RESUMO
Selective activation of the M4 muscarinic acetylcholine receptor subtype offers a novel strategy for the treatment of psychosis in multiple neurological disorders. Although the development of traditional muscarinic activators has been stymied due to pan-receptor activation, muscarinic receptor subtype selectivity can be achieved through the utilization of a subtype of a unique allosteric site. A major challenge in capitalizing on this allosteric site to date has been achieving a balance of suitable potency and brain penetration. Herein, we describe the design of a brain penetrant series of M4 selective positive allosteric modulators (PAMs), ultimately culminating in the identification of 21 (PF-06852231, now CVL-231/emraclidine), which is under active clinical development as a novel mechanism and approach for the treatment of schizophrenia.
Assuntos
Encéfalo , Desenho de Fármacos , Receptor Muscarínico M4 , Receptor Muscarínico M4/metabolismo , Receptor Muscarínico M4/agonistas , Regulação Alostérica/efeitos dos fármacos , Humanos , Animais , Encéfalo/metabolismo , Encéfalo/efeitos dos fármacos , Relação Estrutura-Atividade , Ratos , Cricetulus , Células CHO , Agonistas Muscarínicos/farmacologia , Agonistas Muscarínicos/síntese química , Agonistas Muscarínicos/química , Esquizofrenia/tratamento farmacológico , Esquizofrenia/metabolismoRESUMO
The ring strain present in azetidines can lead to undesired stability issues. Herein, we described a series of N-substituted azetidines which undergo an acid-mediated intramolecular ring-opening decomposition via nucleophilic attack of a pendant amide group. Studies were conducted to understand the decomposition mechanism enabling the design of stable analogues.
RESUMO
PF-06751979 is a selective inhibitor of the beta-site amyloid precursor protein cleaving enzyme-1, which is a key aspartyl protease in the generation of amyloid-ß (Aß) peptides, thought to be critical for the cerebral degeneration observed in Alzheimer's disease. Two Phase I studies (NCT02509117, NCT02793232) investigated the safety/tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of PF-06751979. Single-ascending doses up to 540âmg and multiple-ascending doses up to 275âmg once daily (QD) in healthy adults, and multiple doses of 50âmg or 125âmg QD in healthy older subjects were assessed. PF-06751979 was well tolerated at all doses given, and all treatment-related adverse events (AEs) were mild to moderate. PK parameters remained consistent across the PF-06751979 QD dosing regimens, and no notable food effects were observed. PD analysis showed that PF-06751979 reduced the cerebrospinal fluid (CSF) and plasma levels of Aß peptides in a dose-dependent manner, with the greatest reductions observed in subjects treated with 275âmg QD (approximately 92% and 93% reduction in CSF Aß1-40 and Aß1-42 observed at 24âh after Day 14 dose, respectively). A drug interaction study (NCT03126721) using midazolam indicated that there was no clinically meaningful effect of multiple doses of PF-06751979 100âmg QD on the PK of single-dose midazolam in healthy adults. Overall, these data suggest that PF-06751979 with daily dosing is favorable for further clinical development.
Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Peptídeos beta-Amiloides/antagonistas & inibidores , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Inibidores de Proteases , Piranos , Tiazinas , Tiazóis , Administração Oral , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Secretases da Proteína Precursora do Amiloide/sangue , Secretases da Proteína Precursora do Amiloide/líquido cefalorraquidiano , Peptídeos beta-Amiloides/sangue , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Ácido Aspártico Endopeptidases/sangue , Ácido Aspártico Endopeptidases/líquido cefalorraquidiano , Estudos Cross-Over , Método Duplo-Cego , Feminino , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Inibidores de Proteases/administração & dosagem , Inibidores de Proteases/efeitos adversos , Inibidores de Proteases/farmacocinética , Piranos/administração & dosagem , Piranos/efeitos adversos , Piranos/farmacocinética , Tiazinas/administração & dosagem , Tiazinas/efeitos adversos , Tiazinas/farmacocinética , Tiazóis/administração & dosagem , Tiazóis/efeitos adversos , Tiazóis/farmacocinética , Adulto JovemRESUMO
Palladium catalyzed hydrodefluorination was developed for fine-tuning the properties of fluoro-(hetero)aromatic compounds. The robust reaction can be set up in air, requires only commercially available components, and tolerates a variety of heterocycles and functionalities relevant to drug discovery. Given the prevalence of fluorine incorporation around metabolic hotspots, the corresponding deuterodefluorination reaction may prove useful for converting fluorinated libraries to deuterated analogues to suppress the oxidative metabolism by kinetic isotope effects.
