The efficacy and safety of Hirudin plus Aspirin versus Warfarin in the secondary prevention of Cardioembolic Stroke due to Nonvalvular Atrial Fibrillation: A multicenter prospective cohort study.

Background: To investigate the efficacy and safety of hirudin plus aspirin therapy compared with warfarin in the secondary prevention of cardioembolic stroke due to nonvalvular atrial fibrillation (NVAF). Methods: Patients with cardioembolic stroke due to NVAF were prospectively enrolled from 18 collaborating hospitals from Dec 2011 to June 2015. Fourteen days after stroke onset, eligible patients were assigned to the hirudin plus aspirin group (natural hirudin prescribed as the traditional Chinese medicine Maixuekang capsule, 0.75 g, three times daily, combined with aspirin 100 mg, once daily) or the warfarin group (dose-adjusted warfarin targeting international normalized ratio (INR) 2-3, with an initial daily dose of 1.25 mg). Patients were followed up at 1, 2, 3, 6, 9, and 12 months after stroke onset. Time in therapeutic range (TTR) was calculated according to Rosendaal methodology to evaluate the quality of INR management in the warfarin group. The primary efficacy endpoint was the recurrence of stroke within 12 months after stroke onset. Safety was assessed as the occurrence of the composite event "intracranial hemorrhage and other bleeding events, death, and other serious adverse events". The Cox proportional hazard model and Kaplan-Meier curve were used to analyze the efficacy and safety events. Results: A total of 221 patients entered final analysis with 112 patients in the hirudin plus aspirin group and 109 in the warfarin group. Over the whole duration of our study, TTR for patients taking warfarin was 66.5 % ± 21.5%. A significant difference was not observed in the recurrence of stroke between the two groups (3.57% vs. 2.75%; P = 0.728). The occurrence of safety events was significantly lower in the hirudin plus aspirin group (2.68% vs.10.09%; P = 0.024). The risk for efficacy event was similar between the two groups (hazard ratio (HR), 1.30; 95% confidence interval (CI), 0.29-5.80). The safety risk was significantly lower in the hirudin plus aspirin group (HR, 0.27; 95% CI, 0.07-0.95). Kaplan-Meier analysis revealed significant difference in the temporal distribution in safety events (P = 0.023) but not in stroke recurrence (P = 0.726). Conclusion: Significant difference in efficacy was not detected between warfarin group and hirudin plus aspirin group. Compared with warfarin, hirudin plus aspirin therapy had lower safety risk in the secondary prevention of cardioembolic stroke due to NVAF.

Hirudin improves renal interstitial fibrosis by reducing renal tubule injury and inflammation in unilateral ureteral obstruction (UUO) mice.

Renal interstitial fibrosis (RIF) often occurs in many chronic kidney diseases (CKD). Hirudin now is applied to treat fibrosis in some organs. In this study, we verified the treatment effects of hirudin on RIF in vivo and in vitro with the underlying mechanism. The RIF in vivo was the unilateral ureteral obstruction (UUO) model and RIF in vitro was the renal tubular epithelial cells induced by TGF-ß. The renal pathological changes and renal fibrosis were observed by hematoxylin and eosin (H&E) staining and Masson staining. The α-SMA in renal tissues was detected by immunohistochemistry. The inflammatory factors were analyzed by the ELISA assay. The cell apoptosis was observed by TUNEL assay. The related proteins of fibrosis, epithelial-mesenchymal transition (EMT) and apoptosis were assessed by western blot analysis. The experimental data demonstrated that hirudin decreased fibrosis, EMT, inflammation and cell apoptosis in renal tissues of UUO rats and TGF-ß-induced renal tubular epithelial cells. Furthermore, hirudin also reduced the expression of collgen-I, FN, α-SMA, N-cad, slug, E-cad, IL-1ß, IL-6 and TNF-α in mice serum and TGF-ß-induced renal tubular epithelial cells. The apoptosis related proteins (pro-caspase3, pro-caspase9, bcl2 and bax) expression was also down-regulated in renal tissues of UUO rats. In conclusion, hirudin depressed the fibrosis in renal tissues and renal tubular epithelial cells by inhibiting the inflammation, regulating the related proteins of fibrosis and ETM and decreasing the apoptosis of renal tubular epithelial cells. These findings may offer an effective treatment method for RIF.

