cgp-39393 and Hemorrhage

Direct thrombin inhibitors (DTIs) are an emerging class of anticoagulants in routine clinical practice, although they have been under investigation for quite some time. Desirudin (Iprivask®, Canyon Pharmaceuticals™) is a recombinant hirudin derivative that directly inhibits free and fibrin-bound thrombin. Desirudin was the first DTI approved for deep vein thrombosis (DVT) prophylaxis in Europe (Revasc®) and is the newest injectable DTI commercially available in the USA. Desirudin is one of the few nonheparin subcutaneous drugs that has demonstrable efficacy for DVT prophylaxis. Subcutaneous desirudin has been shown to be more effective than both subcutaneous unfractionated heparin and enoxaparin, with comparable bleeding rates in the prevention of DVT in patients undergoing elective hip replacement. Desirudin also offers the advantage of a fixed dosing regimen while being less immunogenic than unfractionated heparin. However, owing to its pharmacokinetic properties, patients with renal dysfunction require dosing modifications. The favorable profile shown with desirudin thus far will allow its clinical use to grow and will promote further investigation into broadening its clinical applications.

Topics: Animals; Anticoagulants; Antithrombins; Dose-Response Relationship, Drug; Hemorrhage; Hirudins; Humans; Recombinant Proteins; Renal Insufficiency; Venous Thrombosis

The options for drug-controlled anticoagulation are becoming noticeably more manifold. In the area of anaesthesiology and intensive care, there are furthermore special disease patterns, such as heparin-induced thrombocytopenia (HIT) to be known, diagnosed and treated. This article gives a review of the substance groups of the direct thrombin inhibitors (DTI) as alternative anticoagulants for HIT in combination with cardiovascular diseases. For the administration of DTIs, experience and the correct dose are the keys to success and are the deciding factors for the two sides of haemostasis: thrombosis and haemorrhage.

Topics: Anesthesia; Anticoagulants; Cardiovascular Surgical Procedures; Critical Care; Hemorrhage; Hemostasis; Heparin; Heparin Antagonists; Hirudins; Humans; Peptide Fragments; Recombinant Proteins; Thrombin; Thrombosis

The anticoagulant properties of heparin were discovered in 1916, and by the 1930s researchers were evaluating its therapeutic use in clinical trials. Treatment of unstable angina with unfractionated heparin (UFH), in addition to aspirin, was introduced into clinical practice in the early 1980s. UFH was combined with aspirin to suppress thrombin propagation and fibrin formation in patients presenting with acute coronary syndromes (ACS) or patients undergoing percutaneous coronary intervention (PCI). However, UFH stimulates platelets, leading to both activation and aggregation, which may further promote clot formation. Clinical trials have demonstrated that newer agents, such as the low-molecular-weight heparins (LMWHs), are superior to UFH for medical management of unstable angina or non-ST-segment elevation myocardial infarction. Increasingly, the LMWHs have been used as the anticoagulant of choice for patients presenting with ACS. For patients undergoing PCI, LMWH provides no sub-stantial benefit over UFH for anticoagulation; however, direct thrombin inhibitors (DTIs) have demonstrated safety and efficacy in this setting. UFH is likely to be replaced by more effective and safer antithrombin agents, such as DTIs. DTIs have antiplatelet effects, anticoagulant action, and most do not bind to plasma proteins, thereby providing a more consistent dose-response effect than UFH. The FDA has approved 4 parenteral DTIs for various indications: lepirudin, argatroban, bivalirudin, and desirudin. The antiplatelet, anticoagulant, and pharmacokinetic properties of bivalirudin support its use as the anticoagulant of choice for both lower- and higher-risk patients, including those undergoing PCI.

