The production of coagulation factor VII by adipocytes is enhanced by tumor necrosis factor-α or isoproterenol.

BACKGROUND: A relationship has been reported between blood concentrations of coagulation factor VII (FVII) and obesity. In addition to its role in coagulation, FVII has been shown to inhibit insulin signals in adipocytes. However, the production of FVII by adipocytes remains unclear. OBJECTIVE: We herein investigated the production and secretion of FVII by adipocytes, especially in relation to obesity-related conditions including adipose inflammation and sympathetic nerve activation. METHODS: C57Bl/6J mice were fed a low- or high-fat diet and the expression of FVII messenger RNA (mRNA) was then examined in adipose tissue. 3T3-L1 cells were used as an adipocyte model for in vitro experiments in which these cells were treated with tumor necrosis factor-α (TNF-α) or isoproterenol. The expression and secretion of FVII were assessed by quantitative real-time PCR, Western blotting and enzyme-linked immunosorbent assays. RESULTS: The expression of FVII mRNA in the adipose tissue of mice fed with high-fat diet was significantly higher than that in mice fed with low-fat diet. Expression of the FVII gene and protein was induced during adipogenesis and maintained in mature adipocytes. The expression and secretion of FVII mRNA were increased in the culture medium of 3T3-L1 adipocytes treated with TNF-α, and these effects were blocked when these cells were exposed to inhibitors of mitogen-activated kinases or NF-κB activation. The ß-adrenoceptor agonist isoproterenol stimulated the secretion of FVII from mature adipocytes via the cyclic AMP/protein kinase A pathway. Blockade of secreted FVII with the anti-FVII antibody did not affect the phosphorylation of Akt in the isoproterenol-stimulated adipocytes. CONCLUSION: Obese adipose tissue produced FVII. The production and secretion of FVII by adipocytes was enhanced by TNF-α or isoproterenol via different mechanisms. These results indicate that FVII is an adipokine that plays an important role in the pathogenesis of obesity.

The effect of aleglitazar on the pharmacokinetics and pharmacodynamics of S- and R-warfarin in healthy male subjects.

: Aleglitazar acts through balanced activation of peroxisome proliferator-activated receptors α and γ; warfarin is a commonly prescribed anticoagulant. Given the extent of cardiovascular disease in patients with type 2 diabetes, cotreatment with aleglitazar and warfarin is likely in this population. This open-label, randomized, 2-period, crossover study in 12 healthy male subjects investigated the potential for drug-drug interactions between warfarin and aleglitazar (final data drawn from 11 white subjects). The primary objective was to investigate the effect of aleglitazar on the pharmacokinetic properties of S-warfarin and on the pharmacodynamics of the racemic mixture; the secondary objectives included the effect of aleglitazar on R-warfarin pharmacokinetics and of racemic warfarin on aleglitazar pharmacokinetics. Subjects were randomized to single-dose warfarin on day 1 or aleglitazar once daily (12 days) plus single-dose warfarin on day 6 followed by a 14-day washout period, then crossover. Coadministration of aleglitazar reduced S- and R-warfarin exposure (AUC0-∞) by 18% and 13%, respectively, but did not change its pharmacodynamic effects (prothrombin time and factor VII activity). After warfarin dosing, aleglitazar trough concentrations remained within the same range. These findings indicate that coadministration of aleglitazar and warfarin is unlikely to affect the efficacy or safety of either agent.

Effective treatment of chemoresistant breast cancer in vitro and in vivo by a factor VII-targeted photodynamic therapy.

