15-hydroxy-11-alpha-9-alpha-(epoxymethano)prosta-5-13-dienoic-acid and terutroban

We conducted a multicenter double-blind pharmacokinetic/pharmacodynamic (PK/PD) study of the new oral thromboxane receptor antagonist S18886 in 30 patients with peripheral artery disease, who were randomized to receive five different oral dosages of S18886 (1, 2.5, 5, 10 or 30 mg) for 12 weeks (83 days). Primary objective was to determine the effect of S18886 on platelet aggregation ex vivo.. Pharmacokinetics of S18886 was linear, with peak plasma levels being reached between 30 min and 2 h and a terminal half-life of 5.8-10 h. No significant accumulation of S18886 in plasma was observed after repeated dosing. The relationship between the S18886 concentration and platelet inhibition was examined in terms of U46619-induced platelet aggregation. Over the range of doses studied, there was a predictable relation between the plasma drug concentration and the degree of platelet inhibition at each dose. Maximal inhibition of U46619-induced platelet aggregation was achieved within 1 h with all oral doses of S18886, and this effect was maintained for at least 12 h. The PK/PD relationship was direct, and U46619-induced platelet aggregation was strongly inhibited by S18886 plasma concentrations above 10 ng mL(-1). This concentration was thus the minimal effective antiplatelet level in this population, and was maintained only by the dosages of 10 and 30 mg. The safety profile of S18886 was excellent, whatever the unit dose, with no attributable adverse events.. The results of this study, which included modeling and simulation, help identify the minimal effective plasma concentration of S18886 required for potent antiplatelet efficacy in patients with stable peripheral arterial disease.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Adenosine Diphosphate; Administration, Oral; Aged; Arachidonic Acid; Area Under Curve; Collagen; Female; Humans; Kinetics; Male; Middle Aged; Naphthalenes; Platelet Aggregation; Platelet Aggregation Inhibitors; Propionates; Receptors, Thromboxane; Time Factors

Patients with high cardiovascular risk due to ageing and/or comorbidity (diabetes, atherosclerosis) that require effective management of chronic pain may take advantage from new non-steroidal anti-inflammatory drugs (NSAIDs) that at clinical dosages may integrate the anti-inflammatory activity and reduced gastrointestinal side effects of selective cyclooxygenase-2 (COX-2) inhibitor (coxib) with a cardioprotective component involving antagonism of thromboxane A2 prostanoid (TP) receptor.. New compounds were obtained modulating the structure of the most potent coxib, lumiracoxib, to obtain novel multitarget NSAIDs endowed with balanced coxib and TP receptor antagonist properties. Antagonist activity at TP receptor (pA2) was evaluated for all compounds in human platelets and in an heterologous expression system by measuring prevention of aggregation and Gq-dependent production of intracellular inositol phosphate induced by the stable thromboxane A2 (TXA2) agonist U46619. COX-1 and COX-2 inhibitory activities were assessed in human washed platelets and lympho-monocytes suspension, respectively. COX selectivity was determined from dose-response curves by calculating a ratio (COX-2/COX-1) of IC50 values.. The tetrazole derivative 18 and the trifluoromethan sulfonamido-isoster 20 were the more active antagonists at TP receptor, preventing human platelet aggregation and intracellular signalling, with pA2 values statistically higher from that of lumiracoxib. Comparative data regarding COX-2/COX-1 selectivity showed that while compounds 18 and 7 were rather potent and selective COX-2 inhibitor, compound 20 was somehow less potent and selective for COX-2.. These results indicate that compounds 18 and 20 are two novel combined TP receptor antagonists and COX-2 inhibitors characterized by a fairly balanced COX-2 inhibitor activity and TP receptor antagonism and that they may represent a first optimization of the original structure to improve their multitarget activity.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Adolescent; Adult; Blood Platelets; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Diclofenac; Female; HEK293 Cells; Humans; Male; Middle Aged; Naphthalenes; Naproxen; Propionates; Receptors, Thromboxane; Young Adult

