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Ritlecitinib is an oral once-daily irreversible inhibitor of Janus kinase 3 and tyrosine-protein kinase family being developed for the treatment of moderate-to-severe alopecia areata. This study examined the disposition of ritlecitinib in male participants following oral and intravenous administration using accelerator mass spectroscopy methodology to estimate pharmacokinetic parameters and characterize metabolite profiles. The results indicated ritlecitinib had a systemic clearance of 43.7 L/h, a steady state volume of distribution of 73.8 L, extent of absorption of 89%, time to maximum plasma concentration of ~0.5 hour, and absolute oral bioavailability of 64%. An observed long terminal half-life of total radioactivity was primarily attributed to ritlecitinib binding to plasma albumin. Ritlecitinib was the main circulating drug species in plasma (~30%) with one major pharmacologically inactive cysteine conjugated metabolite (M2) at >10%. Oxidative metabolism (fractional clearance 0.47) and glutathione related conjugation (fractional clearance 0.24) were the primary routes of elimination for ritlecitinib with the greatest disposition of radioactivity shown in the urine (~71%). In vitro phenotyping indicated ritlecitinib cytochrome P450 fraction of metabolism assignments of 0.29 for CYP3A, 0.09 for CYP2C8, 0.07 for CYP1A2, and 0.02 for CYP2C9. In vitro phenotyping in recombinant human glutathione S-transferases indicated ritlecitinib was turned over by a number of cytosolic and microsomal enzyme isoforms. Significance Statement This study provides a detailed understanding of the disposition and metabolism of ritlecitinib, a JAK3 and TEC family kinase inhibitor for alopecia areata, in humans, as well as characterization of clearance pathways and PK of ritlecitinib and its metabolites. As an AMS-based ADME study design, we have expanded on reporting the standard ADME endpoints, providing key pharmacokinetic parameters like clearance, volume of distribution and bioavailability allowing for a more comprehensive understanding of drug disposition.
RESUMEN
There is a growing incidence of heat-related illnesses due to rising global temperatures. Heat-related illnesses range from mild to severe, with heat stroke being the most critical. The wet bulb global temperature index considers humidity and solar intensity; its use is recommended to estimate heat stress on an individual and mitigate risk. Efficient cooling methods, such as cold water immersion, are essential in severe cases. Prevention is through hydration, appropriate clothing, recognition of high risk medications, and awareness of environmental conditions. Recognizing heat-related illnesses early in the clinical course and implementing rapid cooling strategies reduces morbidity and mortality.
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Trastornos de Estrés por Calor , Humanos , Trastornos de Estrés por Calor/terapia , Trastornos de Estrés por Calor/diagnóstico , CalorRESUMEN
OBJECTIVE: The aim of this study was to evaluate whether dimensions of sleep quality were associated with homeostatic and hedonic eating behaviors among children with healthy weight (BMI-for-age < 90%) but varying maternal weight status. METHODS: A total of 77 children (mean [SD], age: 7.4 [0.6] years; BMI z score: -0.10 [0.7]) with healthy weight and high (n = 32) or low (n = 45) familial obesity risk based on maternal weight status were served an ad libitum meal (homeostatic eating) followed by palatable snacks to assess eating in the absence of hunger (EAH; hedonic eating). Habitual sleep quality was quantified from seven nights of wrist actigraphy. Partial correlations, adjusted for child energy needs, pre-meal hunger, food liking, and socioeconomic status, evaluated associations of sleep with meal intake and EAH. Additionally, sleep-by-obesity risk interactions were assessed. RESULTS: Greater sleep fragmentation was associated with higher homeostatic meal energy intake, but only among children at high familial obesity risk (p value for interaction = 0.001; ß high risk = 48.6, p = 0.001). Sleep fragmentation was not associated with total EAH but was related to higher and lower intake of carbohydrates (r = 0.33, p = 0.003) and fat (r = -0.33, p = 0.003), respectively. CONCLUSIONS: Adverse associations of poor sleep with energy intake may be amplified among children already predisposed to obesity. Furthermore, that fragmented sleep relates to preferential intake of carbohydrates over fat during EAH may suggest alterations in taste preferences with poor sleep.
