RESUMEN
Although the S3 pocket of the thrombin active site is lined with lipophilic amino acid residues, the accommodation of polarity within the lipophilic P3 moiety of small molecule inhibitors is possible provided that the polar functionality is capable of pointing away from the binding pocket outwards toward solvent while simultaneously allowing the lipophilic portion of the P3 ligand to interact with the S3 amino acid residues. Manipulation of this motif provided the means to effect optimization of functional potency, in vivo antithrombotic efficacy and oral bioavailability in a series of 3-aminopyrazinone thrombin inhibitors which contained non-charged groups at the P1 position.
Asunto(s)
Anticoagulantes/síntesis química , Trastornos de la Coagulación Sanguínea/tratamiento farmacológico , Diseño de Fármacos , Pirazinas/síntesis química , Trombina/antagonistas & inhibidores , Administración Oral , Animales , Anticoagulantes/química , Anticoagulantes/farmacología , Sitios de Unión , Disponibilidad Biológica , Perros , Estructura Molecular , Pirazinas/química , Pirazinas/farmacología , Ratas , Relación Estructura-ActividadRESUMEN
A novel 1,3,5-trisubstituted benzamide thrombin inhibitor template was designed via hybridization of a known aminopyridinoneacetamide and a known 1,3,5-trisubstituted phenyl ether. Optimization of this lead afforded a novel potent series of biaryl 1,3,5-trisubstituted benzenes with excellent functional anticoagulant potency.
Asunto(s)
Antitrombinas/síntesis química , Benceno/síntesis química , Diseño de Fármacos , Trombina/antagonistas & inhibidores , Antitrombinas/química , Antitrombinas/farmacología , Benceno/química , Benceno/farmacología , Humanos , Modelos Moleculares , Estructura Molecular , Relación Estructura-ActividadRESUMEN
Antagonism of the bradykinin B(1) receptor represents a potential treatment for chronic pain and inflammation. Novel antagonists incorporating alpha-hydroxy amides were designed that display low-nanomolar affinity for the human bradykinin B(1) receptor and good bioavailability in the rat and dog. In addition, these functionally active compounds show high passive permeability and low susceptibility to phosphoglycoprotein mediated efflux, predictive of good CNS exposure.
Asunto(s)
Amidas/farmacología , Antagonistas del Receptor de Bradiquinina B1 , Amidas/química , Amidas/farmacocinética , Animales , Disponibilidad Biológica , Barrera Hematoencefálica , Inhibidores Enzimáticos del Citocromo P-450 , Perros , Semivida , Humanos , Ratas , Ratas Sprague-Dawley , Relación Estructura-ActividadRESUMEN
Optimization of a previously reported thrombin inhibitor, 9-hydroxy-9-fluorenylcarbonyl-l-prolyl-trans-4-aminocyclohexylmethylamide (1), by replacing the aminocyclohexyl P1 group provided a new lead structure, 9-hydroxy-9-fluorenylcarbonyl-l-prolyl-2-aminomethyl-5-chlorobenzylamide (2), with improved potency (K(i) = 0.49 nM for human thrombin, 2x APTT = 0.37 microM in human plasma) and pharmacokinetic properties (F = 39%, iv T(1/2) = 13 h in dogs). An effective strategy for reducing plasma protein binding of 2 and improving efficacy in an in vivo thrombosis model in rats was to replace the lipophilic fluorenyl group in P3 with an azafluorenyl group. Systematic investigation of all possible azafluorenyl P3 isomers and azafluorenyl-N-oxide analogues of 2 led to the identification of an optimal compound, 3-aza-9-hydroxyfluoren-9(R)-ylcarbonyl-l-prolyl-2-aminomethyl-5-chlorobenzylamide (19b), with high potency (K(i) = 0.40 nM, 2x APTT = 0.18 microM), excellent pharmacokinetic properties (F = 55%, T(1/2) = 14 h in dogs), and complete efficacy in the in vivo thrombosis model in rats (inhibition of FeCl(3)-induced vessel occlusions in six of six rats receiving an intravenous infusion of 10 microg/kg/min of 19b). The stereochemistry of the azafluorenyl group in 19b was determined by X-ray crystallographic analysis of its N-oxide derivative (23b) bound in the active site of human thrombin.
