ABSTRACT
Systematic SAR studies of in vitro factor Xa inhibitory activity around compound 1 were performed by modifying each of the three phenyl rings. A class of highly potent, selective, efficacious and orally bioavailable direct factor Xa inhibitors was discovered. These compounds were screened in hERG binding assays to examine the effects of substitution groups on the hERG channel affinity. From the leading compounds, betrixaban (compound 11, PRT054021) has been selected as the clinical candidate for development.
Subject(s)
Anticoagulants/chemical synthesis , Anticoagulants/pharmacology , Benzamides/chemical synthesis , Benzamides/pharmacology , Drug Discovery/methods , Factor Xa Inhibitors , Pyridines/chemical synthesis , Pyridines/pharmacology , Administration, Oral , Animals , Anticoagulants/administration & dosage , Benzamides/administration & dosage , Catalytic Domain/drug effects , Cell Line , Dogs , Dose-Response Relationship, Drug , ERG1 Potassium Channel , Ether-A-Go-Go Potassium Channels/genetics , Factor Xa/metabolism , Humans , Macaca fascicularis , Pyridines/administration & dosage , Rabbits , RatsABSTRACT
A class of N,N-dialkylated 4-(4-arylsulfonylpiperazine-1-carbonyl)-benzamidines and 4-((4-arylsulfonyl)-2-oxo-piperazin-1-ylmethyl)-benzamidines has been discovered as potent factor Xa inhibitors with desirable in vitro and in vivo anticoagulant activity, but with low oral bioavailability. The 5-chloroindole and 6-chlorobenzo[b]thiophene groups are optimal as the factor Xa S1 binding elements. The strategy of incorporating a side chain on the piperazine nucleus to enhance binding affinity has been examined.
Subject(s)
Benzamidines/pharmacology , Factor Xa Inhibitors , Serine Proteinase Inhibitors/pharmacology , Benzamidines/chemistry , Benzamidines/pharmacokinetics , Biological Availability , Serine Proteinase Inhibitors/chemistry , Serine Proteinase Inhibitors/pharmacokineticsABSTRACT
A variety of P4 motifs have been examined to increase the binding affinity and in vitro anticoagulant potency of our biphenyl 1-(2-naphthyl)-1H-pyrazole-5-carboxylamide-based fXa inhibitors. Highly potent 2-naphthyl-P1 fXa inhibitors (K(i)< or =2 nM) with improved in vitro anticoagulant activity (2xTG< or =1 microM) and respectable pharmacokinetic properties have been discovered.
Subject(s)
Amides/chemistry , Antithrombin III/chemistry , Factor Xa Inhibitors , Pyrazoles/chemistry , Amides/metabolism , Amides/pharmacology , Animals , Antithrombin III/metabolism , Antithrombin III/pharmacology , Humans , Protein Binding , Pyrazoles/metabolism , Pyrazoles/pharmacology , Rats , Rats, Sprague-DawleyABSTRACT
OBJECTIVE: In this study we test the hypothesis that blood/plasma-based prothrombinase assays, rather than inhibition of purified factor Xa (fXa), are predictive of in vivo antithrombotic activity. METHODS AND RESULTS: Six fXa inhibitors with equivalent nanomolar Ki were studied in thrombin generation assays using human plasma/blood and endogenous macromolecular substrate. In all assays, benzamidine inhibitors were more potent (100 to 800 nmol/L) than the aminoisoquinolines (5 to 58 micromol/L) or neutral inhibitors (3 to 10 micromol/L). A similar rank order of compound inhibition was also seen in purified prothrombinase assays as well as in a rabbit model of deep vein thrombosis. CONCLUSIONS: Assays using prothrombinase with protein substrates are better predictors of in vivo efficacy than fXa Ki using amidolytic substrates.
