Defining platelet response to acetylsalicylic acid: the relation between inhibition of serum thromboxane B2 and agonist-induced platelet aggregation.

Arachidonic acid (AA)-induced platelet aggregation (PA) and serum thromboxane B2 (TxB2) inhibition are widely used to indicate cyclooxygenase-1 activity and the antiplatelet effect of acetylsalicylic acid (ASA). Despite decades of investigations, the relation between these measurements remains unclear. We sought to evaluate the relation between AA-PA and serum TxB2 inhibition. We serially measured AA-PA (conventional aggregation), serum TxB2, plasma ASA and salicylic acid (SA) (liquid chromatography-mass spectrometry), and urinary 11-dehydro thromboxane B2 (u11-dh TxB2) (enzyme-linked immunosorbent assay) levels at 10 times over 24 hours in seventeen healthy volunteers receiving a single dose of 162 mg chewed and swallowed ASA (n = 6), 50 mg inhaled ASA (n = 6), or 100 mg inhaled ASA (n = 5) (ClinicalTrials.gov Identifier: NCT04328883, April 1, 2020). Baseline variability was more pronounced with serum TxB2 (31-680 ng/mL) as compared to maximal AA-PA (65-81%) and u11-dh TxB2 (1556-4440 pg/mg creatinine). The relation between serum TxB2 inhibition and AA-PA was stepwise; after 30-40% inhibition of serum TxB2, AA-PA fell to < 5%. By receiver operating characteristic curve analysis using AA-PA < 5% to define aspirin responsiveness, serum TxB2 inhibition > 49% and u11-dh TxB2 < 1520 pg/mg creatinine met the definition. Our study demonstrates a non-linear relation between serum TxB2 inhibition and AA-PA. Aggregation was nil once TxB2 inhibition reached > 49%. Moreover, these results suggest that the definition of > 95% inhibition of serum TxB2 to indicate the level of platelet COX-1 inhibition needed for clinical efficacy may be overestimated and should be re-considered in future translational research investigations that attempt to link the clinical efficacy of ASA with a laboratory measurement cutoff.

Pharmacokinetic/pharmacodynamic assessment of a novel, pharmaceutical lipid-aspirin complex: results of a randomized, crossover, bioequivalence study.

Aspirin (acetylsalicylic acid, ASA) can lead to gastrointestinal mucosal injury through disruption of its protective phospholipid bilayer. A liquid formulation of a novel pharmaceutical lipid-aspirin complex (PL-ASA) was designed to prevent this disruption. We sought to determine the pharmacokinetic (PK)/pharmacodynamic (PD) characteristics of PL-ASA compared with immediate release aspirin (IR-ASA). In this active-control crossover study, 32 healthy volunteers were randomized to receive 1 of 2 dose levels (a single dose of 325 mg or 650 mg) of either PL-ASA or IR-ASA. After a 2-week washout period between treatment assignments, subjects received a single dose of the alternative treatment, at the same dose level. The primary objectives of the study were to assess, for PL-ASA and IR-ASA at 325 mg and 650 mg dose levels, PK and PD bioequivalence, and safety, over a 24-h period after administration of both drugs. PK parameters were similar for PL-ASA and IR-ASA, and met FDA-criteria for bioequivalence. Regarding PD, both drugs also showed Cmin TxB2 values below 3.1 ng/mL (cut-off associated with decreased cardiovascular events) and > 99% inhibition of serum TxB2 ( ≥ 95% inhibition represents the cut-off for aspirin responders) along with similar results in several secondary PK/PD parameters. There were no serious adverse events or changes from baseline in vital signs or laboratory values in either of the 2 treatment groups. PL-ASA's novel liquid formulation has similar PK and PD performance compared with IR-ASA, supporting functional and clinical equivalence. These data coupled with the improved gastric safety of PL-ASA suggest that this novel formulation may exhibit an improved benefit-risk profile, warranting evaluation in future trials.Clinical trial registration: http://www.clinicaltrials.gov . Unique Identifier: NCT04008979.

Thromboxane inhibition during concurrent therapy with low-dose aspirin and over-the-counter naproxen sodium.

