Angiotensin II and endothelin-1 activate their respective AT 1 and ET A receptors on vascular smooth muscle cells, producing vasoconstriction, and both peptides are implicated in the pathogenesis of essential hypertension. Angiotensin II potentiates the production of endothelin, and conversely endothelin augments the synthesis of angiotensin II. Both AT 1 and ET A receptor antagonists lower blood pressure in hypertensive patients; thus, a combination AT 1 /ET A receptor antagonist may have greater efficacy and broader utility compared with each drug alone. By rational drug design a biphenyl ET A receptor blocker was modified to acquire AT 1 receptor antagonism. These compounds (C and D) decreased Sar-Ile-Angiotensin II binding to AT 1 receptors and endothelin-1 binding to ET A receptors, and compound C inhibited angiotensin II-and endothelin-1-mediated Ca 2ϩ transients. In rats compounds C and D reduced blood pressure elevations caused by intravenous infusion of angiotensin II or big endothelin-1. Compound C decreased blood pressure in Na ϩ -depleted spontaneously hypertensive rats and in rats with mineralocorticoid hypertension. Compound D was more efficacious than AT 1 receptor antagonists at reducing blood pressure in spontaneously hypertensive rats, and its superiority was likely due to its partial blockade of ET A receptors. Therefore compounds C and D are novel agents for treating a broad spectrum of patients with essential hypertension and other cardiovascular diseases.

Thrombin-activatable fibrinolysis inhibitor (TAFI) is a plasma carboxypeptidase that renders a fibrin-containing thrombus less sensitive to lysis. Since the role of TAFI in thrombus formation is still controversial in mice, our present study was designed to evaluate mice deficient in TAFI (TAFI(-/-)) on FeCl(3)-induced vena cava and carotid artery thrombosis. Parallel studies were carried out in wild-type mice using a potato carboxypeptidase inhibitor (PCI), a selective inhibitor of activated TAFI (TAFIa). Significant reduction in thrombus formation was observed in TAFI(-/-) mice (n = 8, P < 0.05 compared to wild-type littermates) but not in heterozygous (TAFI(+/-)) mice in 3.5% FeCl(3)-induced vena cava thrombosis. A similar effect was observed following treatment with 5 mg/kg bolus plus 5 mg/kg/h PCI in the same venous thrombosis model in C57BL/6 mice (n = 8, P < 0.01 compared to vehicle). No compositional difference was observed for the venous thrombi in TAFI(-/-) and wild-type littermates with or without PCI treatment using histological assessment. In contrast, neither TAFI deficiency nor treatment with PCI showed antithrombotic efficacy in the 3.5% FeCl(3)-induced carotid artery thrombosis model. In a tail transection bleeding time model, both TAFI deficiency and PCI treatment increased bleeding time up to 4.5 and 3.5 times, respectively, over controls (P < 0.05, n = 8). Similar ex vivo fibrinolytic activities were demonstrated for both TAFI deficiency and PCI treatment as enhanced lysis of thrombin-induced plasma clots and lysis of whole blood clot in a thrombelastograph. These data provide direct evidence for the role of TAFIa in vena cava thrombosis without the addition of exogenous thrombolytic in mice. The strong ex vivo fibrinolytic activity of TAFI deficiency or TAFIa inhibition by PCI provides a biomarker of TAFIa inhibition that tracks in vivo antithrombotic efficacy.

Substitution at the ortho position of N-(3,4-dimethyl-5-isoxazolyl) benzenesulfonamide led to the identification of the biphenylsulfonamides as a novel series of endothelin-A (ETA) selective antagonists. Appropriate substitutions on the pendant phenyl ring led to improved binding as well as functional activity. A hydrophobic group such as isobutyl or isopropoxyl was found to be optimal at the 4'-position. Introduction of an amino group at the 2'-position also led to improved analogues. Combination of the optimal 4'-isobutyl substituent with the 2'-amino function afforded an analogue (20, BMS-187308) with improved ETA binding affinity and functional activity. Compound 20 also has good oral activity in inhibiting the pressor effect caused by an ET-1 infusion in rats. Doses of 10 and 30 micromol/kg iv 20 attenuated the pressor responses due to the administration of exogenous ET-1 to conscious monkeys, indicating that the compound inhibits the in vivo activity of endothelin-1 in nonhuman primates.

The synthesis and structure-activity relationship (SAR) studies of a series of 4'-oxazolyl-N-(3,4-dimethyl-5-isoxazolyl)[1, 1'-biphenyl]-2-sulfonamide derivatives as endothelin-A (ET(A)) receptor antagonists are described. The data reveal a remarkable improvement in potency and metabolic stability when the 4'-position of the biphenylsulfonamide is substituted with an oxazole ring. Additional 2'-substitution of an acylaminomethyl group further increased the binding activity and provided one of the first subnanomolar ET(A)-selective antagonists in the biphenylsulfonamide series (17, ET(A) K(i) = 0.2 nM). Among the compounds described, 3 (N-(3,4-dimethyl-5-isoxazolyl)-4'-(2-oxazolyl)[1, 1'-biphenyl]-2-sulfonamide; BMS-193884) had the optimum pharmacological profile and was therefore selected as a clinical candidate for studies in congestive heart failure.

3-hydroxy-3-methylglutaryl coenzyme-A reductase (HMGR) inhibitors, more commonly known as statins, represent the gold standard in treating hypercholesterolemia. Although statins are regarded as generally safe, they are known to cause myopathy and, in rare cases, rhabdomyolysis. Statin-dependent effects on plasma lipids are mediated through the inhibition of HMGR in the hepatocyte, whereas evidence suggests that myotoxicity is due to inhibition of HMGR within the myocyte. Thus, an inhibitor with increased selectivity for hepatocytes could potentially result in an improved therapeutic window. Implementation of a strategy that focused on in vitro potency, compound polarity, cell selectivity, and oral absorption, followed by extensive efficacy and safety modeling in guinea pig and rat, resulted in the identification of compound 1b (BMS-644950). Using this discovery pathway, we compared 1b to other marketed statins to demonstrate its outstanding efficacy and safety profile. With the potential to generate an excellent therapeutic window, 1b was advanced into clinical development.