thromboxane-a2 and nitroaspirin

The goal of this study was to test the hypothesis that NCX-4016 may have broader anti-inflammatory and antithrombotic effects as well as better gastric tolerability than aspirin in humans.. NCX-4016 is an aspirin derivative containing a nitric oxide-releasing moiety that prevents platelet activation and modulates tissue factor (TF) expression and cytokine release from lipopolysaccharide (LPS)-stimulated monocytes.. This was a blind-observer, placebo-controlled, parallel-group study in which 48 healthy subjects were randomized to receive NCX-4016 800 mg twice a day, NCX-4016 800 mg twice a day plus aspirin 325 mg, aspirin 325 mg, or placebo for 21 days.. Similar to aspirin alone, NCX-4016 effectively inhibited platelet aggregation induced by 0.6 mmol/ arachidonic acid, clot-stimulated thromboxane (TX) B2 generation in whole blood, and urinary excretion of 11-dehydro-TXB2. Unlike aspirin alone, the administration of NCX-4016 significantly inhibited TF expression in monocytes stimulated ex vivo with 10 micromol/l LPS (determined by flow-cytometry analysis of TF on CD14 positive cells). NCX-4016 also inhibited the rapid TF expression induced in monocytes by a proteinase activated receptor agonist (thrombin receptor activator protein, 2 micromol/l) as well as LPS-induced expression of CD11b . Ex vivo, release of MCP-1 and interleukin-6 were significantly inhibited by NCX-4016, but not by aspirin. NCX-4016 was not associated with gastric damage, and significantly reduced gastric injury when co-administered with aspirin, although both drugs reduced gastric PGE2 production to the same extent.. NCX-4016 is equally effective as aspirin in inhibiting cyclooxygenase activity. However, NCX-4016 causes less gastric damage and prevents monocyte activation. Larger multicenter trials are warranted to establish clinical efficacy and safety of NCX-4016.

Topics: Administration, Oral; Adult; Aspirin; Drug Administration Schedule; Drug Combinations; Drug Therapy, Combination; Duodenum; Flow Cytometry; Gastric Mucosa; Humans; Intestinal Mucosa; Male; Monocytes; Platelet Activation; Platelet Aggregation Inhibitors; Reference Values; Single-Blind Method; Stomach; Thromboxane A2; Thromboxane B2

Several attempts have been made to replace aspirin with compounds without gastric toxicity; a cyclooxygenase-2 (COX-2) inhibitor, celecoxib, and a nitric oxide-aspirin, NCX-4016, have been developed for this purpose. This paper compares effects of celecoxib, NCX-4016 and aspirin on production of prostacyclin (PGI2) and thromboxane A2 (TXA2) and activation of the inducible form of nitric oxide synthase (iNOS) in infarcted heart in situ. Aspirin was most effective in reducing myocardial PGI2 synthesis and formation of TXA2. Myocardial effects of celecoxib resemble those of NCX-4016, although the two compounds have different modes of action.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Aspirin; Celecoxib; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Epoprostenol; Heart; Isoenzymes; Male; Myocardial Infarction; Myocardium; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Platelet Aggregation Inhibitors; Prostaglandin-Endoperoxide Synthases; Pyrazoles; Rabbits; Sulfonamides; Thromboxane A2