The effects of a hirudin/liposome complex on a diabetic nephropathy rat model.

BACKGROUND: Hirudin, an extract from Hirudo spp., is an anticoagulant used to treat a variety of renal diseases, including diabetic nephropathy (DN). Currently, hirudin has to be used at high dosages to treat DN because it poorly targets the kidneys, although at high dosages it can have severe side effects. Developing a targeted drug delivery system for hirudin, then, could boost its positive therapeutic effects while lowering the risk of side effects. Liposomes have been demonstrated to have significant renal targeting potential, but here we show that a hirudin-loaded liposome is an effective delivery method for patients with DN. METHOD: In this study, we prepared a hirudin/liposome complex and tested its efficacy by injecting it into a rat model. We then compared the renal accumulation of hirudin between complex-injected rat models and rat models that received injections of hirudin alone. We also investigated the mechanisms behind the complex's effects. RESULT: The hirudin/liposome complex increased the accumulation of hirudin in kidney tissues and relieved the renal injury in DN rat models. Moreover, the hirudin/liposome complex down-regulated the expression of TGF-ß1 and VEGF in the kidneys. CONCLUSION: We demonstrated that a hirudin/liposome complex can have a significant positive effect on DN. The mechanism may be that the complex inhibits the expression of VEGF and TGF-ß1.

Bivalirudin for left ventricular assist device thrombosis.

Pump thrombosis remains a serious complication of implantable ventricular assist device therapy and is associated with increased risk of morbidity and mortality. Optimal management strategies remain controversial and are guided largely by limited literature and expert opinion. Medical management of pump thrombosis, including the use of direct thrombin inhibitors, has been associated with mixed results. The purpose of this study is to report the outcomes associated with bivalirudin therapy in LVAD patients with suspected pump thrombosis. A single-center, retrospective observational study of 15 patients with suspected pump thrombosis that were all treated with bivalirudin therapy was conducted. The majority of subjects' initial treatment courses were unsuccessful [9/15 (60%)]; however, 6/15 (40%) achieved an initial improvement in serum lactate dehydrogenase (LDH) levels and were stabilized to be successfully discharged from the hospital. Of the subjects discharged, there was a high rate of recurrence of pump thrombosis within 6 months [5/6 (83.3%)]. Bivalirudin therapy was not associated with a consistent reduction in LDH among all subjects studied, and clinical responses to therapy appear to be associated with high rates of thrombosis recurrence. This study analyzes the largest cohort to date of LVAD patients with pump thrombosis treated with bivalirudin therapy, and suggests that alternative therapies should be considered in management.

SAK-HV Triggered a Short-period Lipid-lowering Biotherapy Based on the Energy Model of Liver Proliferation via a Novel Pathway.

The accumulations of excess lipids within liver and serum are defined as non-alcoholic fatty liver disease (NAFLD) and hyperlipemia respectively. Both of them are components of metabolic syndrome that greatly threaten human health. Here, a recombinant fusion protein (SAK-HV) effectively treated NAFLD and hyperlipemia in high-fat-fed ApoE-/- mice, quails and rats within just 14 days. Its triglyceride and cholesterol-lowering effects were significantly better than that of atorvastatin during the observation period. We explored the lipid-lowering mechanism of SAK-HV by the hepatic transcriptome analysis and serials of experiments both in vivo and in vitro. Unexpectedly, SAK-HV triggered a moderate energy and material-consuming liver proliferation to dramatically decrease the lipids from both serum and liver. We provided the first evidence that PGC-1α mediated the hepatic synthesis of female hormones during liver proliferation, and proposed the complement system-induced PGC-1α-estrogen axis via the novel STAT3-C/EBPß-PGC-1α pathway in liver as a new energy model for liver proliferation. In this model, PGC-1α ignited and fueled hepatocyte activation as an "igniter"; PGC-1α-induced estrogen augmented the energy supply of PGC-1α as an "ignition amplifier", then triggered the hepatocyte state transition from activation to proliferation as a "starter", causing triglyceride and cholesterol-lowering effects via PPARα-mediated fatty acid oxidation and LDLr-mediated cholesterol uptake, respectively. Collectively, the SAK-HV-triggered distinctive lipid-lowering strategy based on the new energy model of liver proliferation has potential as a novel short-period biotherapy against NAFLD and hyperlipemia.

