WO2014033551A2 - The use of direct thrombin inhibitors in critically ill patients - Google Patents

Abstract

The present disclosure is directed to methods of achieving anticoagulation in a patient in need thereof. The typical patient is expected to be in need for anticoagulation treatment for an extended period of time, and therefore has an increased risk of developing heparin resistance. The method comprises administering a therapeutically effective amount of a direct thrombin inhibitor, such as argatroban. The disclosed methods are particularly suited for the treatment of critically ill patients who are expected to be in the need for an extended period of anticoagulation treatment, including but not limited to, ICU patients, and/or patients suffering from sepsis, SIRS, MODS, and/or MOF.

Description

THE USE OF DIRECT THROMBIN INHIBITORS IN CRITICALLY ILL PATIENTS

I. FIELD

[0001] The present invention relates to methods of treating critically ill patients with direct thrombin inhibitors, such as argatroban, to achieve a desired anticoagulant effect. The disclosed treatment methods are particularly suited for patients who are at risk of developing, or have developed resistance to heparin.

II. BACKGROUND

[0002] Thrombosis is a condition that occurs when a blood clot (i.e., a thrombus) forms inside a blood vessel, thereby obstructing the flow of blood through the circulatory system (Owens et al. (2011) Circ. Res. 108(10) : 1284- 1297). When a blood vessel is first injured, the circulatory system employs platelets and fibrin to form a blood clot. Such blood clots can form in both the veins and arteries of the body. The blood clot is formed in order to repair the blood vessel and prevent blood loss. The blood flow to a tissue is reduced when a thrombus occupies more than 75% of the surface area of the lumen of an artery. This will cause symptoms such as severe pain because of decreased oxygen availability to the tissues (i.e., hypoxia) and the accumulation of metabolic products like lactic acid. When the blood vessel is 90% obstructed it can come to a complete deprivation of oxygen (i.e., anoxia), and eventual infarction of a tissue or organ, such as a heart attack or stroke.

[0003] There are several types of thrombosis depending on the type and location of the thrombus. Examples are deep vein thrombosis (DVT), renal vein thrombosis, cerebral venous thrombosis, and coronary thrombosis. Along the same lines, excessive blood clotting may cause a blood clot to eventually dislodge and break free. Once a blood clot breaks free it is called an embolus. Thus, the term thromboembolism refers to a condition wherein an embolus travels inside the bloodstream to plug another blood vessel, eventually leading to organ damage. For example, a thromboembolism can produce damage to the lungs (i.e., pulmonary embolism), the brain (i.e., stroke) and/or the heart (i.e., heart attack). Venous thromboembolism (VTE) is especially common in the elderly (Choi et al. (2012) /. Am. Acad. Nurse Pract. 24(6) :335-344) and is the most common cause for preventable death in hospitalized patients (Ho et al. (2011) /. Geriatr. Cardiol. 8(2) : 114-120). There are several different causes for thrombosis in subjects including being prone to particular diseases (e.g., arteriosclerosis), immobility, certain medications, hardening of the arteries, and injury to a vein. Notably, subjects can be predisposed to blood clots and, thus, be at greater risk for thrombosis, such as those with inherited medical conditions, certain blood disorders, obesity and habits such as smoking.

[0004] Current treatment options for thrombosis and related disorders include antiplatelet drugs such as aspirin, thienopyridine (e.g., ticlopidin, clopidogrel), and GP-IIb/IIIa-receptorantagonist; indirect antithrombotic substances such as heparin, fondaparinux, danaparoid, and oral anticoagulants; direct antithrombotic substances (i.e., direct thrombin inhibitors) such as rivaroxaban, dabigatran bivalirudin, and argatroban; and fibrinolytic therapy such as streptokinase, urokinase, and recombinant tissue plasminogen activator (rtPA). Thrombosis is a dangerous condition that affects many people

worldwide. According to the American Public Health Association, in 2002 two million Americans developed DVT and about 200,000 people died from it. Today, complications from DVT kill more Americans than breast cancer and AIDS combined (Gerotziafas et al. (2004) Curr. Opin. Pulm. Med. 10:356-365).

[0005] One of the most common and widely used remedies for

thrombosis is heparin, which is known as an indirect antithrombotic substance (supra) or anticoagulant (i.e., blood thinner) that prevents the formation of blood clots. It is used for both the prevention and the treatment of thrombosis.

Heparin works in an indirect manner by inactivating thrombin and activated factor X through an antithrombin-dependent mechanism. More specifically, heparin binds to the enzyme inhibitor antithrombin (AT) causing a

conformational change. The activated AT then inactivates thrombin and other proteases involved in blood clotting, including factor Xa. It is generally known in the art that the rate of inactivation of these proteases by AT can increase by up to 1000-fold due to the binding of heparin. [0006] Heparin is available in two forms, i.e., unfractionated heparin

(UFH) that can be injected under the skin (subcutaneously) or administered through an intravenous infusion (IV), and low molecular weight heparin

(LMWH) that is generally given subcutaneously. The initial treatment for DVT is anticoagulation via heparin. The current DVT treatment guidelines recommend short-term anticoagulation with subcutaneous LMWH, intravenous UFH, subcutaneous fixed-dose unfractionated heparin (FDUH), or subcutanenous fondaparinux, which is a synthetic factor Xa inhibitor. In a number of acute clinical situations, for example after venous thromboembolism, heparin is also administered as an immediate acting anticoagulant to reduce the risk of further thrombosis, which can result in stroke or heart attack (Uprichard et al. (2010) Br. I. Haematol. 149:613-6109: Lagerstedt et al. (1984) Lancet 2:515-518.

