Abstract:
A free-flowing anti-coagulant powder composition, the anti-coagulant composition containing heparin and a bulking agent that is lyophilized or spray dried and ground into a powder. The powdered anti-coagulant composition can be dry filled into syringes and other blood collections systems for rapid dissolution and mixing with collected blood sample without agitation of the container. The formulation may also retain a portion of the initial moisture, which may improve the shelf life and stability of the composition.

Description:
RELATED APPLICATION 
       [0001]    The present application claims the benefit of U.S. Provisional Application No. 61/619,754 entitled FREE FLOWING POWDERED HEPARIN BULKING AGENT FORMULATION, filed Apr. 3, 2012, which is incorporated herein in its entirety by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention is directed to a heparin-bulking agent composition, which can be used in blood collection containers as an anticoagulant. Specifically, the present invention is directed to a heparin salt such as lithium, sodium, calcium, or zinc and a bulking agent provided in formulation, which can be lyophilized or spray dried into a heparin-bulking agent composition, which can be ground into a free-flowing powder and loaded into a blood collection container, and methods and systems related thereto. 
       BACKGROUND OF THE INVENTION 
       [0003]    Blood gas analysis is a commonly performed blood test used to evaluate the dissolved gas balance and acidity of a blood sample, as well as selected electrolyte levels. A blood sample is drawn from the patient into a sample container, such as syringe, and placed into a blood gas analyzer to be evaluated. Typically, the blood analyzer inserts electrodes surrounded by a semi-permeable membrane into the sample to create a potential across in the membrane drawing hydrogen ions through the membrane. The hydrogen ion activity is measured to determine the acidity of the sample. This method of the blood gas analysis, along with the analyses of other gases and/or electrolytes, requires that the blood remain in the liquid phase throughout the analysis. In addition, if the blood coagulates within the analyzer, the analyzer must be cleaned or may become damaged. As a result, an anti-coagulant, such as heparin, is normally introduced into the blood sample prior to the sample being inserted into the analyzer to prevent the blood from coagulating during testing and thereby eliminating the drawbacks associated with coagulated blood samples. 
         [0004]    A common approach to introducing electrolyte balanced heparin into a blood sample is to first draw a liquid heparin aliquot into the syringe that is to be used to draw blood. The majority of the heparin aliquot is then expelled leaving either a small amount of liquid heparin in the syringe or a heparin coating on the internal walls of the syringe. A drawback of this approach is that actuating the syringe to draw or expel heparin can introduce air bubbles into the syringe. In addition to the health risks of introducing air bubbles into the blood stream while drawing the blood sample, any air bubbles in the blood sample can significantly alter the resulting blood gas analysis. 
         [0005]    Another common approach is preloading a container with heparin by atomizing the liquid heparin onto the interior of the container and then subsequently drying as described in US Patent Publication No. 2003/0120198. A drawback of atomizing the heparin into a container and then subsequently drying it is that the resulting heparin composition has a glassy consistency, which makes it difficult for quick dissolution of the heparin in a blood sample. A similar drawback is that the dosage of heparin applied, which may have a varying heparin activity from production lot to lot, is limited by the surface area of the container. 
         [0006]    Another approach to introducing heparin is to place a tablet or pledget of heparin within the container that dissolves when the blood sample is drawn into the container. This approach is described in U.S. Pat. Nos. 5,093,263 and 5,916,202. Although the dosage of heparin can be varied with this approach, the container must be agitated to dissolve and distribute the heparin throughout the sample. Another drawback is that the rate of dissolution of the heparin is limited by the surface area of the tablet or pledget. If the heparin is not effectively or quickly mixed, portions of the sample may coagulate preventing effective analysis of the blood sample. A common source of this problem is medical personnel who draw the blood sample without sufficiently agitating the container to dissolve and mix the heparin throughout the blood sample. 
         [0007]    Thus, although heparin is commonly used as an anti-coagulant for blood gas samples, there remains a need for an anti-coagulant for blood samples with an efficient rate of dissolution. In particular, the current approaches are dependent on medical personnel sufficiently agitating the blood sample to properly dissolve the heparin throughout the blood sample. It is also always desirable to find alternative solutions to blood sample management. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention is directed to a heparin-bulking agent formulation in which a heparin component is combined with one or more bulking agents, the heparin-bulking agent formulation lyophilized or spray dried and ground to provide a free-flowing powered heparin-bulking agent composition that readily dissolves in a blood sample. 