Cyclosporine (CSA) elevates blood pressure (BP) and alters arterial baroreflex sensitivity (BRS) and vasoreactivity. In this study we determined whether the renin-angiotensin system (RAS) interplays with other vasopressor pathways in mediating the CSA actions.. Whole animal and isolated vascular preparations were employed to determine the effects of pharmacologic interruption of angiotensin II (Ang II), endothelin (ET), or thromboxane (TXA2) signaling on the adverse cardiovascular effects of CSA.. CSA (25mg/kg/day i.p. for 7days) caused significant increases in BP that were paralleled with (i) reduced BRS measured by phenylephrine (BRSPE) or sodium nitroprusside (BRSSNP), (ii) enhanced aortic contractile responses to Ang II and U-46619 (thromboxane analogue), and (iii) reduced aortic eNOS expression and acetylcholine, but not SNP, vasorelaxations. Except for the reduced BRSSNP, the CSA effects disappeared upon concurrent administration of losartan (angiotensin AT1 receptor antagonist), captopril (angiotensin converting enzyme inhibitor), or their combination. Moreover, CSA augmentation of Ang II contractions was abolished after cyclooxygenase inhibition (indomethacin) or endothelin ETA/ETB receptor blockade (atrasentan/BQ788). By contrast, the blockade of thromboxane receptors (terutroban) failed to alter the CSA-evoked facilitation of Ang II responsiveness.. The facilitation of baroreflex control and inhibition of vascular responsiveness to Ang II and thromboxane contribute to the BP lowering effect of RAS inhibitors in CSA-treated rats. Further, endothelin receptors and vasoconstrictor prostanoids contribute to the CSA-evoked exaggeration of Ang II vascular responsiveness and hypertension.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Angiotensin II; Animals; Aorta; Atrasentan; Baroreflex; Blood Pressure; Captopril; Cyclosporine; Hypertension; Indomethacin; Losartan; Male; Naphthalenes; Nitric Oxide Synthase Type III; Nitroprusside; Oligopeptides; Phenylephrine; Piperidines; Propionates; Pyrrolidines; Rats; Renin-Angiotensin System; Vasoconstriction; Vasodilation

Thromboxane (TX) A2, prostaglandin endoperoxides and F2-isoprostanes exert their effects through a TX-prostanoid (TP) receptor, also expressed in endothelial cells. We investigated a role of the TP receptor in the endothelial expression of tissue factor (TF), a key trigger to thrombosis.. Human umbilical vein endothelial cells (HUVEC) exposed to the TP receptor agonist U46619 featured a concentration-dependent increase in TF surface exposure and procoagulant activity. HUVEC pre-incubation with the TP receptor antagonist S18886, followed by stimulation with either U46619 or tumor necrosis factor-α (TNF-α), attenuated TF surface exposure and activity compared with stimulated control. Aspirin or indomethacin, while inhibiting cyclooxygenase (COX)-1 and -2 activities, did not mimic this effect. Probing of underlying mechanisms by selective pharmacological and gene silencing experiments showed that S18886 reduced U46619- or TNF-α-induced TF expression inhibiting ROS production, NAD(P)H oxidase and PKC activation. In addition, S18886 also inhibited ERK activation in the presence of both U46619 and TNF-α alone, while inhibition of JNK activation only occurred in the presence of U46619.. The endothelial TP receptor contributes to TF surface exposure and activity induced not only by known TP receptor agonists, but also by TNF-α. Such findings expand the therapeutic potential of TP receptor inhibition.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Cells, Cultured; Cyclooxygenase 1; Cyclooxygenase 2; Endothelium; Human Umbilical Vein Endothelial Cells; Humans; MAP Kinase Signaling System; NADP; Naphthalenes; Propionates; Protein Kinase C; Reactive Oxygen Species; Receptors, Thromboxane; Signal Transduction; Thromboplastin; Tumor Necrosis Factor-alpha

