug Metab Dispos ; 2024 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-38408867

RESUMO

In vitro time-dependent inhibition (TDI) kinetic parameters for cytochrome P450 (CYP) 1A2, 2B6, 2C8, 2C9, 2C19, and 2D6, were determined in pooled human liver microsomes for 19 drugs (and 2 metabolites) for which clinical drug-drug interactions (DDI) are known. In vitro TDI data were incorporated into the projection of the magnitude of DDIs using mechanistic static models and Simcyp®. Results suggest that for the mechanistic static model, use of estimated average unbound exit concentration of the inhibitor from the liver resulted in a successful prediction of observed magnitude of clinical DDIs and was similar to Simcyp®. Overall, predictions of DDI magnitude (i.e., fold increase in AUC of a CYP-specific marker substrate) were within 2-fold of actual values. Geometric mean-fold errors were 1.7 and 1.6 for static and dynamic models, respectively. Projections of DDI from both models were also highly correlated to each other (r2 = 0.92). This investigation demonstrates that DDI can be reliably predicted from in vitro TDI data generated in HLM for several CYP enzymes. Simple mechanistic static model equations as well as more complex dynamic PBPK models can be employed in this process. Significance Statement Cytochrome P450 time-dependent inhibitors (TDI) can cause drug-drug interactions (DDI). An ability to reliably assess the potential for a new drug candidate to cause DDI is essential during drug development. In this report, TDI data for 19 drugs (and 2 metabolites) were measured and used in static and dynamic models to reliably project the magnitude of DDI resulting from inhibition of CYP1A2, 2B6, 2C8, 2C9, 2C19, and 2D6.

2.
Protein Expr Purif ; 177: 105749, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32911062

RESUMO

Human aldehyde oxidase (AOX) has emerged as a key enzyme activity for consideration in modern drug discovery. The enzyme catalyzes the oxidation of a wide variety of compounds, most notably azaheterocyclics that often form the building blocks of small molecule therapeutics. Failure to consider and assess AOX drug exposure early in the drug development cycle can have catastrophic consequences for novel compounds entering the clinic. AOX is a complex molybdopterin-containing iron-sulfur flavoprotein comprised of two identical 150 kDa subunits that has proven difficult to produce in recombinant form, and a commercial source of the purified human enzyme is currently unavailable. Thus, the potential exposure of novel drug development candidates to human AOX metabolism is usually assessed by using extracts of pooled human liver cytosol as a source of the enzyme. This can complicate the assignment of AOX-specific compound exposure due to its low activity and the presence of contaminating enzymes that may have overlapping substrate specificities. Herein is described a two-step process for the isolation of recombinant human AOX dimers to near homogeneity following production in the baculovirus expression vector system (BEVS). The deployment of this BEVS-produced recombinant human AOX as a substitute for human liver extracts in a fraction-of-control AOX compound-exposure screening assay is described. The ability to generate this key enzyme activity readily in a purified recombinant form provides for a more accurate and convenient approach to the assessment of new compound exposure to bona fide AOX drug metabolism.


Assuntos
Aldeído Oxidase/metabolismo , Clonagem Molecular/métodos , Coenzimas/metabolismo , Flavoproteínas/metabolismo , Proteínas Ferro-Enxofre/metabolismo , Metaloproteínas/metabolismo , Subunidades Proteicas/metabolismo , Pteridinas/metabolismo , Aldeído Oxidase/genética , Sequência de Aminoácidos , Animais , Baculoviridae/genética , Baculoviridae/metabolismo , Bioensaio , Cinamatos/química , Cinamatos/metabolismo , Coenzimas/genética , Flavoproteínas/genética , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Células HEK293 , Humanos , Proteínas Ferro-Enxofre/genética , Cinética , Metaloproteínas/genética , Cofatores de Molibdênio , Multimerização Proteica , Subunidades Proteicas/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Células Sf9 , Spodoptera , Especificidade por Substrato
4.
Drug Metab Dispos ; 45(1): 1-7, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27784718