         [0009]    In certain aspects of the present invention, the heparin component is separately lyophilized and ground to a predetermined particulate size before being combined with a bulking agent. In certain other aspects of the present invention, the heparin-bulking agent formulation is lyophilized and ground to the desired particulate size. The free flowing powdered heparin-bulking agent composition can be filled into a container, such as a blood collection container. In some other aspects of the present invention, the heparin-bulking agent formulation is spray dried into a solid mass before being ground to a desired particulate size. The free flowing powdered heparin-bulking agent composition can be filled into a container, such as a blood collection container. In some other aspects of the present invention, the heparin component and the one or more bulking agent components are combined, mixed and dissolved in solution to form the heparin-bulking agent formulation before being spray dried or lyophilized and then ground to a predetermined particulate size. In some aspects, the heparin component and the one or more bulking agent components are provided as either a solid material or in solution before being combined and/or mixed together into a solution heparin-bulking agent formulation. 
         [0010]    In certain aspects of the present invention, the heparin-bulking agent composition in a free-flowing powder form can be filled into a container, such as a blood sample collection tube, syringe, vacuum tube, and the like. In certain aspects of the present invention, the heparin-bulking agent composition in a free-flowing powder form can be preloaded into the barrel of a syringe to mix with a blood sample as the blood sample is drawn into the barrel, whether directly from a patient or from another blood collection container. The amount of free-flowing, powdered heparin-bulking agent composition placed in the container can be varied depending on the circumstances, such as the volume of the blood sample to be taken, the container size, and the desired activity concentration of the respective heparin component. In a powder form, the heparin-bulking agent composition dissolves more rapidly than heparin coatings or tablets due to a higher surface area, thereby creating faster dissolution. In some aspects, the heparin-bulking agent composition provided in a powder form dissolves and distributes throughout the sample by virtue of the flow of the blood sample entering into the container, and without requiring agitation of the container by the medical personnel drawing the blood sample. 
         [0011]    In certain aspects of the present invention, an anti-coagulant formulation is provided comprising a heparin component and at least one bulking agent. The bulking-agent can be non-reactive with blood enzymes and otherwise not have any effect on the clinical chemistry of the blood sample. The heparin component and the at least one bulking agent component can be provided as a solution of a heparin-bulking agent formulation. The solvent content of the heparin-bulking agent formulation is reduced by lyophilization into a heparin-bulking agent composition or spray drying into a heparin-bulking agent composition, and then the heparin-bulking agent composition can be ground into a free-flowing powder. The bulking agent provided in the heparin-bulking agent composition provides enough mass to the composition, such that after the heparin-bulking agent composition is ground to a free-flowing powder, the free-flowing powder can be filled into a container, such as a blood collection container. The free-flowing powder also readily dissolves within a blood sample as the blood sample is introduced into the sample container containing the heparin-bulking agent composition. 
         [0012]    In certain aspects of the present invention, an anti-coagulant formulation is provided consisting of a heparin component and at least one bulking agent. The bulking agent can be non-reactive with blood enzymes and otherwise not have any effect on the clinical chemistry of the blood sample. The heparin component and the at least one bulking agent component can be provided as a solution a heparin-bulking agent formulation. The solvent content of the heparin-bulking agent formulation is reduced by lyophilization into a heparin-bulking agent composition or spray drying into a heparin-bulking agent composition, and then the heparin-bulking agent composition can be ground into a free-flowing powder. The bulking agent provided in the heparin-bulking agent composition provides enough mass to the composition, such that after the heparin-bulking agent composition is ground to a free-flowing powder, the free-flowing powder can be filled into a container, such as a blood collection container. The free-flowing powder also readily dissolves within a blood sample as the blood sample is introduced into the sample container containing the heparin-bulking agent composition. 
         [0013]    In certain aspects of the present invention, an anti-coagulant formulation is provided consisting essentially of a heparin component and at least one bulking agent. The bulking agent can be non-reactive with blood enzymes and otherwise not have any effect on the clinical chemistry of the blood sample. The heparin component and the at least one bulking agent component can be provided as a solution of a heparin-bulking agent formulation. The solvent content of the heparin-bulking agent formulation is reduced by lyophilization into a heparin-bulking agent composition or spray drying into a heparin-bulking agent composition, and then the heparin-bulking agent composition can be ground into a free-flowing powder. The bulking agent provided in the heparin-bulking agent composition provides enough mass to the composition, such that after the heparin-bulking agent composition is ground to a free-flowing powder, the free-flowing powder can be filled into a container, such as a blood collection container. The free-flowing powder also readily dissolves within a blood sample as the blood sample is introduced into the sample container containing the heparin-bulking agent composition. 