Aspirin is the dominant antiplatelet therapy for cardiovascular disease. Naproxen is frequently used in aspirin-treated patients and may influence the antiplatelet effect of aspirin. We evaluated the pharmacodynamic interaction (lower bound of the one-sided 95% CI for serum TxB2 inhibition < 95%) between 220 mg immediate-release naproxen sodium (once or twice daily) and 81 mg daily immediate release aspirin at various dosing intervals. There was no interaction during the first day of concurrent treatment. After 10 days, irrespective of the timing and dose of naproxen in relation to aspirin dosing, a pharmacodynamic interaction occurred which persisted after discontinuing naproxen. In the control group (aspirin alone), the lower bound for serum TxB2 inhibition was > 98% at all time points. The clinical relevance of these observations remains unknown and merits further investigation since over-the-counter naproxen is widely used to relieve pain by individuals taking low dose aspirin for cardioprotection. CLINICAL TRIAL REGISTRATION: NCT02229461.

Comparison of aspirin and indobufen in healthy volunteers.

The aim of this study is to quantify the extent and recovery of platelet inhibition after administration of indobufen and aspirin in healthy volunteers. Indobufen inhibits platelet aggregation by reversibly inhibiting the platelet cyclooxygenase enzyme, thereby suppressing thromboxane synthesis. Twenty healthy volunteers completed the study and received aspirin (200 mg/day for 2 weeks) followed by a 4-week washout period and then indobufen (200 mg twice a day for 2 weeks). The percent (%) inhibition of platelet aggregation (IPA) was assessed using arachidonic acid (0.5 mg/ml) and adenosine diphosphate (5 µM) at 4, 12, 24 and 48 hours after last dose of each drug. IPA assessed using arachidonic acid as the agonist was similar at 4 hours after the last dose of indobufen (81.07 ± 9.36%) and aspirin (96.99 ± 0.29%, p = 0.10), but significantly lower at 12 hours (74.04 ± 9.55% vs. 97.94 ± 0.28%, p = 0.02), 24 hours (33.39 ± 11.13% vs. 97.48 ± 0.32%, p < 0.001) and 48 hours (14.12 ± 9.74% vs. 98.22 ± 0.31%, p < 0.001) after indobufen, compared to the relative values for aspirin. IPA assessed using adenosine diphosphate as the agonist was similar in the two groups at 4, 12 and 24 hours after the last dose, but significantly lower 48 hours after the last dose of indobufen, compared to the relative value for aspirin (1.98 ± 3.57% vs. 12.61 ± 2.71%, p = 0.002). Indobufen (200 mg twice a day) caused equivalent initial inhibition of platelet aggregation to aspirin (200 mg daily), and the anti-aggregation effect diminished faster than after aspirin.

Dactyloditerpenol acetate, a new prenylbisabolane-type diterpene from Aplysia dactylomela with significant in vitro anti-neuroinflammatory activity.

A new regular diterpene possessing an unusual 1,6-anti-3-methylcyclohex-2-en-1-ol ring system, dactyloditerpenol acetate (1), has been extracted from the tropical sea hare Aplysia dactylomela and its stereostructure elucidated by spectroscopic methods. The absolute configuration of 1 was determined as 1S, 6S, 7R, 10S, and 11R by application of Kishi's method for the assignment of absolute configuration of alcohols. The new diterpene potently inhibited in vitro thromboxane B2 (TXB2) (IC50 0.4µM) and superoxide anion (O2(-)) (IC50 1µM) generation from Escherichia coli lipopolysaccharide (LPS)-activated rat neonatal microglia, with concomitant low short-term toxicity.

Rhamnetin attenuates melanogenesis by suppressing oxidative stress and pro-inflammatory mediators.

Rhamnetin is a naturally occurring polyphenolic compound. In this report, experimental evidence is presented on the suppression of melanogenesis by rhamnetin using B16 murine melanoma cells (B16 cells). To document the underlying anti-melanogenic action of rhamnetin, several key biochemical mediators were quantified: superoxide (O2(•-)), nitric oxide (·NO) and peroxynitrite (ONOO(-)) in vitro, and total reactive species (RS) generation, O2(•-), ·NO and ONOO(-), reduced glutathione (GSH)/GSH-to-oxidized glutathione (GSSG) ratio, prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) in B16 cells. Results revealed that rhamnetin inhibited murine tyrosinase activity, suppressed melanin content and oxidative stress, reducing O2(•-),·NO and ONOO(-) in vitro and total RS generation, O2(•-), ·NO and ONOO(-) in B16 cells, while maintaining a well-balanced GSH/GSSG ratio in B16 cells. Results further revealed that rhamnetin suppressed key pro-inflammatory mediators such as PGE2 and TXB2. Thus, these results strongly indicate that rhamnetin has powerful anti-melanogenic properties through its anti-oxidative and anti-inflammatory actions.