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Predisposición Genética a la Enfermedad , Calidad del Sueño , Humanos , Niño , Conducta Alimentaria , Obesidad/genética , Ingestión de Energía , Hambre , Ingestión de AlimentosRESUMEN
This cross-sectional study was conducted as an experiential project in a graduate Program Evaluation class. We worked together as a team to solve difficulties that occurred when evaluating a program for the first time, including overcoming initial fears and identifying the appropriate focus. The goal of this study was to identify the most common barriers to attendance at Bridgehaven Mental Health Services, a community-based outpatient program tailored to aid in the transition from hospitals to community living. External barriers to attendance were examined by an adapted version of the Structural Barriers to Clinic Attendance Scale (SCBA) and a researcher-created qualitative measure. Between-group t-tests and non-parametric analyses indicated that a far walk from the bus stop and negative perceptions of staff behavior were significant external barriers to Bridgehaven attendance among 42 adult members with severe mental illness. Additionally, themes from the qualitative data revealed that 74.7% of members viewed other obligations and appointments as barriers to their attendance. About half of the members surveyed indicated the positive impact of groups on attendance. Overall findings revealed the importance of considering external barriers, particularly issues related to transportation, scheduling, and social perceptions when identifying solutions to declining attendance rates. Through the process of conducting this study, we learned invaluable skills (e.g., problem-solving, teamwork, collaboration, and flexibility) that will carry with us as we evaluate programs in the future.
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Aprendizaje , Aprendizaje Basado en Problemas , Adulto , Humanos , Estudios Transversales , Encuestas y Cuestionarios , MotivaciónRESUMEN
Discovery efforts leading to the identification of ervogastat (PF-06865571), a systemically acting diacylglycerol acyltransferase (DGAT2) inhibitor that has advanced into clinical trials for the treatment of non-alcoholic steatohepatitis (NASH) with liver fibrosis, are described herein. Ervogastat is a first-in-class DGAT2 inhibitor that addressed potential development risks of the prototype liver-targeted DGAT2 inhibitor PF-06427878. Key design elements that culminated in the discovery of ervogastat are (1) replacement of the metabolically labile motif with a 3,5-disubstituted pyridine system, which addressed potential safety risks arising from a cytochrome P450-mediated O-dearylation of PF-06427878 to a reactive quinone metabolite precursor, and (2) modifications of the amide group to a 3-THF group, guided by metabolite identification studies coupled with property-based drug design.
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Diacilglicerol O-Acetiltransferasa , Enfermedad del Hígado Graso no Alcohólico , Humanos , Diseño de Fármacos , Cirrosis Hepática , Enfermedad del Hígado Graso no Alcohólico/tratamiento farmacológicoRESUMEN
Abrocitinib is an oral once-daily Janus kinase 1 selective inhibitor being developed for the treatment of moderate-to-severe atopic dermatitis. This study examined the disposition of abrocitinib in male participants following oral and intravenous administration using accelerator mass spectroscopy methodology to estimate pharmacokinetic parameters and characterize metabolite (M) profiles. The results indicated abrocitinib had a systemic clearance of 64.2 L/h, a steady-state volume of distribution of 100 L, extent of absorption >90%, time to maximum plasma concentration of â¼0.5 hours, and absolute oral bioavailability of 60%. The half-life of both abrocitinib and total radioactivity was similar, with no indication of metabolite accumulation. Abrocitinib was the main circulating drug species in plasma (â¼26%), with 3 major monohydroxylated metabolites (M1, M2, and M4) at >10%. Oxidative metabolism was the primary route of elimination for abrocitinib, with the greatest disposition of radioactivity shown in the urine (â¼85%). In vitro phenotyping indicated abrocitinib cytochrome P450 fraction of metabolism assignments of 0.53 for CYP2C19, 0.30 for CYP2C9, 0.11 for CYP3A4, and â¼0.06 for CYP2B6. The principal systemic metabolites M1, M2, and M4 were primarily cleared renally. Abrocitinib, M1, and M2 showed pharmacology with similar Janus kinase 1 selectivity, whereas M4 was inactive. SIGNIFICANCE STATEMENT: This study provides a detailed understanding of the disposition and metabolism of abrocitinib, a Janus kinase inhibitor for atopic dermatitis, in humans, as well as characterization of clearance pathways and pharmacokinetics of abrocitinib and its metabolites.