         [0014]    In certain aspects, the heparin component and the at least one bulking agent component are both provided as solid material components, with the heparin component, the at least one bulking agent component, and/or both components being provided in solution before being combined, mixed and dissolved in solution. In certain aspects, the heparin component is provided in solution and the at least one bulking agent component is provided as a solid material component before both components being mixed together and dissolved in solution. In certain aspects, the heparin component is provided as a solid material component and the at least one bulking agent component is provided in solution before both components being mixed together and dissolved in solution. In certain aspects, the heparin component is provided as a solid material component, the at least one bulking agent component is provided as a solid material component, and a solvent is added to the heparin component and/or the at least one bulking agent component to dissolve the heparin and bulking agent components and provide a heparin-bulking agent formulation in solution. After the heparin component and the at least one bulking agent component are mixed together and dissolved in solution, the heparin-bulking agent formulation solution can be lyophilized or spray dried into a heparin-bulking agent composition. In some aspects, at least a portion of the heparin-bulking agent composition is ground into a free-flowing powder using various milling processes, including mortar and pestle, ball mill, cryogenic grinding, cryo-milling, or combinations thereof. 
         [0015]    In certain aspects of the present invention, a range of the particle size distribution range between the X 10  and the X 90  values of the powdered heparin-bulking agent composition is less than about 320 microns, in some aspects less than about 300 microns, in some aspects less than about 270 microns, and in some other aspects less than about 250 microns. 
         [0016]    In certain aspects of the present invention, the powdered heparin-bulking agent composition has a particle size distribution with respect to the X 10  and the X 90  values that is in the range between about 4 microns to about 400 microns, in some aspects about 8 microns to about 390 microns, in some aspects about 10 microns to about 380 microns, in some aspects about 15 microns to about 350 microns, in some aspects about 35 microns to about 280 microns, and still in some other aspects about 40 microns to about 380 microns. 
         [0017]    In certain aspects of the present invention, the powdered heparin-bulking agent composition has a particle size distribution X 10  value of at least about 4 microns, in some aspects at least about 8 microns, in some aspects at least about 10 microns, in some aspects at least about 15 microns, in some aspects at least about 25 microns, and in some aspects at least about 30 microns. In some aspects, the powdered heparin-bulking agent composition has a particle size distribution X 10  value in the range of about 4 microns to about 40 microns, in some aspects about 4 microns to about 35 microns, in some aspects about 4 microns to about 30 microns, in some other aspects about 8 microns to about 32 microns, in some aspects about 8 microns to about 18 microns, in some aspects about 10 microns to about 18 microns, and in some other aspects about 25 microns to about 40 microns. 
         [0018]    In certain aspects of the present invention, the powdered heparin-bulking agent has a particle size distribution X 90  value less than about 400 microns, in some aspects less than about 390 microns, in some aspects less than about 350 microns, in some aspects less than about 340 microns, in some aspects less than about 320 microns, in some aspects less than about 300 microns, in some aspects less than about 280 microns, and in some other aspects less than about 260 microns. In some aspects, the powdered heparin-bulking agent composition has a particle size distribution X 90  value in the range of about 260 microns to about 400 microns, in some aspects about 260 microns to about 280 microns, in some aspects about 280 microns to about 400 microns, in some other aspects about 280 microns to about 320 microns, in some aspects about 280 microns to about 340 microns, in some aspects about 250 microns to about 320 microns, and in some other aspects about 300 microns to about 320 microns. 
         [0019]    In certain aspects of the present invention, the powdered heparin-bulking agent composition has a particle size distribution X 50  value in the range of about 80 microns to about 140 microns, in some aspects about 80 microns to about 100 microns, in some aspects about 85 microns to about 95 microns, in some aspects about 120 microns to about 140 microns, and in some other aspects about 125 microns to about 135 microns. 
         [0020]    In certain aspects of the present invention, the heparin component has a known activity concentration. In certain aspects, the source of heparin may be either a dry or solution of a heparin salt, such as heparin salts chosen from lithium, sodium, calcium, or zinc. In certain aspects, the source of heparin comprises lyophilized heparin. 
         [0021]    In certain aspects of the present invention, the bulking agent is a water soluble material. In certain aspects, the bulking agent is a water soluble material chosen from a sugar alcohol, a carbohydrate such as a monosaccharide, a disaccharide, a trisaccharide, a polysaccharide, a water-soluble polymer, or combinations thereof. In certain aspects, the bulking agent is a water soluble material chosen from a monosaccharide alcohol, a α1-1 disaccharide, a α1-6, β1-2 trisaccharide, an α1-β2 disaccharide, an β1-4 disaccharide, a polyvinylpyrollidone, or combinations thereof. In certain aspects, the bulking agent is chosen from mannitol, trehalose, raffinose, sorbitol, sucrose, lactose, polyvinylpyrollidone, and combinations thereof. In some aspects, the bulking agent is the monosaccharide alcohol D-Mannitol. In some aspects, the bulking agent is the monosaccharide D-Sorbitol. In some aspects, the bulking agent is the α1-β2 disaccharide Sucrose. In some aspects, the bulking agent is the β1-4 disaccharide α-Lactose. In some aspects, the bulking agent is the α1-1 disaccharide D(+) Trehalose dihydrate. In some aspects, the bulking agent is the α1-6, β1-2 trisaccharide D-Raffinose pentahydrate. In some aspects, the bulking agent is a polyvinylpyrollidone. In some aspects, the bulking agent is one or more of the monosaccharide D-Sorbitol, the α1-β2 disaccharide Sucrose, the β1-4 disaccharide a-Lactose, the α1-1 disaccharide D(+) Trehalose dehydrate, the α1-6, β1-2 trisaccharide D-Raffinose pentahydrate, and polyvinylpyrollidone. 