Influence of oxytetracycline on carprofen pharmacodynamics and pharmacokinetics in calves.

A tissue cage model of inflammation in calves was used to determine the pharmacokinetic and pharmacodynamic properties of individual carprofen enantiomers, following the administration of the racemate. RS(±) carprofen was administered subcutaneously both alone and in combination with intramuscularly administered oxytetracycline in a four-period crossover study. Oxytetracycline did not influence the pharmacokinetics of R(-) and S(+) carprofen enantiomers, except for a lower maximum concentration (Cmax ) of S(+) carprofen in serum after co-administration with oxytetracycline. S(+) enantiomer means for area under the serum concentration-time curve (AUC0-96 h were 136.9 and 128.3 µg·h/mL and means for the terminal half-life (T(1/2) k10 ) were = 12.9 and 17.3 h for carprofen alone and in combination with oxytetracycline, respectively. S(+) carprofen AUC0-96 h in both carprofen treatments and T(1/2) k10 for carprofen alone were lower (P < 0.05) than R(-) carprofen values, indicating a small degree of enantioselectivity in the disposition of the enantiomers. Carprofen inhibition of serum thromboxane B2 ex vivo was small and significant only at a few sampling times, whereas in vivo exudate prostaglandin (PG)E2 synthesis inhibition was greater and achieved overall significance between 36 and 72 h (P < 0.05). Inhibition of PGE2 correlated with mean time to achieve maximum concentrations in exudate of 54 and 42 h for both carprofen treatments for R(-) and S(+) enantiomers, respectively. Carprofen reduction of zymosan-induced intradermal swelling was not statistically significant. These data provide a basis for the rational use of carprofen with oxytetracycline in calves and indicate that no alteration to carprofen dosage is required when the drugs are co-administered.

BM-573 inhibits the development of early atherosclerotic lesions in Apo E deficient mice by blocking TP receptors and thromboxane synthase.

Atherosclerosis is the principal cause of mortality in industrialized countries. Its development is influenced by several mediators of which thromboxane A(2) (TXA(2)) and 8-iso-PGF(2α) have recently received a lot of attention. This study aimed to investigate the effect of a dual thromboxane synthase inhibitor and thromboxane receptor antagonist (BM-573) and ASA on lesion formation in apolipoprotein E-deficient mice. The combination of ASA and BM-573 was also studied. Plasma measurements demonstrated that the treatments did not affect body weight or plasma cholesterol levels. BM-573, but not ASA, significantly decreased atherogenic lesions as demonstrated by macroscopic analysis. Both treatments alone inhibited TXB(2) synthesis but only BM-573 and the combination therapy were able to decrease firstly, plasma levels of soluble intracellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) and secondly, the expression of these proteins in the aortic root of Apo E. These results were confirmed in endothelial cell cultures derived from human saphenous vein endothelial cells (HSVECs). In these cells, BM-573 also prevented the increased mRNA expression of ICAM-1 and VCAM-1 induced by U-46619 and 8-iso-PGF(2α). Our results show that a molecule combining receptor antagonism and thromboxane synthase inhibition is more efficient in delaying atherosclerosis in Apo E(-/-) mice than sole inhibition of TXA(2) formation.

Inhibition of platelet aggregation and immunomodulation of NK lymphocytes by administration of ascorbic acid.

Platelets aggregation around migrating tumor cells offers protection against the cytotoxic activity of the natural killers cells (NKC). The ascorbic acid in 3 x 10(-3) M concentration completely inhibited platelet aggregation, decreased thromboxane B2 levels, and inhibited the expression of platelet membranic receptor GpIIb/IIIa in non stimulated platelets, and increased the NKC cytotoxicity in an average rate of 105, 61, and 285% in the NKC/targets cells ratios 12.5:1, 25:1 and 50:1 respectively. The results suggest the role of ascorbic acid in increasing the susceptibility of tumor cells to NKC; the ascorbic acid could be used as part of a multidrug therapy to treat diseases which up to now have been treated only through chemotherapy.

Effects of New NSAID-CAI Hybrid Compounds in Inflammation and Lung Fibrosis.

