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PubMed1995

Evaluation of anticoagulant control in a pharmacist operated anticoagulant clinic.

AIMS: To compare the quality of outpatient anticoagulant control before and after the transfer of dosing responsibility to designated trained pharmacists from rotating junior medical staff. METHODS: All International Normalised Ratio (INR) values for an eight month period either side of the staff changeover were assessed for precision of therapeutic control according to described standards. Allowing for patient associated effects, observed and expected frequencies of "successful" control for the two staff groups were compared under the hypothesis of no association. RESULTS: INR results (n = 2219) for 382 patients were analysed. For patients in stable therapeutic control, there was no significant difference in performance between the two staff groups. Patients with an INR result "out" of control limits were more likely to be returned "in" to control at their next visit by the pharmacists than by the doctors. CONCLUSIONS: The quality of anticoagulant control in outpatient clinics benefits from dedicated trained staff using standard protocols.

Anticoagulants↗
PubMed2003

Pharmacokinetics and anticoagulant properties of the factor VIIa-tissue factor inhibitor recombinant Nematode Anticoagulant Protein c2 following subcutaneous administration in man. Dependence on the stoichiometric binding to circulating factor X.

Recombinant Nematode Anticoagulant Protein c2 (rNAPc2) is a potent (K(i) =10 pM), inhibitor of the factor VIIa/tissue factor (fVIIa/TF) complex that requires the prerequisite binding to zymogen or activated factor X (fX). In two double blind, place-bo-controlled, sequential dose-escalation phase I studies, rNAPc2 was found to be safe and well tolerated following single and repeat subcutaneous administrations in healthy human male volunteers at doses ranging from 0.3 to 5 micro g/kg. There was a dose-dependent elevation of the prothrombin time reaching almost 4-fold above the baseline value in the highest dose group that directly correlated with rNAPc2 plasma concentration. In contrast, there was little or no effect on the activated partial thromboplastin time, thrombin time or template bleeding time. The pharmacokinetic behavior of rNAPc2 revealed a dose-independent and prolonged elimination half-life (t(1/2)beta) with a mean of >50 hours. A high affinity interaction between rNAPc2 and plasma fX was shown to be essential for the prolonged t(1/2)beta in man using crossed immunoelectrophoresis and was confirmed by exploiting the considerably weaker interaction between rNAPc2 and bovine fX which resulted in an attenuated t(1/2)beta of approximately 1.5 hours in calves. The accumulated data suggests that rNAPc2 is safe and well tolerated following repeat subcutaneous administrations at doses up to 5 micro g/kg in healthy volunteers. In addition, the in vivo fate of rNAPc2 in man appears to be governed by its high affinity interaction with circulating fX. This data supports the continued development of this novel anticoagulant for the prevention and treatment of acute thrombotic disorders.

Animals↗
PubMed2005

Modulation of the intestinal response to ionizing radiation by anticoagulant and non-anticoagulant heparins.

Endothelial dysfunction is involved in radiation responses in many normal tissues, including intestine. Endothelium-directed interventions ameliorate intestinal radiation injury (radiation enteropathy) in animal models, and anecdotal reports also suggest a beneficial effect of heparin. This study assessed low molecular weight heparin as an intestinal radiation response modifier. Rats underwent localized small bowel irradiation. Groups of rats were treated with saline, nadroparin (3 mg/kg/d), or a non-anticoagulant heparin (SR80258, 3 mg/kg/d), from 3 days before to 2 weeks after irradiation. The intestinal radiation response was assessed 2 weeks and 6 weeks after irradiation using quantitative histology; morphometry, and cellular and molecular end-points. Compared to vehicle-treated controls, nadroparin significantly exacerbated structural radiation injury, neutrophil infiltration, and TGFbeta and collagen I immunoreactivity levels 2 weeks after irradiation. SR80258 was associated with increased TGFbeta levels, but the other parameters did not reach statistical significance. At 6 weeks, structural, cellular, and molecular injury was similar in the three experimental groups. Heparin, in contrast to antiplatelet agents and direct thrombin inhibitors, does not ameliorate, but exacerbates acute intestinal radiation toxicity. These data underscore the importance of heparin as an inhibitor of physiological anti-inflammatory mechanisms during tissue injury, as well as the non-anticoagulant effects of heparin. Moreover, these data may have implications for the use of heparin during radiation therapy.