RESUMO

The concept of target-specific covalent enzyme inhibitors appears attractive from both an efficacy and a selectivity viewpoint considering the potential for enhanced biochemical efficiency associated with an irreversible mechanism. Aside from potential safety concerns, clearance prediction of covalent inhibitors represents a unique challenge due to the inclusion of nontraditional metabolic pathways of direct conjugation with glutathione (GSH) or via GSH S-transferase-mediated processes. In this article, a novel pharmacokinetic algorithm was developed using a series of Pfizer kinase selective acrylamide covalent inhibitors based on their in vitro-in vivo extrapolation of systemic clearance in rats. The algorithm encompasses the use of hepatocytes as an in vitro model for hepatic clearance due to oxidative metabolism and GSH conjugation, and the use of whole blood as an in vitro surrogate for GSH conjugation in extrahepatic tissues. Initial evaluations with clinical covalent inhibitors suggested that the scaling algorithm developed from rats may also be useful for human clearance prediction when species-specific parameters, such as hepatocyte and blood stability and blood binding, were considered. With careful consideration of clearance mechanisms, the described in vitro-in vivo extrapolation approach may be useful to facilitate candidate optimization, selection, and prediction of human pharmacokinetic clearance during the discovery and development of targeted covalent inhibitors.


Assuntos
Hepatócitos/metabolismo , Microssomos Hepáticos/metabolismo , Modelos Biológicos , Preparações Farmacêuticas/metabolismo , Plasma/metabolismo , Inibidores de Proteínas Quinases/farmacocinética , Algoritmos , Animais , Avaliação Pré-Clínica de Medicamentos , Glutationa/metabolismo , Humanos , Técnicas In Vitro , Masculino , Taxa de Depuração Metabólica , Camundongos Endogâmicos C57BL , Preparações Farmacêuticas/sangue , Valor Preditivo dos Testes , Ligação Proteica , Inibidores de Proteínas Quinases/sangue , Ratos , Ratos Sprague-Dawley , Especificidade da Espécie
5.
Bioorg Med Chem Lett ; 24(4): 1144-7, 2014 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-24461291

RESUMO

A design for the selective release of drug molecules in the liver was tested, involving the attachment of a representative active agent by an ester linkage to various 2-substituted 5-aminovaleric acid carbamates. The anticipated pathway of carboxylesterase-1-mediated carbamate cleavage followed by lactamization and drug release was frustrated by unexpectedly high sensitivity of the ester linkage toward hydrolysis by carboxylesterase-2 and other microsomal components.


Assuntos
Aminoácidos Neutros/farmacologia , Carbamatos/farmacologia , Carboxilesterase/antagonistas & inibidores , Hidrolases de Éster Carboxílico/antagonistas & inibidores , Desenho de Fármacos , Fígado/efeitos dos fármacos , Aminoácidos Neutros/síntese química , Aminoácidos Neutros/química , Carbamatos/síntese química , Carbamatos/química , Carboxilesterase/metabolismo , Hidrolases de Éster Carboxílico/metabolismo , Relação Dose-Resposta a Droga , Humanos , Fígado/enzimologia , Estrutura Molecular , Relação Estrutura-Atividade
6.
Eur J Med Chem ; 57: 441-8, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22840492

RESUMO

Metabolic stability of drug candidates are often determined in both liver microsome and hepatocyte assays. Comparison of intrinsic clearance values between the two assays provides additional information to guide drug design. Intrinsic clearance values from human liver microsomes and hepatocytes were compared for a set of commercial drugs with known metabolic pathways and transporter characteristics. The results showed that for compounds that were predominately metabolized by CYP mediated mechanisms, the intrinsic clearance values from the two assays were comparable. For compounds with non-CYP pathways, such as UGT and AO, intrinsic clearance was faster in hepatocytes than in microsomes. Substrates of uptake or efflux transporters in this study did not have significant differences of intrinsic clearance between microsomes and hepatocytes, when uptake into the hepatocytes was not the rate-limiting step. When hepatic uptake was rate limiting, intrinsic clearance in microsomes was faster than that in hepatocytes, which was more prevalent for compounds with rapid metabolism. Low passive permeability can limit the exposure to drug molecules to the metabolizing enzymes in the hepatocytes in relationship to the rate of metabolism. The faster the rate of metabolism, the higher permeability is needed for molecule to enter the cells and not becoming rate-limiting. The findings are very useful for drug discovery programs to gain additional insights on mechanistic information to help drug design without added experiments. Follow-up studies can then be designed to address specific questions.


Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Desenho de Fármacos , Drogas em Investigação/metabolismo , Hepatócitos/enzimologia , Microssomos Hepáticos/enzimologia , Medicamentos sob Prescrição/metabolismo , Transporte Biológico , Proteínas de Transporte/metabolismo , Células Cultivadas , Descoberta de Drogas , Drogas em Investigação/farmacocinética , Hepatócitos/efeitos dos fármacos , Ensaios de Triagem em Larga Escala , Humanos , Cinética , Taxa de Depuração Metabólica , Redes e Vias Metabólicas , Microssomos Hepáticos/efeitos dos fármacos , Modelos Biológicos , Medicamentos sob Prescrição/farmacocinética
7.
Drug Metab Dispos ; 40(7): 1441-8, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22522748

RESUMO

Aldehyde oxidase (AO) metabolism could lead to significant underestimation of clearance in prediction of human pharmacokinetics as well as unanticipated exposure to AO-generated metabolites, if not accounted for early in drug research. We report a method using cryopreserved human hepatocytes and the time-dependent AO inhibitor hydralazine (K(I) = 83 ± 27 µM, k(inact) = 0.063 ± 0.007 min(-1)), which estimates the contribution of AO metabolism relative to total hepatic clearance. Using zaleplon as a probe substrate and simultaneously monitoring the AO-catalyzed formation of oxozaleplon and the CYP3A-catalyzed formation of desethyzaleplon in the presence of a range of hydralazine concentrations, it was determined that >90% inhibition of the AO activity with minimal effect on the CYP3A activity could be achieved with 25 to 50 µM hydralazine. This method was used to estimate the fraction metabolized due to AO [f(m(AO))] for six compounds with clearance attributed to AO along with four other drugs not metabolized by AO. The f(m(AO)) values for the AO substrates ranged between 0.49 and 0.83. Differences in estimated f(m(AO)) between two batches of pooled human hepatocytes suggest that sensitivity to hydralazine varies slightly with hepatocyte preparations. Substrates with a CYP2D6 contribution to clearance were affected by hydralazine to a minor extent, because of weak inhibition of this enzyme. Overall, these findings demonstrate that hydralazine, at a concentration of 25 to 50 µM, can be used in human hepatocyte incubations to estimate the contribution of AO to the hepatic clearance of drugs and other compounds.


Assuntos
Aldeído Oxidase/metabolismo , Hepatócitos/metabolismo , Hidralazina/farmacologia , Acetamidas/farmacocinética , Criopreservação , Citocromo P-450 CYP2D6/metabolismo , Citocromo P-450 CYP3A/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Citosol/efeitos dos fármacos , Citosol/enzimologia , Citosol/metabolismo , Ativação Enzimática/efeitos dos fármacos , Hepatócitos/efeitos dos fármacos , Hepatócitos/enzimologia , Humanos , Hidralazina/farmacocinética , Fígado/efeitos dos fármacos , Fígado/enzimologia , Fígado/metabolismo , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/enzimologia , Microssomos Hepáticos/metabolismo , Pirimidinas/farmacocinética
8.
Drug Metab Dispos ; 40(3): 625-34, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22190693

RESUMO

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-Dawley
9.
J Med Chem ; 53(24): 8468-84, 2010 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-21105711

RESUMO

There is a critical need for safer and more convenient treatments for organ transplant rejection and autoimmune disorders such as rheumatoid arthritis. Janus tyrosine kinases (JAK1, JAK3) are expressed in lymphoid cells and are involved in the signaling of multiple cytokines important for various T cell functions. Blockade of the JAK1/JAK3-STAT pathway with a small molecule was anticipated to provide therapeutic immunosuppression/immunomodulation. The Pfizer compound library was screened against the catalytic domain of JAK3 resulting in the identification of a pyrrolopyrimidine-based series of inhibitors represented by CP-352,664 (2a). Synthetic analogues of 2a were screened against the JAK enzymes and evaluated in an IL-2 induced T cell blast proliferation assay. Select compounds were evaluated in rodent efficacy models of allograft rejection and destructive inflammatory arthritis. Optimization within this chemical series led to identification of CP-690,550 1, a potential first-in-class JAK inhibitor for treatment of autoimmune diseases and organ transplant rejection.


Assuntos
Doenças Autoimunes/tratamento farmacológico , Rejeição de Enxerto/tratamento farmacológico , Janus Quinases/antagonistas & inibidores , Pirimidinas/síntese química , Pirróis/síntese química , Animais , Proteínas Sanguíneas/metabolismo , Células CACO-2 , Linhagem Celular Tumoral , Permeabilidade da Membrana Celular , Proliferação de Células/efeitos dos fármacos , Monoterpenos Cicloexânicos , Cães , Feminino , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Humanos , Técnicas In Vitro , Ativação Linfocitária/efeitos dos fármacos , Macaca fascicularis , Masculino , Modelos Moleculares , Monoterpenos/síntese química , Monoterpenos/farmacocinética , Monoterpenos/farmacologia , Piperidinas/síntese química , Piperidinas/farmacocinética , Piperidinas/farmacologia , Ligação Proteica , Pirimidinas/farmacocinética , Pirimidinas/farmacologia , Pirróis/farmacocinética , Pirróis/farmacologia , Ratos , Ratos Sprague-Dawley , Estereoisomerismo , Relação Estrutura-Atividade , Linfócitos T/citologia , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologia , Distribuição Tecidual
10.
J Med Chem ; 52(23): 7446-57, 2009 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-19775168