Asunto(s)
Fluorenos/síntesis química , Prolina/análogos & derivados , Prolina/síntesis química , Trombina/antagonistas & inhibidores , Administración Oral , Animales , Disponibilidad Biológica , Proteínas Sanguíneas/metabolismo , Cristalografía por Rayos X , Perros , Fluorenos/química , Fluorenos/farmacología , Semivida , Humanos , Técnicas In Vitro , Macaca mulatta , Masculino , Microsomas Hepáticos/metabolismo , Modelos Moleculares , Prolina/química , Prolina/farmacología , Unión Proteica , Ratas , Ratas Sprague-Dawley , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
In an effort to discover potent, clinically useful thrombin inhibitors, a rapid analogue synthetic approach was used to explore the P(1) region. Various benzylamines were coupled to a pyridine/pyrazinone P(2)-P(3) template. One compound with an o-thiadiazole benzylic substitution was found to have a thrombin K(i) of 0.84 nM. A study of ortho-substituted five-membered-ring heterocycles was undertaken and subsequently demonstrated that the o-triazole and tetrazole rings were optimal. Combination of these potent P(1) aryl heterocycles with a variety of P(2)-P(3) groups produced a compound with an extraordinary thrombin inhibitory activity of 1.4 pM. It is hoped that this potency enhancement in P(1) will allow for more diversification in the P(2)-P(3) region to ultimately address additional pharmacological concerns.
Asunto(s)
Compuestos Heterocíclicos/síntesis química , Trombina/antagonistas & inhibidores , Bencilaminas/síntesis química , Bencilaminas/química , Sitios de Unión , Compuestos Heterocíclicos/química , Modelos Moleculares , Pirazinas/síntesis química , Pirazinas/química , Piridinas/síntesis química , Piridinas/química , Relación Estructura-Actividad , Tetrazoles/síntesis química , Tetrazoles/química , Tiadiazoles/síntesis química , Tiadiazoles/química , Trombina/química , Triazoles/síntesis química , Triazoles/químicaRESUMEN
Recent efforts in the field of thrombin inhibitor research have focused on the identification of compounds with good oral bioavailability and pharmacokinetics. In this manuscript we describe a metabolism-based approach to the optimization of the 3-(2-phenethylamino)-6-methylpyrazinone acetamide template (e.g., 1) which resulted in the modification of each of the three principal components (i.e., P1, P2, P3) comprising this series. As a result of these studies, several potent thrombin inhibitors (e.g., 20, 24, 25) were identified which exhibit high levels of oral bioavailability and long plasma half-lives.
Asunto(s)
Acetamidas/farmacocinética , Anticoagulantes/farmacocinética , Inhibidores de Proteasas/síntesis química , Pirazinas/farmacocinética , Piridinas/farmacocinética , Trombina/antagonistas & inhibidores , Acetamidas/síntesis química , Acetamidas/farmacología , Administración Oral , Animales , Anticoagulantes/síntesis química , Anticoagulantes/farmacología , Disponibilidad Biológica , Cristalografía por Rayos X , Perros , Macaca mulatta , Modelos Moleculares , Inhibidores de Proteasas/química , Inhibidores de Proteasas/farmacología , Pirazinas/síntesis química , Pirazinas/farmacología , Piridinas/síntesis química , Piridinas/farmacología , Ratas , Relación Estructura-ActividadRESUMEN
The cardiac electrophysiologic effects of ISQ-1, an isoquinolinone I(Kur) blocker, were characterized in vivo. In rat, ISQ-1 elicited maximal 33% to 36% increases in atrial and ventricular refractoriness at a plasma concentration of 11.5 microM. In African green monkey, ISQ-1 increased atrial refractory period (maximal 17% at plasma concentration up to 20 microM) with no effect on ventricular refractory period or ECG QTc. Likewise in dog, ISQ-1 increased atrial refractory period (maximal 16% at plasma concentration up to 2 microM) with no effect on ventricular refractory period or QTc. In contrast, studies with ibutilide in nonhuman primate and dog demonstrated concomitant increases in atrial and ventricular refractoriness and QTc. Additionally, in a dog model of atrial flutter, ISQ-1 terminated ongoing flutter at doses (2.5 +/- 0.5 mg/kg IV) that selectively prolonged atrial refractoriness (13% increase), whereas flutter termination with ibutilide occurred at doses that increased both atrial and ventricular refractoriness as well as QTc. Of note, the cardiac electrophysiologic profiles displayed by ISQ-1 in these species were similar to those reported previously by our lab with a structurally distinct I(Kur) blocker. Taken together, these results further support the inhibition of I(Kur) as an approach to terminate atrial arrhythmia.
