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
Using N,N-dialkylated benzamidines as the novel P4 motifs, we have designed and synthesized a class of 1-(2-naphthyl)-1H-pyrazole-5-carboxylamides as highly potent and selective fXa inhibitors with significantly improved hydrophilicity and in vitro anticoagulant activity. These benzamidine-P4 fXa inhibitors have displayed excellent oral bioavailability and long half-life.
Subject(s)
Amides/chemical synthesis , Antithrombin III/chemical synthesis , Benzamidines/antagonists & inhibitors , Pyrazoles/chemical synthesis , Administration, Oral , Amides/administration & dosage , Amides/metabolism , Animals , Antithrombin III/administration & dosage , Antithrombin III/metabolism , Benzamidines/metabolism , Biological Availability , Drug Design , Humans , Pyrazoles/administration & dosage , Pyrazoles/metabolism , Rats , Rats, Sprague-Dawley , Structure-Activity RelationshipABSTRACT
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.