Animals↗
PubMed2000

Implications of stroke risk criteria on the anticoagulation decision in nonvalvular atrial fibrillation: the Anticoagulation and Risk Factors in Atrial Fibrillation (ATRIA) study.

BACKGROUND: Warfarin dramatically reduces the risk of stroke in patients with nonvalvular atrial fibrillation (NVAF) but increases the likelihood of bleeding. Accurately identifying patients who need anticoagulation is critical. We assessed the potential impact of prominent stroke risk classification schemes on this decision in a large sample of patients with NVAF. METHODS AND RESULTS: We used clinical and electrocardiographic databases to identify 13 559 ambulatory patients with NVAF from July 1996 through December 1997. We compared the proportion of patients classified as having a low enough stroke risk to receive aspirin using published criteria from the Atrial Fibrillation Investigators (AFI), American College of Chest Physicians (ACCP), and the Stroke Prevention in Atrial Fibrillation Investigators (SPAF). In this cohort, AFI criteria classified 11% as having a low stroke risk, compared with 23% for ACCP and 29% for SPAF (kappa range, 0.44 to 0.85). This 2- to-3-fold increase in low stroke risk patients by ACCP and SPAF criteria primarily resulted from the inclusion of many older subjects (65 to 75 years+/-men >75 years) with no additional clinical stroke risk factors. CONCLUSIONS: The age threshold for assigning an increased stroke risk has a dramatic impact on whether to recommend warfarin in populations of patients with NVAF. Large, prospective studies with many stroke events are needed to precisely determine the relationship of age to stroke risk in AF and to identify which AF subgroups are at a sufficiently low stroke risk to forego anticoagulation.

Aged↗
PubMed1997

Anticoagulant synergism of heparin and activated protein C in vitro. Role of a novel anticoagulant mechanism of heparin, enhancement of inactivation of factor V by activated protein C.

Interactions between standard heparin and the physiological anticoagulant plasma protein, activated protein C (APC) were studied. The ability of heparin to prolong the activated partial thromboplastin time and the factor Xa- one-stage clotting time of normal plasma was markedly enhanced by addition of purified APC to the assays. Experiments using purified clotting factors showed that heparin enhanced by fourfold the phospholipid-dependent inactivation of factor V by APC. In contrast to factor V, there was no effect of heparin on inactivation of thrombin-activated factor Va by APC. Based on SDS-PAGE analysis, heparin enhanced the rate of proteolysis of factor V but not factor Va by APC. Coagulation assays using immunodepleted plasmas showed that the enhancement of heparin action by APC was independent of antithrombin III, heparin cofactor II, and protein S. Experiments using purified proteins showed that heparin did not inhibit factor V activation by thrombin. In summary, heparin and APC showed significant anticoagulant synergy in plasma due to three mechanisms that simultaneously decreased thrombin generation by the prothrombinase complex. These mechanisms include: first, heparin enhancement of antithrombin III-dependent inhibition of factor V activation by thrombin; second, the inactivation of membrane-bound FVa by APC; and third, the proteolytic inactivation of membrane-bound factor V by APC, which is enhanced by heparin.

Animals↗
PubMed2000

The Lupus Ratio test--an interlaboratory study on the detection of Lupus anticoagulants by an APTT-based, integrated, and semi-quantitative test. Fifth International Survey of Lupus Anticoagulants--ISLA 5.