Subject(s)
Benzamidines/pharmacology , Enzyme Inhibitors/pharmacology , Factor Xa Inhibitors , Fibrinolytic Agents/pharmacology , Isoquinolines/pharmacology , Prothrombin/metabolism , Thromboplastin/antagonists & inhibitors , Animals , Binding Sites/drug effects , Dose-Response Relationship, Drug , Drug Evaluation, Preclinical , Enzyme Inhibitors/classification , Fibrinolytic Agents/classification , Humans , Male , Molecular Structure , Sensitivity and Specificity , Substrate Specificity , Thrombin/biosynthesis , Venous Thrombosis/prevention & controlABSTRACT
A series of benzoxazinone derivatives was designed and synthesized as factor Xa inhibitors. We demonstrated that the naphthyl moiety in the aniline-based compounds 1 and 2 can be replaced with benzene-fused heterobicycles and biaryls to give factor Xa inhibitors with improved trypsin selectivity. The P4 modifications lead to monoamidines which are moderately active. The benzoxazinones 41-45 are potent against factor Xa, retain the improved trypsin selectivity of the corresponding aniline-based compounds, and show strong antithrombotic effect dose responsively.
Subject(s)
Factor Xa Inhibitors , Oxazines/chemical synthesis , Oxazines/pharmacology , Aniline Compounds/chemical synthesis , Aniline Compounds/pharmacology , Animals , Binding, Competitive/drug effects , Crystallography, X-Ray , Dose-Response Relationship, Drug , Drug Design , In Vitro Techniques , Indicators and Reagents , Models, Molecular , Molecular Conformation , Rabbits , Structure-Activity Relationship , Thrombin/metabolism , Trypsin Inhibitors/chemical synthesis , Trypsin Inhibitors/pharmacologyABSTRACT
In addition to our previously reported fluoro acrylamides Xa inhibitors 2 and 3, a series of potent and novel cyclic diimide amidine compounds has been identified. In efforts to improve their oral bioavailability, replacement of the amidine group with methyl amidrazone gives compounds of moderate potency (14, IC(50)=0.028 microM). In the amidoxime prodrug approach, the amidoxime compounds show good oral bioavailability in rats and dogs. High plasma level of prodrug 26 and significant concentration of active drug 26a were obtained upon oral administration of prodrug 26 in rats.
Subject(s)
Factor Xa Inhibitors , Prodrugs/chemical synthesis , Serine Proteinase Inhibitors/chemical synthesis , Serine Proteinase Inhibitors/pharmacology , Amidines/chemical synthesis , Amidines/pharmacology , Animals , Biological Availability , Dogs , Drug Design , Prodrugs/pharmacology , Rats , Structure-Activity RelationshipABSTRACT
To overcome the low bioavailability of our substituted acrylamide P1 benzamidine factor Xa inhibitors reported previously, neutral and less basic groups were used to replace the benzamidine. As a result, a series of P1 aminoisoquinoline substituted acrylamide Xa inhibitors was identified to be potent, selective, and orally bioavailable. Modification of P4 moiety of these compounds further improved their pharmacokinetic properties.
Subject(s)
Acrylamides/chemistry , Acrylamides/pharmacokinetics , Antithrombin III/chemical synthesis , Antithrombin III/pharmacokinetics , Factor Xa Inhibitors , Animals , Asparagine/chemistry , Benzamidines/chemistry , Biological Availability , Dogs , Half-Life , Hydrocarbons, Halogenated/chemistry , Inhibitory Concentration 50 , Isoquinolines/chemical synthesis , Isoquinolines/chemistry , Isoquinolines/pharmacokinetics , Prothrombin Time , Rabbits , Rats , Stereoisomerism , Structure-Activity Relationship , Thrombin/antagonists & inhibitors , Trypsin/drug effectsABSTRACT
Substituted acrylamides were used as templates that bridge P1 and P4 binding elements, resulting in a series of potent (sub-nanomolar) and selective factor Xa inhibitors. In this template, cis-geometry of P1 and P4 ligands is highly preferred. SAR on the substituting groups, as well as on modification of P1 and P4 moieties is described. Compounds in this series show good in vivo efficacy in animal models.