Alternative anticoagulation during cardiovascular procedures in pediatric patients with heparin-induced thrombocytopenia.

Patients with heparin-induced thrombocytopenia (HIT) that require anticoagulation for cardiovascular procedures represent a challenging and high-risk group. Bivalirudin and argatroban have been successfully used as alternative anticoagulants in adult patients with HIT. There have been few experiences published involving the pediatric population and controversy exists regarding the properties and optimal dosing of these drugs. This report describes the experience of managing two pediatric patients with HIT that underwent cardiovascular procedures requiring anticoagulation. Bivalirudin was used in both cases for anticoagulation during cardiopulmonary bypass, while argatroban was used without complications during cardiac catheterization. A description of perfusion and anticoagulation protocols is included.

Successful use of hirudin during cardiac surgery using minimized extracorporeal circulation in patients with heparin-induced thrombocytopenia.

In this case series, we describe our successful use of a reduced hirudin dosage as an anticoagulant during cardiac surgery using minimized extracorporeal circulation in patients with heparin-induced thrombocytopenia.

A randomized two-by-two comparison of high-dose bolus tirofiban versus abciximab and unfractionated heparin versus bivalirudin during percutaneous coronary revascularization and stent placement: the tirofiban evaluation of novel dosing versus abciximab with clopidogrel and inhibition of thrombin (TENACITY) study trial.

BACKGROUND: In the absence of high-dose thienopyridines, placebo-controlled trials have demonstrated a reduction in ischemic events with intravenous glycoprotein IIb/IIIa antagonists during percutaneous coronary intervention (PCI). One head-to-head trial comparing abciximab and tirofiban among PCI patients found tirofiban to be inferior, and laboratory evidence confirmed that the bolus dose of tirofiban tested in that trial to be less effective than abciximab. Whether a higher bolus dose of tirofiban would be as efficacious as abciximab during PCI is uncertain. METHODS AND RESULTS: Patients undergoing PCI were randomized equally to abciximab or to tirofiban, given as high-dose bolus (25 µg/kg) plus 12-hr infusion (0.15 µg/kg/min). All patients received aspirin and clopidogrel and were additionally randomized to unfractionated heparin or bivalirudin. Approximately 8,000 patients were to be studied, but after 383 were enrolled, the study sponsor discontinued the trial for financial reasons. The primary endpoint of 30-day death, myocardial infarction, or urgent target vessel revascularization occurred in 8.8% of patients randomized to abciximab and 6.9% of those randomized to tirofiban. The respective rates of major bleeding were 1.5 and 1.6%. Additionally, the primary endpoint occurred in 8.1% of patients randomized to unfractionated heparin and 7.6% of those randomized to bivalirudin. The respective rates of major bleeding were 2.5% and 0.5%. CONCLUSION: With limited assessment, this direct comparison of high-dose bolus tirofiban versus abciximab produced encouraging results and suggests that further study of this tirofiban dose regimen is warranted. The limited assessments comparing heparin and bivalirudin are consistent with prior observations.

[Studies on preparation of recombinant hirudin-2 liposome and its pharmacokinetics by nasal delivery in rats].

OBJECTIVE: To promote the nasal absorption of recombinant hirudin-2, the preparation and physicochemical properties of recombinant hirudin-2 liposomes, as well as its pharmacokinetic characteristics and bioavailability in rats after nasal administration were investigated. METHOD: Recombinant hirudin-2 liposomes were prepared by reversal phase evaporation; the test of physicochemical properties including encapsulation efficiency, particle size and stability of liposome suspensions were determined by HPLC; Recombinant hirudin-2 concentration in plasma was determined by chromogenic substrate method and the relative bioavailability and pharmacokinetic parameters were also calculated using software program 3p87. RESULT: The encapsulation efficiency of recombinant hirudin-2 liposome reached greater than 76.95%, with an average particle size of about 168.3 nm, size distribution ranging from 24 to 286 nm, relative peak width of +/- 0.47, and a good stability. CONCLUSION: Compared with recombinant hirudin-2 solution, liposome preparation enhanced the nasal absorption of recombinant hirudin-2.

Nasal recombinant hirudin-2 delivery: absorption and its mechanism in vivo and in vitro studies.