Topics: Acute Disease; Angina Pectoris; Angina, Unstable; Angioplasty, Balloon, Coronary; Anticoagulants; Arginine; Fondaparinux; Hemorrhage; Heparin; Heparin, Low-Molecular-Weight; Hirudins; Humans; Models, Molecular; Molecular Structure; Myocardial Ischemia; Peptide Fragments; Pipecolic Acids; Platelet Activation; Polysaccharides; Recombinant Proteins; Sulfonamides; Syndrome; Thrombin; Thrombosis

Leeches have been in medical use for many years. Hirudin, the anticoagulant obtained from the medicinal leech has been purified, characterized and can now be produced by recombinant (r) technology. R-hirudin is a potent inhibitor of thrombin and is therefore a potentially valuable anticoagulant and antithrombotic drug. This article reviews the current status of r-hirudin in this role and compares the pharmacokinetics, mechanism of action and clinical efficacy of this agent with heparin. The methods available for laboratory assessment and clinical monitoring of r-hirudin and the possible ways of antagonizing its effects are also discussed. Finally, the potential clinical applications of r-hirudin are outlined, although further laboratory and clinical studies, together with a fall in the cost of this compound are required before r-hirudin can be more widely accepted as an anticoagulant and antithrombotic agent.

Topics: Amino Acid Sequence; Animals; Blood Coagulation; Blood Platelets; Drug Evaluation; Fibrinolytic Agents; Hemorrhage; Heparin; Hirudin Therapy; Hirudins; Humans; Molecular Sequence Data; Postoperative Complications; Recombinant Proteins; Thrombin; Thrombosis

Because of an extreme risk for thromboemboli, patients with suspected heparin-induced thrombocytopenia (HIT) require immediate initiation of an alternative anticoagulant. The only therapies approved by the Food and Drug Administration require intravenous infusion of expensive direct thrombin inhibitors. This prospective, randomized, open-label, exploratory study compared the clinical and economic utility of subcutaneous desirudin vs argatroban, the most frequently used agent for suspected or immunologically confirmed HIT, with or without thrombosis. Sixteen patients were randomized to treatment with fixed-dose desirudin (15 or 30 mg) every 12 hours or activated partial thromboplastin time-adjusted argatroban by intravenous infusion. Arm A included 8 patients naive to direct thrombin inhibitor therapy, whereas Arm B included 8 patients on argatroban for at least 24 hours before randomization. The primary efficacy measure was the composite of new or worsening thrombosis (objectively documented), amputation, or death. Other end points included major and minor bleeding while on drug therapy, time to platelet count recovery, and pharmacoeconomics. No amputations or deaths occurred. One patient randomized to argatroban had worsening of an existing thrombosis. Major bleeding occurred in 2 patients on argatroban and in none during desirudin treatment. There was 1 minor bleed in each treatment group. The average medication cost per course of treatment was $1688 for desirudin and $8250 for argatroban. Desirudin warrants further study as a potentially cost-effective alternative to argatroban in patients with suspected HIT.

Topics: Adolescent; Adult; Aged; Anticoagulants; Arginine; Disease Progression; Female; Hemorrhage; Heparin; Hirudins; Humans; Male; Middle Aged; Pilot Projects; Pipecolic Acids; Platelet Count; Postoperative Complications; Postoperative Period; Recombinant Proteins; Sulfonamides; Thrombin; Thrombocytopenia; Thrombosis; Treatment Outcome; Young Adult

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.

Topics: Adult; Aged; Aged, 80 and over; Blood Loss, Surgical; Dose-Response Relationship, Drug; Female; Fibrinolytic Agents; Hemorrhage; Hip Prosthesis; Hirudin Therapy; Hirudins; Humans; Injections, Subcutaneous; Male; Middle Aged; Partial Thromboplastin Time; Postoperative Complications; Recombinant Proteins; Risk Factors; Safety; Thrombin; Thromboembolism