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Dermatitis Atópica , Inhibidores de las Cinasas Janus , Pirimidinas , Sulfonamidas , Administración Oral , Dermatitis Atópica/tratamiento farmacológico , Humanos , Janus Quinasa 1/antagonistas & inhibidores , Inhibidores de las Cinasas Janus/administración & dosificación , Inhibidores de las Cinasas Janus/farmacocinética , Inhibidores de las Cinasas Janus/farmacología , Masculino , Pirimidinas/administración & dosificación , Pirimidinas/farmacocinética , Pirimidinas/farmacología , Sulfonamidas/administración & dosificación , Sulfonamidas/farmacocinética , Sulfonamidas/farmacologíaRESUMEN
Ongoing interest in the discovery of selective JAK3 inhibitors led us to design novel covalent inhibitors that engage the JAK3 residue Cys909 by cyanamide, a structurally and mechanistically differentiated electrophile from other cysteine reacting groups previously incorporated in JAK3 covalent inhibitors. Through crystallography, kinetic, and computational studies, interaction of cyanamide 12 with Cys909 was optimized leading to potent and selective JAK3 inhibitors as exemplified by 32. In relevant cell-based assays and in agreement with previous results from this group, 32 demonstrated that selective inhibition of JAK3 is sufficient to drive JAK1/JAK3-mediated cellular responses. The contribution from extrahepatic processes to the clearance of cyanamide-based covalent inhibitors was also characterized using metabolic and pharmacokinetic data for 12. This work also gave key insights into a productive approach to decrease glutathione/glutathione S-transferase-mediated clearance, a challenge typically encountered during the discovery of covalent kinase inhibitors.
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Cianamida/química , Cianamida/farmacología , Janus Quinasa 3/antagonistas & inhibidores , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/farmacología , Animales , Cianamida/farmacocinética , Evaluación Preclínica de Medicamentos , Humanos , Concentración 50 Inhibidora , Janus Quinasa 3/química , Masculino , Modelos Moleculares , Conformación Proteica , Inhibidores de Proteínas Quinasas/farmacocinética , Ratas , Distribución TisularRESUMEN
A novel series of morpholine-based nonsteroidal mineralocorticoid receptor antagonists is reported. Starting from a pyrrolidine HTS hit 9 that possessed modest potency but excellect selectivity versus related nuclear hormone receptors, a series of libraries led to identification of morpholine lead 10. After further optimization, cis disubstituted morpholine 22 was discovered, which showed a 45-fold boost in binding affinity and corresponding functional potency compared to 13. While 22 had high clearance in rat, it provided sufficient exposure at high doses to favorably assess in vivo efficacy (increased urinary Na+/K+ ratio) and safety. In contrast to rat, the dog and human MetID and PK profiles of 22 were adequate, suggesting that it could be suitable as a potential clinical asset.
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Antagonistas de Receptores de Mineralocorticoides/química , Antagonistas de Receptores de Mineralocorticoides/farmacología , Morfolinos/química , Morfolinos/farmacología , Oxazinas/química , Receptores de Mineralocorticoides/metabolismo , Animales , Ensayos Clínicos Fase I como Asunto , Evaluación Preclínica de Medicamentos , Femenino , Humanos , Concentración 50 Inhibidora , Modelos Moleculares , Conformación Proteica , Ratas , Ratas Wistar , Receptores de Mineralocorticoides/química , Relación Estructura-ActividadRESUMEN
PF-06651600, a newly discovered potent JAK3-selective inhibitor, is highly efficacious at inhibiting γc cytokine signaling, which is dependent on both JAK1 and JAK3. PF-06651600 allowed the comparison of JAK3-selective inhibition to pan-JAK or JAK1-selective inhibition, in relevant immune cells to a level that could not be achieved previously without such potency and selectivity. In vitro, PF-06651600 inhibits Th1 and Th17 cell differentiation and function, and in vivo it reduces disease pathology in rat adjuvant-induced arthritis as well as in mouse experimental autoimmune encephalomyelitis models. Importantly, by sparing JAK1 function, PF-06651600 selectively targets γc cytokine pathways while preserving JAK1-dependent anti-inflammatory signaling such as the IL-10 suppressive functions following LPS treatment in macrophages and the suppression of TNFα and IL-1ß production in IL-27-primed macrophages. Thus, JAK3-selective inhibition differentiates from pan-JAK or JAK1 inhibition in various immune cellular responses, which could potentially translate to advantageous clinical outcomes in inflammatory and autoimmune diseases.