BACKGROUND: The purpose of this study was to test a novel, dual tumour vascular endothelial cell (VEC)- and tumour cell-targeting factor VII-targeted Sn(IV) chlorin e6 photodynamic therapy (fVII-tPDT) by targeting a receptor tissue factor (TF) as an alternative treatment for chemoresistant breast cancer using a multidrug resistant (MDR) breast cancer line MCF-7/MDR. METHODS: The TF expression by the MCF-7/MDR breast cancer cells and tumour VECs in MCF-7/MDR tumours from mice was determined separately by flow cytometry and immunohistochemistry using anti-human or anti-murine TF antibodies. The efficacy of fVII-tPDT was tested in vitro and in vivo and was compared with non-targeted PDT for treatment of chemoresistant breast cancer. The in vitro efficacy was determined by a non-clonogenic assay using crystal violet staining for monolayers, and apoptosis and necrosis were assayed to elucidate the underlying mechanisms. The in vivo efficacy of fVII-tPDT was determined in a nude mouse model of subcutaneous MCF-7/MDR tumour xenograft by measuring tumour volume. RESULTS: To our knowledge, this is the first presentation showing that TF was expressed on tumour VECs in chemoresistant breast tumours from mice. The in vitro efficacy of fVII-tPDT was 12-fold stronger than that of ntPDT for MCF-7/MDR cancer cells, and the mechanism of action involved induction of apoptosis and necrosis. Moreover, fVII-tPDT was effective and safe for the treatment of chemoresistant breast tumours in the nude mouse model. CONCLUSIONS: We conclude that fVII-tPDT is effective and safe for the treatment of chemoresistant breast cancer, presumably by simultaneously targeting both the tumour neovasculature and chemoresistant cancer cells. Thus, this dual-targeting fVII-tPDT could also have therapeutic potential for the treatment of other chemoresistant cancers.

Inhibitors of the initiation of coagulation.

Initiation of blood coagulation occurs mainly through tissue factor (TF) that becomes exposed to blood following vascular injury. Cell-associated TF binds to the serine protease FVIIa and initiates a cascade of amplified zymogen activation reactions leading to thrombus formation. As TF-FVIIa directed inhibitors might achieve anticoagulant efficacy without significantly interfering with normal haemostasis, the TF-FVIIa complex is an interesting target in thrombosis-related disease. Various approaches have been used to inhibit the TF-FVIIa complex including active site-inhibited FVIIa, TF antibodies, tissue factor pathway inhibitor (TFPI), naturally occurring inhibitors, peptide exosite inhibitors and active site inhibitors. Several experimental studies using these inhibitors have displayed promise. However, none of these TF/FVIIa inhibitors has reached clinical testing. Further studies are required to evaluate the clinical efficacy of these novel inhibitors.

Vitamin K2 (Menaquinone-7) supplementation does not affect vitamin K-dependent coagulation factors activity in healthy individuals.

BACKGROUND: Vitamin K has long been regarded as a procoagulant drug by physicians, and concerns have been raised with regard to its effects on hemostasis. Although many studies have shown that vitamin K supplementation is safe for thrombotic events, the effect of vitamin K supplementation on the activities of vitamin K dependent procoagulation factors in healthy individuals is not available. OBJECTIVES: This study aimed to investigate whether vitamin K2 supplementation at recommended doses affects the activity of vitamin K dependent procoagulation factors in healthy individuals without any anticoagulation treatment. DESIGN: Forty healthy volunteers between 25 and 40 years of age were recruited. Menaquinone-7 (MK-7) was administrated at 90 µg for 30 days. Prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), and blood coagulation factors II, VII, IX, and X activities and Protein induced by vitamin K absence or antagonist-II (PIVKA-II) were measured on days 0 and 30 after MK-7 administration. RESULTS: PT, APTT, and TT showed no significant differences on day 30 when compared with baseline. The activities of coagulation factors II, VII, IX, and X on day 30 showed no significant differences with those at baseline. PIVKA-II levels were unchanged after 30 days of MK-7 supplementation. CONCLUSIONS: MK-7 supplementation at recommended dosage does not affect vitamin K-dependent coagulation factors' coagulation activity, and does not enhance the carboxylation of prothrombin in healthy individuals. This indicated that MK-7 administration does not alter hemostatic balance in healthy populations without anticoagulation treatment.

Effect of dietary omega-3 and omega-6 fatty acids on clotting activities of Factor V, VII and X in fatty liver haemorrhagic syndrome-susceptible laying hens.

1. The relationship between concentrations of omega-3 and omega-6 fatty acids in plasma and Factor V, VII and X clotting activities was determined using a crossover feeding trial with diets supplemented with either soy oil or flax oil. 2. Laying hens on the soy diet, which is high in omega-6 fatty acids, had substantially higher clotting activity for all three factors compared to laying hens on the flax diet that was high in omega-3 fatty acids. 3. Positive associations were seen between liver haemorrhage score and the percentage of liver weight and between the percentage of liver weight and the severity of haemorrhagic and fatty changes seen on histology. 4. These results support the hypothesis that concentrations of omega-6 and omega-3 fatty acids in plasma affect clotting activity; however, there was no relationship between the extent of liver haemorrhages and the composition of plasma fatty acids.