Dexmedetomidine is an α(2)-adrenoceptor agonist and anesthetic. The present study was designed to characterize the receptor subtypes and the downstream mechanisms of the vascular effects of dexmedetomidine in small (mesenteric artery) and large (aorta) arteries ex vivo. Isometric tension was measured in Sprague-Dawley rat mesenteric and aortic rings (with or without endothelium). To study relaxations, cumulative concentrations of dexmedetomidine, 5-bromo-N-(2-imidazolin-2-yl)-6-quinoxalinamine, (UK14304), or clonidine were added to rings contracted with 9,11-dideoxy-9α,11α-methanoepoxy prostaglandin F(2α) (U46619) in the presence or absence of indomethacin; N(ω)-nitro-l-arginine methyl ester hydrochloride (l-NAME); 2-[2H-(1-methyl-1,3-dihydroisoindole)methyl]-4,5-dihydroimidazole maleate (BRL44408); 2-[2-(4-(2-methoxyphenyl)piperazin-1-yl)ethyl]-4,4-dimethyl-1,3-(2H,4H)-isoquinolindione dihydrochloride (ARC239); l-657,743, (2S-trans)-1,3,4,5',6,6',7,12b-octahydro-1',3'-dimethyl-spiro[2H-benzofuro[2,3-a]quinolizine-2,4'(1'H)-pyrimidin]-2'(3'H)-one hydrochloride hydrate (MK912); rauwolscine; prazosin; or pertussis toxin. To study contractions, dexmedetomidine was added to quiescent rings without endothelium or after incubation with l-NAME, rauwolscine, prazosin, indomethacin, or 3-[(6-amino-(4-chlorobenzensulfonyl)-2-methyl-5,6,7,8-tetrahydronaphth)-1-yl]propionic acid (S18886). Dexmedetomidine evoked relaxation at low concentrations (10 pM-30 nM) followed by contraction at higher concentrations (>30 nM) in the mesenteric artery. In the aorta, the relaxation was significantly smaller. The relaxation to dexmedetomidine depended on nitric oxide, endothelium, and G(i) protein, and it was mediated by α(2A/D)-adrenoceptors and possibly α(2B)-adrenoceptors. The contraction was mediated mainly by α(2B)- and α(1)-adrenoceptors and involved the action of prostanoids. UK14304 and clonidine induced greater and smaller relaxations, respectively, than dexmedetomidine. In conclusion, depending on the concentration used and the presence of functional endothelium, dexmedetomidine may evoke both relaxation and contraction in isolated arteries. The vascular effects also vary depending on the blood vessel studied. Its vascular effect is different from that of clonidine and UK14304.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Adrenergic alpha-1 Receptor Antagonists; Adrenergic alpha-2 Receptor Agonists; Adrenergic alpha-2 Receptor Antagonists; Animals; Aorta; Brimonidine Tartrate; Clonidine; Dexmedetomidine; Endothelium, Vascular; In Vitro Techniques; Indomethacin; Male; Mesenteric Arteries; Models, Biological; Muscle Contraction; Muscle Relaxation; Muscle, Smooth, Vascular; Naphthalenes; NG-Nitroarginine Methyl Ester; Pertussis Toxin; Prazosin; Propionates; Quinoxalines; Rats; Rats, Sprague-Dawley; Receptors, Adrenergic, alpha-2; Receptors, Thromboxane