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Artritis Experimental/tratamiento farmacológico , Encefalomielitis Autoinmune Experimental/tratamiento farmacológico , Janus Quinasa 3/antagonistas & inhibidores , Inhibidores de Proteínas Quinasas/uso terapéutico , Pirimidinas/uso terapéutico , Pirroles/uso terapéutico , Animales , Artritis Experimental/inmunología , Modelos Animales de Enfermedad , Descubrimiento de Drogas , Encefalomielitis Autoinmune Experimental/inmunología , Humanos , Interleucina-10/inmunología , Interleucina-1beta/inmunología , Janus Quinasa 1/antagonistas & inhibidores , Janus Quinasa 1/metabolismo , Janus Quinasa 3/metabolismo , Macrófagos/citología , Macrófagos/efectos de los fármacos , Macrófagos/inmunología , Ratones , Modelos Moleculares , Inhibidores de Proteínas Quinasas/farmacocinética , Inhibidores de Proteínas Quinasas/farmacología , Pirimidinas/farmacocinética , Pirimidinas/farmacología , Pirroles/farmacocinética , Pirroles/farmacología , Ratas , Células TH1/citología , Células TH1/efectos de los fármacos , Células TH1/inmunología , Células Th17/citología , Células Th17/efectos de los fármacos , Células Th17/inmunología , Factor de Necrosis Tumoral alfa/inmunologíaRESUMEN
N-Methyl-2-[3-((E)-2-pyridin-2-yl-vinyl)-1H-indazol-6-ylsulfanyl]-benzamide (axitinib) is an oral inhibitor of vascular endothelial growth factor receptors 1-3, which is approved for the treatment of advanced renal cell cancer. Human [(14)C]-labeled clinical studies indicate axitinib's primary route of clearance is metabolism. The aims of the in vitro experiments presented herein were to identify and characterize the enzymes involved in axitinib metabolic clearance. In vitro biotransformation studies of axitinib identified a number of metabolites including an axitinib sulfoxide, several less abundant oxidative metabolites, and glucuronide conjugates. The most abundant NADPH- and UDPGA-dependent metabolites, axitinib sulfoxide (M12) and axitinib N-glucuronide (M7) were selected for phenotyping and kinetic study. Phenotyping experiments with human liver microsomes (HLMs) using chemical inhibitors and recombinant human cytochrome P450s demonstrated axitinib was predominately metabolized by CYP3A4/5, with minor contributions from CYP2C19 and CYP1A2. The apparent substrate concentration at half-maximal velocity (Km) and Vmax values for the formation of axitinib sulfoxide by CYP3A4 or CYP3A5 were 4.0 or 1.9 µM and 9.6 or 1.4 pmol·min(-1)·pmol(-1), respectively. Using a CYP3A4-specific inhibitor (Cyp3cide) in liver microsomes expressing CYP3A5, 66% of the axitinib intrinsic clearance was attributable to CYP3A4 and 15% to CYP3A5. Axitinib N-glucuronidation was primarily catalyzed by UDP-glucuronosyltransferase (UGT) UGT1A1, which was verified by chemical inhibitors and UGT1A1 null expressers, with lesser contributions from UGTs 1A3, 1A9, and 1A4. The Km and Vmax values describing the formation of the N-glucuronide in HLM or rUGT1A1 were 2.7 µM or 0.75 µM and 8.9 or 8.3 pmol·min(-1)·mg(-1), respectively. In summary, CYP3A4 is the major enzyme involved in axitinib clearance with lesser contributions from CYP3A5, CYP2C19, CYP1A2, and UGT1A1.
