ABSTRACT
Recombinant Nematode Anticoagulant Protein c2 (rNAPc2) is a potent (K(i) =10 pM), inhibitor of the factor VIIa/tissue factor (fVIIa/TF) complex that requires the prerequisite binding to zymogen or activated factor X (fX). In two double blind, place-bo-controlled, sequential dose-escalation phase I studies, rNAPc2 was found to be safe and well tolerated following single and repeat subcutaneous administrations in healthy human male volunteers at doses ranging from 0.3 to 5 micro g/kg. There was a dose-dependent elevation of the prothrombin time reaching almost 4-fold above the baseline value in the highest dose group that directly correlated with rNAPc2 plasma concentration. In contrast, there was little or no effect on the activated partial thromboplastin time, thrombin time or template bleeding time. The pharmacokinetic behavior of rNAPc2 revealed a dose-independent and prolonged elimination half-life (t(1/2)beta) with a mean of >50 hours. A high affinity interaction between rNAPc2 and plasma fX was shown to be essential for the prolonged t(1/2)beta in man using crossed immunoelectrophoresis and was confirmed by exploiting the considerably weaker interaction between rNAPc2 and bovine fX which resulted in an attenuated t(1/2)beta of approximately 1.5 hours in calves. The accumulated data suggests that rNAPc2 is safe and well tolerated following repeat subcutaneous administrations at doses up to 5 micro g/kg in healthy volunteers. In addition, the in vivo fate of rNAPc2 in man appears to be governed by its high affinity interaction with circulating fX. This data supports the continued development of this novel anticoagulant for the prevention and treatment of acute thrombotic disorders.
Subject(s)
Anticoagulants/pharmacokinetics , Factor VIIa/antagonists & inhibitors , Helminth Proteins/administration & dosage , Thromboplastin/antagonists & inhibitors , Animals , Anticoagulants/administration & dosage , Anticoagulants/immunology , Blood Coagulation/drug effects , Cattle , Dose-Response Relationship, Drug , Factor X/metabolism , Helminth Proteins/pharmacokinetics , Humans , Isoantibodies/blood , Male , Pharmacokinetics , Recombinant ProteinsABSTRACT
Novel, potent, and highly selective classes of thrombin inhibitors were identified, which resulted from judicious combination of P4-aromatics and P2-P3-heterocyclic dipeptide surrogates with weakly basic (calcd pKa approximately non-basic-8.6) bicyclic P1-arginine mimics. The design, synthesis, and biological activity of achiral, non-covalent, orally bioavailable inhibitors NC1-NC44 featuring P1-indazoles, benzimidazoles, indoles, benzotriazoles, and aminobenzisoxazoles is disclosed.
Subject(s)
Bridged Bicyclo Compounds/chemical synthesis , Bridged Bicyclo Compounds/pharmacology , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Heterocyclic Compounds, 3-Ring/chemical synthesis , Heterocyclic Compounds, 3-Ring/pharmacology , Thrombin/antagonists & inhibitors , Animals , Area Under Curve , Biological Availability , Bridged Bicyclo Compounds/pharmacokinetics , Crystallography, X-Ray , Enzyme Inhibitors/pharmacokinetics , Heterocyclic Compounds, 3-Ring/pharmacokinetics , Indicators and Reagents , Rats , Structure-Activity Relationship , Tumor Cells, CulturedABSTRACT
Investigations on P(2)-P(3)-heterocyclic dipeptide surrogates directed towards identification of an orally bioavailable thrombin inhibitor led us to pursue novel classes of achiral, non-covalent P(1)-arginine derivatives. The design, synthesis, and biological activity of inhibitors NC1-NC30 that feature three classes of monocyclic P(1)-arginine surrogates will be disclosed: (1) (hetero)aromatic amidines, amines and hydroxyamidines, (2) 2-aminopyrazines, and (3) 2-aminopyrimidines and 2-aminotetrahydropyrimidines.