RESUMO
ß-secretase 1 (BACE1) is a key enzyme in the generation of ß-amyloid, which is accumulated in the brain of Alzheimer disease patients. PF-06684511 was identified as a candidate PET ligand for imaging BACE1 in the brain and showed high specific binding in an initial assessment in a nonhuman primate (NHP) PET study using 18F-PF-06684511. In this effort, we aimed to quantitatively evaluate the regional brain distribution of 18F-PF-06684511 in NHPs under baseline and blocking conditions and to assess the target occupancy of BACE1 inhibitors. In addition, NHP whole-body PET measurements were performed to estimate the effective radiation dose. Methods: Initial brain PET measurements were performed at baseline and after oral administration of 5 mg/kg of LY2886721, a BACE1 inhibitor, in 2 cynomolgus monkeys. Kinetic analysis was performed with the radiometabolite-corrected plasma input function. In addition, a wide dose range of another BACE1 inhibitor, PF-06663195, was examined to investigate the relationship between the brain target occupancy and plasma concentration of the drug. Finally, the effective radiation dose of 18F-PF-06684511 was estimated on the basis of the whole-body PET measurements in NHPs. Results: Radiolabeling was accomplished successfully with an incorporation radiochemical yield of 4%-12% (decay-corrected) from 18F ion. The radiochemical purity was greater than 99%. The whole-brain uptake of 18F-PF-06684511 peaked (â¼220% SUV) at approximately 20 min and decreased thereafter (â¼100% SUV at 180 min). A 2-tissue-compartment model described the time-activity curves well. Pretreatment with LY2886721 reduced the total distribution volume of 18F-PF-06684511 by 48%-80% depending on the brain region, confirming its in vivo specificity. BACE1 occupancy of PF-06663195, estimated using the Lassen occupancy plot, showed a dose-dependent increase. The effective dose of 18F-PF-06684511 was 0.043 mSv/MBq for humans. Conclusion: 18F-PF-06684511 is the first successful PET radioligand for BACE1 brain imaging that demonstrates favorable in vivo binding and brain kinetics in NHPs.
Assuntos
Secretases da Proteína Precursora do Amiloide/metabolismo , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Radioisótopos de Flúor/metabolismo , Tomografia por Emissão de Pósitrons , Pirazinas/metabolismo , Tiazinas/metabolismo , Animais , Feminino , Cinética , Ligantes , Macaca fascicularis , Masculino , Modelos Biológicos , Radioquímica , Imagem Corporal TotalRESUMO
A facile method for late stage diversification of lead molecules for the M1 PAM program using biosynthesis is described. Liver microsomes from several species are screened to identify a high turnover system. Subsequent incubations using less than 1â¯mg of substrate generate nanomole quantities of drug metabolites that are purified, characterized by microcryoprobe NMR spectroscopy, and quantified to known concentrations to enable rapid biology testing. The late-stage diversification of lead compounds provides rapid SAR feedback to the medicinal chemistry design cycle.
Assuntos
Compostos Bicíclicos com Pontes/metabolismo , Cicloexanos/metabolismo , Compostos Heterocíclicos/metabolismo , Compostos Bicíclicos com Pontes/química , Cicloexanos/química , Relação Dose-Resposta a Droga , Compostos Heterocíclicos/química , Espectroscopia de Ressonância Magnética , Microssomos Hepáticos/química , Microssomos Hepáticos/metabolismo , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
A major challenge in the development of ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitors for the treatment of Alzheimer's disease is the alignment of potency, drug-like properties, and selectivity over related aspartyl proteases such as Cathepsin D (CatD) and BACE2. The potential liabilities of inhibiting BACE2 chronically have only recently begun to emerge as BACE2 impacts the processing of the premelanosome protein (PMEL17) and disrupts melanosome morphology resulting in a depigmentation phenotype. Herein, we describe the identification of clinical candidate PF-06751979 (64), which displays excellent brain penetration, potent in vivo efficacy, and broad selectivity over related aspartyl proteases including BACE2. Chronic dosing of 64 for up to 9 months in dog did not reveal any observation of hair coat color (pigmentation) changes and suggests a key differentiator over current BACE1 inhibitors that are nonselective against BACE2 in later stage clinical development.
Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Encéfalo/metabolismo , Desenho de Fármacos , Hipopigmentação , Inibidores de Proteases , Piranos , Pigmentação da Pele/efeitos dos fármacos , Tiazinas , Tiazóis , Precursor de Proteína beta-Amiloide/metabolismo , Animais , Encéfalo/efeitos dos fármacos , Células Cultivadas , Cães , Humanos , Hipopigmentação/induzido quimicamente , Masculino , Melanócitos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Modelos Moleculares , Estrutura Molecular , Inibidores de Proteases/administração & dosagem , Inibidores de Proteases/efeitos adversos , Inibidores de Proteases/química , Conformação Proteica , Piranos/administração & dosagem , Piranos/efeitos adversos , Piranos/química , Tiazinas/administração & dosagem , Tiazinas/efeitos adversos , Tiazinas/química , Tiazóis/administração & dosagem , Tiazóis/efeitos adversos , Tiazóis/químicaRESUMO
Monoacylglycerol lipase (MAGL) inhibition provides a potential treatment approach to neuroinflammation through modulation of both the endocannabinoid pathway and arachidonoyl signaling in the central nervous system (CNS). Herein we report the discovery of compound 15 (PF-06795071), a potent and selective covalent MAGL inhibitor, featuring a novel trifluoromethyl glycol leaving group that confers significant physicochemical property improvements as compared with earlier inhibitor series with more lipophilic leaving groups. The design strategy focused on identifying an optimized leaving group that delivers MAGL potency, serine hydrolase selectivity, and CNS exposure while simultaneously reducing log D, improving solubility, and minimizing chemical lability. Compound 15 achieves excellent CNS exposure, extended 2-AG elevation effect in vivo, and decreased brain inflammatory markers in response to an inflammatory challenge.
Assuntos
Anti-Inflamatórios não Esteroides/síntese química , Anti-Inflamatórios não Esteroides/farmacologia , Carbamatos/síntese química , Carbamatos/farmacologia , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Monoacilglicerol Lipases/antagonistas & inibidores , Neurite (Inflamação)/tratamento farmacológico , Amidoidrolases/antagonistas & inibidores , Animais , Ácidos Araquidônicos/metabolismo , Biomarcadores , Química Encefálica/efeitos dos fármacos , Cães , Desenho de Fármacos , Descoberta de Drogas , Endocanabinoides/metabolismo , Glicerídeos/metabolismo , Humanos , Macaca mulatta , Modelos Moleculares , Ratos , Ratos Wistar , Relação Estrutura-AtividadeRESUMO
Late-stage oxidation using liver microsomes was applied to phosphodiesterase 2 inhibitor 1 to reduce its clearance by cytochrome P450 enzymes, introduce renal clearance, and minimize the risk for victim drug-drug interactions. This approach yielded PF-06815189 (2) with improved physicochemical properties and a mixed metabolic profile. This example highlights the importance of C-H diversification methods to drug discovery.
RESUMO
Alzheimer's disease (AD) is characterized by accumulation of ß-amyloid (Aß) plaques and neurofibrillary tau tangles in the brain. ß-Site amyloid precursor protein cleaving enzyme 1 (BACE1) plays a key role in the generation of Aß fragments via extracellular cleavage of the amyloid precursor protein (APP). We became interested in developing a BACE1 PET ligand to facilitate clinical assessment of BACE1 inhibitors and explore its potential in the profiling and selection of patients for AD trials. Using a set of PET ligand design parameters, compound 3 (PF-06684511) was rapidly identified as a lead with favorable in vitro attributes and structural handles for PET radiolabeling. Further evaluation in an LC-MS/MS "cold tracer" study in rodents revealed high specific binding to BACE1 in brain. Upon radiolabeling, [18F]3 demonstrated favorable brain uptake and high in vivo specificity in nonhuman primate (NHP), suggesting its potential for imaging BACE1 in humans.