The objective of this study was to investigate the feasibility of systemic absorption of recombinant hirudin-2 (rHV2) by nasal delivery, and its possible absorption mechanism. The degradation of rHV2 in the nasal tissue homogenate and extracts of mucosae of rabbit, as well as the degradation inhibition of enzyme inhibitor (bacitracin) was evaluated. The bioavailability of rHV2 and the improvement with enhancers, after nasal administration in rats was investigated. For further understanding of the transport and uptake characteristics of rHV2, in vitro transport experiment under various conditions using diffusion chamber technique in excised rabbit nasal epithelium was performed. It was found that rHV2 underwent rapid degradation in rabbit nasal homogenate, but it was more stable in the extracts of nasal mucosae surface. Bacitracin was able to inhibit the degradation of rHV2 to certain extent. rHV2 was detected in the rat plasma by chromogenic substrate assay after nasal administration and some enhancers also significantly increased the nasal absorption of rHV2. The transport and uptake of rHV2 across nasal epithelium was concentration-dependent and unsaturated, and was significantly inhibited by low temperature, NaN(3), DNP and colchicines, while was less affected by alteration of transport direction. These results demonstrate that the possible absorption mechanism of rHV2 by nasal mucosa appears to be associated with the endocytosis as well as passive diffusion process.

Direct thrombin inhibitors are not equally effective in vivo against arterial thrombosis: in vivo evaluation of DuP714 and argatroban in a porcine angioplasty model and comparison to r-hirudin.

BACKGROUND: Qualitative differences in antithrombotic efficacy between thrombin inhibitors may be explained by the affinity for which they bind thrombin. This affinity is inversely proportional to the inhibitory constant for the agent (Ki). Thrombin inhibitors, DuP714 (Ki=10(-11)) and argatroban (Ki=10(-8)), were compared to our previous studies with r-hirudin (Ki=10(-13)). METHODS AND RESULTS: Prior to balloon angioplasty, thirty pigs randomly received DuP714 (0.1 mg/kg bolus and 0.6 mg/kg/h infusion; n=8), argatroban (0.2 mg/kg/min. continuous infusion; n=9), or saline (n=17). Injured arterial segments were measured for (111)In-platelet and 125I-fibrin(ogen) deposition and the incidence of macroscopic thrombus. In DuP714-treated animals, platelet and fibrin(ogen) deposition were significantly lower than controls in both carotid (10+/-2 vs. 62+/-18 and 20+/-4 vs. 74+/-6) and coronary (10+/-4 vs. 160+/-63 and 17+/-3 vs. 86+/-22) arteries (p<0.005). In contrast, platelet and fibrin(ogen) deposition were similar when comparing argatroban to saline in carotid (41+/-20 vs. 40+/-9 and 71+/-5 vs. 49+/-7) and coronary (92+/-33 vs. 151+/-45 and 114+/-37 vs. 89+/-38) arteries (p=0.82 and 0.38, respectively). Compared to argatroban, fibrin(ogen) (p<0.001) and coronary platelet deposition (p<0.05) were significantly reduced in animals treated with DuP714 with no significant difference in carotid platelet deposition (p=0.10). Neither inhibitor prevented macroscopic thrombosis. In previous studies with r-hirudin in this model, platelet deposition was limited to a monolayer with complete inhibition of macroscopic thrombus. CONCLUSIONS: Direct thrombin inhibitors do not equally prevent arterial thrombosis. Qualitative differences may be explained in part by the affinity for which they bind thrombin.

[Studies on the nasal epithelium toxicity of adjuvants and recombination hirudin (rHV2) nasal spary].

OBJECTIVE: To investigate the nasal epithelium toxicity of adjuvants and rHV2 nasal spary(HVS). METHOD: Ciliary movement were evaluated with in situ toad palate model; The histology assessment of nasal epithelium were carried out after long-lasting and repeated use of HVS. RESULT AND CONCLUSION: Adjuvants included SDS, Brij 35, azone, lecithin, EDTA, menthol, nipagin and thiomersal were able to significantly inhibited the ciliary movement, while tween80, glycyrrhizic acid monoammonium salt, benzalkonium bromide, sodium benzoate and adhensive materials investigated had less influence on it. HVS was able to damaged the nasal epithelium, but this effect recovered soon after stopping administration. It was demonstrated that SDS, Brij 35, azone,lecithin, EDTA, menthol, nipagin and thiomersal. It had significant cilitoxity, while tween80, glycyrrhizic acid monoammonium salt, benzalkonium bromide, sodium benzoate and adhensive materials investigated had no significance; Chitosan co-administration with some adjuvants may make the cillitoxity severer; It is available that rHV2 be administered by nasal spary.