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Inhibidores de la Angiogénesis/metabolismo , Citocromo P-450 CYP3A/metabolismo , Glucuronosiltransferasa/metabolismo , Imidazoles/metabolismo , Indazoles/metabolismo , Microsomas Hepáticos/enzimología , Inhibidores de Proteínas Quinasas/metabolismo , Axitinib , Citocromo P-450 CYP1A2/metabolismo , Citocromo P-450 CYP2C19/metabolismo , Citocromo P-450 CYP3A/genética , Inhibidores Enzimáticos del Citocromo P-450/farmacología , Femenino , Genotipo , Glucurónidos/metabolismo , Glucuronosiltransferasa/genética , Humanos , Inactivación Metabólica , Cinética , Masculino , Tasa de Depuración Metabólica , Microsomas Hepáticos/efectos de los fármacos , Modelos Biológicos , Oxidación-Reducción , Fenotipo , Proteínas Recombinantes/metabolismo , Especificidad por Sustrato , Sulfóxidos/metabolismoRESUMEN
The contribution of drug metabolites to the pharmacologic and toxicologic activity of a drug can be important; however, for a variety of reasons metabolites can frequently be difficult to synthesize. To meet the need of having samples of drug metabolites for further study, we have developed biosynthetic methods coupled with quantitative NMR spectroscopy (qNMR) to generate solutions of metabolites of known structure and concentration. These quantitative samples can be used in a variety of ways when a synthetic sample is unavailable, including pharmacologic assays, standards for in vitro work to help establish clearance pathways, and/or as analytical standards for bioanalytical work to ascertain exposure, among others. We illustrate five examples of metabolite biosynthesis and qNMR. The types of metabolites include one glucuronide and four oxidative products. Concentrations of the isolated metabolite stock solutions ranged from 0.048 to 8.3 mM, with volumes from approximately 0.04 to 0.150 ml in hexadeutarated dimethylsulfoxide. These specific quantified isolates were used as standards in the drug discovery setting as substrates in pharmacology assays, for bioanalytical assays to establish exposure, and in variety of routine absorption, distribution, metabolism, and excretion assays, such as protein binding and determining blood-to-plasma ratios. The methods used to generate these materials are described in detail with the objective that these methods can be generally used for metabolite biosynthesis and isolation.
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Espectroscopía de Resonancia Magnética/métodos , Microsomas Hepáticos/metabolismo , Preparaciones Farmacéuticas/metabolismo , Farmacología/métodos , Estándares de Referencia , Biotransformación , Femenino , Humanos , Masculino , Estructura Molecular , Preparaciones Farmacéuticas/químicaRESUMEN
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.
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Aminoácidos Neutros/farmacología , Carbamatos/farmacología , Carboxilesterasa/antagonistas & inhibidores , Hidrolasas de Éster Carboxílico/antagonistas & inhibidores , Diseño de Fármacos , Hígado/efectos de los fármacos , Aminoácidos Neutros/síntesis química , Aminoácidos Neutros/química , Carbamatos/síntesis química , Carbamatos/química , Carboxilesterasa/metabolismo , Hidrolasas de Éster Carboxílico/metabolismo , Relación Dosis-Respuesta a Droga , Humanos , Hígado/enzimología , Estructura Molecular , Relación Estructura-ActividadRESUMEN
The United States Public Health Service Administration is alerting medical professionals that a substantial percentage of cocaine imported into the United States is adulterated with levamisole, a veterinary pharmaceutical that can cause blood cell disorders such as severe neutropenia and agranulocytosis. Levamisole was previously approved in combination with fluorouracil for the treatment of colon cancer; however, the drug was withdrawn from the U.S. market in 2000 because of the frequent occurrence of agranulocytosis. The detection of autoantibodies such as antithrombin (lupus anticoagulant) and an increased risk of agranulocytosis in patients carrying the human leukocyte antigen B27 genotype suggest that toxicity is immune-mediated. In this perspective, we provide an historical account of the levamisole/cocaine story as it first surfaced in 2008, including a succinct review of levamisole pharmacology, pharmacokinetics, and preclinical/clinical evidence for levamisole-induced agranulocytosis. Based on the available information on levamisole metabolism in humans, we propose that reactive metabolite formation is the rate-limiting step in the etiology of agranulocytosis associated with levamisole, in a manner similar to other drugs (e.g., propylthiouracil, methimazole, captopril, etc.) associated with blood dyscrasias. Finally, considering the toxicity associated with levamisole, we propose that the 2,3,5,6-tetrahydroimidazo[2,1-b]thiazole scaffold found in levamisole be categorized as a new structural alert, which is to be avoided in drug design.