[0007] A phenomena known as Heparin-induced thrombocytopenia (HIT) is the development of an immune reaction called thrombocytopenia (i.e., a low platelet count), due to the administration of various forms of heparin. HIT is caused by platelet-, endothelial-, and monocyte-activating antibodies that target multimolecular complexes of platelet factor 4 (PF4) and heparin. This disorder classically presents with a platelet count fall that begins 5 to 14 days after initial heparin exposure. Rapid-onset HIT, in which the platelet count drops within hours of heparin administration, can occur in patients with preexisting anti- PF4/heparin antibodies. The most dangerous clinical complication of HIT is thrombosis, which can be limb- and life- threatening. Historically, up to 40% of patients without clinically apparent thrombosis develop a thromboembolism within ten (10) days after heparin is stopped if an alternative parenteral anticoagulant is not administered (Cuker at al. (2012) Blood 119(10):2209- 2218). Thus, HIT predisposes a patient to developing thrombosis, and when thrombosis is identified the condition is called heparin-induced

thrombocytopenia and thrombosis (HITT). If a patient receives heparin and develops new or worsening thrombosis, or if the platelet count falls, HIT can be confirmed with specific blood tests. In addition, HIT patients may develop specific symptoms as a result of receiving heparin including fever, chills, high blood pressure, a fast heart rate, shortness of breath, chest pain and/or a rash. [0008] In 2000, argatroban was licensed by the Food and Drug

Administration (FDA) for prophylaxis or treatment of thrombosis in patients with heparin-induced thrombocytopenia (HIT). In 2002, it was approved for use during percutaneous coronary interventions in patients who have HIT or are at risk for developing it. Today, HIT patients widely receive argatroban instead of heparin as a treatment with or without thrombosis. In fact, in 2006, a decision- tree analysis was used to estimate the average cost per HIT patient using argatroban for early treatment (<48 hours after thrombocytopenia onset) compared with delayed treatment (> or =48 hours after thrombocytopenia onset) with or without thrombosis. The clinical data used to create this model was obtained from argatroban clinical trials and from published clinical literature. The results of this analysis support the recommendation that it is better to initiate early argatroban treatment when HIT is suspected in patients in order to reduce the thrombotic consequences of HIT and associated healthcare costs. As such, it became clear that argatroban therapy should not be delayed pending the results of HIT diagnostic tests (Arnold et al. (2006) Cardiol. Rev. 14(1) :7-13). In addition, argatroban has proven to be effective in treating critically ill HIT patients who suffer from sepsis or multiple organ dysfunction syndrome (MODS) (Saugel et al. (2009) Critical Care 13 (1) :P442 and (2010) Critical Care 14:R90: l-7).

[0009] As the model of HIT has shown, there is a need in the art for treatment options that provide alternative agents for patient populations where heparin is contra-indicated, particularly in patients that are critically ill and are prone to developing thrombosis and related disorders. However, the art remains resistant to the use of newer and costlier agents in such patient populations (Cuker et al, 2012, supra). Notably, critically ill patients prone to thrombosis such as those that are diagnosed with sepsis, systemic inflammatory response syndrome (SIRS) and/or MODS and/or multi-organ failure (MOF) are at the highest risk of developing heparin resistance at some point in their disease progression. Such patients are in need of new treatment options, which are provided herein. III. BRIEF SUMMARY

[0010] One aspect of the disclosure provides a method of achieving anticoagulation in a patient in need thereof, wherein the patient does not have heparin-induced thrombocytopenia (HIT). The disclosed method includes administering a therapeutically effective amount of a direct thrombin inhibitor to the patient, who, in some aspects of the invention, has heparin resistance, or is expected to develop heparin resistance. Likelihood of heparin resistence may be determined, e.g., A decrease in antithrombin (AT).

[0011] In one aspect of the invention, the thrombin inhibitor

administered to the patient is argatroban. I other aspects, a number of alternative direct thrombin inhibitors may be suited to practice the invention are suited to practice the invention, including but not limited to bivalirudin, lepirudin , and dabigatran etexilate.

[0012] In one aspect the patient is affected by at least one of sepsis or systemic inflammatory response syndrome (SIRS).

[0013] In certain aspects, the patient is expected to require

anticoagulation treatment for more than one (1) day. In other aspects, the patient is expected to require anticoagulation treatment for more than five (5), ten (10), fifteen (15) or thirty (30) days.

[0014] In certain aspects, the patient is a critically ill patient. In some aspects, patient is an Intensive Care Unit (ICU) patient.

[0015] In some aspects patient has an at least about a 10% chance of developing heparin resistance during the medically anticipated length of anticoagulation treatment. In other aspects, the patient has an at least about 50% chance of developing heparin resistance during the medically anticipated length of anticoagulation treatment. In yet other aspects, the patient has an at least about 80% chance of developing heparin resistance during the medically anticipated length of anticoagulation treatment.