RESUMO

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 Microbiana
11.
J Pharm Sci ; 95(6): 1334-41, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16625658

RESUMO

The small intestine is regarded as an absorptive organ in the uptake of orally administered drugs, but also has the ability to metabolize drugs by both phase 1 and phase 2 reactions. The amount of drug that reaches the systemic circulation can be reduced by both intestinal and hepatic metabolism. 1-Aminobenzotriazole (ABT) is an irreversible inhibitor of cytochrome P450s. Through in vivo and in vitro studies, ABT has been evaluated for its utility in studying intestinal metabolism in rats. Rats have been exposed to ABT through varied routes of administration followed by p.o. and i.v. administration of midazolam (MDZ), a CYP3A substrate. The MDZ bioavailablity in rats dosed orally and in rats dosed intravenously with ABT is 58.5% and 0.7%, respectively (%F = 2.3% w/o ABT). The approximately 80-fold difference between the two groups suggests the majority of the extraction occurs in the intestine following an oral dose. To further study the utility of ABT, the antihistamine fexofenadine (Fex), which is not significantly metabolized and is a substrate for the uptake and efflux transporters, OATP and P-gp, was tested in rat. There was no change in oral or systemic exposure of Fex when animals were predosed with ABT, suggesting that ABT does not affect these transporters. These findings may lead to a better understanding of the interdependent role of absorption and metabolism and the specificity of ABT. This method should have utility in drug discovery for the identification of factors limiting oral bioavailability.


Assuntos
Inibidores das Enzimas do Citocromo P-450 , Intestinos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Triazóis/farmacologia , Triazóis/farmacocinética , Administração Oral , Animais , Área Sob a Curva , Disponibilidade Biológica , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Injeções Intravenosas , Intestinos/enzimologia , Fígado/enzimologia , Masculino , Ratos , Ratos Sprague-Dawley , Triazóis/administração & dosagem
12.
Drug Metab Dispos ; 33(11): 1621-7, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16049128

RESUMO

Human liver microsomes are a reagent commonly used to predict human hepatic clearance of new chemical entities via phase 1 metabolism. Another common metabolic pathway, glucuronidation, can also be observed in human liver microsomes, although the scalability of this process has not been validated. In fact, several groups have demonstrated that clearance estimated from liver microsomes with UDP-glucuronic acid typically underpredicts the actual in vivo clearance more than 10-fold for compounds that are predominantly glucuronidated. In contrast, clearance predicted using human hepatocytes, for these same compounds, provides a more accurate assessment of in vivo clearance. We sought to characterize the kinetics of glucuronidation of the selective UGT2B7 substrate AZT (3'-azido-3'-deoxythymidine), a selective UGT2B7 substrate, in human liver microsomes (HLMs), recombinant UGT2B7, and human hepatocytes. Apparent Km values in these three preparations were 760, 490, and 87 microM with apparent Vmax values highest in hepatocytes. The IC50 for ibuprofen against AZT glucuronidation, when run at its Km concentration in HLMs and hepatocytes, was 975 and 170 microM respectively. Since incubation conditions have been shown to modulate glucuronidation rates, AZT glucuronidation was performed in various physiological and nonphysiological buffer systems, namely Tris, phosphate, sulfate, carbonate, acetate, human plasma, deproteinized human liver cytosol, and Williams E medium. The data showed that carbonate and Williams E medium, more physiologically relevant buffers, yielded the highest rates of AZT glucuronidation. Km observed in HLM/carbonate was 240 microM closer to that found in hepatocytes, suggesting that matrix differences might cause the kinetic differences observed between liver preparations. Caution should be exercised when extrapolating metabolic lability via glucuronidation or inhibition of UGT enzymes from human liver microsomes, since this system appears to underpredict the degree of lability or inhibition, respectively, due in part to an apparent decrease in substrate affinity.