Early manifestations of kidney disease occur in atherosclerosis and activation of TP (thromboxane A(2)) receptors is implicated in atherosclerotic, diabetes, and renal diseases. The purpose of the present study was to analyze, in isolated, perfused mouse kidneys, the participation of TP receptors in renal vasoconstrictions and vasodilatations. In kidneys, taken from wild-type C57BL6, apolipoprotein E-deficient (ApoE-KO) and diabetic ApoE-KO mice, changes in perfusion pressure were recorded. Constrictions to TP receptor ligands U 46619, arachidonic acid, PGH(2), and 8-iso-PGF(2alpha), but not those to angiotensin II, endothelin, or norepinephrine, were inhibited by the selective TP receptor antagonist Triplion (S 18886; 10 nM). Acetylcholine and prostacyclin evoked biphasic responses during methoxamine constrictions; the constrictor part was blocked by Triplion. In ApoE-KO mouse kidneys, compared with C57BL6, a specific decrease in norepinephrine response and no modification in dilator responses were observed. In diabetic ApoE-KO mouse kidneys, constrictions to U 46619 and those to 8-iso-PGF(2alpha) were significantly and selectively augmented, without modification in the expression of the TP receptor, and again without any significant change in vasodilator activity. Thus TP receptors are functional, and their activation is not involved in norepinephrine, endothelin, and angiotensin II vasoconstrictions but is implicated in the unusual vasoconstrictions to acetylcholine and prostacyclin. Increased responsiveness of TP receptors occurs in diabetic ApoE-KO mouse kidneys. Thus early changes in TP receptor-mediated vasoconstrictor activity may participate in the development of kidney disease in atherosclerosis and diabetes.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Acetylcholine; Animals; Apolipoproteins E; Atherosclerosis; Diabetes Mellitus, Experimental; Dinoprost; Disease Models, Animal; Epoprostenol; Kidney; Male; Methoxamine; Mice; Mice, Inbred C57BL; Mice, Knockout; Naphthalenes; Propionates; Receptors, Thromboxane A2, Prostaglandin H2; Streptozocin; Vasoconstriction; Vasoconstrictor Agents; Vasodilation; Vasodilator Agents

The present study examined the hypothesis that prostaglandin E2 (PGE2) through activation of prostaglandin E (EP) receptor contributes to endothelium-dependent contractions.. Western blotting revealed that the protein expression of EP1 receptor was significantly down-regulated in the aorta of the spontaneously hypertensive rat (SHR), but there was no significant difference in the expression of EP2, EP4, and total EP3 receptors between preparations of Wistar Kyoto rats (WKY) and SHR. Isometric tension studies showed that low concentrations of PGE2 caused endothelium-dependent relaxations in WKY but not in aortas of the SHR. High concentrations of PGE2 evoked contractions predominately through the activation of thromboxane-prostanoid (TP) receptors in the WKY, but involves the dual activation EP and TP receptors in the SHR. SQ29,548, BAYu3405 and Terutroban (TP receptor antagonists), and AH6809 (non-selective EP receptor antagonist) abolished, while SC19220 (preferential EP1 receptor antagonist) did not inhibit endothelium-dependent contractions. Both SC19220 and AH6809 significantly inhibited contractions to U46619 (TP receptor agonist).. The present study demonstrates that the contraction caused by PGE2 in the SHR aorta is dependent on the activation of EP1 and TP receptors, but that endothelium-dependent contractions do not require the former. Thus, PGE2 is unlikely to be an endothelium-derived contracting factor in this artery. The ability of AH6809 to inhibit endothelium-dependent contractions can be attributed to its partial antagonism at TP receptors. Nevertheless, the impairment of PGE2-mediated relaxation may contribute to endothelial dysfunction in the aorta of the SHR.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Aorta, Thoracic; Blotting, Western; Bridged Bicyclo Compounds, Heterocyclic; Carbazoles; Dibenz(b,f)(1,4)oxazepine-10(11H)-carboxylic acid, 8-chloro-, 2-acetylhydrazide; Dinoprostone; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelium, Vascular; Fatty Acids, Unsaturated; Hydrazines; Hypertension; Immunohistochemistry; Naphthalenes; Phenylephrine; Potassium Chloride; Propionates; Prostaglandin Antagonists; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptors, Prostaglandin E; Receptors, Prostaglandin E, EP1 Subtype; Receptors, Thromboxane; Sulfonamides; Vasoconstriction; Vasoconstrictor Agents; Vasodilation; Xanthones