[0016] In some aspects, the patient is already resistant, i.e., requires 1200

IU or more heparin to achieve the desired level of anticoagulation.

[0017] In certain aspects, dosage levels of argatroban administered to the patient are in the range of about 0.2 to about 2.0 μg/kg of subject body weight per minute. In other aspects, the dosage levels of argatroban administered to the patient are in the range of about 2.0 μg/kg/min.

[0018] In yet other aspects, the patient has decreased antithrombin levels.

IV. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present disclosure is best understood when read in

conjunction with the accompanying figures, which serve to illustrate the preferred embodiments. It is understood, however, that the disclosure is not limited to the specific embodiments disclosed in the figures.

[0020] FIGURE 1 depicts the changes of aPTT in twenty (20) patients with continuous infusion of heparin, i.e., three (3) days, two (2) days, and one (1) day, before administration of argatroban, and the changes in the aPTT beginning with the administration of argatroban, from day one (1) to day five (5).

[0021] FIGURE 2 depicts apTT values before and after administration of argatroban in twenty (20) patients with SIRS and/or sepsis. Before

administration of argatroban all patients received more than 1.200 IU of heparin for several days without achieving prophylactical apTT levels. Immediately after administration of argatroban, apTT increased and all patients reached their target apTT without causing any bleeding complication or thromboemblic complication.

V. DETAILED DESCRIPTION OF THE DISCLOSURE

General Overview

[0022] In the treatment and prophylaxis of thrombosis and related disorders the phenomenon of heparin resistance is mainly responsible for insufficient antithrombotic prophylaxis and/or therapy in critically ill patients. Physicians continue to treat these patients with heparin because it conforms to the established hospital practice and there is often a reluctance to offer these patients access to more costly drugs in light of their nearly hopeless and ever declining state of health.

[0023] The critically ill are extremely prone to developing

thromboemolisms because of repeated surgeries, immobility, certain medical conditions and blood disorders, a general weakening of the circulatory system, and declining overall health. Yet, the art continues to shy away from employing agents other than heparin that promise to be more potent in preventing thromboemboslisms, mainly because the critically ill are not considered primary candidates for costly and improved medicines, and are generally labeled as too frail to be exposed to potential side effects. In addition, this population falls prey to hospital errors due to improper monitoring of heparin administration. Many of the critically ill suffer from sepsis, SIRS, and/or MODS and/or multi-organ failure (MOF) and eventually succumb to a sudden thromboemolism that could have been prevented if alternative treatment options would have been

considered at the beginning of their treatment.

[0024] The present disclosure proposes the use of a direct thrombin inhibitor (DTI) like argatroban as an improved and alternative treatment option for the critically ill patient population that presents, for example, with sepsis, SIRS, and/or MODS and/or MOF. These patients are prone to developing thrombotic disorders including, but not limited to, venous thromboembolism (VTE), pulmonary embolism, deep vein thrombosis (DVT), renal vein thrombosis, cerebral venous thrombosis, and coronary thrombosis.

[0025] Since DTIs like argatroban bind directly to the active site of thrombin, their pharmacologic action does not require endogenous antithrombin (AT) as heparin does. Argatroban is a potent and effective anticoagulant that can be easily monitored by the activated partial thromboplastin time (aPTT).

Because of its small molecular size, agratroban is also effective in inhibiting clot- bound thrombin, which is resistant to neutralization by the heparin/AT complex. Unlike heparin, argatroban exhibits a relatively low protein binding in plasma, which results in a more reliable anticoagulant effect independent of the level of acute phase reactants. Thus, DTIs like argatroban provide an improved treatment option for the critically ill.

Definitions.

[0026] The term "critically ill patient," as used herein, is a patient, including a patient suffering from SIRS or sepsis, who is expected to receive anticoagulation treatment for at least one (1) day, frequently more than thirty (30) days.

[0027] The term "heparin resistance", as used herein, refers to a state where the patient does not respond to 1200 IU per hour of heparin or more.

[0028] The term "sepsis" as used herein is a medical condition that is characterized by a whole-body inflammatory state (referred to as "systemic inflammatory response syndrome" or "SIRS," see, infra] and the presence of a known or suspected infection. The body may develop this inflammatory response by the immune system to microbes in the blood, urine, lungs, skin, or other tissues. Severe sepsis is the systemic inflammatory response, infection and the presence of organ dysfunction. In ICU patients, the incidence of SIRS varies from about 49% (most restrictive setting) to 99% (most liberal setting), while the incidences of sepsis, severe sepsis and septic shock ranges from 4% up to 31%.

[0029] The term "systemic inflammatory response syndrome," or "SIRS," as used herein, is a condition that is diagnosed by the presence of at least two criteria outlined in TABLE 1:

TABLE 1

Argatroban.