Enhanced thrombin activity has been associated with acute and long-term complications following balloon angioplasty (percutaneous transluminal coronary angioplasty (PTCA). We evaluated, in a 2-to-1 randomized, double-blind trial, the effects of recombinant hirudin, CGP 39 393, relative to unfractionated sodium heparin on periprocedural events, bleeding, early angiographic outcome, and coagulation in 113 patients with stable angina undergoing PTCA.. Prior to PTCA, 20 mg CGP 39 393 was administered as a bolus, followed by continuous infusion at a rate of 0.16 mg.kg-1 x h-1, or 10,000 IU sodium heparin was administered as a bolus and continued at a rate of 12 IU.kg-1 x h-1 for 24 hours. Infusion was adjusted to activated partial thromboplastin time (APTT) levels. ST segment was monitored for 24 hours, and angiograms were analyzed with quantitative technique (QCA). In 74 CGP 39 393- and 39 heparin-treated patients, 132 lesions were dilated. Myocardial infarction and/or emergency coronary bypass surgery occurred in 1 (1.4%) CGP 39 393 patient compared with 4 (10.3%) heparin patients (relative risk, 7.6; 95% confidence interval, 0.9, 65.6). At 24 hours, complete perfusion was present in 91% heparin and 100% CGP 39 393 patients. Significant ST segment displacement was found in 11% of heparin versus 4% of CGP 39 393 subjects. Bleeding occurred only at the puncture site in 4 CGP 39 393-treated patients. QCA did not reveal significant differences between the groups. APTT values were more often in the target range and more stable in CGP 39 393 patients. Levels of thrombin-antithrombin III complexes, prothrombin fragment F1+2, and fibrinopeptide A indicated that CGP 39 393 was an effective inhibitor of thrombin activity.. CGP 39 393 can safely be administered to patients undergoing elective PTCA for stable anginal symptoms and may have a more favorable anticoagulant profile than heparin.

Topics: Aged; Angina Pectoris; Angioplasty, Balloon, Coronary; Blood Coagulation; Coronary Angiography; Densitometry; Double-Blind Method; Female; Fibrinolytic Agents; Hemorrhage; Heparin; Hirudin Therapy; Hirudins; Humans; Male; Middle Aged; Recombinant Proteins; Treatment Outcome

The novel recombinant hirudin analog CX-397 was investigated with respect to its pharmacological activity and antithrombin profiles in vivo and in vitro. In three different types of thrombosis models in rats, including stasis and thrombin-induced venous, glass surface-activated arterio-venous shunt, and ferric chloride-induced arterial thrombosis models, CX-397 and rHV-1 elicited potent antithrombotic effects, where the minimum effective doses of rHV-1 tended to be higher than those of CX-397 in the arterio-venous shunt and arterial thrombosis models. The hemorrhagic risk of CX-397 in template bleeding in rats was not higher than that of rHV-1, indicating that CX-397 is superior to rHV-1 for treating the platelet-dominant type of thrombosis. However, no differences were detected between CX-397 and rHV-1 in their effects on in vitro coagulation times and thrombin-induced platelet aggregation, suggesting the possibility that some unknown mechanisms other than simple thrombin inhibition are also involved in their antithrombotic actions.

Topics: Amino Acid Sequence; Animals; Arginine; Arterial Occlusive Diseases; Arteriovenous Shunt, Surgical; Chlorides; Drug Evaluation, Preclinical; Ferric Compounds; Fibrinolytic Agents; Glass; Hemorrhage; Heparin; Hirudin Therapy; Hirudins; Molecular Sequence Data; Pipecolic Acids; Platelet Aggregation; Platelet Aggregation Inhibitors; Rats; Recombinant Proteins; Sequence Alignment; Sequence Homology, Amino Acid; Serine Proteinase Inhibitors; Sulfonamides; Thrombin; Thrombosis; Vena Cava, Inferior; Venous Thrombosis

Topics: Fibrinolytic Agents; Hematoma; Hemorrhage; Hirudin Therapy; Hirudins; Humans; Pulmonary Embolism; Recombinant Proteins; Venous Thrombosis