Intake of phenol-rich virgin olive oil improves the postprandial prothrombotic profile in hypercholesterolemic patients.

BACKGROUND: Oxidative stress associated with postprandial lipemia contributes to endothelial dysfunction, which shifts hemostasis to a more thrombogenic state. OBJECTIVE: We investigated whether a high concentration of phenols in olive oil can partly reverse this phenomenon. DESIGN: Twenty-one hypercholesterolemic volunteers received 2 breakfasts rich in olive oils with different phenolic contents (80 or 400 ppm) according to a randomized, sequential crossover design. Plasma concentrations of lipid fractions, factor VII antigen (FVIIag), activated factor VII (FVIIa), and plasminogen activator inhibitor-1 (PAI-1) activity were measured at baseline and postprandially. RESULTS: Concentrations of FVIIa increased less (P = 0.018) and plasma PAI-1 activity decreased more (P = 0.021) 2 h after the high-phenol meal than after the low-phenol meal. FVIIa concentrations 120 min after intake of the olive oil with a high phenol content correlated positively with fasting plasma triacylglycerols (P = 0.001), area under the curve (AUC) of triacylglycerols (P = 0.001), and AUC of nonesterified fatty acids (P = 0.024) and negatively with hydroxytyrosol plasma concentrations at 60 min (P = 0.039) and fasting HDL-cholesterol concentrations (P = 0.005). PAI-1 positively correlated with homeostasis model assessment of insulin resistance (P = 0.005) and fasting triacylglycerols (P = 0.025) and inversely with adiponectin (P = 0.026). In a multivariate analysis, the AUCs of nonesterified fatty acids (R(2) = 0.467; beta: 0.787; SE: 0.02; P < 0.001) and adiponectin (R(2) = 0.232; beta: -1.594; SE: 0.629; P < 0.05) were the strongest predictors of plasma FVIIa and PAI-1, respectively. CONCLUSIONS: A virgin olive oil with a high content of phenolic compounds changes the postprandial hemostatic profile to a less thrombogenic state.

Influence of warfarin therapy on activated factor VII clotting activity.

Oral anticoagulant therapy has been widely employed to prevent and treat a variety of thrombotic disorders, although a new generation of antithrombotic drugs, which offer inhibition of clot-bound as well as fluid-phase thrombin, has been developed and tested in several clinical trials. Although most anticoagulant responses to hydroxycoumarin compounds are well established, there are controversial evidences on their influence on activated factor VII (FVIIa). After analyzing the prothrombin time (PT) (International Normalized Ratio reference range, 0.92-1.08), factor VII clotting activity (FVII:C) (reference range, 75-130 U/dl) and activated factor VII clotting activity (FVIIa:C) (reference range, 30-110 U/l) in 46 consecutive patients on stable warfarin therapy for atrial fibrillation, a consistent trend towards decreased values of both FVII:C and FVIIa:C was observed as PT values increased. At moderate-intensity anticoagulation, with international normalized ratios between 2 and 3, the mean activities of FVII:C and FVIIa:C dropped to 28 U/dl (range, 9-61 U/dl) and 5.8 U/l (range, 1-18 U/l), respectively. Results of our investigations indicate that warfarin therapy decreases FVIIa:C, highlighting the potential benefits of oral anticoagulants in thrombotic disorders and other clinical conditions characterized by increased levels of FVIIa. Owing to the good correlation with FVIIa:C, we also hypothesize that the PT and/or FVII:C might be employed for monitoring recombinant FVIIa therapy.

Pharmacogenetics of acenocoumarol pharmacodynamics.