[0030] The chemical name for argatroban is l-[5- [(aminoiminomethyl)amino]-l-oxo-2-[[(l,2,3,4-tetrahydro-3- methyl-8- quinolinyl)sulfonyl]amino]pentyl]-4-methyl-2-piperidinecarboxylic acid, monohydrate. It has four (4) asymmetric carbons. One of the asymmetric carbons has an R configuration (stereoisomer Type I) and an S configuration (stereoisomer Type II). Argatroban is a mixture of R and S stereoisomers at a ratio of about 65:35. The molecular formula of Argatroban is C23H36N60sS»H20. Its molecular weight is 526.66. Argatroban is a synthetic, selective and potent direct thrombin inhibitor (DTI). It binds directly and reversibly to the catalytic site of thrombin.

[0031] Unlike heparin, argatroban does not require antithrombin (AT) or any other cofactor for its activity, and it inhibits both clot-bound and free thrombin. Argatroban exerts its anticoagulant activity by inhibiting the effects of thrombin, including fibrin formation; activation of coagulation factors V, VIII, and XIII; activation of protein C; and platelet aggregation. In contrast to hirudin and heparin, agragtroban is equally effective in inhibiting platelet aggregation and thromboxane B2 release in the presence of both free thrombin and clot-bound thrombin.

[0032] Argatroban is administered intravenously and drug plasma concentrations reach steady state in about one (1) to about three (3) hours. It is metabolized in the liver and has a half-life of about 40 to 50 minutes. Notably, argatroban does not require dosage adjustments for age, sex, or renal

impairment, including in patients that need dialysis. It is monitored by activated partial thromboplastin time (aPTT), i.e., the conversion of prothrombin to thrombin by thromboplastin. It predictably increases aPTT and activated clotting time (ACT) in a dose dependent manner. An infusion of 2 μg/kg per minute increases the aPTT by about 1.5 times baseline and 10 μg/kg per minute increases the aPTT by about 3 times baseline. When argatroban is discontinued, the aPTT and ACT return to normal in about 1 to 2 hours in healthy patients that receive about 1 μg/kg per minute of the drug. Patients with liver failure generally have a longer elimination half-life (Yeh et al. (2006) Am. Heart J.

151:1131-1138).

[0033] Critically ill patients with existing or developing heparin resistance suffering from sepsis, SIRS, and/or MODS, and/or MOF are administered argatroban or a similar DTI intravenously at an infusion rate of from about 0.1 μg/kg/min to about 2.0 μg/kg/min in order to achieve desirable anticoagulation. This dosing range is sufficient and safe for effective anticoagulation in this specific patient population and may need to be further adjusted based on patient age/weight/general condition, concurrent medications, etiology, and other factors.

Heparin Resistance.

[0034] The clinical effectiveness of heparin is dependent on achieving a defined anticoagulant effect. In vivo, there is a huge variation in response to a fixed dose of heparin between individuals. In this context, a phenomenon known as heparin resistance should be taken into consideration, in particular postoperatively and in the setting of cardiac bypass surgery. A decrease in antithrombin (AT) levels represents one of the greatest risks among the risk factors for developing heparin resistance. The binding of heparin to plasma proteins including platelet factor 4 (PF4), fibrinogen, factor VIII, and histidine- rich glycoprotein can also lead to heparin resistance. As many heparin-binding proteins are acute phase reactants, the phenomenon of heparin resistance is often encountered in acutely ill patients, in patients with malignancy, and in patients during peri- or post-partum periods. In addition to altered mechanisms of heparin clearance, heparin resistance has also been associated with drug- induced causes including aprotinin and nitroglycerin, although the latter is controversial. The association of heparin with low AT levels is still a point of heated discussion in the literature. Heparin therapy produces a decrease in circulating AT that is independent on the initial heparin dose, is detectable after one (1) day, and peaks after two (2) to four (4) days.

[0035] Cessation of heparin therapy leads to a normalization of AT levels, but it is not clear if this initial reduction of AT contributes to the heparin resistance seen in patients undergoing treatment for venous thromboembolism, or in patients undergoing cardiac bypass surgery. It is however clear that low levels of AT are potentially detrimental to a patient because AT functions like a natural blood thinner. If AT levels are low, a person will have a tendency to clot more easily. Conversely, elevated levels of AT do not appear to cause bleeding or have any clinical significance. Generally, heparin is associated with dosing difficulties because of its unpredictability, which is due to a number of factors including, but not limited to, nonspecific protein binding (i.e., heparin binds non- specifically to different plasma proteins such as acute phase proteins including PF4, fibrinogen, factor VIII, and histidine-rich glycoproteins); indirect inhibition (i.e., heparin requires adequate plasma levels of AT to downregulate thrombin); and inconsistent compositions of different heparin preparations (e.g., UFH, LWMW, etc).

[0036] In clinical practice, dosages of more than 28,000 U per 24 hours

(1,200 U per hour) of heparin are indicative of heparin resistance. For the treatment of thromboembolic complications, heparin resistance is defined as the need for more than 35,000 U per 24 hours (1,500 U per hour) to prolong the activated partial thromboplastin time (aPTT) into the therapeutic range. During cardiac bypass procedures, the definition of heparin resistance is based on the activated clotting time (ACT), with at least one ACT less than 400 seconds after heparinization and/or the need for exogenous AT administration. An inadequate response to heparin, known as heparin resistance, has been reported in up to 22% of patients undergoing CPB. Heparin resistance is largely underestimated in clinical practice because (a) standard dosages are used without any dose adjustment, and (b) misleading coagulation tests/aPTT prolongation may have other causes (e.g., but not limited to FXII deficiency, presence of

antiphospholipid antibodies) than the anticoagulant effects of heparin.