Asunto(s)
Arritmias Cardíacas/tratamiento farmacológico , Arritmias Cardíacas/fisiopatología , Técnicas Electrofisiológicas Cardíacas , Isoquinolinas/farmacología , Bloqueadores de los Canales de Potasio/farmacología , Primates , Análisis de Varianza , Animales , Antiarrítmicos/sangre , Antiarrítmicos/farmacología , Aleteo Atrial/tratamiento farmacológico , Aleteo Atrial/fisiopatología , Función Atrial/efectos de los fármacos , Presión Sanguínea/efectos de los fármacos , Chlorocebus aethiops , Modelos Animales de Enfermedad , Perros , Relación Dosis-Respuesta a Droga , Femenino , Sistema de Conducción Cardíaco/efectos de los fármacos , Sistema de Conducción Cardíaco/fisiopatología , Frecuencia Cardíaca/efectos de los fármacos , Infusiones Intravenosas , Isoquinolinas/sangre , Masculino , Bloqueadores de los Canales de Potasio/sangre , Ratas , Ratas Sprague-Dawley , Periodo Refractario Electrofisiológico/efectos de los fármacos , Factores de TiempoRESUMEN
The voltage-gated potassium channel, Kv1.5, which underlies the ultrarapid delayed rectifier current, I(Kur), is reported to be enriched in human atrium versus ventricle, and has been proposed as a target for novel atrial antiarrhythmic therapy. The administration of the novel I(Kur) blocker (2-isopropyl-5-methyl-cyclohexyl) diphenylphosphine oxide (DPO-1) (0.06, 0.2, and 0.6 mg/kg/min i.v. x 20 min; total doses 1.2, 4.0, and 12.0 mg/kg, respectively) to rat, which exhibits I(Kur) in both atria and ventricle, elicited significant, dose-dependent increases in atrial and ventricular refractory period (9-42%) at all doses tested, with no changes in cardiac rate or indices of cardiac conduction. Plasma levels achieved in rat at the end of the three infusions were 1.1, 4.1, and 7.7 microM. Reverse transcription-polymerase chain reaction analysis of African green monkey atria and ventricle demonstrated an atrial preferential distribution of Kv1.5 transcript. The administration of DPO-1 (1.0, 3.0, and 10.0 mg/kg i.v.; 5-min infusions) to African green monkey elicited significant increases in atrial refractoriness (approximately 15% increase at the 10.0 mg/kg dose), with no change in ventricular refractory period, ECG intervals, heart rate, or blood pressure. Plasma levels of DPO-1 achieved in African green monkey were 0.58, 1.12, and 5.43 microM. The concordance of effect of DPO-1 on myocardial refractoriness with distribution of Kv1.5 in these two species is consistent with the I(Kur) selectivity of DPO-1 in vivo. Moreover, the selective increase in atrial refractoriness in primate supports the concept of I(Kur) blockade as an approach for the development of atrial-specific antiarrhythmic agents.
Asunto(s)
Antiarrítmicos/farmacología , Corazón/efectos de los fármacos , Canal de Potasio Kv1.5/metabolismo , Miocardio/metabolismo , Fosfinas/farmacología , Bloqueadores de los Canales de Potasio/farmacología , Animales , Presión Sanguínea/efectos de los fármacos , Chlorocebus aethiops , Relación Dosis-Respuesta a Droga , Electrofisiología , Femenino , Corazón/fisiología , Atrios Cardíacos/efectos de los fármacos , Atrios Cardíacos/metabolismo , Frecuencia Cardíaca/efectos de los fármacos , Ventrículos Cardíacos/efectos de los fármacos , Ventrículos Cardíacos/metabolismo , Masculino , Ratas , Especificidad de la EspecieRESUMEN
The antiarrhythmic efficacy of the novel ultrarapid delayed rectifier potassium current (IKur) blocker (2-isopropyl-5-methylcyclohexyl) diphenylphosphine oxide (DPO-1) was compared with efficacies of the standard class III rapidly activating component of delayed rectifier potassium current (IKr) blockers [+-N-[1'-(6-cyano-1,2,3,4-tetrahydro-2-napthalenyl)-3,4-dihydro-4-hydroxyspiro[2H-1-benzopyran-2,4'-piperidin]-6-yl] methanesulfonamide hydrochloride (MK499) and ibutilide and the class IC agent propafenone in a canine model of Y-shaped intracaval and right atrial free wall surgical lesions producing the substrate for reentrant atrial flutter. Electrocardiographic and cardiac electrophysiologic effects also were assessed at the effective antiarrhythmic doses of test agents. DPO-1 terminated atrial arrhythmia (six/six preparations; 5.5 +/- 2.0 mg/kg i.v.) while significantly increasing atrial relative and effective refractory periods (+15.7 and +15.2%, respectively) but having no significant effects on ventricular refractory periods or electrocardiogram (ECG) intervals. Effective antiarrhythmic doses of MK499 (five/five preparations; 0.004 +/- 0.002 mg/kg i.v.) and ibutilide (five/five preparations; 0.003 +/- 0.001 mg/kg i.v.) similarly increased atrial relative (+23.2 and +25.1%, respectively) and effective (+21.6 and +31.9%, respectively) refractory periods. However, antiarrhythmic doses of MK499 and ibutilide also consistently and significantly increased ventricular relative (+9.9 and +7.6%, respectively) and effective (+10.4 and +9.9%, respectively) refractory periods, rate-corrected ECG QTc (+6.7 and +7.8%, respectively), and paced QT (+7.3 and +8.5%, respectively) intervals. Doses of propafenone that terminated atrial arrhythmia (five/five preparations; 0.94 +/- 0.54 mg/kg i.v.) significantly increased ECG QRS interval (+11.1%). These findings support the approach of atrial selective modulation of refractoriness through block of IKur for the development of potentially safer and more effective atrial antiarrhythmic agents.
Asunto(s)
Antiarrítmicos/farmacología , Función Atrial/efectos de los fármacos , Electrocardiografía/efectos de los fármacos , Electrofisiología , Bloqueadores de los Canales de Potasio/farmacología , Animales , Aleteo Atrial/fisiopatología , Función Atrial/fisiología , Perros , Femenino , Canal de Potasio Kv1.5/antagonistas & inhibidores , Masculino , Fosfinas/química , Fosfinas/metabolismo , Fosfinas/farmacología , Propafenona/farmacología , Sulfonamidas/farmacologíaRESUMEN
In this study, we have demonstrated that the critical hydrogen bonding motif of the established 3-aminopyrazinone thrombin inhibitors can be effectively mimicked by a 2-aminopyridine N-oxide. As this peptidomimetic core is more resistant toward oxidative metabolism, it also overcomes the metabolic liability associated with the pyrazinones. An optimization study of the P(1) benzylamide delivered the potent thrombin inhibitor 21 (K(i) = 3.2 nM, 2xaPTT = 360 nM), which exhibited good plasma levels and half-life after oral dosing in the dog (C(max) = 2.6 microM, t(1/2) = 4.5 h).
Asunto(s)
Antitrombinas/química , Pirimidinas/química , Enlace de Hidrógeno , Modelos Moleculares , Imitación MolecularRESUMEN
Suppression of malignant ventricular arrhythmias by selective blockade of the cardiac slowly activating delayed rectifier current (I(Ks)) has been demonstrated with the benzodiazepine L-768673 [(R)-2-(2,4-trifluoromethyl-phenyl)-N-[2-oxo-5-phenyl-1-(2,2,2-trifluoro-ethyl)-2,3-dihydro-1H-benzo[e][1,4]diazepin-3-yl]acetamide] in canine models of recent and healed myocardial infarction. The present study extends the initial antiarrhythmic assessment of I(Ks) blockade by demonstrating prevention of ischemic malignant arrhythmias in dogs with recent (8.0 +/- 0.4 days) anterior myocardial infarction with the coadministration of a subeffective dose of L-768673 and a subeffective, minimally beta-adrenergic blocking dose of timolol. Administered individually, neither 0.3 microg/kg i.v. L-768673 nor 1.0 microg/kg i.v. timolol prevented the induction of ventricular tachyarrhythmia (VT) by programmed ventricular stimulation (PVS) or the development of malignant ventricular arrhythmia in response to acute coronary artery thrombosis. In contrast, coadministration of 0.3 microg/kg i.v. L-768673 + 1.0 microg/kg i.v. timolol suppressed the induction of VT by PVS (8/10, 80% rendered noninducible versus 1/10, 10% noninducible in vehicle group; p < 0.01) and prevented the development of acute ischemic lethal arrhythmias (3/10, 30% incidence versus 8/10, 80% incidence in vehicle group; p < 0.05). Concomitant administration of low-dose L-768673 + timolol produced modest increases in QTc and paced QT intervals (4.5 +/- 1.2 and 5.5 +/- 1.4%; both p < 0.01), increases in noninfarct zone relative and effective refractory periods (7.0 +/- 1.7 and 12.3 +/- 3.0%; both p < 0.01), and lesser increases in infarct zone relative and effective refractory periods (5.3 +/- 1.6 and 5.8 +/- 1.4%; both p < 0.01). These findings suggest that concomitant low-dose I(Ks) and beta-adrenergic blockade may constitute a potential pharmacologic strategy for prevention of malignant ischemic ventricular arrhythmias.