OBJECTIVE: The aim of this study was to investigate the respective contribution of the different cytochrome P450 (CYP) 2C9 genetic polymorphisms to the interindividual variability of acenocoumarol pharmacodynamic response. METHODS: A total of 263 healthy volunteers were genotyped for CYP2C9*2, CYP2C9*3, CYP2C9*4, and CYP2C9*5 alleles, as well as for the nicotinamide adenine dinucleotide phosphate, reduced, quinone oxidoreductase 1 genetic polymorphism (NQO1*2). Moreover, the 5'-flanking region of the CYP2C9 gene was investigated for new polymorphisms, and haplotype analysis was then performed. Finally, CYP2C9 phenotype was evaluated after a single oral dose of 4 mg of acenocoumarol. Factor VII coagulant activity was measured before and 24 hours after acenocoumarol intake. RESULTS: The CYP2C9*3 allele was the only nonsynonymous single nucleotide polymorphism (SNP) influencing acenocoumarol pharmacodynamics; the percentages of remaining factor VII were 60% +/- 19%, 39% +/- 17%, and 17% for CYP2C9*1/CYP2C9*1, CYP2C9*1/CYP2C9*3, and CYP2C9*3/CYP2C9*3 subjects, respectively (P =.001). Among the white subjects, the CYP2C9 promoter showed the existence of 6 SNPs at positions G-1538A, T-1189C, G-1097A, G-982A, T-640 del, and G-620T with allelic frequencies of 0.085, 0.0398, 0.136, 0.086, 0.005, and 0.0138, respectively. Four major haplotypes could be inferred among white subjects. The haplotype that contains the CYP2C9*3 allele was the only one influencing acenocoumarol pharmacodynamics, explaining 14.3% of its interindividual variability. Body weight explained 5% of acenocoumarol pharmacodynamic variability, whereas the NQO1*2 allele had no significant effect. CONCLUSION: Overall, CYP2C9-related genetic variability accounts for 14% of the interindividual variability in acenocoumarol pharmacodynamic response. The information found by haplotype analysis is mainly related to the CYP2C9*3 SNP.

Dietary oleic and palmitic acids and postprandial factor VII in middle-aged men heterozygous and homozygous for factor VII R353Q polymorphism.

BACKGROUND: The R353Q genotype is a major determinant of factor VII coagulant (FVIIc) activity, which is associated with an increased risk of ischemic heart disease (IHD) and elevated plasma triacylglycerol concentrations. OBJECTIVE: The objectives were to 1) compare the effects of meals rich in palmitate or oleate with those of a meal low in fat on FVIIc in subjects with moderately elevated plasma nonfasting triacylglycerol concentrations and 2) determine whether the postprandial increase in FVIIc induced by dietary oleate differs in carriers of the Q allele. DESIGN: Fifty-two men aged >52 y with nonfasting plasma triacylglycerol concentrations between 2 and 5.5 mmol/L were randomly assigned to receive isoenergetic (5.1 MJ) meals providing 50 g high-oleate or high-palmitate oils or a low-fat meal providing 15 g high-oleate oil. In a second study, 17 men aged >52 y who were heterozygous for factor VII R353Q polymorphism were age-matched with subjects homozygous for the R allele and their responses to a 50-g, high-oleate meal were measured. RESULTS: FVIIc decreased by 11% after the low-fat meal. FVIIc increased by 9% and FVIIa (the activated form of FVII) increased by 55% after the high-oleate meal, whereas FVIIc did not change but FVIIa increased by 25% after the high-palmitate meal. Fasting FVIIc and FVIIa concentrations were 24% and 48% lower, respectively, in men with the RQ genotype than in men with the RR genotype but increased postprandially in both groups with no evidence of a genotype interaction. CONCLUSIONS: A high-fat meal rich in oleate increases FVIIa, whereas a low-fat meal does not, in men at high risk of IHD, independent of R353Q genotype.

Are olive oil diets antithrombotic? Diets enriched with olive, rapeseed, or sunflower oil affect postprandial factor VII differently.

BACKGROUND: The incidence of ischemic heart disease (IHD) in Crete was lower than expected on the basis of blood lipid concentrations of participants in the Seven Countries Study. A favorable effect of a high intake of olive oil on thrombogenesis may have contributed to this finding. OBJECTIVE: We compared the effects of virgin olive oil with those of rapeseed and sunflower oils on blood coagulation factor VII (FVII), a key factor in thrombogenesis. DESIGN: In a randomized and strictly controlled crossover study, 18 healthy young men consumed diets enriched with 5 g/MJ (19% of total energy) olive oil, sunflower oil, or rapeseed oil for periods of 3 wk. On the final day of each period, participants consumed standardized high-fat meals (42% of energy as fat). Fasting and nonfasting blood samples were collected after each period. RESULTS: Mean (+/-SEM) nonfasting peak concentrations of activated FVII (FVIIa) were 11.3 +/- 5.1 U/L lower after olive oil than after sunflower oil, an 18% reduction (P < 0.05). Olive oil also tended to cause lower FVIIa peak concentrations than did rapeseed oil (mean difference: 8.6 U/L, a 15% reduction; P = 0.09). There were no significant differences between diets with respect to nonfasting factor VII coagulant activity (FVII:c), prothrombin fragment 1+2 (F1+2), and tissue factor pathway inhibitor (TFPI) concentrations, or with respect to fasting plasma values of FVII protein, FVII:c, FVIIa, F1+2, or TFPI. CONCLUSION: A background diet rich in olive oil may attenuate the acute procoagulant effects of fatty meals, which might contribute to the low incidence of IHD in Mediterranean areas.