[0037] Thus, in the treatment and prophylaxis of venous

thromboembolism and other related thrombotic disorders the phenomenon of heparin resistance is responsible for insufficient antithrombotic prophylaxis or therapy. In this context, the use of direct thrombin inhibitors (DTIs) provides a new and improved treatment option. Since thrombin inhibitors like argatroban bind directly to the active site of thrombin, their pharmacologic action is instant and reliable and does not require endogenous AT. Due to its small molecular size, argatroban is uniquely effective in inhibiting clot-bound thrombin, which is resistant to neutralization by the heparin/AT complex.

The Critically III Patient Population.

[0038] The critically ill patient may suffer from severe and/or multiple trauma and/or injury; may require a stay in the Intensive Care Unit (ICU); may be afflicted by sepsis, SIRS, and/or MODS, and/or MOF; may receive multiple medications and/or blood transfusions; may be the recipient of one or more surgeries including emergency surgery; may be largely immobile; and/or present with heparin resistance, or the likelihood of developing heparin resistance during the hospital stay.

[0039] In addition, the critically ill patient's pathophysiology includes possible deep vein thrombosis (DVT) /venous thromboembolism (VTE);

pharmacological prophylaxis of DVT/VTE; monitoring via aPTT; monitoring via antiXa (i.e., heparin activity including LMWH activity); mechanical prophylaxis (e.g., compression stockings, pneumonic compression devices (PCDs), and the like) and vena cava filter. The difficulty with stratifying this patient population is the assignment of two opposite risk factors such as the risk of bleeding excessively (e.g., sudden internal hemorrhage) vs. the risk of deadly

thromboembolisms.

[0040] In the current medical establishment, the concern of excessive bleeding in the fragile and critically ill patient has largely overshadowed the much more common danger of developing thromboembolisms. Yet, the incidence of thromboembolisms in the ICU ranges between about 13% to about 31%. This is further complicated by the fact that a thromboemblism may be silent and devoid of clinical warning signs. For example, 80% of pulmonary embolisms leading to death in the ICU show no clinical signs of thrombosis and are therefore overlooked. Similarly, about 30% of all autopsies of ICU patients show signs of pulmonary embolisms that were never identified in the living patients (Cushman, M. (2007) Semin. Hematol. 44(2):62-69). Additional risk factor include, but are not limited to, age, history of DVT/VTE, severe trauma, prolonged ICU stay, mechanical ventilation, sedation/relaxation, emergency surgery, central venous line in the V.femoralis, and a general lack of

thromboprophylaxis. The frequency of DVT in surgical and medical patients with no prophylaxis is about 40% to about 80% in patients with multiple trauma; about 60% to about 80% in spinal injury patients; and about 10% to about 80% in general ICU patients. The risk factors for developing a

thromboembolism in trauma patients include, but are not limited to, age > 40, fracture of lower extremity (AIS > 3), ventilator days > 3, head Injury (AIS > 3), venous injury, and one or more major surgical procedures.

[0041] In summary, critically ill patients with existing or developing heparin resistance face the following shortcomings, including, but not limited to, a high risk for developing thromboembolic complications (depending on their individual situation); misleading coagulation monitoring using standard coagulation tests, which may prevent thrombosis prophylaxis; difficulty in achieving adequate heparinisation with standard dosages because of he heparin resistance; and little evidence for the effectiveness of UFH and/or LMWH in severly traumatized patients. Thus, these patients rquire new antithrombotic medications such as DTIs to achieve consistent and adequate anticoagulation when needed.

Dosages and Formulation.

[0042] DTIs are formulated as pharmaceuticals to be used in the methods of the disclosure. Any composition or compound that can stimulate a biological response associated with the binding of a biologically or pharmaceutically active DTI (e.g., argatroban) in order to down-regulate thrombin can be used as a pharmaceutical in the disclosure. General details on techniques for formulation and administration are well described in the scientific literature (see

Remington's Pharmaceutical Sciences, Maack Publishing Co, Easton Pa.).

Pharmaceutical formulations containing a pharmaceutically active DTI can be prepared according to any method known in the art for the manufacture of pharmaceuticals. The formulations containing a pharmaceutically active DTI or DTI agonists used in the methods of the disclosure can be formulated for administration in any conventionally acceptable way including, but not limited to, intravenously, subcutaneously, intramuscularly, sublingually, intranasally, intracerebrally, intracerebroventricularly, topically, orally, intravitrealy and/or via inhalation. Illustrative examples are set forth below. In one preferred embodiment, the DTI is administered intravenously.