Pulmonary fibrosis is a severe lung disease with progressive worsening of dyspnea, characterized by chronic inflammation and remodeling of lung parenchyma. Carbonic anhydrases are a family of zinc-metallo-enzymes that catalyze the reversible interconversion of carbon-dioxide and water to bicarbonate and protons. Carbonic Anhydrase Inhibitor (CAI) exhibited anti-inflammatory effects in animals with permanent-middle-cerebral artery occlusion, arthritis and neuropathic pain. The pharmacological profile of a new class of hybrid compounds constituted by a CAI connected to a Nonsteroidal-Anti-Inflammatory Drug (NSAID) was studied in the modulation of inflammation and fibrosis. In-vitro tests were performed to assess their effects on cyclo-oxygenase enzyme (COX)-1 and COX-2, namely inhibition of platelet aggregation and thromboxane B2 production in the human-platelet-rich plasma, and reduction of Prostaglandin-E2 production in lipopolysaccharide-treated-RAW-264.7 macrophage cell line. The activity of compound 3, one of the most active, was studied in a model of bleomycin-induced lung fibrosis in C57BL/6 mice. The hybrid compounds showed a higher potency in inhibiting PGE2 production, but not in modifying the platelet aggregation and the TXB2 production in comparison to the reference molecules, indicating an increased activity in COX-2 inhibition. In the in-vivo murine model, the compound 3 was more effective in decreasing inflammation, lung stiffness and oxidative stress in comparison to the reference drugs given alone or in association. In conclusion, these CAI-NSAID hybrid compounds are promising new anti-inflammatory drugs for the treatment of lung chronic inflammatory diseases.

Chinese herbal medicinal ingredients inhibit secretion of IL-6, IL-8, E-selectin and TXB2 in LPS-induced rat intestinal microvascular endothelial cells.

The aim of the research was to investigate the anti-inflammatory mechanism of Pulsatillae Decoction (PD), the levels of interleukin (IL)-6, IL-8, E-selectin, and thromboxane B(2) (TXB(2)) secreted by cultured rat intestinal microvascular endothelial cells (RIMECs) were determined after treatment with its active ingredients, namely anemoside B4, anemonin, berberine, jatrorrhizine, palmatine, aesculin, and esculetin. RIMECs were challenged with 1 microg/mL lipopolysaccharide (LPS) for 3 h, and then treated with each of the seven ingredients at three concentrations (1, 5 and 10 microg/mL) for 24 h. The results revealed that anemonin, aesculin and esculetin inhibited the production of IL-6, aesculin and esculetin inhibited the secretion of IL-8, anemoside B4, berberine and jatrorrhizine downregulated E-selectin expression, anemonin, berberine, jatrorrhizine and palmatine decreased the content of TXB(2). All these changes were significant. Taken together, the data suggest that all seven active ingredients of PD can effectively reduce inflammatory response, thus relieving intestinal dysfunction via multiple pathways.

S-ibuprofen effectively inhibits thromboxane B2 levels and platelet function in an experimental model of lipopolysaccharide-stimulated and non-stimulated whole blood.

OBJECTIVE: The present study aimed at testing the effect of S- and R-ibuprofen on thromboxane B(2) (TXB(2)), collagen-epinephrine closure time (CEPI-CT) and collagen-adenosine 5'-diphosphate closure time (CADP-CT) in lipopolysaccharide (LPS)-stimulated and non-stimulated human whole blood. MATERIALS AND METHODS: Whole blood was incubated with S- or R-ibuprofen with and without prior stimulation with LPS. To verify ibuprofen's potential effects on TXB(2), varying ratios of concentrations of S- and R-ibuprofen ranging from 0 to 100% were used. TXB(2) levels were measured by ELISA. The effects of S- and R-ibuprofen enantiomers on platelet aggregability were tested utilizing a PFA-100 apparatus. RESULTS: In non-stimulated and LPS-stimulated whole blood, S-ibuprofen markedly decreased TXB(2) levels at concentrations ranging from 10 to 200 microg/ml. R-ibuprofen showed its inhibiting effect at concentrations >100 microg/ml. In inflammatory and non-inflammatory conditions, CEPI-CT was prolonged at concentrations of 12.5 and 75 microg/ml for S-ibuprofen and at a concentration of 150 microg/ml of combined R- and S-ibuprofen. S-ibuprofen was significantly more effective than R-ibuprofen (p < 0.05). The combined use of S- and R-ibuprofen did not additively or synergistically prolong CEPI-CTs. CADP-CTs remained unaffected by both enantiomers. CONCLUSIONS: S-ibuprofen was more effective than the R-ibuprofen enantiomer in inhibiting TXB(2) plasma levels and aggregability of thrombocytes in non-inflammatory and inflammatory conditions.