Unopposed estrogen increases total plasma factor VII, but not active factor VII--a short-term placebo-controlled study in healthy postmenopausal women.

Estrogen therapy may increase the risk of arterial thromboembolism, at least in the short term. In a randomized, double-blind and placebo-controlled study in 25 healthy postmenopausal women (52.5 +/- 2.8 years), we therefore examined the short-term effect of unopposed estrogen on the fasting and fat-load-stimulated plasma levels of total factor VII versus active factor VII. Plasma total factor VII was measured by use of a chromogenic assay; plasma active FVII by a recently developed method using truncated tissue factor. As compared to placebo, 8 weeks of oral 17beta-estradiol (2 mg daily) increased the mean fasting and postprandial plasma levels of total factor VII by 17 and 21% points, respectively (both P < 0.01 ), but did not affect the fasting and/or postprandial plasma levels of active factor VII (mean change both 0.05 ng/mL; P > 0.35). Furthermore, the change in the fasting level of total factor VII after therapy was not associated with the change in the fasting level of active factor VII (r = 0.27; P = 0.21). These findings argue against the idea that elevated levels of total factor VII underlie an increased risk of arterial thromboembolism in postmenopausal women using unopposed estrogen replacement.

The effects of long-term diet and omega-3 fatty acid supplementation on coagulation factor VII and serum phospholipids with special emphasis on the R353Q polymorphism of the FVII gene.

The aim of the present study was to investigate the effect of long-term diet and very long chain n-3 fatty acids (VLC n-3) intervention on plasma coagulation factor VII (FVII), choline-containing phospholipids (PC) and triglycerides (TG), especially related to the R353Q polymorphism of the FVII gene. The present investigation included 219 subjects from the Diet and Omega-3 Intervention Trial on atherosclerosis (DOIT), a 2x2 factorial designed study in elderly men with long-standing hypercholesterolemia. The subjects were randomly allocated to receive placebo capsules (corn oil) (control), placebo capsules and dietary advice ("Mediterranean type" diet), VLC n-3 capsules, or VLC n-3 capsules and dietary advice combined. The R353Q genotype and the levels of FVIIc, FVIIag, FVIIa, PC, and TG at baseline and after 6 months were determined. Diet intervention was followed by a significant reduction of 5.1% in the levels of FVIIag and 2.4 mU/ml in FVIIa (95% CI -7.4, -2.9, and -3.8, -1.1, respectively) (both p<0.001) compared to the no diet group, independent of genotype. No effects of diet intervention on FVIIc, PC or TG were observed. After VLC n-3 supplementation the TG levels were significantly reduced compared to placebo (p=0.01), whereas all FVII levels and PC remained unchanged. Dietary advice towards a "Mediterranean type" diet, but not VLC n-3 supplementation, was shown to reduce the levels of FVIIag and FVIIa after 6 months, independent of genotype. The results indicate the dietary advice to be more favourable in reducing this risk factor for CVD as compared to specific VLC n-3 supplementation.

Effects of diets containing olive oil, sunflower oil, or rapeseed oil on the hemostatic system.

Various studies have already shown that the fatty acid composition of dietary fat has different effects on hemostasis and platelet function. However, knowledge on this topic is incomplete. In the present study, fifty-eight healthy students received either a 4-week rapeseed oil [high content of monounsaturated fatty acids (MUFA) and high n-3/n-6 PUFA ratio], an olive oil (high content of MUFA, low n-3/n-6 PUFA ratio) or a sunflower oil (low content of MUFA, low n-3/n-6 PUFA ratio) diet. In each group, effects on hemostatic parameters were compared with a wash-in diet rich in saturated fatty acids with respect to intermediate-time effects on the hemostatic system and platelet function. With the olive oil diet, a reduction of coagulation factors VIIc, XIIc, XIIa, and Xc was found, whereas sunflower oil led to lower values of coagulation factors XIIc, XIIa, and IXc. In all study groups levels of plasmin-alpha2-antiplasmin were lower in week 4 than at baseline. Lower fibrinogen binding on platelets was found after the sunflower oil diet, whereas expression of CD62 and spontaneous platelet aggregation were slightly higher after the olive oil diet. However, given the major differences in the fatty acid compositions of the diets, the differences between the groups with respect to hemostasis tended to be small. Therefore, the clinical significance of the present findings remains to be evaluated.