Asunto(s)
Acetamidas/farmacología , Antagonistas Adrenérgicos beta/farmacología , Antiarrítmicos , Benzodiazepinonas/farmacología , Bloqueadores de los Canales de Potasio , Agonistas Adrenérgicos beta/farmacología , Animales , Perros , Estimulación Eléctrica , Electrofisiología , Femenino , Corazón/efectos de los fármacos , Frecuencia Cardíaca/efectos de los fármacos , Ventrículos Cardíacos/efectos de los fármacos , Técnicas In Vitro , Isoproterenol/farmacología , Masculino , Infarto del Miocardio/patología , Isquemia Miocárdica/patología , Timolol/farmacología , Función VentricularRESUMEN
Modification of lead compound 1 by reducing lipophilicity in the P3 group produced a series of low molecular weight thrombin inhibitors with excellent potency in functional assays, metabolic stability, and oral bioavailability. These modifications led to the identification of two optimized compounds, 14 and 16.
Asunto(s)
Antitrombinas/farmacología , Administración Oral , Antitrombinas/administración & dosificación , Antitrombinas/farmacocinética , Disponibilidad Biológica , Estabilidad de Medicamentos , Peso MolecularRESUMEN
We describe a series of highly potent and efficacious thrombin inhibitors based on a 3-amino-4-sulfonylpyridinone acetamide template. The functionally dense sulfonyl group stabilizes the aminopyridinone, conformationally constrains the 4-substituent, and forms a hydrogen bond to the insertion loop tyrosine OH. We also describe a related series of fused bicyclic dihydrothiadiazinedioxide derivatives, of which one had improved pharmacokinetics in dogs after oral dosing.
Asunto(s)
Acetamidas/química , Acetamidas/farmacología , Piridonas/química , Piridonas/farmacología , Tiadiazinas/química , Tiadiazinas/farmacología , Trombina/antagonistas & inhibidores , Acetamidas/farmacocinética , Administración Oral , Animales , Modelos Animales de Enfermedad , Perros , Compuestos Férricos/toxicidad , Humanos , Modelos Moleculares , Piridonas/farmacocinética , Ratas , Relación Estructura-Actividad , Sulfonas/química , Sulfonas/farmacocinética , Sulfonas/farmacología , Tiadiazinas/farmacocinética , Trombosis/inducido químicamente , Inhibidores de Tripsina/química , Inhibidores de Tripsina/farmacocinética , Inhibidores de Tripsina/farmacologíaRESUMEN
Potent non-peptidic alpha(v)beta(3) antagonists have been prepared incorporating various beta-amino acids as aspartic acid mimetics. Modification of the beta-alanine 3-substituents alters the potency and physicochemical properties of these receptor antagonists and in some cases provides orally bioavailable alpha(v)beta(3) inhibitors.
Asunto(s)
Oligopéptidos/farmacocinética , Receptores de Vitronectina/antagonistas & inhibidores , Aminoácidos/química , Animales , Ácido Aspártico , Unión Competitiva , Perros , Evaluación Preclínica de Medicamentos , Humanos , Concentración 50 Inhibidora , Imitación Molecular , Oligopéptidos/administración & dosificación , Oligopéptidos/química , Osteoporosis/prevención & control , Unión Proteica , Receptores de Vitronectina/metabolismo , Relación Estructura-ActividadRESUMEN
In this manuscript we demonstrate that a modification principally directed toward the improvement of the aqueous solubility (i.e., introduction a P3 pyridine N-oxide) of the previous lead compound afforded a new series of potent orally bioavailable P1 N-benzylamide thrombin inhibitors. An expedited investigation of the P1 SAR with respect to oral bioavailability, plasma half-life, and human liver microsome stability revealed 5 as the best candidate for advanced evaluation.