Increased renal thromboxane production in murine lupus nephritis.

To determine whether the amount of cyclooxygenase metabolites correlates with the development of lupus nephritis, intrarenal eicosanoid production was measured in autoimmune mice. Disease progression was related to the renal biosynthesis of prostaglandin (PGE2), prostacyclin (6 keto PGF1 alpha), and thromboxane (TXB2) using the MRL-lpr and NZB X NZW F1 hybrid mouse strains with predictably progressive forms of renal disease that mimic the human illness. Mice were evaluated for renal disease by measuring urinary protein excretion and renal immunopathological conditions and these features were related to renal eicosanoid production. These studies show that: (a) intrarenal synthesis of TXB2 increased incrementally in MRL-lpr and NZB X NZW F1 hybrid mice as renal function deteriorated and renal pathologic events progressed; (b) there were no consistent increases in the levels of two other cyclooxygenase metabolites, PGE2 or 6 keto PGF1 alpha; (c) increased TXB2 production occurred in the renal medulla, cortex, and within enriched preparations of cortical glomeruli; (d) when renal disease was prevented by pharmacologic doses of PGE2, intrarenal TXB2 did not increase; (e) administration of a dose of ibuprofen (9 mg/kg), a cyclooxygenase inhibitor capable of reducing 90% of platelet TXB2 without affecting intrarenal levels, did not retard the progression of renal damage. Taken together, these data indicate that the intrarenal level of TXB2 rises in relation to the severity of murine lupus nephritis. Furthermore, because of the potential deleterious effects of TXA2, enhanced production of this eicosanoid may be an important mediator of renal injury.

Pharmacodynamic interaction of naproxen with low-dose aspirin in healthy subjects.

OBJECTIVES: We investigated the occurrence of pharmacodynamic interaction between low-dose aspirin and naproxen. BACKGROUND: The uncertainty of cardioprotection by naproxen has encouraged its combination with aspirin in patients with arthritis and cardiovascular disease. METHODS: The incubation of washed platelets with naproxen for 5 min before the addition of aspirin reduced the irreversible inhibition of thromboxane (TX)B(2) production by aspirin. The pharmacodynamic interaction between the two drugs was then investigated in four healthy volunteers who received aspirin (100 mg daily) for 6 days and then the combination of aspirin and naproxen for further 6 days: aspirin 2 h before naproxen (500 mg, twice-daily dosing). After 14 days of washout, naproxen was given 2 h before aspirin for further 6 days. RESULTS: The inhibition of serum TXB(2) production (index of platelet cyclooxygenase [COX]-1 activity) and platelet aggregation ex vivo and urinary 11-dehydro-TXB(2) levels (index of TXB(2) biosynthesis in vivo) by aspirin alone (99 +/- 0.2%, 95 +/- 0.6%, and 81 +/- 4%, respectively) was not significantly altered by the co-administration of naproxen, given either 2 h after aspirin or in reverse order. In a second study, the concurrent administration of a single dose of aspirin and naproxen did not affect platelet TXB(2) production and aggregation at 1 h after dosing, when aspirin alone causes maximal inhibitory effect. Moreover, the rapid recovery of platelet COX-1 activity and function supports the occurrence of a pharmacodynamic interaction between naproxen and aspirin. CONCLUSIONS: Naproxen interfered with the inhibitory effect of aspirin on platelet COX-1 activity and function. This pharmacodynamic interaction might undermine the sustained inhibition of platelet COX-1 that is necessary for aspirin's cardioprotective effects.

New mechanism for an old drug: aspirin triggers anti-inflammatory lipid mediators with gender implications.

Aspirin increases anti-inflammatory aspirin-triggered lipoxin A4 levels in healthy subjects in a gender-specific manner in a randomized clinical study. Thus, formation of aspirin-triggered lipoxin A4 may provide a novel mechanism underlying aspirin's clinical benefits, and shed light on gender-dependent therapeutics of aspirin.

Antithrombotic activity of Vitis labrusca extract on rat platelet aggregation.