Factor VII activation, apolipoprotein A-I and reverse cholesterol transport: possible relevance for postprandial lipaemia.

Postprandial lipaemia is associated with activation of factor VII (FVII) and efflux of cholesterol from tissues to nascent plasma high density lipoproteins (HDL) containing apolipoprotein A-I (apo A-I). To determine whether FVII activation and cholesterol efflux occur together in other situations, the responses to intravenous infusion of HDL-like apo A-I/phosphatidylcholine discs were measured in 10 healthy men. Disc infusion (40 mg apo A-I/kg body weight) over 4 h was followed by increases in HDL cholesteryl ester and plasma apo A-I (p <0.0001). Significant activation of FVII was apparent during infusion in fasting subjects (p = 0.03), activated FVII averaging 123% of baseline value by 12 h (p <0.0001). Plasma thrombin-antithrombin (TAT) complex increased to 156% of baseline level by 12 h (p >0.05) but individual responses differed considerably. Peak TAT post-infusion was associated inversely with peak HDL triglyceride concentration (p = 0.004). The coagulation responses to disc-infusion may be due to transfer of phosphatidylserine to cell surfaces during cholesterol efflux.

Blockade by ruthenium red of tissue factor-initiated coagulation.

The ability of ruthenium red (RuR) to inhibit tissue factor (TF)-initiated blood coagulation was demonstrated at the protein and cellular levels as well as in human plasma. In a single-stage clotting assay, RuR concentration-dependently inhibited rabbit brain thromboplastin (rbTF)-induced coagulation and offset bacterial endotoxin (LPS)-induced monocytic TF (mTF) hypercoagulation; the IC(50)s were estimated at 7.5 and 12.3 microM, respectively. A 15-min preincubation of RuR with rbTF or monocyte suspension resulted in the pronounced inhibition with a significantly lowered IC(50) at 1.8 or 7.7 microM for rbTF or mTF procoagulation, respectively. The differences in IC(50)s between rbTF and mTF without or with the preincubation indicated that TF was a primary target for RuR action. The effect of RuR on the physiological function of TF in FVII activation was demonstrated by the proteolytic cleavage of FVII zymogen to its active forms of serine protease on Western blotting analyses. RuR readily blocked TF-catalyzed FVII activation (diminished FVIIa formation), thus down regulating the initiation of blood coagulation. Inclusion of RuR into human plasma samples in vitro significantly prolonged prothrombin time, indicating the depressed coagulation. FVII activity was inhibited by 30 - 60% depending on the dose; as a result, FX activity also decreased. However, RuR showed no effect on thrombin time. Thus, RuR inhibited FVII activation to block the initiation of coagulation.

Effects of fixed low-dose warfarin on hemostatic factors in continuous ambulatory peritoneal dialysis patients.

Increased coagulation factors found in dialysis patients may explain in part the high prevalence of thrombotic cardiovascular disease. Several studies showed low-dose warfarin is effective in decreasing coagulation factors and preventing thrombosis without increasing the risk of bleeding. To evaluate the effects of fixed low-dose warfarin therapy on thrombogenesis in continuous ambulatory peritoneal dialysis (CAPD) patients, 76 CAPD patients were assigned randomly to treatment and disease control groups. The treatment group received 2 mg of warfarin daily for 12 months. International normalized ratio (INR) of the prothrombin time and plasma levels of factor VII, D-dimer, von Willebrand factor (vWF), and plasminogen activator inhibitor-1 (PAI-1) were measured before and 3, 6, and 12 months after the start of medication. The same parameters were measured in 30 healthy volunteers at the beginning of the study and in the disease control group during the study period. Of 76 patients, 60 completed the study. Deaths from atherosclerotic cardiovascular disease (cerebral infarction or acute myocardial infarction) occurred in 1 patient in the treatment group (n = 29) and 3 in the disease control group (n = 31), which was not statistically significant. No major bleeding occurred during the study period. With administration of warfarin, there was a small increase in INR in the treatment group. CAPD patients at baseline had significantly higher plasma factor VII, D-dimer, vWF, and PAI-1 levels than normal controls. Warfarin therapy lowered plasma factor VII and D-dimer levels. No change was seen in vWF and PAI-1 levels. In the disease control group, these hemostatic factors showed no change during the study period. There was a negative correlation between serum albumin and INR in the treatment group during the study period. Fixed low-dose warfarin was effective in partially reversing the thrombogenic coagulation profile in CAPD patients without a big increase in the risk of bleeding.