Effects of ximelagatran, the oral form of melagatran, in the treatment of caval vein thrombosis in conscious rats.

The antithrombotic effects of direct (ximelagatran and hirudin) and indirect (dalteparin) anticoagulants were compared using a deep venous thrombosis (DVT) treatment model in conscious rats. Thrombus formation was induced in the inferior caval vein by total stasis plus topically applied ferric chloride. After 1-h thrombus maturation, one group of 10 rats were sacrificed and the mean thrombus weight in this group was 27.3 +/- 2.7 mg. This thrombus weight was handled as a reference to which all other results were compared. In all other groups, the total occlusion was removed after 1 h but a partial stasis was retained, permitting some blood flow around the thrombus. Groups of animals received subcutaneous (s.c.) dalteparin (200 IU/kg), s.c. hirudin (0.75 micromol/kg), one of four oral doses of ximelagatran (2.5, 5, 10 or 20 micromol/kg) or s.c. saline (control). After the 3-h treatment, mean thrombus weight in the saline group (26.5 +/- 3.3 mg) did not differ significantly from that of the reference group (27.3 +/- 2.7 mg, see above). Ximelagatran decreased thrombus weight in a dose-dependent manner, with an estimated ID(50) of 15 micromol/kg. Mean thrombus weight with the highest ximelagatran dose (11.1 +/- 1.3 mg) was similar to that with hirudin (13.0 +/- 1.5 mg). The effect of dalteparin on thrombus regression was much less pronounced (20.2 +/- 1.2 mg), compared with ximelagatran and hirudin, even though it was administered at a dose that yielded a similar activated partial thromboplastin time (APTT) prolongation. In conclusion, the results from this DVT treatment model showed that direct thrombin inhibitors ximelagatran and hirudin exhibited superior antithrombotic properties to low molecular weight heparin (LMWH).

Comparison of enoxaparin, hirulog, and heparin as adjunctive antithrombotic therapy during thrombolysis with rtPA in the stenosed canine coronary artery.

A canine model of electrolytic injury-induced coronary artery thrombosis and rtPA-induced thrombolysis was used to evaluate the relative antithrombotic efficacy of enoxaparin (a low molecular weight heparin), conventional therapy (heparin or heparin plus aspirin), and hirulog (a direct thrombin inhibitor), when used as adjunctive therapy during thrombolysis. After 60 min of clot aging, adjunctive therapy was begun at doses which elevated APTT approximately 2-fold over baseline. Fifteen minutes after the start of adjunctive therapy, recombinant tissue plasminogen activator (rtPA) was administered (100 microg/kg i.v. bolus + 20 microg/kg/min for 60 min). Adjunctive therapy continued for 1 h after termination of rtPA and blood flow was monitored for two additional hours. Enoxaparin (1 mg/kg i.v. bolus + 30 microg/kg/min, n = 10 for each treatment group) was the only adjunctive treatment that significantly increased the total minutes of flow (143 +/- 25 min out of a possible 240 min, vs 54 +/- 25 min for vehicle, p <0.05) and decreased thrombus mass (6.0 +/- 1.3 mg vs 11.8 +/- 3.2 mg for vehicle). Although hirulog (2 mg/kg i.v. bolus + 40 microg/kg/min) did not significantly increase the minutes of flow (120 +/- 27 min, p <0.06) or decrease thrombus mass (8.7 +/- 1.7 mg) compared to vehicle, these values were not significantly different than those measured in the enoxaparin group. However, the results with hirulog were achieved at the expense of a significantly greater increase in template bleeding time than that measured during enoxaparin treatment. Minutes of flow for heparin (50 U/kg i.v. bolus + 0.6 U/kg/min) and heparin plus aspirin (5 mg/kg i.v. bolus) were 69 +/- 20 and 60 +/- 23 min, respectively; thrombus masses were 8.2 +/- 1.3 and 7.3 +/- 1.0 mg, respectively. In summary, enoxaparin was more effective than conventional therapy in this model in terms of vessel patency and thrombus mass, and was as effective as hirulog, at least at a dose of hirulog that only modestly impaired hemostasis. Therefore, enoxaparin may prove to be a safe and effective alternative agent for adjunctive therapy during thrombolysis with rtPA.