The Lupus Ratio (LR) test for lupus anticoagulants integrates screening, mixing with normal plasma and confirmation procedures into one assay. The sensitivity and reproducibility of the APTT based version of this assay was tested in an interlaboratory study that was part of the Fifth International Survey of Lupus Anticoagulants (ISLA-5). One LA negative plasma containing heparin, six LA positive plasmas and a normal pooled plasma (NP) were distributed to 31 laboratories world-wide together with two APTT reagents, one with a high and one with a low phospholipid concentration. The laboratories performed two APTTs, one with each reagent, on 1:1 mixtures of test plasma and NP. The ratio between the two clotting times was divided by the corresponding ratio for the NP. This final ratio is the LR of that plasma. The overall sensitivity was found to be 95.1%, and the normal, heparin-containing sample was reported to be negative by all the laboratories. When the results were grouped in low, medium and high positive plasmas, a "consensus" regarding the strength of each plasma was easily found. 85.0% of the results were in agreement with this consensus. This study shows that with the LR test, it is possible to obtain high interlaboratory agreement regarding the presence or absence of LA as well as the semi-quantification of this inhibitor.

Anticoagulants↗
PubMed2005

Management of oral anticoagulant therapy in the real practice of an anticoagulation clinic: focus on atrial fibrillation.

Oral anticoagulant treatment (OAT) is increasingly used for preventing venous thromboembolic and cardiovascular disease. Our study was aimed to evaluate the efficacy and safety of OAT management in a real-practice situation, in particular in non-valvular atrial fibrillation (NVAF) patients. Among 1,596 consecutive unselected patients (follow-up, 3,364 patient-years) referring to the Anticoagulation Clinic, 558 (follow-up, 958 patient-years) suffered from NVAF. Total bleeding events were recorded in 39/558 NVAF patients (rate, 4.2/100 patient-years) and in 132/1,038 of all other patients (rate, 5.4/100 patient-years) (P<0.003). The rate of major bleeding and thrombotic complications was not different between NVAF patients and all the other patients. Considering NVAF patients, the rate of major bleeding was slightly higher in females than in males (P=0.06). NVAF females showed a higher rate of stroke than males (P=0.004). In NVAF patients the rate of bleeding complications was not different in relation to age; instead, total and major thrombotic events occurred more frequently in patients >or= 75 years than in younger patients (P=0.05 and P=0.01, respectively). NVAF patients on OAT show a low rate of complications. However, females show a trend to higher risk of bleeding complications and suffered more frequently from stroke with respect to males in spite of therapy.

Administration, Oral↗
PubMed1991

Comparison of the in vivo anticoagulant properties of standard heparin and the highly selective factor Xa inhibitors antistasin and tick anticoagulant peptide (TAP) in a rabbit model of venous thrombosis.

An in vivo thromboplastin (TP)-induced venous stasis thrombosis model in rabbits was used to compare the efficacy of standard heparin with the selective factor Xa inhibitors, recombinant tick anticoagulant peptide (rTAP) and recombinant antistasin (rATS), in prophylactic prevention of thrombus formation. Heparin significantly reduced TP-induced clot formation at doses of 55 and 100 U kg-1h-1 yielding clot weights of 9 +/- 4 and 6 +/- 2%, respectively. Clot formation was significantly decreased by i.v. infusions of rTAP at doses of 21, 37 and 64 micrograms kg-1 min-1 resulting in normalized clot weights of 13 +/- 3, 8 +/- 2 and 2 +/- 1%, respectively. rATS was approximately 10-fold more potent than rTAP, reducing normalized clot weights to 16 +/- 5, 2 +/- 1 and 1 +/- 0.8% at rATS doses of 1.25, 2.5 and 5.0 micrograms kg-1 min-1, respectively. These data suggest that factor Xa-mediated inhibition of coagulation with rTAP and rATS is as effective as conventional anticoagulant treatment with heparin in preventing venous thrombosis.

Animals↗
PubMed1990

Detection of lupus anticoagulant by means of dilute Russell's viper venom time is affected by oral anticoagulant therapy.