Effect of the endothelin-receptor antagonist bosentan on the pharmacokinetics and pharmacodynamics of warfarin.

To investigate the effects of bosentan (Ro 47-0203), an endothelin receptor antagonist, on the pharmacokinetics and pharmacodynamics of warfarin, a double-blind, placebo-controlled, randomized, two-way crossover study was performed in 12 healthy male volunteers. All subjects received a single oral dose of 26 mg racemic warfarin twice, once in the morning of the 6th day of treatment with 500 mg bosentan twice daily for 10 days and once at the same time point during treatment with placebo twice daily for 10 days. Both treatments were separated by a 2- to 3-week washout period. Blood samples were collected at intervals up to 120 hours following the warfarin dose for the measurement of prothrombin time and factor VII activity and for determination of plasma concentrations of R- and S-warfarin. Bosentan treatment led to a statistically significant reduction of the maximal prothrombin time (PTmax) and the AUC0-120 h of PT and factor VII activity compared to placebo, on average, by 23% to 38%. This reduction could be explained by an increase in the elimination of the pharmacologically more active S-enantiomer whose mean AUC0-infinity was reduced by 29%. The mean AUC0-infinity of R-warfarin was also decreased by 38%. Cmax and tmax of both enantiomers did not change. Close monitoring in patients receiving warfarin is recommended at initiation or discontinuation of treatment with bosentan.

The effects of acetaminophen on pharmacokinetics and pharmacodynamics of warfarin.

The oral anticoagulant warfarin is clinically administered as a racemic mixture of two enantiomers, (R) and (S). Many relevant drug interactions with warfarin have been attributed to the specific metabolic inhibition of the elimination of the more pharmacologically active (S)-enantiomer. To investigate reports that acetaminophen can potentiate the anticoagulant effect of warfarin, 20 healthy male volunteers were each given single oral 20 mg doses of racemic warfarin on three separate occasions: (1) alone, (2) after 1 day of acetaminophen (4 g/d), and (3) after 2 weeks of acetaminophen (4 g/d). The urinary excretion pattern of acetaminophen and its metabolites was not significantly altered over its course of administration. The (R)- and (S)-enantiomers of warfarin exhibited significantly different pharmacokinetic properties. However, acetaminophen did not alter the disposition of either (R)- or (S)-warfarin. All subjects exhibited a pharmacodynamic response to racemic warfarin. The response was not significantly altered in the presence of acute or chronic acetaminophen dosing, as assessed by prothrombin time and factor VII concentrations.

Somatotropin and somatostatin effects on vitamin K-dependent plasma coagulation factors.

The effects of somatotropin (0.2 mg/kg body mass) and somatostatin (0.1 mg/kg body mass) on plasma coagulation factors II, VII, IX, X and some general indexes of hemocoagulation were examined. Hormones were injected subcutaneously in male Wistar rats on 3 consecutive days. Boehringer Mannheim tests and Schnitger and Gross coagulometer were used for clotting factor determination. Somatotropin caused significantly decreased activity of factors II, VII and X (P < 0.001) and IX (P < 0.05). Somatostatin alone, as well as somatotropin after somatostatin pretreatment considerably increased the activity of factors II, VII and X (P < 0.001), while factor IX was non-significantly suppressed. It is concluded that somatotropin and somatostatin are possible regulators of biosynthesis of vitamin K-dependent plasma coagulation factors. Somatotropin depresses the activity of factors II, VII, IX and X and causes hypocoagulability, while somatostatin not only prevents the inhibiting effect on factors II, VII and X, but also increases their activity and causes hypercoagulability.