[Prevention of thromboembolism as a cause of thromboembolic complications. A study of the incidence of heparin-induced thrombocytopenia type II]. / Thromboembolieprophylaxe als Auslöser thrombembolischer Komplikationen. Eine Untersuchung zur Inzidenz der Heparin-induzierten Thrombozytopenie (HIT) Typ II.

PROBLEM: A life-threatening complication of the thrombembolism prophylaxis with heparin is heparin-induced thrombocytopenia (HIT) type II. HIT type II is based on immunological mechanisms. Even low, subcutaneously applied doses may produce HIT type II. In those patients, continued application may cause thromboembolic complications. The most important symptom of HIT type II is a decrease of platelets. METHODS: In a prospective study, we investigated the incidence of HIT type II within the period from 01.07.95 to 30.06.96 in orthopedic patients. We also evaluated the importance of the daily platelet count from the fifth postoperative day for the early diagnosis of HIT type II and a possible reduction of the thrombosis rate. The study included 307 patients after primary implantation of hip and knee endoprosthesis and after hip endoprosthesis replacement. All patients received 3 x 5000 IU/d of unfractionated heparin subcutaneously. Whenever there was a decrease of platelets of at least 50% in relation to the preoperative value or whenever thrombembolic complications occurred, serum was analyzed by the heparin-induced platelet activation test (HIPA). RESULTS: 20 patients developed HIT type II. This corresponds to an incidence of 6.5%. 10 of the HIT type II antibody positive patients (50%) developed thrombembolic complications. 3 patients (0.9%) of the group studied developed clinically symptomatic thrombembolic complications without evidence of heparin antibodies. The total risk of getting thrombembolic complications was 4.2% (13 patients). 3.3% (10 patients) of the entire group developed HIT type II antibody associated thrombembolic complications; 1 patient died. The lethality in the HIT type II antibody positive patient group amounted to 5%. The patients with HIT type II received LMW heparinoid Orgaran (AKZO-Organon, The Netherlands) or hirudin (as a clinical trial). The comparison group (retrospective study from 17.10.92 to 16.10.93) was composed of 262 patients with the same operations and equal thromboembolism prophylaxis. The platelet count was made only as part of routine diagnostic tests. 21 patients (8.0%) developed clinically symptomatic thrombembolic complications. The difference in the thrombosis rate between these two groups of patients is statistically significant. Unrecognized HIT type II is probably the reason for the high thrombembolic complication rate in the comparison group. CONCLUSIONS: The daily platelet count from the fifth postoperative day and from the first day in case of reexposure to heparin is an important measure for the early diagnosis of HIT type II.

Modulating platelet function with selective thrombin inhibitors.

In addition to its pivotal role in blood coagulation, thrombin is one of the most important agonists for platelet recruitment and aggregation. Thrombin inhibitors impede thrombin-induced platelet aggregation but have no effect on aggregation induced by other agonists. A review is presented of selective thrombin inhibitors now in clinical investigation, some of which are also orally active.

Prevention of microvascular thrombosis by topical application of recombinant tissue factor pathway inhibitor.

Tissue factor pathway inhibitor is a naturally occurring protein inhibitor of factor X and the tissue factor-factor VII complex of the extrinsic pathway of coagulation. The potential of tissue factor pathway inhibitor as a topical antithrombotic agent was evaluated in a rabbit model of thrombosis that combined intimal injury, anastomosis, and a twisted pedicle. In 207 rabbit ears, a near-complete amputation was performed, preserving the central ear artery and vein. The central ear artery was transected, the intima was removed mechanically over a 1-cm length, the artery was anastomosed, and the ear was twisted 360 degrees, wrapping the intact vein around the artery. Before recirculation, the lumen was irrigated on a blinded, randomized basis with either hirudin (100 or 500 units/ml), heparin (50 or 100 units/ml), tissue factor pathway inhibitor (10, 40, 125, or 250 microgram/ml), heparin and tissue factor pathway inhibitor together, or vehicle (control). Upon arterial reflow, the ears were observed for 7 days. Patency rates after 7 days were as follows: hirudin, 30 and 55 percent; heparin, 43 and 50 percent; tissue factor pathway inhibitor, 75 and 90 percent; heparin and tissue factor pathway inhibitor, 75 percent; and vehicle, 6 percent. The higher concentrations of tissue factor pathway inhibitor led to significantly higher patency rates than heparin, hirudin, or control solutions. Electron microscopic evaluation of specimens irrigated with gold- labeled tissue factor pathway inhibitor revealed the inhibitor bound to the injured intimal surface for at least 3 days postoperatively. Coagulation studies showed no change in the clotting profile upon intravascular infusion with tissue factor pathway inhibitor even at the highest dose used topically. We conclude that tissue factor pathway inhibitor is a more effective topical antithrombotic agent than either heparin or hirudin.