Vitis labrusca is a grapevine that has antioxidant, neuroprotective, hepatoprotective, and anticarcinogenic activity. However, the antithrombotic effect of Vitis labrusca leaves on platelets is yet to be ascertained. We investigated the inhibitory effect of V. labrusca leaf extract (VLE) on platelet aggregation in vitro and ex vivo. The thromboxane B2 (TXB2) and serotonin concentrations were measured by ELISA. The flavonoids content was measured by ultraperformance liquid chromatography (UPLC). The antithrombotic activity of VLE was evaluated using various agonists in vitro. VLE strongly inhibited adenosine diphosphate (ADP)-induced platelet aggregation. In rats, VLE treatment (100 mg/kg) reduced ADP-stimulated platelet aggregation, without affecting tail bleeding and coagulation time. Moreover, VLE significantly suppressed TXB2 and serotonin secretion. UPLC analysis indicated that VLE contains quercetin, isorhamnetin, and rutin. Our results indicate that VLE possesses antiplatelet activity via the suppression of TXB2 and serotonin, without affecting bleeding. Further, we identified the flavonoids present in VLE. Thus, VLE may be a potential agent for the prevention of cardiovascular diseases.

Long-term treatment with the dual antithromboxane agent picotamide decreases microalbuminuria in normotensive type 2 diabetic patients.

Picotamide both inhibits thromboxane synthetase and acts as a thromboxane antagonist at the receptor level. We investigated the long-term effect of picotamide on urinary albumin excretion (UAE) at rest and induced by exercise in 30 type 2 diabetic patients who were normotensive and had microalbuminuria while at rest. The subjects of our study had a mean age of 52.5 +/- 1.6 years, BMI of 28.5 +/- 0.7 kg/m2, diabetes duration of 9.1 +/- 1.8 years, and HbA1c of 7.0 +/- 0.8%. The study was a randomized double-blind placebo-controlled trial. The patients were randomly allocated to receive for 1 year either picotamide, 300 mg, 3 tablets/day, or placebo, 3 tablets/day. The patients were asked to visit our outpatient clinic after 1, 3, 6, 9, and 12 months of treatment. At all times, blood pressure, microalbuminuria at rest, blood glucose, serum creatinine, serum picotamide, and creatinine clearance were measured; at baseline and after 6 and 12 months, all patients underwent submaximal physical exercise. After 6 months of picotamide, baseline and exercise-induced microalbuminuria were significantly decreased (up to one-third) as compared with the baseline and placebo level, with no further drops at month 12 of picotamide treatment. On placebo treatment, UAE at rest and after exercise was slightly increased compared with baseline values. The effects of picotamide occurred without significant side effects or changes in either blood pressure levels or glycometabolic control. Our study is the first long-term intervention trial in type 2 diabetes showing that an antithromboxane agent is able to decrease microalbuminuria, which in this disease is a dual marker of macro- and microangiopathy. Our findings suggest an important role for thromboxane in the pathophysiology of microalbuminuria in diabetes; moreover, we hypothesize that antithromboxane agents may have a place in the treatment/prevention of both macro- and microvascular complications in type 2 diabetic patients.

Inhibition of thromboxane biosynthesis by triflusal in type 2 diabetes mellitus.

Triflusal is an antiplatelet drug related to aspirin, with different pharmacological properties and a lower haemorrhagic risk. We aimed at comparing their effects on platelet and endothelial activation in type 2 diabetes mellitus (T2DM). In a randomized, double-blind, parallel group study, we compared the effects of three daily regimens (300, 600, and 900 mg) of triflusal, and aspirin (100mg/day) on urinary 11-dehydro-thromboxane (TX)B(2), index of in vivo platelet activation, ex vivo platelet function using the analyzer PFA-100, plasma von Willebrand factor (vWF), P-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and serum nitrite and nitrate (NO(2)(-)+NO(3)(-)) in 60 T2DM patients. Triflusal induced a dose-dependent reduction in 11-dehydro-TXB(2) and a prolongation of closure time in the presence of collagen plus epinephrine (Coll/Epi-CT). The effects of the highest triflusal dose were not different from those of aspirin. The closure time in the presence of collagen plus ADP (Coll/ADP-CT), ICAM-1, VCAM-1, and NO(2)(-)+NO(3)(-) were not modified either by triflusal or aspirin. Plasma P-selectin and vWF were reduced by triflusal but not by aspirin. In T2DM triflusal causes a profound inhibition of platelet TXA(2) biosynthesis in vivo, acting on different targets involved in the platelet-endothelial cell interactions.