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Agranulocitosis/inducido químicamente , Agranulocitosis/inmunología , Agranulocitosis/metabolismo , Cocaína/metabolismo , Contaminación de Medicamentos , Levamisol/metabolismo , Animales , Cocaína/química , Cocaína/envenenamiento , Humanos , Levamisol/química , Levamisol/envenenamiento , Estados Unidos , United States Public Health Service/legislación & jurisprudencia , Drogas Veterinarias/química , Drogas Veterinarias/metabolismo , Drogas Veterinarias/envenenamientoRESUMEN
The measurement of the effect of new chemical entities on human UDP-glucuronosyltransferase (UGT) marker activities using in vitro experimentation represents an important experimental approach in drug development to guide clinical drug-interaction study designs or support claims that no in vivo interaction will occur. Selective high-performance liquid chromatography-tandem mass spectrometry functional assays of authentic glucuronides for five major hepatic UGT probe substrates were developed: ß-estradiol-3-glucuronide (UGT1A1), trifluoperazine-N-glucuronide (UGT1A4), 5-hydroxytryptophol-O-glucuronide (UGT1A6), propofol-O-glucuronide (UGT1A9), and zidovudine-5'-glucuronide (UGT2B7). High analytical sensitivity permitted characterization of enzyme kinetic parameters at low human liver microsomal and recombinant UGT protein concentration (0.025 mg/ml), which led to a new recommended optimal universal alamethicin activation concentration of 10 µg/ml for microsomes. Alamethicin was not required for recombinant UGT incubations. Apparent enzyme kinetic parameters, particularly for UGT1A1 and UGT1A4, were affected by nonspecific binding. Unbound intrinsic clearance for UGT1A9 and UGT2B7 increased significantly after addition of 2% bovine serum albumin, with minimal changes for UGT1A1, UGT1A4, and UGT1A6. Eleven potential UGT and cytochrome P450 inhibitors were evaluated as UGT inhibitors, resulting in observation of nonselective UGT inhibition by chrysin, mefenamic acid, silibinin, tangeretin, ketoconazole, itraconazole, ritonavir, and verapamil. The pan-cytochrome P450 inhibitor, 1-aminobenzotriazole, minimally inhibited UGT activities and may be useful in reaction phenotyping of mixed UGT and cytochrome P450 substrates. These methods should prove useful in the routine assessments of the potential for new drug candidates to elicit pharmacokinetic drug interactions via inhibition of human UGT activities and the identification of UGT enzyme-selective chemical inhibitors.
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Alameticina/química , Descubrimiento de Drogas/métodos , Inhibidores Enzimáticos/farmacología , Glucurónidos/metabolismo , Glucuronosiltransferasa/antagonistas & inhibidores , Glucuronosiltransferasa/metabolismo , Cromatografía Líquida de Alta Presión , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/metabolismo , Glucuronosiltransferasa/genética , Humanos , Técnicas In Vitro , Microsomas Hepáticos/efectos de los fármacos , Microsomas Hepáticos/enzimología , Microsomas Hepáticos/metabolismo , Estructura Molecular , Unión Proteica , Albúmina Sérica Bovina/farmacología , Especificidad por Sustrato , Espectrometría de Masas en TándemRESUMEN
Backbone N-methylation is common among peptide natural products and has a substantial impact on both the physical properties and the conformational states of cyclic peptides. However, the specific impact of N-methylation on passive membrane diffusion in cyclic peptides has not been investigated systematically. Here we report a method for the selective, on-resin N-methylation of cyclic peptides to generate compounds with drug-like membrane permeability and oral bioavailability. The selectivity and degree of N-methylation of the cyclic peptide was dependent on backbone stereochemistry, suggesting that conformation dictates the regiochemistry of the N-methylation reaction. The permeabilities of the N-methyl variants were corroborated by computational studies on a 1,024-member virtual library of N-methyl cyclic peptides. One of the most permeable compounds, a cyclic hexapeptide (molecular mass = 755 Da) with three N-methyl groups, showed an oral bioavailability of 28% in rat.