Assuntos
Secretases da Proteína Precursora do Amiloide/metabolismo , Ácido Aspártico Endopeptidases/metabolismo , Encéfalo/metabolismo , Inibidores de Proteases/farmacologia , Pirazinas/farmacologia , Compostos Radiofarmacêuticos/farmacologia , Tiazinas/farmacologia , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Animais , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Radioisótopos de Flúor , Ligantes , Masculino , Camundongos , Tomografia por Emissão de Pósitrons , Inibidores de Proteases/síntese química , Inibidores de Proteases/química , Inibidores de Proteases/farmacocinética , Pirazinas/síntese química , Pirazinas/química , Pirazinas/farmacocinética , Compostos Radiofarmacêuticos/síntese química , Compostos Radiofarmacêuticos/química , Compostos Radiofarmacêuticos/farmacocinética , Tiazinas/síntese química , Tiazinas/química , Tiazinas/farmacocinéticaRESUMO
Monoacylglycerol lipase (MAGL) is the main enzyme responsible for degradation of the endocannabinoid 2-arachidonoylglycerol (2-AG) in the CNS. MAGL catalyzes the conversion of 2-AG to arachidonic acid (AA), a precursor to the proinflammatory eicosannoids such as prostaglandins. Herein we describe highly efficient MAGL inhibitors, identified through a parallel medicinal chemistry approach that highlighted the improved efficiency of azetidine and piperidine-derived carbamates. The discovery and optimization of 3-substituted azetidine carbamate irreversible inhibitors of MAGL were aided by the generation of inhibitor-bound MAGL crystal structures. Compound 6, a highly efficient and selective MAGL inhibitor against recombinant enzyme and in a cellular context, was tested in vivo and shown to elevate central 2-AG levels at a 10 mg/kg dose.
Assuntos
Azetidinas/farmacologia , Carbamatos/farmacologia , Inibidores Enzimáticos/farmacologia , Monoacilglicerol Lipases/antagonistas & inibidores , Piperidinas/farmacologia , Animais , Azetidinas/química , Azetidinas/farmacocinética , Carbamatos/química , Carbamatos/farmacocinética , Linhagem Celular , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacocinética , Humanos , Camundongos Endogâmicos C57BL , Modelos Moleculares , Monoacilglicerol Lipases/metabolismo , Piperidinas/química , Piperidinas/farmacocinética , Proteínas Recombinantes/metabolismoRESUMO
Recent data demonstrated that activation of the muscarinic M1 receptor by a subtype-selective positive allosteric modulator (PAM) contributes to the gastrointestinal (GI) and cardiovascular (CV) cholinergic adverse events (AEs) previously attributed to M2 and M3 activation. These studies were conducted using PAMs that also exhibited allosteric agonist activity, leaving open the possibility that direct activation by allosteric agonism, rather than allosteric modulation, could be responsible for the adverse effects. This article describes the design and synthesis of lactam-derived M1 PAMs that address this hypothesis. The lead molecule from this series, compound 1 (PF-06827443), is a potent, low-clearance, orally bioavailable, and CNS-penetrant M1-selective PAM with minimal agonist activity. Compound 1 was tested in dose escalation studies in rats and dogs and was found to induce cholinergic AEs and convulsion at therapeutic indices similar to previous compounds with more agonist activity. These findings provide preliminary evidence that positive allosteric modulation of M1 is sufficient to elicit cholinergic AEs.