[0043] When a DTI is delivered by intravenous injection (e.g., infusion, bolus, pump), the formulations containing the pharmaceutically active DTI or a pharmaceutically effective DTI agonist can be in the form of a sterile injectable preparation, such as a sterile injectable aqueous or oleaginous suspension. This suspension can be formulated according to the known art using those suitable dispersing or wetting agents and suspending agents, which have been mentioned above. The sterile injectable preparation can also be a sterile injectable solution or suspension in a nontoxic parenterally-acceptable diluent or solvent. For example, a DTI like argatroban is a white, odorless crystalline powder that is freely soluble in glacial acetic acid, slightly soluble in ethanol, and insoluble in acetone, ethyl acetate, and ether. Among the acceptable vehicles and solvents that can be employed are water and Ringer's solution, an isotonic sodium chloride. In addition, sterile fixed oils can be employed as a solvent or suspending medium. For this purpose any bland fixed oil can be employed including synthetic mono- or diglycerides. In addition, fatty acids such as oleic acid can likewise be used in the preparation of injectables.

[0044] Aqueous suspensions of the disclosure contain the DTI in admixture with excipients suitable for the manufacture of aqueous suspensions. Such excipients include a suspending agent, such as sodium

carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose, sodium alginate, polyvinylpyrrolidone, gum tragacanth and gum acacia, and dispersing or wetting agents such as a naturally occurring phosphatide (e.g., lecithin), a condensation product of an alkylene oxide with a fatty acid (e.g.,

polyoxyethylene stearate), a condensation product of ethylene oxide with a long chain aliphatic alcohol (e.g., heptadecaethylene oxycetanol), a condensation product of ethylene oxide with a partial ester derived from a fatty acid and a hexitol (e.g., polyoxyethylene sorbitol mono-oleate), or a condensation product of ethylene oxide with a partial ester derived from fatty acid and a hexitol anhydride (e.g., polyoxyethylene sorbitan monooleate). The aqueous suspension can also contain one or more preservatives such as ethyl or n-propyl p- hydroxybenzoate, one or more coloring agents, one or more flavoring agents and one or more sweetening agents, such as sucrose, aspartame or saccharin.

Formulations can be adjusted for osmolarity.

[0045] Oil suspensions can be formulated by suspending the DTI in a vegetable oil, such as arachis oil, olive oil, sesame oil or coconut oil, or in a mineral oil such as liquid paraffin. The oil suspensions can contain a thickening agent, such as beeswax, hard paraffin or cetyl alcohol. Sweetening agents can be added to provide a palatable oral preparation. These formulations can be preserved by the addition of an antioxidant such as ascorbic acid.

[0046] Dispersible powders and granules of the disclosure suitable for preparation of an aqueous suspension by the addition of water can be

formulated from Y in admixture with a dispersing, suspending and/or wetting agent, and one or more preservatives. Suitable dispersing or wetting agents and suspending agents are exemplified by those disclosed above. Additional excipients, for example sweetening, flavoring and coloring agents, can also be present.

[0047] The pharmaceutical formulations of the disclosure can also be in the form of oil-in-water emulsions. The oily phase can be a vegetable oil, such as olive oil or arachis oil, a mineral oil, such as liquid paraffin, or a mixture of these. Suitable emulsifying agents include naturally-occurring gums, such as gum acacia and gum tragacanth, naturally occurring phosphatides, such as soybean lecithin, esters or partial esters derived from fatty acids and hexitol anhydrides, such as sorbitan mono-oleate, and condensation products of these partial esters with ethylene oxide, such as polyoxyethylene sorbitan mono-oleate.

Administration and Dosing Regimen of DTI Formulations.

[0048] As discussed, supra, the formulations containing a

pharmaceutically active DTI or pharmaceutically effective DTI agonist used in the methods of the disclosure can be administered in any conventionally acceptable way including, but not limited to, intravenously, subcutaneously, intramuscularly, sublingually, intranasally, intracerebrally,

intracerebroventricularly, topically, orally, intravitrealy and/or via inhalation. Administration will vary with the pharmacokinetics and other properties of the drugs and the patients' condition of health. General guidelines are presented below.

[0049] The methods of the disclosure reduce blot clotting in critically ill patients with existing or developing heparin resistance. These patients often, but not always, present with sepsis, SIRS, and/or MODS, and/or MOF and are prone to thrombosis. The amount of DTI alone or in combination with another agent or drug that is adequate to accomplish this is considered the

therapeutically effective dose. The dosage schedule and amounts effective for this use, i.e., the "dosing regimen," will depend upon a variety of factors, including the stage of the patient's disorder(s) or condition(s), the severity of the patient's disorder or condition, the severity of the adverse side effects, the general state of the patient's health, the patient's physical status, age and the like. In calculating the dosage regimen for a patient, the mode of administration is also taken into consideration. The dosage regimen must also take into

consideration the pharmacokinetics, i.e., the rate of absorption, bioavailability, metabolism, clearance, and the like. Based on those principles, the DTI can be used to treat existing or suspected thrombosis, existing or suspected

thromboembolism, or related thrombotic disorders in critically ill patients afflicted with developing or existing heparin resistance who may also suffer from sepsis, SIRS and/or MODS. Such patients may also benefit from DTI prophylaxis.