The effects of oral anticoagulant therapy on the detection of lupus anticoagulant (LA) were studied in 110 patients with histories of thrombosis. LA was clearly positive in only two (2%) of the patients. Factor defects caused by warfarin therapy did not affect the kaolin clotting time (KCT) or recalcification time (RT) in mixing tests, but markedly affected the dilute Russell's viper venom time (DRVVT), resulting in 45 weak false-positive results. However, the problem was overcome in 93% of these cases by taking account of the basal prolongation of patients' DRVVT and the sensitivity of plasmas to dilution of the phospholipid reagent. A simple mathematical formula is suggested.

Administration, Oral↗
PubMed1995

Subcutaneous low-molecular weight heparin or oral anticoagulants for the prevention of deep-vein thrombosis in elective hip and knee replacement? Fraxiparine Oral Anticoagulant Study Group.

OBJECTIVE: To compare efficacy, safety, and feasibility of adjusted-dose oral anticoagulants (OAC) versus fixed-dose subcutaneous low molecular weight heparin (LMWH) for the prevention of deep venous thrombosis (DVT) in patients who have undergone elective hip or knee replacement. DESIGN: Multicentre, single blind randomised trial. OAC (acenocoumarol, target International Normalised Ratio, 2.0-3.0) and LMWH (nadroparine, 60 aXa IU/kg once daily) were started preoperatively and continued for 10 days. All outcome measures were adjudicated by an independent committee unaware of treatment allocation. SUBJECTS: 672 consecutive patients scheduled for elective hip or knee replacement surgery. All patients wore bilateral graduated compression stockings. MAIN OUTCOME MEASURES: The endpoint for the assessment of efficacy was venography confirmed DVT or confirmed symptomatic pulmonary embolism. The endpoint for the assessment of safety was clinically important bleeding during study treatment or within 48 h of the end of treatment. RESULTS: Among the 517 patients with interpretable venograms, 391 had a hip replacement and 126 had a knee implant. DVT was demonstrated in 50 (20%) of 257 patients allocated to OAC and 43 (17%) of 260 patients allocated to nadroparine (p = 0.45), for an absolute difference in DVT incidence of 2.9% in favour of nadroparine (95% CI, -3.7-9.5). Clinically important bleeding occurred in eight (2.3%) of the 342 oral anticoagulant treated patients and in five (1.5%) of the 330 nadroparine treated patients (p = 0.62), for an absolute difference in favour of nadroparine of 0.8% (95% Cl, -1.3-2.9). CONCLUSION: Patients who undergo major orthopaedic operations have a high risk of venous thromboembolism. Once daily fixed-dose subcutaneous nadroparine is at least as efficacious and safe as daily adjusted OAC for prophylaxis against DVT after hip or knee implantation but is more simple to administer.

Administration, Oral↗
PubMedDate not supplied

[Therapeutic ranges of oral anticoagulant therapy in different diseases. Guidelines of the Federation of Centers of Surveillance of Patients on Anticoagulation. Ad hoc Study Group].

The "ad hoc" Study Group of the Federation of Italian Anticoagulation Clinics has proposed a series of guidelines for oral anticoagulant therapy in different pathological states for which this treatment is indicated. These indications are based on the scientific literature available through March 1996. While there is wide consensus for some indications, opinions diverge regarding others. Finally, there are a number of indications which are potentially useful but are not supported by adequate studies. For the applications of guidelines in individual cases, however, careful clinical evaluation is necessary.

Administration, Oral↗
PubMed1996

A cost analysis of coronary stenting without anticoagulation versus stenting with anticoagulation using warfarin.

A case-controlled study was performed comparing hospitalization costs and length of hospital stay in a group of patients managed with antiplatelet therapy only, versus a group treated with anticoagulation using warfarin after coronary artery stenting. The patients managed with antiplatelet therapy alone had significantly reduced total hospitalization costs and a significantly reduced average hospital stay than patients managed with anticoagulation.