Nitric oxide (NO) donors are heterogeneous substances which release NO, a biologically active compound. NO released by nitric oxide donors has important effects on the circulation by causing vasodilation, diminishing myocardial contractile force, inhibiting platelet aggregation, and counteracting the effects of thromboxane A2. In the infarcted heart, activation of the inducible form of nitric oxide synthase (iNOS) and the formation of prostacyclin and thromboxane A2 by cyclooxygenase (COX) were increased. Myocardial infarction also resulted in increased myocardial NO production. Aspirin (acetylsalicylic acid. ASA) at low concentration (35 mg/kg/day) fails to change iNOS production, in contrast to higher dose (150 mg/kg/day) which, as previously shown, inhibits iNOS activity. ASA at all doses also suppresses myocardial prostanoid formation because of inhibition of COX. Recently, two NO donors have been synthesized: NCX 4016 and Diethylenetriamine/NO (DETA/NO). NCX 4016 combines an NO-releasing moiety with a carboxylic residue via an esteric bond. We describe here that NCX 4016 (65 mg/kg/day) increased prostacyclin and thromboxane A2 production in the infarcted heart muscle, overcoming the inhibitory effects of ASA. As a result of nitric oxide release, oxidation products of NO (NO2- and NO3-; NOx) in arterial blood rose following administration of NCX 4016. On oral administration, NCX 4016 did not change systemic arterial pressure. The effects of a single NO donor, DETA/NO (1.0 mg/kg/day) on the infarcted heart were also investigated On intravenous administration, the compound increased NO concentration in arterial blood slightly but to a lesser degree than NCX 4016. Like NCX 4016, it raised myocardial production of prostacyclin and thromboxane A2 in the infarcted heart. However, it caused a severe fall in blood pressure. These findings demonstrate that newly-synthesized NO donors release nitric oxide in situ and increase myocardial production of prostanoids. NCX 4016 has therapeutic potential because it can be orally administered, lacks hypotensive effects, increases blood levels of nitric oxide and myocardial prostacyclin production.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Aspirin; Cyclooxygenase Inhibitors; Drug Interactions; Enzyme Activation; Heart Rate; Male; Myocardial Infarction; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Rabbits; Thromboxane A2; Triazenes; Ventricular Pressure

The antiplatelet activity of two new nitrocompounds, chemically related to acetylsalicylic acid (NCX 4215 and NCX 4016), was studied in vitro to verify the hypothetical dual action of these drugs. Both drugs, in a dose-dependent way, inhibited arachidonic acid-induced platelet aggregation and thromboxane A2 production, measured as thromboxane B2 concentration in whole blood. These effects are likely to be related to cyclo-oxygenase inhibition. NCX 4215 and NCX 4016 in a dose-dependent way inhibited also thrombin-induced aggregation of platelets pretreated with acetylsalicylic acid. These inhibitory effects are related to nitric oxide release and cGMP increase and significantly reversed by oxyhaemoglobin and methylene blue. Either as a cyclo-oxygenase inhibitor or as a nitric oxide donor, NCX 4016 proved to be significantly more potent than NCX 4215.

Topics: Arachidonic Acid; Aspirin; Cyclooxygenase Inhibitors; Dose-Response Relationship, Drug; Humans; In Vitro Techniques; Nitric Oxide; Platelet Aggregation; Platelet Aggregation Inhibitors; Thrombin; Thromboxane A2; Thromboxane B2

We studied in vitro the antiplatelet activity of a new nitroderivative chemically related to acetylsalicylic acid: 2 acetoxybenzoate 2-[1-nitroxy-methyl]-phenyl ester (NCX 4016), in order to identify any effects due to the release of nitric oxide and the blockade of cyclo-oxygenase. The effects of scalar doses of NCX 4016 on the early phase of platelet activation, platelet aggregation and thromboxane A2 production were investigated. We observed inhibitory effects of NCX 4016 on platelet adhesion (IC50 = 7.3 x 10(-5) M), platelet cytosolic calcium concentration, assayed by fluorescent probe Fura 2, and the expression of glycoprotein IIb/IIIa (CD41/alpha IIb beta 3) (IC50 = 3.4 x 10(-5) M) and P-selectin (CD62/GMP-140) (IC50 = 4.9 x 10(-5) M) measured by flow cytometry. NCX 4016 also prevented thrombin-induced platelet aggregation (IC50 = 3.9 x 10(-5) M). None of these parameters were affected by acetylsalicylic acid. These inhibitory activities of NCX 4016 were abolished by oxyhaemoglobin and methylene blue. Intracellular cyclic GMP observed during thrombin-induced aggregation was increased by incubation with NCX 4016. These results appear to be attributable to the release of nitric oxide, which activates soluble platelet guanylylcyclase and promotes intracellular cyclic GMP increase. NCX 4016 almost completely inhibited platelet thromboxane A2 production and arachidonic acid-induced platelet aggregation. This also occurred in the presence of oxyhaemoglobin and methylene blue, indicating that its antiplatelet activity can be attributed not only to nitric oxide release but also to cyclo-oxygenase inhibition.

Topics: Adult; Aspirin; Blood Platelets; Calcium; Cyclic GMP; Humans; P-Selectin; Platelet Activation; Platelet Adhesiveness; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIIb-IIIa Complex; Thromboxane A2