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Péptidos Cíclicos/metabolismo , Péptidos Cíclicos/farmacocinética , Animales , Disponibilidad Biológica , Química Farmacéutica , Técnicas Químicas Combinatorias , Simulación por Computador , Descubrimiento de Drogas/métodos , Masculino , Metilación , Estructura Molecular , Péptidos Cíclicos/química , Ratas , Relación Estructura-ActividadRESUMEN
Because of a preconceived notion that eliminating reactive metabolite (RM) formation with new drug candidates could mitigate the risk of idiosyncratic drug toxicity, the potential for RM formation is routinely examined as part of lead optimization efforts in drug discovery. Likewise, avoidance of "structural alerts" is almost a norm in drug design. However, there is a growing concern that the perceived safety hazards associated with structural alerts and/or RM screening tools as standalone predictors of toxicity risks may be over exaggerated. In addition, the multifactorial nature of idiosyncratic toxicity is now well recognized based upon observations that mechanisms other than RM formation (e.g., mitochondrial toxicity and inhibition of bile salt export pump (BSEP)) also can account for certain target organ toxicities. Hence, fundamental questions arise such as: When is a molecule that contains a structural alert (RM positive or negative) a cause for concern? Could the molecule in its parent form exert toxicity? Can a low dose drug candidate truly mitigate metabolism-dependent and -independent idiosyncratic toxicity risks? In an effort to address these questions, we have retrospectively examined 68 drugs (recalled or associated with a black box warning due to idiosyncratic toxicity) and the top 200 drugs (prescription and sales) in the United States in 2009 for trends in physiochemical characteristics, daily doses, presence of structural alerts, evidence for RM formation as well as toxicity mechanism(s) potentially mediated by parent drugs. Collectively, our analysis revealed that a significant proportion (â¼78-86%) of drugs associated with toxicity contained structural alerts and evidence indicating that RM formation as a causative factor for toxicity has been presented in 62-69% of these molecules. In several cases, mitochondrial toxicity and BSEP inhibition mediated by parent drugs were also noted as potential causative factors. Most drugs were administered at daily doses exceeding several hundred milligrams. There was no obvious link between idiosyncratic toxicity and physicochemical properties such as molecular weight, lipophilicity, etc. Approximately half of the top 200 drugs for 2009 (prescription and sales) also contained one or more alerts in their chemical architecture, and many were found to be RM-positive. Several instances of BSEP and mitochondrial liabilities were also noted with agents in the top 200 category. However, with relatively few exceptions, the vast majority of these drugs are rarely associated with idiosyncratic toxicity, despite years of patient use. The major differentiating factor appeared to be the daily dose; most of the drugs in the top 200 list are administered at low daily doses. In addition, competing detoxication pathways and/or alternate nonmetabolic clearance routes provided suitable justifications for the safety records of RM-positive drugs in the top 200 category. Thus, while RM elimination may be a useful and pragmatic starting point in mitigating idiosyncratic toxicity risks, our analysis suggests a need for a more integrated screening paradigm for chemical hazard identification in drug discovery. Thus, in addition to a detailed assessment of RM formation potential (in relationship to the overall elimination mechanisms of the compound(s)) for lead compounds, effects on cellular health (e.g., cytotoxicity assays), BSEP inhibition, and mitochondrial toxicity are the recommended suite of assays to characterize compound liabilities. However, the prospective use of such data in compound selection will require further validation of the cellular assays using marketed agents. Until we gain a better understanding of the pathophysiological mechanisms associated with idiosyncratic toxicities, improving pharmacokinetics and intrinsic potency as means of decreasing the dose size and the associated "body burden" of the parent drug and its metabolites will remain an overarching goal in drug discovery.