Aged↗
PubMed1997

Transient lupus anticoagulants associated with hemorrhage rather than thrombosis: the hemorrhagic lupus anticoagulant syndrome.

Lupus anticoagulants (LAs) represent a diverse group of antibodies directed against phospholipids. Patients with LAs may be free of symptoms but can have thrombotic complications including stroke, placental infarction, and fetal loss. Rarely hemorrhagic symptoms have been reported. We describe six previously healthy children who were first seen with clinical bleeding and prolonged activated partial thromboplastin time. Laboratory evaluation revealed positive results on mixing studies and evidence of phospholipid dependence of the anticoagulant, suggesting LAs. Four of six patients had anticardiolipin antibodies, and all four who were tested had reduced factor II activity levels. In all patients, bleeding symptoms resolved spontaneously within 3 months, and laboratory findings returned to normal within 6 months. The hemorrhagic LA syndrome should be considered in previously healthy children with new-onset bleeding and prolonged activated partial thromboplastin time. This clinical entity probably represents pathogenic mechanism distinct from thrombotic LA syndromes.

Brain↗
PubMed1997

Thyroid antibodies and their relation to antithrombin antibodies, anticardiolipin antibodies and lupus anticoagulant in women with recurrent spontaneous abortions (antithyroid, anticardiolipin and antithrombin autoantibodies and lupus anticoagulant in habitual aborters).

OBJECTIVE: This study was undertaken to evaluate the incidence of thyroid autoantibodies in women with a history of recurrent spontaneous abortions (RSA) and to investigate their relationship to non-organ specific autoantibodies. STUDY DESIGN: 28 euthyroid non-pregnant habitual aborters were analysed for thyreoglobulin (TG), thyroid peroxidase antibodies (TPO), and autoantibodies to thromboplastin, cardiolipin and lupus anticoagulant. 28 multigravidae without previous abortions or endocrine dysfunctions served as controls. RESULTS: 11 of 28 women with recurrent spontaneous miscarriage (39%), but only 2 of 28 controls (7%) (Chi square test: p < 0.01) demonstrated positive titres of TG, TPO, or both antibodies, 12 patients were positive for antithrombin antibodies and 3 for anticardiolipin. Only one women was lupus anticoagulant positive. No significant correlation between thyroid antibody positivity and positivity for antiphospholipids (Fisher's exact test: p = 0.441), anticardiolipin (p = 0.664) or lupus coagulant (p = 0.607) was found. CONCLUSIONS: The incidence of thyroid antibodies in euthyroid women with recurrent pregnancy loss appears to be significantly increased compared with controls of reproductive age without previous abortions. No correlation between the presence of thyroid autoantibodies and non-organ specific autoantibodies could be established.

Abortion, Habitual↗
PubMed2002

The Activated Seven Lupus Anticoagulant (ASLA) assay: a new test for lupus anticoagulants (LAs). Evidence that some LAs are detectable only in extrinsic pathway-based assays.

Accurate and timely detection of lupus anticoagulants (LAs) is of diagnostic and prognostic importance due to the association of persistent LAs with thrombotic disease. In the present study, a sensitive and specific assay for LAs has been developed using recombinant activated factor VII to initiate in vitro coagulation. The Activated Seven Lupus Anticoagulant (ASLA) assay uses dilute brain-derived phospholipid in the screening test and a platelet neutralization procedure (PNP) in the confirmatory test. Tests are reported as ratios of patient clotting time to normal control clotting time and percentage correction by PNP assessed for abnormal ratios. Evaluation with 70 known LA-positive plasmas demonstrated higher detection rates than with individual assays from a wide range of commonly employed LA tests. The ASLA assay identified 61 of 70 (87%) known LAs, compared with 65.7% with the most sensitive of the other assays. The various LA assays were used to test 110 plasma samples from patients with thrombotic disease previously negative for LA. These experiments demonstrated that 18 of 110 (16.4%) contained LAs detectable only in extrinsic pathway-based assays, 10 of these by ASLA testing alone. ASLA testing showed high diagnostic precision and has the potential to make a significant contribution to LA detection.