[0050] The disclosure also provides the use of DTIs in the manufacture of a medicament for treating thrombosis and related disorders, wherein the medicament is specifically prepared for treating afflicted and critically ill patients. Further contemplated is the use of the DTI in the manufacture of a medicament for treating thrombosis and related disorders, wherein the patient has previously (e.g., a few hours before, one or more days before, etc.) been treated with a different drug. In one embodiment, the other drug is still active in vivo in the patient. In another embodiment, the other drug is no longer active in vivo in the patient.

[0051] The state of the art allows the clinician to determine the dosage regimen of the DTI for each individual patient. As an illustrative example, the guidelines provided below for DTIs can be used as guidance to determine the dosage regimen, i.e., dose schedule and dosage levels, of formulations containing pharmaceutically active DTI administered when practicing the methods of the disclosure. Anticoagulation via a DTI can be measured via aPTT. For example, an infusion of 2 μg/kg of patient weight per minute increases the aPTT by about 1.5 times baseline and 10 μg/kg per minute increases the aPTT by about 3 times baseline. When the DTI is discontinued, the aPTT and ACT should return to normal in about one (1) to about four (4) hours in a critically ill patient that receives about 1 μg/kg per minute of the drug. Critically ill patients with existing or developing heparin resistance suffering from sepsis, SIRS, and/or MODS and/or MOF are administered a DTI intravenously at an infusion rate of from about 0.1 μg/kg/min to about 10 μg/kg/min in order to achieve desirable anticoagulation.

[0052] As a general guideline, it is expected that the daily dose of a pharmaceutically active DTI [e.g., synthetic, recombinant, analog, agonist, etc.) is typically in an amount in a range of about 0.2 to about 2.0 μg/kg of subject body weight per min. In one embodiment, the dosages of DTI are about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 μg/kg/min. In another embodiment, the dosages of DTI are about 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0 μg/kg/min. In yet another embodiment, the dosages of DTI are about 2.05, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, and 3.0 μg/kg/min. In another embodiment, these dosages result in serum concentrations of DTI of about 10, 50, 100, 500 or 1000 ng/ml. In one embodiment, a pharmaceutically effective DTI or an agonist thereof is administered at about 2 μg/kg/min. In another embodiment, a pharmaceutically effective DTI or an agonist thereof is administered at about 0.2 to about 2 μg/kg/min. In another embodiment, the administration of the DTI is continued as to maintain a serum concentration of DTI of about 0.25 μg/ml, more preferably of about 0.5 μg/ml, and most preferably from about 1.5 μg/ml. In one preferred embodiment, the administration of the DTI is continued as to maintain a serum concentration of the DTI of about 0.25 to about 0.75 μg/ml for prophylaxis and about 0.5 to about

1.5 μg/ml for treatment of thrombosis. Thus, the methods of the present disclosure include administrations that result in these serum concentrations of DTI. These DTI concentrations can ameliorate or reduce blot clotting and thrombosis related disorders, including, but not limited to thromboembolisms, DVT, VTE, and the like. Furthermore, these DTI concentrations can ameliorate or reduce thrombosis in critically ill patients with disorders that are not

traditionally known as thrombotic disorders or associated with thrombosis. Depending on the subject, the DTI administration is maintained for as specific period of time or for as long as needed to achieve anticoagulation stability in the subject.

[0053] Single, multiple or continuous administrations of DTI formulations may be administered depending on the dosage and frequency as required and tolerated by the critically ill patient who suffers from thrombosis related disorders. The formulations should provide a sufficient quantity of DTI to effectively ameliorate the condition such as thrombosis, thromboembolism, VTE, DVT, and the like. A typical pharmaceutical formulation for intravenous administration of the DTI would depend on the specific therapy. For example, the DTI may be administered to a patient through monotherapy (i.e., with no other concomitant medications) or in combination therapy with another medication. In one embodiment, the DTI is administered to a patient daily as monotherapy. In another embodiment, the DTI is administered to a patient continuously or in combination with another drug such as platelet inhibitors. Notably, the dosages and frequencies of the DTI administered to a patient may vary depending on age, degree of illness, drug tolerance, and concomitant medications and conditions. In some embodiments, a DTI is provided as a 100 mg/ml injectable solution. The DTI injection is supplied in a 2.5 ml solution in single-use vials. Each vial contains 250 mg of DTI. Placebo, which is identical to the diluent for DTI, is provided in identical vials. DTI or placebo can be administered intravenously or subcutaneously to the patient in small volumes using a syringe in combination with normal saline. Doses are administered on a weight basis and adjusted for each patient by adjusting the rate of the type of DTI delivery by, for example, the syringe.

VI. EXAMPLES

[0054] The following specific examples are intended to illustrate the disclosure and should not be construed as limiting the scope of the claims.

Example 1: Serial Case Study of Heparin-Resistant Patients treated with

Argatroban [0055] The following example demonstrates that treatment with argatroban prolongs the activated partial thrombosis time (aPTT) in patients who do not show the same response to heparin treatment. In this study, twenty (20) critically ill patients were treated at the Department for General and Surgical Critical Care Medicine at the Medical University Innsbruck. All patients suffered from severe multi-organ failure (MOF), and were resistant to intravenous heparin infusion. Although the patients received dosages of more than 1.500 I.U. per hour, no prolongation of aPTT was measured.