Thromboxane (Tx) A2 is a vasoconstrictor and platelet agonist. Aspirin affords cardioprotection through inhibition of TxA2 formation by platelet cyclooxygenase (COX-1). Prostacyclin (PGI2) is a vasodilator that inhibits platelet function. Here we show that injury-induced vascular proliferation and platelet activation are enhanced in mice that are genetically deficient in the PGI2 receptor (IP) but are depressed in mice genetically deficient in the TxA2 receptor (TP) or treated with a TP antagonist. The augmented response to vascular injury was abolished in mice deficient in both receptors. Thus, PGI2 modulates platelet-vascular interactions in vivo and specifically limits the response to TxA2. This interplay may help explain the adverse cardiovascular effects associated with selective COX-2 inhibitors, which, unlike aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs), inhibit PGI2 but not TxA2.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Carotid Artery Injuries; Carotid Artery, Common; Cell Division; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Endothelium, Vascular; Epoprostenol; Humans; Isoenzymes; Lactones; Male; Membrane Proteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Muscle, Smooth, Vascular; Naphthalenes; Platelet Activation; Platelet Aggregation; Propionates; Prostaglandin-Endoperoxide Synthases; Receptors, Epoprostenol; Receptors, Prostaglandin; Receptors, Thromboxane; Sulfones; Tetrahydronaphthalenes; Thromboxane A2; Tunica Intima

Atherosclerosis involves a complex array of factors, including leukocyte adhesion and platelet vasoactive factors. Aspirin, which is used to prevent secondary complications of atherosclerosis, inhibits platelet production of thromboxane (Tx) A(2). The actions of TxA(2) as well as of other arachidonic acid products, such as prostaglandin (PG) H(2), PGF(2alpha), hydroxyeicosatetraenoic acids, and isoprostanes, can be effectively antagonized by blocking thromboxane (TP) receptors. The purpose of this study was to determine the role of platelet-derived TxA(2) in atherosclerotic lesion development by comparing the effects of aspirin and the TP receptor antagonist S18886. The effect of 11 weeks of treatment with aspirin (30 mg. kg(-1). d(-1)) or S18886 (5 mg. kg(-1). d(-1)) on aortic root atherosclerotic lesions, serum levels of intercellular adhesion molecule-1 (ICAM-1), and the TxA(2) metabolite TxB(2) was determined in apolipoprotein E-deficient mice at 21 weeks of age. Both treatments did not affect body or heart weight or serum cholesterol levels. Aspirin, to a greater extent than S18886, significantly decreased serum TxB(2) levels, indicating the greater efficacy of aspirin in preventing platelet synthesis of TxA(2). S18886, but not aspirin, significantly decreased aortic root lesions as well as serum ICAM-1 levels. S18886 also prevented the increased expression of ICAM-1 in cultured human endothelial cells stimulated by the TP receptor agonist U46619. These results indicate that inhibition of platelet TxA(2) synthesis with aspirin has no significant effect on atherogenesis or adhesion molecule levels. The effects of S18886 suggest that blockade of TP receptors inhibits atherosclerosis by a mechanism independent of platelet-derived TxA(2), perhaps by preventing the expression of adhesion molecules whose expression is stimulated by eicosanoids other than TxA(2).

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Aorta; Apolipoproteins E; Arteriosclerosis; Aspirin; Body Weight; Cell Adhesion; Cholesterol; Endothelium, Vascular; Female; Humans; Intercellular Adhesion Molecule-1; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Naphthalenes; Platelet Aggregation Inhibitors; Propionates; Receptors, Thromboxane; Tetrahydronaphthalenes; Thromboxane A2; Thromboxane B2; U937 Cells; Umbilical Veins; Vasoconstrictor Agents

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Bronchoconstriction; Dogs; Guinea Pigs; Humans; Muscle Contraction; Muscle, Smooth; Naphthalenes; Platelet Aggregation; Propionates; Rabbits; Receptors, Thromboxane; Species Specificity; Stereoisomerism; Tetrahydronaphthalenes; Trachea