Blood Coagulation Disorders↗
PubMed2004

Life-threatening bleeding, pregnancy and lupus anticoagulant: success after steroid and anticoagulant therapy.

PROBLEM: The clinical manifestations associated with the presence of the lupus anticoagulant (LAC) are usually thrombotic and/or obstetric complications, specially miscarriages and/or repeated fetal deaths. The bleeding episodes in patients with LAC with no other coagulation disorders are exceptional, especially during pregnancy, intra- and postpartum. METHOD OF STUDY: Here we present two cases of patients with classification criteria of primary antiphospholipid antibody syndrome, a history of recurrent complicated pregnancies and massive bleeding during abortion and postpartum. We studied anticardiolipin (IgG/IgM), beta2glicoprotein-1 (IgG) and antimitochondrial (type 5) antibodies, LAC, rapid plasma reagin, coagulation test, clotting factors and, placental vascular flow from the second trimester of their last pregnancies. RESULTS: LAC was repeatedly detected in both cases. The prothrombin time and clotting factors including factors II and XIII were normal. Intrauterine growth restriction was also observed in both patients. Pre-eclampsia was detected in patient 2. We tried enoxaparin (60-80 mg/day) and prednisone (1 mg/kg/day) therapy and no maternal, hemorrhagic or thrombotic episodes were observed. CONCLUSIONS: Exceptionally, LAC may be associated with recurrent, life-threatening bleeding, even in patients with no prothrombin deficiency. The close follow-up and early anticoagulant and steroid therapy seems to be able to control thrombotic and hemorrhagic complications during the pregnancy and postpartum.

Adult↗
PubMed1990

Coagulation and anticoagulation systems in newborns--correlation with their mothers at delivery. Lower levels of anticoagulants and fibrinolytic activity in the newborn.

The neonatal period is probably the only time when a higher incidence of spontaneous thromboembolic complications may occur in the otherwise normal healthy individual, and this may be related to the activation of the coagulation system at the time of parturition. This study was performed to look at the newborn coagulation and anticoagulation systems and compare these with the changes in the maternal circulation in normal cases. Paired umbilical cord venous and maternal venous blood samples were obtained and plasma levels of protein C, protein S, antithrombin III, fibrinopeptide A, fibrinogen, plasminogen, and fibrinolytic inhibitory activity were measured. The maternal plasma level was significantly higher in all cases except for fibrinopeptide A which was similar, and for fibrinolytic inhibitory activity which was lower (p less than 0.05). A significant correlation exists between maternal and newborn protein C levels (p less than 0.02) and fibrinolytic inhibitory activity (p less than 0.05). The findings indicate that parturition leads to a similar degree of activation of the newborn coagulation system as shown by the fibrinopeptide A level. As their anticoagulants and fibrinolytic activity levels are lower and the fibrinolytic inhibitory activity is higher, the newborns are thus predisposed to thrombosis even in the absence of complications such as sepsis.

Antithrombin III↗
PubMed1988

Lupus anticoagulant: a unique case with lupus anticoagulant and habitual abortion together with antifactor II antibody and bleeding tendency.

Lupus anticoagulants (LA) are associated with various forms of thrombotic events. Of particular interest to obstetrics is the association with placental infarcts and habitual abortion. In the case described a near full-term viable infant was delivered subsequent to four early miscarriages. However, the mother had then developed an antifactor II antibody leading to grave hypoprothrombinemia with bleeding tendency, indicating efficient autoanticoagulation. This natural experiment indicates that these patients should receive anticoagulation during pregnancy, possibly in combination with steroids to depress the LA level.

Abortion, Habitual↗