Sulfonamide peri-substituted bicyclics for occlusive artery disease

#The invention relates to a chemical genus of peri-substituted, bicyclic acyl sulfonamides useful for the treatment and prophylaxis of occlusive artery disease and related prostaglandin-mediated disorders.

#Atherosclerosis is the pathology underlying several of mankind's most lethal diseases, such as myocardial infarction and peripheral arterial occlusive disease (PAOD). PAOD represents atherosclerosis of the large and medium arteries of the limbs, particularly to the lower extremities, and includes the aorta and iliac arteries. It often coexists with coronary artery disease and cerebrovascular disease. Persons with PAOD are at increased risk of other vascular events such as myocardial infarction or stroke [Waters, R E, Terjung R L, Peters K G & Annex B H. J. Appl. Physiol. 2004; Ouriel K. Lancet, 2001, 258:1257-64; Kroger, K. Angiology, 2004, 55:135-138]. Clinically significant lesions may gradually narrow the peripheral arteries leading to pain on walking usually relieved by rest (claudication), ischemic ulcers, gangrene, and sometimes limb amputation. Medical therapy is generally ineffective but operations bypassing or replacing the lesion with artificial or venous grafts improve blood flow distally, at least until they become restenosed [Haustein, K. O., Int. J. Clin. Pharmacol. Ther., 35:266 (1997)]. Recently, it has been discovered through human genetic linkage studies that DNA variants of the PTGER3 gene that encodes the prostaglandin E2 receptor subtype 3 (known as EP3) increase the risk of an individual developing PAOD (see US published application 2003/0157599). Thus, antagonists of prostaglandin E2 (PGE2) binding to the EP3 receptor may provide effective treatment or prophylaxis for PAOD.

#In response to various extracellular stimuli, prostaglandins are rapidly generated from free arachidonic acid through the consecutive action of the cyclo-oxygenases and synthases. The prostaglandins exert their action in close proximity to the site of their synthesis. To date, eight prostanoid receptors have been cloned and characterized. These receptors are members of the growing class of G-protein-coupled receptors. PGE2 binds preferentially to the EP1, EP2, EP3, and EP4 receptors; PGD2 to the DP and FP receptors; PGF2α to the FP and EP3 receptors; PGI2 to the IP receptor and TXA2 to the TP receptor. PGE2 binding to the EP3 receptor has been found to play a key role in the regulation of ion transport, smooth muscle contraction of the GI tract, acid secretion, uterine contraction during fertilization and implantation, fever generation and hyperalgesia. The EP3 receptor has been detected in many organs such as the kidney, the gastrointestinal tract, the uterus and the brain. In the cardiovascular system, EP3 is expressed by vascular endothelium and smooth muscle, and at least four isoforms of EP3 are expressed on human platelets [Paul, B. Z., B. Ashby, and S. B. Sheth, Distribution of prostaglandin IP and EP receptor subtypes and isoforms in platelets and human umbilical artery smooth muscle cells. British Journal of Haematology, 1998. 102(5): p. 1204-11.]

#Compounds of the genera represented by formulae Ia and Ic above are antagonists at the EP3 receptor. As such they have utility in treating and preventing prostaglandin-mediated conditions, as described above, particularly for such conditions as occlusive vascular disease.

#Compositions of the invention comprise an effective dose or a pharmaceutically effective amount or a therapeutically effective amount of a compound described above and may additionally comprise other therapeutic agents, such as platelet aggregation inhibitors (tirofiban, dipyridamole, clopidogrel, ticlopidine and the like); HMG-CoA reductase inhibitors (lovastatin, simvastatin, pravastatin, rosuvastatin, mevastatin, atorvastatin, cerivastatin, pitavastatin, fluvastatin and the like); and cyclooxygenase inhibitors. A further listing of non-limiting examples of antihyperlipidemic agents that may be used in combination with the compounds of the present invention may be found in columns 5-6 of U.S. Pat. No. 6,498,156, the disclosure of which is incorporated herein by reference. Preferred cyclooxygenase-2 inhibitors are those that are selective for cyclooxygenase-2 over cyclooxygenase-1. Preferred cyclooxygenase-2 inhibitors include rofecoxib, meloxicam, celecoxib, etoricoxib, lumiracoxib, valdecoxib, parecoxib, cimicoxib, diclofenac, sulindac, etodolac, ketoralac, ketoprofen, piroxicam and LAS-34475, although the invention is not restricted to these or other known cyclooxygenase-2 inhibitors.

#Methods of the invention parallel the compositions and formulations. The methods comprise administering to a patient in need of treatment a therapeutically effective amount of a peri-substituted, fused A/B ring compound according to the invention. The present invention is also directed to methods for in vitro screening for selective prostanoid receptor agonists and antagonists. Prostanoid receptors include EP1, EP2, EP3, EP4, IP and FP receptors. Selective EP3 ligands are of great interest, for which the method comprises bringing a labeled compound according to the invention into contact with a cloned human EP3 receptor and measuring its displacement by a test compound.