Increased renal production of angiotensin II and thromboxane B2 in conscious diabetic rats.

BACKGROUND: The mechanisms involved in development of cardiovascular complications associated with diabetes mellitus are not well elucidated. Among the vasoactive factors that may play a role in development of these complications are angiotensin II and thromboxane B2 (TXB2). We hypothesized that diabetes increases renal production of TXB2 through stimulation of angiotensin type-1 receptor. METHODS: We used a microdialysis technique to monitor changes in renal interstitial fluid (RIF) TXB2 in conscious streptozotocin-induced diabetes rat model. The RIF levels of angiotensin II and TXB2 were monitored before and during 6 weeks after development of diabetes and during treatment with the angiotensin type-1 receptor blocker valsartan at 10 mg/kg. Measurement of the urinary albumin excretion (UAE) was used to monitor the development and progression of diabetic nephropathy. RESULTS: The UAE was 81.62 +/- 1.31 ng/min, 184.75 +/- 9.41 ng/min (P < .01), and 229.84 +/- 4.49 ng/min (P < .0001) at baseline, week 3, and week 6, respectively, after induction of diabetes. Basal levels of RIF angiotensin II were 4.28 +/- 0.02 pg/mL and significantly increased to 6.24 +/- 0.31 pg/mL (P < .001) and 7.66 +/- 0.05 pg/mL (P < .001) at 3 and 6 weeks after development of diabetes. Similarly, basal RIF TXB2 was 197 +/- 27 pg/mL and increased to 488 +/- 80 pg/mL (P < .01) and 703 +/- 130 pg/mL (P < .01) at 3 and 6 weeks after development of diabetes. Valsartan caused further increase in RIF angiotensin II levels. In contrast, valsartan decreased RIF TXB2 levels at baseline to 85 +/- 11 pg/mL (P < .01), at 3 weeks to 141 +/- 17 pg/mL (P < .01), and at 6 weeks to 255 +/- 45 pg/mL (P < .01) after development of diabetes. CONCLUSIONS: These results demonstrate that diabetes mellitus is accompanied by increased renal production of angiotensin II and TXB2. The increase in TXB2 is mediated through stimulation of angiotensin type-1 receptor.

Double-blind, randomized, parallel, placebo-controlled study of ibuprofen effects on thromboxane B2 concentrations in aspirin-treated healthy adult volunteers.

BACKGROUND: Patients taking aspirin for cardioprotection may occasionally take over-the-counter (OTC) ibuprofen for pain relief, which might interfere with the antiplatelet effects of aspirin. OBJECTIVE: The present study was undertaken to determine whether ibuprofen, taken according to OTC label directions, would affect inhibition of thromboxane B2 (TXB2), a surrogate for platelet inhibition. METHODS: This was a prospective, multiple-dose,single-center, double-blind, randomized, parallel, placebo-controlled study. Eligible subjects received chewable, immediate-release aspirin 81 mg QD for 8 days, and were then randomized to receive either ibuprofen 400 mg TID or placebo TID, in addition to aspirin, for 10 days. RESULTS: Fifty-one subjects were randomized; 47(24 placebo, 23 ibuprofen) completed the study. No subjects withdrew prematurely. Subjects were predominantly white (49%) or black (38%), and 53% were male. The mean (SD) age was 38.4 (9.8) years and mean (SD) body weight was 173.2 (26.7) pounds. On days 1, 3, 7, and 10 of the study period, mean TXB2 inhibitions were 99.24%, 98.88%, 97.75%, and 98.17% for ibuprofen and 98.82%, 98.93%, 98.75%, and 98.83% for placebo. Although a statistically significant reduction of TXBZ inhibition was seen in the ibuprofen group at days 7 and 10 (P = 0.003 and P = 0.023, respectively), TXBZ inhibition was >90% on all days tested in all subjects. Aspirin, ibuprofen, and placebo were all well tolerated. There were 3 adverse events (1 mild and 2 moderate) during the aspirin run-in period and 8 (2 mild and 6 moderate) during the randomized study period. CONCLUSIONS: No clinically meaningful loss of cardioprotection was found, as reflected by TXB2 inhibition in healthy volunteers who received OTC doses of ibuprofen. When using this regimen of OTC ibuprofen with immediate-release, low-dose aspirin, concerns about the loss of cardioprotective antiplatelet effects of aspirin are not supported by this study.