Hirulog in the treatment of unstable angina. Results of the Thrombin Inhibition in Myocardial Ischemia (TIMI) 7 trial.

BACKGROUND: Direct thrombin inhibitors are a new class of drugs that may offer a more effective and potentially simpler alternative to heparin. Hirulog is a synthetic peptide based on the leech-derived compound hirudin and, like hirudin, is a highly specific, direct inhibitor of free and clot-bound thrombin. METHODS AND RESULTS: TIMI 7 was a randomized, double-blind study of Hirulog, given with 325 mg/d aspirin to 410 patients with unstable angina. Patients received a constant infusion of Hirulog for 72 hours at one of four doses: 0.02 (n = 160), 0.25 (n = 81), 0.5 (n = 88), and 1.0 (n = 81) mg.kg-1.h-1. The primary efficacy end point was "unsatisfactory outcome," defined as death, nonfatal myocardial infarction (MI), rapid clinical deterioration, or recurrent ischemic pain at rest with ECG changes by 72 hours. Unsatisfactory outcome was not different among the four dose groups: 8.1%, 6.2%, 11.4%, and 6.2% (P = NS). However, the secondary end point of death or nonfatal MI through hospital discharge occurred in 10.0% of patients treated with 0.02 mg.kg-1.h-1 compared with 3.2% of patients treated with the three higher doses of Hirulog (0.25, 0.5, and 1.0 mg.kg-1.h-1, P = .008). Only 2 of 410 patients (0.5%) experienced a major hemorrhage attributed to Hirulog. CONCLUSIONS: The direct thrombin inhibitor Hirulog is a promising new antithrombotic agent that deserves further study. The results of TIMI 7 lend support to the use of an antithrombin agent with aspirin in patients with unstable angina.

Direct thrombin inhibition with Rec-hirudin CGP 39393 as prophylaxis of thromboembolic complications after total hip replacement.

Hirudin is an anticoagulant originally extracted from the leech Hirudo medicinalis. Using recombinant DNA technology a new compound, recombinant desulphato hirudin CGP 39393 has now been produced. The aim of this study was to determine the maximum tolerated dose in patients undergoing elective hip replacement. This open safety trial represents, to our knowledge, the first experience of recombinant hirudin in orthopedic patients. In this study 48 patients undergoing primary total hip replacement were included and the safety of subcutaneous injections of 10, 15, 20 and 40 mg CGP 39393 twice daily, was evaluated. Prophylaxis was started immediately pre-operatively and continued for 8-10 days. A mandatory bilateral phlebography was performed at the end of the prophylactic treatment period and a clinical follow-up was done 6 weeks after surgery. A major bleeding event occurred in the first 3 patients receiving 40 mg CGP 39393 b.i.d. and the prophylaxis regimen at this dosage level was therefore discontinued. Median values of total blood loss and requirements of blood transfusion in the patients receiving 10-20 mg CGP 39393 were similar to those reported in previous studies on total hip replacement performed at the same centre, using other prophylactic drugs. Deep vein thrombosis (DVT) was confirmed by phlebography in 5 out of 12 patients in the 10 mg group (41.7%, 95% confidence limits [CL]: 15.2-72.3%), 1 out of 11 patients in the 15 mg group (9.1%, CL: 0.23-41.3%) and 2 out of 20 patients in the 20 mg group (10.0%, CL: 1.2-31.7%) during the prophylaxis period. CGP 39393 was safe and well tolerated, when administered as subcutaneous injections of 10-20 mg twice daily. The dose level of 40 mg CGP 39393 twice daily resulted in serious disturbance of the hemostasis in patients after hip prosthesis surgery.