Topics: Anticoagulants; Antithrombin III; Antithrombins; Clinical Trials as Topic; Hemorrhage; Heparin, Low-Molecular-Weight; Hip Prosthesis; Hirudin Therapy; Hirudins; Humans; Postoperative Complications; Recombinant Proteins; Thrombophlebitis; Thrombosis

The infusion of a high dose of recombinant desulphatohirudin HVI (CGP 39393) for 40 min at 30 micrograms/kg/min, resulted in a prolongation of bleeding time in the rat when evaluated using transection of the tail. The prolonged bleeding was evident both immediately, and 30 min after cessation of the infusion of hirudin (CGP 39393). Bleeding time returned to normal after 60 min. The effect of several agents, reported to be successful in reducing bleeding tendencies in man, were evaluated in this rat model. The agents were administered immediately following cessation of the CGP 39393 infusion and their ability to normalize the prolonged bleeding-time, observed at 30 min after cessation of the CGP 39393 infusion, determined. Desmopressin (DDAVP), recombinant factor VIII and Vueffe reduced the bleeding time to the control range but did not exert any significant effects on the bleeding time in rats which did not receive CGP 39393. Epsilon-aminocaproic acid (EACA) and recombinant factor VII were ineffective, at the doses used. In conclusion, DDAVP, factor VIII and Vueffe are effective in reversing the effect of direct thrombin inhibition on bleeding in the rat.

Topics: Aminocaproic Acid; Animals; Bleeding Time; Blood Coagulation; Deamino Arginine Vasopressin; Factor VIIa; Factor VIII; Fibrinolytic Agents; Hemorrhage; Hirudins; Male; Peptides; Rats; Rats, Wistar; Recombinant Proteins

In contrast to thrombin the fibrinogen coagulant effect of the thrombin-like enzyme batroxobin in vitro and in vivo is not inhibited by the specific thrombin inhibitor hirudin. The haemostyptic effect of batroxobin has been studied in rats after bleeding had been induced by corresponding hirudin dosages. Dependent on batroxobin concentration bleeding time was shortened by local application of batroxobin containing solutions. Strong bleeding induced by i.v. injection of 5 mg r-hirudin/kg was stopped almost immediately when a batroxobin concentration of 40 BU/ml was used. Thrombin was less active to stop bleeding after r-hirudin administration than batroxobin.

Topics: Animals; Antifibrinolytic Agents; Batroxobin; Bleeding Time; Drug Interactions; Female; Fibrinolytic Agents; Hemorrhage; Hemostasis; Hirudins; Male; Rats; Rats, Wistar; Recombinant Proteins; Thrombin

The in vitro anticoagulant activities of recombinant desulphatohirudin (r-hirudin) were studied in the activated partial thromboplastin time (APTT) and the thrombin generation test systems. In the APTT, at concentrations below 5 micrograms/ml, r-hirudin showed a dose-response curve. At concentrations above 5 micrograms/ml, the plasma became unclottable, but in the thrombin generation test, at least 10 micrograms/ml of r-hirudin was required for full inhibition of thrombin generation. The antithrombotic effect was assessed using a rabbit venous stasis model; 150 micrograms/kg r-hirudin completely prevented thrombus formation at 10 and 20 min stasis. At this full antithrombotic dose, the mean bleeding time ratio measured in a rabbit ear template model, was not prolonged over control values. At higher doses, the bleeding time ratios were higher than those observed for the same dosage of heparin. These data indicate that while r-hirudin is an effective antithrombotic agent, antithrombotic doses have to be carefully titrated to avoid excessive bleeding.

Topics: Animals; Fibrinolytic Agents; Hemorrhage; Heparin; Hirudins; Humans; In Vitro Techniques; Partial Thromboplastin Time; Rabbits; Recombinant Proteins; Thrombin Time; Thrombophlebitis