[0056] The patients were given argatroban (Argatra® formulation, Mitsubishi Pharma Europe, Ltd., London, U.K.), at a dosage of 0.2 μg/kg bodyweight per hour or more. As shown in TABLE 2 below, aPTT increases with argatroban treatment compared to heparin treatment.

TABLE 2

aPTT In Seconds (Median) During Heparin Infusion And Following The

Administration Of Argatroban

Antikoagulation Median (in Max-Min

seconds)

Heparin 38.5 (31-51)

Heparin 41.5 (29-50)

Heparin 37 (31-61)

Heparin 39 (33-51)

Argatroban 49 (31-64)

Argatroban 50 (31-80)

Argatroban 50 (31-65)

Argatroban 50 (32-52)

[0057] The aPTT is measured as the number of seconds for the patient's plasma to form a fibrin clot. As shown in Fig. 1, following the infusion of argatroban, the aPTT started to increase immediately (i.e., it took longer for a clot to form as expected), peaked at about 1.4 sec at day two (2), and leveled off at about 1.2 sec at day three (3) of the argatroban treatment. This shows that following the infusion of Argatroban (Argatra®formulation), aPTT increased within a reasonable time and was maintained increased over the whole treatment period. None of the patients showed clinical signs of bleeding nor were any thromboembolic complication detected. It can be concluded from this study that in patients with heparin resistance, argatroban is efficacious and safe in order to achieve prophylactic anticoagulation.

Example 2: Case Study - Anticoagulation Treatment Argatroban In

Heparin- Resistant Patients With SIRS And Sepsis

[0058] The following study shows the effectiveness of argatroban in patients with heparin-resistance. The aim of the study was to demonstrate a means to successfully treat patients for whom the effectiveness of heparin, the drug's anticoagulant effect is diminished. As discussed earlier, among risk factors for developing heparin resistance, decreased Antithrombin (AT) levels are reported to be one of the greatest risks (Anderson et al. (2002), BJA 88:467; Rodriguez-Lopez et al. (2008), Anesth. Analg. 107:1444-1445).

[0059] Methods. The study represents a retrospective analysis of twenty (20) patients unresponsive to heparin administration. All patients were treated at the Department for Critical Care Medicine Innsbruck at the Medical University Innsbruck. aPTT and AT was measured before administration of argatroban (T1-T3) as well as two (2) hours after starting the infusion of argatroban (T4), after six (6) hours (T5), twelve (12) hours (T6), 24 hours (T7), 48 hours (T8) and after one week (T9). The initial dosage of argatroban was 0.2 μg/kg bodyweight (BW).

[0060] Results. AT was nearly in the normal range. Even in patients where attempts were made to normalize AT levels, resistance to heparin was still present. TABLE 3 shows the AT levels of twenty (20) heparin-resistant patients with SIRS/Sepsis and heparin resistance. It was demonstrated that all patients showed AT levels in the normal range. Two (2) patients received AT; as shown, this did not result in a better responsiveness to heparin. In all cases, aPTT levels increased significantly following the administration of argatroban and the target aPTT was achieved within a few hours (P<0,0001).

TABLE 3

AT Levels of Twenty (20) Heparin Resistant Patients Suffering form

SIRS/Sepsis

[0061] Conclusion. Because of the property of argatroban to bind directly to the active site of thrombin, and because of the low protein binding in plasma which result in a more reliable anticoagulant effect independent of the level of acute phase reactants, argatroban may be useful in patients suffering from heparin resistance.

Claims

CLAIMS What is claimed is:

1. A method of achieving anticoagulation in a patient in need thereof, wherein said patient does not have heparin-induced thrombocytopenia (HIT), comprising administering a therapeutically effective amount of a direct thrombin inhibitor to said patient wherein said patient has heparin resistance, or is expected to develop heparin resistance.

2. The method of claim 1, wherein said direct thrombin inhibitor is argatroban.

3. The method of claim 2, wherein the patient is affected by at least one of sepsis or systemic inflammatory response syndrome (SIRS).

4. The method of claim 2, wherein said patient is expected to require anticoagulation treatment for more than one (1) day.

5. The method of claim 4, wherein said patient is expected to require anticoagulation treatment for more than five (5) days.

6. The method of claim 4, wherein said patient is expected to require anticoagulation treatment for more than thirty (30) days.

7. The method of claim 2, wherein said patient is a critically ill patient.

8. The method of claim 2, wherein said patient is an Intensive Care Unit (ICU) patient.

9. The method of claim 2, wherein said patient has an at least about a 10% chance of developing heparin resistance during the medically anticipated length of anticoagulation treatment.

10. The method of claim 2, wherein said patient has an at least about 50% chance of developing heparin resistance during the medically anticipated length of anticoagulation treatment.

11. The method of claim 2, wherein said patient has an at least about 80% chance of developing heparin resistance during the medically anticipated length of anticoagulation treatment.

12. The method of claim 2, wherein the patient is resistant to heparin.

13. The method of claim 2, wherein dosage levels are in the range of about 0.2 to about 2.0 μg/kg of subject body weight per min.

14. The method of claim 13, wherein dosage levels are in the range of at about 2 μg/kg/min.

15. The method of any of claims 1-13, wherein said patient has decreased antithrombin levels.