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Descubrimiento de Drogas/métodos , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/metabolismo , Preparaciones Farmacéuticas/química , Preparaciones Farmacéuticas/metabolismo , Animales , Recall de Medicamento , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/epidemiología , Humanos , Estados Unidos/epidemiologíaRESUMEN
The synthesis and structure-activity relationship studies on 5-trifluoromethylpyrido[4,3-d]pyrimidin-4(3H)-ones as antagonists of the human calcium receptor (CaSR) have been recently disclosed [ Didiuk et al. ( 2009 ) Bioorg. Med. Chem. Lett. 19 , 4555 - 4559 ). On the basis of its pharmacology and disposition attributes, (R)-2-(2-hydroxyphenyl)-3-(1-phenylpropan-2-yl)-5-(trifluoromethyl)pyrido[4,3-d]pyrimidin-4(3H)-one (1) was considered for rapid advancement to first-in-human (FIH) trials to mitigate uncertainty surrounding the pharmacokinetic/pharmacodynamic (PK/PD) predictions for a short-acting bone anabolic agent. During the course of metabolic profiling, however, glutathione (GSH) conjugates of 1 were detected in human liver microsomes in an NADPH-dependent fashion. Characterization of the GSH conjugate structures allowed insight(s) into the bioactivation pathway, which involved CYP3A4-mediated phenol ring oxidation to the catechol, followed by further oxidation to the electrophilic ortho-quinone species. While the reactive metabolite (RM) liability raised concerns around the likelihood of a potential toxicological outcome, a more immediate program goal was establishing confidence in human PK predictions in the FIH study. Furthermore, the availability of a clinical biomarker (serum parathyroid hormone) meant that PD could be assessed side by side with PK, an ideal scenario for a relatively unprecedented pharmacologic target. Consequently, progressing 1 into the clinic was given a high priority, provided the compound demonstrated an adequate safety profile to support FIH studies. Despite forming identical RMs in rat liver microsomes, no clinical or histopathological signs prototypical of target organ toxicity were observed with 1 in in vivo safety assessments in rats. Compound 1 was also devoid of metabolism-based mutagenicity in in vitro (e.g., Salmonella Ames) and in vivo assessments (micronuclei induction in bone marrow) in rats. Likewise, metabolism-based studies (e.g., evaluation of detoxicating routes of clearance and exhaustive PK/PD studies in animals to prospectively predict the likelihood of a low human efficacious dose) were also conducted, which mitigated the risks of idiosyncratic toxicity to a large degree. In parallel, medicinal chemistry efforts were initiated to identify additional compounds with a complementary range of human PK predictions, which would maximize the likelihood of achieving the desired PD effect in the clinic. The back-up strategy also incorporated an overarching goal of reducing/eliminating reactive metabolite formation observed with 1. Herein, the collective findings from our discovery efforts in the CaSR program, which include the incorporation of appropriate derisking steps when dealing with RM issues are summarized.
Asunto(s)
Anabolizantes/química , Anabolizantes/metabolismo , Osteoporosis/tratamiento farmacológico , Piridinas/química , Piridinas/metabolismo , Pirimidinonas/química , Pirimidinonas/metabolismo , Receptores Sensibles al Calcio/antagonistas & inhibidores , Anabolizantes/efectos adversos , Animales , Cristalografía por Rayos X , Humanos , Piridinas/efectos adversos , Pirimidinonas/efectos adversos , RatasRESUMEN
As part of a strategy to deliver short-acting calcium-sensing receptor (CaSR) antagonists, the metabolically labile thiomethyl functionality was incorporated into the zwitterionic amino alcohol derivative 3 with the hope of increasing human clearance through oxidative metabolism, while delivering a pharmacologically inactive sulfoxide metabolite. The effort led to the identification of thioanisoles 22 and 23 as potent and orally active CaSR antagonists with a rapid onset of action and short pharmacokinetic half-lives, which led to a rapid and transient stimulation of parathyroid hormone in a dose-dependent fashion following oral administration to rats. On the basis of the balance between target pharmacology, safety, and human disposition profiles, 22 and 23 were advanced as clinical candidates for the treatment of osteoporosis.
RESUMEN
The design and profile of a series of zwitterionic calcium sensing receptor negative allosteric modulators is described. Evaluation of key analogues using a rat model demonstrate a robust response, significantly improved potency over ronacaleret and have the potential as an oral, anabolic treatment for osteoporosis.