Assuntos
Isoindóis/farmacologia , Lactamas/farmacologia , Oxazóis/farmacologia , Receptor Muscarínico M1/agonistas , Convulsões/induzido quimicamente , Regulação Alostérica , Anfetamina/farmacologia , Animais , Ataxia/induzido quimicamente , Diarreia/induzido quimicamente , Cães , Donepezila , Desenho de Fármacos , Feminino , Humanos , Indanos/farmacologia , Isoindóis/administração & dosagem , Isoindóis/síntese química , Isoindóis/toxicidade , Lactamas/administração & dosagem , Lactamas/síntese química , Lactamas/toxicidade , Masculino , Camundongos Endogâmicos C57BL , Microssomos Hepáticos/metabolismo , Oxazóis/administração & dosagem , Oxazóis/síntese química , Oxazóis/toxicidade , Piperidinas/farmacologia , Ratos Wistar , Receptor Muscarínico M1/antagonistas & inibidores , Escopolamina/farmacologia , Relação Estrutura-Atividade , Sulfonamidas/farmacologia , Tiadiazóis/farmacologia , Vômito/induzido quimicamenteRESUMO
A growing subset of ß-secretase (BACE1) inhibitors for the treatment of Alzheimer's disease (AD) utilizes an anilide chemotype that engages a key residue (Gly230) in the BACE1 binding site. Although the anilide moiety affords excellent potency, it simultaneously introduces a third hydrogen bond donor that limits brain availability and provides a potential metabolic site leading to the formation of an aniline, a structural motif of prospective safety concern. We report herein an alternative aminomethyl linker that delivers similar potency and improved brain penetration relative to the amide moiety. Optimization of this series identified analogues with an excellent balance of ADME properties and potency; however, potential drug-drug interactions (DDI) were predicted based on CYP 2D6 affinities. Generation and analysis of key BACE1 and CYP 2D6 crystal structures identified strategies to obviate the DDI liability, leading to compound 16, which exhibits robust in vivo efficacy as a BACE1 inhibitor.
Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Anilidas/química , Inibidores Enzimáticos/farmacologia , Glicina/química , Sequência de Aminoácidos , Secretases da Proteína Precursora do Amiloide/química , Animais , Encéfalo/metabolismo , Cromatografia Líquida de Alta Pressão , Cristalização , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacocinética , Masculino , Camundongos , Técnicas de Patch-Clamp , Relação Estrutura-Atividade , Espectrometria de Massas em TandemRESUMO
Inhibition of ß-secretase BACE1 is considered one of the most promising approaches for treating Alzheimer's disease. Several structurally distinct BACE1 inhibitors have been withdrawn from development after inducing ocular toxicity in animal models, but the target mediating this toxicity has not been identified. Here we use a clickable photoaffinity probe to identify cathepsin D (CatD) as a principal off-target of BACE1 inhibitors in human cells. We find that several BACE1 inhibitors blocked CatD activity in cells with much greater potency than that displayed in cell-free assays with purified protein. Through a series of exploratory toxicology studies, we show that quantifying CatD target engagement in cells with the probe is predictive of ocular toxicity in vivo. Taken together, our findings designate off-target inhibition of CatD as a principal driver of ocular toxicity for BACE1 inhibitors and more generally underscore the power of chemical proteomics for discerning mechanisms of drug action.
Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Catepsina D/metabolismo , Inibidores Enzimáticos/toxicidade , Olho/patologia , Proteômica/métodos , Testes de Toxicidade , Secretases da Proteína Precursora do Amiloide/metabolismo , Animais , Linhagem Celular , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Olho/efeitos dos fármacos , Humanos , Concentração Inibidora 50 , Espectrometria de Massas , Camundongos Knockout , Sondas Moleculares/síntese química , Sondas Moleculares/química , Peptídeos/metabolismo , Ligação Proteica , Ratos Wistar , Epitélio Pigmentado da Retina/efeitos dos fármacos , Epitélio Pigmentado da Retina/patologia , Coloração e RotulagemRESUMO
It is hypothesized that selective muscarinic M1 subtype activation could be a strategy to provide cognitive benefits to schizophrenia and Alzheimer's disease patients while minimizing the cholinergic side effects observed with nonselective muscarinic orthosteric agonists. Selective activation of M1 with a positive allosteric modulator (PAM) has emerged as a new approach to achieve selective M1 activation. This manuscript describes the development of a series of M1-selective pyridone and pyridine amides and their key pharmacophores. Compound 38 (PF-06767832) is a high quality M1 selective PAM that has well-aligned physicochemical properties, good brain penetration and pharmacokinetic properties. Extensive safety profiling suggested that despite being devoid of mAChR M2/M3 subtype activity, compound 38 still carries gastrointestinal and cardiovascular side effects. These data provide strong evidence that M1 activation contributes to the cholinergic liabilities that were previously attributed to activation of the M2 and M3 receptors.