Assuntos
Glucuronidase/metabolismo , Glucuronosiltransferase/metabolismo , Hepatócitos/metabolismo , Microssomos Hepáticos/metabolismo , Zidovudina/metabolismo , Soluções Tampão , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/farmacologia , Glucuronosiltransferase/antagonistas & inibidores , Humanos , Ibuprofeno/farmacologia , Técnicas In Vitro , Cinética , Proteínas Recombinantes/metabolismo , Reprodutibilidade dos Testes
14.
Science ; 302(5646): 875-8, 2003 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-14593182

RESUMO

Because of its requirement for signaling by multiple cytokines, Janus kinase 3 (JAK3) is an excellent target for clinical immunosuppression. We report the development of a specific, orally active inhibitor of JAK3, CP-690,550, that significantly prolonged survival in a murine model of heart transplantation and in cynomolgus monkeys receiving kidney transplants. CP-690,550 treatment was not associated with hypertension, hyperlipidemia, or lymphoproliferative disease. On the basis of these preclinical results, we believe JAK3 blockade by CP-690,550 has potential for therapeutically desirable immunosuppression in human organ transplantation and in other clinical settings.


Assuntos
Rejeição de Enxerto/prevenção & controle , Transplante de Coração , Imunossupressores/farmacologia , Transplante de Rim , Proteínas Tirosina Quinases/antagonistas & inibidores , Pirimidinas/farmacologia , Pirróis/farmacologia , Animais , Inibidores Enzimáticos/administração & dosagem , Inibidores Enzimáticos/farmacologia , Inibidores Enzimáticos/uso terapêutico , Inibidores Enzimáticos/toxicidade , Regulação da Expressão Gênica/efeitos dos fármacos , Sobrevivência de Enxerto/efeitos dos fármacos , Humanos , Imunossupressores/administração & dosagem , Imunossupressores/uso terapêutico , Imunossupressores/toxicidade , Interleucina-2/imunologia , Janus Quinase 3 , Ativação Linfocitária/efeitos dos fármacos , Contagem de Linfócitos , Teste de Cultura Mista de Linfócitos , Subpopulações de Linfócitos/efeitos dos fármacos , Macaca fascicularis , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Miocárdio/metabolismo , Piperidinas , Proteínas Tirosina Quinases/metabolismo , Pirimidinas/administração & dosagem , Pirimidinas/uso terapêutico , Pirimidinas/toxicidade , Pirróis/administração & dosagem , Pirróis/uso terapêutico , Pirróis/toxicidade , Transplante Heterotópico , Transplante Homólogo , Células Tumorais Cultivadas
15.
Drug Metab Dispos ; 30(10): 1087-93, 2002 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-12228184

RESUMO

Liver microsomes, and more recently cryopreserved hepatocytes, are commonly used in the in vitro characterization of the metabolism of new xenobiotics. The flavin-containing monooxygenases (FMO) are a major non p450 oxidase present in liver microsomes and hepatocytes. Since FMO is known to be thermally labile, and this enzyme may be involved in the metabolic clearance of some drugs, we sought to more completely characterize the metabolic competency of this enzyme in cryopreserved hepatocytes and in liver microsomes preincubated under various conditions using benzydamine as an in vitro and in vivo probe. The metabolism of benzydamine to its major metabolite, the N-oxide, is mediated by FMO3 in humans. We found that the in vitro microsomal t(1/2) was 70% longer when incubations were prewarmed at 37 degrees C in the absence of NADPH compared with prewarming in the presence of an NADPH-regenerating system, and N-oxide formation was inhibited >99%. Interestingly, the in vivo clearance predicted from these incubations and from human hepatocytes overpredicted the observed clearance of benzydamine in humans (>10.5 versus 2.4 ml/min/kg). In contrast, rat hepatocytes successfully predicted rat in vivo benzydamine clearance to within approximately 30% (>68 versus 48 ml/min/kg). Benzydamine N-oxidation in liver microsomes from all common preclinical species demonstrated heat sensitivity. This information should be considered when extrapolating metabolism data of xenobiotics from these in vitro systems.


Assuntos
Benzidamina/metabolismo , Hepatócitos/enzimologia , Microssomos Hepáticos/enzimologia , Oxigenases/metabolismo , Animais , Benzidamina/química , Biotransformação/efeitos dos fármacos , Biotransformação/fisiologia , Cães , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/fisiologia , Humanos , Macaca fascicularis , Taxa de Depuração Metabólica/efeitos dos fármacos , Taxa de Depuração Metabólica/fisiologia , Camundongos , Ratos , Ratos Sprague-Dawley
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