Assuntos
Descoberta de Drogas , Ácidos Picolínicos/farmacologia , Receptor Muscarínico M1/agonistas , Tiazóis/farmacologia , Animais , Relação Dose-Resposta a Droga , Feminino , Masculino , Camundongos , Modelos Moleculares , Estrutura Molecular , Ácidos Picolínicos/síntese química , Ácidos Picolínicos/química , Ratos , Receptor Muscarínico M1/metabolismo , Relação Estrutura-Atividade , Tiazóis/síntese química , Tiazóis/químicaRESUMO
1.The first generation 5HT-4 partial agonist, 4-{4-[4-Tetrahydrofuran-3-yloxy)-benzo[d]isoxazol-3-yloxymethyl]-piperidin-1-ylmethyl}-tetrahydropyran-4-ol, PF-4995274 (TBPT), was metabolized to N-dealkylated (M1) and an unusual, cyclized oxazolidine (M2) metabolites. M1 and M2 demonstrated pharmacological activity at 5HT receptor subtypes warranting further investigation into their dispositional properties in humans; M2 was a minor component in vitro but was the pre-dominant metabolite identified in human plasma. 2.To shift metabolism away from the piperidine ring of TBPT, a series of heterocyclic replacements were designed, synthesized, and profiled. Groups including azetidines, pyrrolidines, as well as functionalized piperidines were evaluated with the goal of identifying an alternative group that maintained the desired potency, functional activity, and reduced turnover in human hepatocytes. 3.Activities of 4-substituted piperidines or pyrrolidine analogs at the pharmacological target were not significantly altered, but the same metabolic pathways of N-dealkylation and oxazolidine formation were still observed. Altering these to bridged ring systems lowered oxazolidine metabolite formation, but not N-dealkylation. 4.The effort concluded with identification of azetidines as second-generation 5HT4 partial agonists. These were neither metabolized via N-dealkylation nor converted to cyclized oxazolidine metabolites rather oxidized on the isoxazole ring. The use of azetidine as a replacement for aliphatic aza-heterocyclic rings in drug design to alter drug metabolism and pharmacology is discussed.
Assuntos
Azetidinas/farmacologia , Piperidinas/farmacologia , Serotonina/metabolismo , Azetidinas/metabolismo , Humanos , Piperidinas/metabolismoRESUMO
Replacement of hydrogen with fluorine is a useful drug design strategy when decreases in cytochrome P450 (P450) metabolic lability are needed. In this paper, a facile two-step method of inserting fluorine into metabolically labile sites of drug molecules is described that utilizes less than 1 mg of starting material and quantitative NMR spectroscopy to ascertain the structures and concentrations of products. In the first step, hydroxyl metabolites are biosynthesized using human P450 enzymes, and in the second step these metabolites are subjected to deoxyfluorination using diethylaminosulfur trifluoride (DAST). The method is demonstrated using midazolam, celecoxib, ramelteon, and risperidone as examples and CYP3A5, 2C9, 1A2, and 2D6 to catalyze the hydroxylations. The drugs and their fluoro analogs were tested for metabolic lability. 9-Fluororisperidone and 4'-fluorocelecoxib were 16 and 4 times more metabolically stable than risperidone and celecoxib, respectively, and 2-fluororamelteon and ramelteon were metabolized at the same rate. 1'-Fluoromidazolam was metabolized at the same rate as midazolam by CYP3A4 but was more stable in CYP3A5 incubations. The P450-catalyzed sites of metabolism of the fluorine-containing analogs were determined. Some of the metabolites arose via metabolism at the fluorine-substituted carbon, wherein the fluorine was lost to yield aldehydes. In summary, this method offers an approach whereby fluorine can be substituted in metabolically labile sites, and the products can be tested to determine whether an enhancement in metabolic stability was obtained.
Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Flúor/química , Preparações Farmacêuticas/química , Aldeídos/química , Celecoxib/química , Dietilaminas/química , Halogenação , Humanos , Hidroxilação , Indenos/química , Espectroscopia de Ressonância Magnética/métodos , Microssomos Hepáticos/metabolismo , Midazolam/química , Risperidona/químicaRESUMO
Selective activation of the M1 receptor via a positive allosteric modulator (PAM) is a new approach for the treatment of the cognitive impairments associated with schizophrenia and Alzheimer's disease. A novel series of azaindole amides and their key pharmacophore elements are described. The nitrogen of the azaindole core is a key design element as it forms an intramolecular hydrogen bond with the amide N-H thus reinforcing the bioactive conformation predicted by published SAR and our homology model. Representative compound 25 is a potent and selective M1 PAM that has well aligned physicochemical properties, adequate brain penetration and pharmacokinetic (PK) properties, and is active in vivo. These favorable properties indicate that this series possesses suitable qualities for further development and studies.
Assuntos
Regulação Alostérica/efeitos dos fármacos , Amidas/química , Amidas/farmacologia , Indóis/química , Indóis/farmacologia , Receptor Muscarínico M1/metabolismo , Amidas/farmacocinética , Animais , Desenho de Fármacos , Humanos , Ligação de Hidrogênio , Indóis/farmacocinética , Camundongos , Simulação de Acoplamento Molecular , Receptor Muscarínico M1/agonistasRESUMO
In recent years, the first generation of ß-secretase (BACE1) inhibitors advanced into clinical development for the treatment of Alzheimer's disease (AD). However, the alignment of drug-like properties and selectivity remains a major challenge. Herein, we describe the discovery of a novel class of potent, low clearance, CNS penetrant BACE1 inhibitors represented by thioamidine 5. Further profiling suggested that a high fraction of the metabolism (>95%) was due to CYP2D6, increasing the potential risk for victim-based drug-drug interactions (DDI) and variable exposure in the clinic due to the polymorphic nature of this enzyme. To guide future design, we solved crystal structures of CYP2D6 complexes with substrate 5 and its corresponding metabolic product pyrazole 6, which provided insight into the binding mode and movements between substrate/inhibitor complexes. Guided by the BACE1 and CYP2D6 crystal structures, we designed and synthesized analogues with reduced risk for DDI, central efficacy, and improved hERG therapeutic margins.
Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Secretases da Proteína Precursora do Amiloide/química , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Ácido Aspártico Endopeptidases/química , Citocromo P-450 CYP2D6/química , Interações Medicamentosas , Inibidores de Proteases/química , Inibidores de Proteases/farmacologia , Sequência de Aminoácidos , Proteínas Amiloidogênicas/metabolismo , Animais , Cristalografia por Raios X , Citocromo P-450 CYP2D6/genética , Citocromo P-450 CYP2D6/metabolismo , Desenho de Fármacos , Canal de Potássio ERG1 , Canais de Potássio Éter-A-Go-Go/antagonistas & inibidores , Canais de Potássio Éter-A-Go-Go/metabolismo , Humanos , Concentração Inibidora 50 , Masculino , Camundongos Endogâmicos , Modelos Moleculares , Dados de Sequência Molecular , Inibidores de Proteases/administração & dosagem , Inibidores de Proteases/farmacocinética , Pirazóis/química , Relação Estrutura-AtividadeRESUMO
The identification of centrally efficacious ß-secretase (BACE1) inhibitors for the treatment of Alzheimer's disease (AD) has historically been thwarted by an inability to maintain alignment of potency, brain availability, and desired absorption, distribution, metabolism, and excretion (ADME) properties. In this paper, we describe a series of truncated, fused thioamidines that are efficiently selective in garnering BACE1 activity without simultaneously inhibiting the closely related cathepsin D or negatively impacting brain penetration and ADME alignment, as exemplified by 36. Upon oral administration, these inhibitors exhibit robust brain availability and are efficacious in lowering central Amyloid ß (Aß) levels in mouse and dog. In addition, chronic treatment in aged PS1/APP mice effects a decrease in the number and size of Aß-derived plaques. Most importantly, evaluation of 36 in a 2-week exploratory toxicology study revealed no accumulation of autofluorescent material in retinal pigment epithelium or histology findings in the eye, issues observed with earlier BACE1 inhibitors.