         [0022]    In certain aspects of the present invention, the heparin-bulking agent formulation contains one or more additives that do not affect the activity of the heparin component or that otherwise negate any effect the heparin activity has on the analysis of a blood sample. Such additives may include a buffering agent, a stabilizer, or combinations thereof. In certain aspects, the heparin-bulking agent formulation contains calcium acetate, as heparin has an affinity for calcium that depletes a blood sample of the calcium giving false low values of the calcium content. The calcium component already loaded in the heparin composition thus allows an accurate reading of a patient blood sample to be obtained. The one or more additives may be added to the heparin component, the bulking-agent component, or to a solution of the heparin component and bulking-agent component. The one or more additives may be added as a solution or a solid material. 
         [0023]    In certain aspects of the present invention, the heparin-bulking agent formulation is lyophilized until the moisture content of the formulation is adequately dry. In certain aspects of the present invention, the heparin-bulking agent formulation is lyophilized until the moisture content of the formulation is between about 0.5% to about 10%, in some aspects about 0.5% to about 7.5%, in some aspects about 0.5% to about 5%, in some about 0.5% to about 2.5%, and in some further aspects about 0.5% to about 1.5%. In certain aspects of the present invention, the heparin-bulking agent formulation is lyophilized until the moisture content of the formulation is less than about 10%, in some aspects less than about 7.5%, in some aspects less than about 5%, in some aspects less than about 2.5%, and in some further aspects less than about 1.5%. The heparin-bulking agent formulation is a solid after lyophilization and can be ground into a powder for dry filling, but retains a portion of the initial moisture within the formulation following the lyophilization. Surprisingly, retaining a moisture content within the heparin-bulking agent composition in the range of about 2% to about 7%, and in some aspects up to about 7%, rather than achieving the lowest possible moisture content may provide improved stability and shelf life for the heparin activity of the heparin-bulking agent composition. Specifically, the retained moisture decreases the sensitivity of the heparin activity to changing environmental conditions allowing the formulation to be stored for longer periods of time in areas with minimal or no environmental controls. 
         [0024]    In certain aspects of the present invention, a free-flowing powder of a heparin-bulking agent composition has a shelf life up to about 5 years, in some aspects between about 1 to about 5 years, in some aspects about 1 year to about 3 years, and in other aspects at least about 4 years. 
         [0025]    In certain aspects of the present invention, a system is provided for collecting and performing blood gas analysis, the system comprising a syringe having a barrel and a quantity of free-flowing anti-coagulant powder filled into the syringe barrel, wherein the anti-coagulant powder comprises a lyophilized heparin-bulking agent formulation into a heparin-bulking agent composition, the heparin-bulking agent composition ground into a free-flowing powder. In certain aspects, the syringe contains the desired amount of free-flowing powder to provide the desired activity concentration of the heparin for the respective system. In certain aspects, the syringe contains about 0.5 mg to about 5 mg of the free-flowing, powdered heparin-bulking agent composition, in some other aspects about 1.0 mg to about 3.0 mg, in some other aspects about 1.5 mg to about 2.0 mg, although other amounts greater or less than the foregoing ranges and subranges being contemplated herein. In another aspect, the heparin-bulking agent composition within the respective system has a moisture content less than about 10%, in some aspects less than about 7.5%, in some aspects less than about 5%, in some aspects less than about 2.5%, and in some further aspects less than about 1.5%. 
         [0026]    In certain aspects, the heparin-bulking agent composition provided as a free-flowing powder is loaded into the container in an inert gas environment to prevent moisture contamination into the container. In certain aspects, the free-flowing, powdered heparin-bulking agent composition is loaded into the container while the container is under vacuum with an inert gas. Alternatively, the container is placed under vacuum after the heparin-bulking agent composition is loaded into the container to remove any air in the container. Preventing air from entering the container or removing the air from the container prevents air bubbles in the blood sample that can disrupt or skew the blood gas analysis. In certain aspects, the container is a syringe with the free-flowing, powdered heparin-bulking agent composition loaded into the barrel of the syringe. 
         [0027]    In certain aspects of the present invention, a method of making an anti-coagulant formulation comprises providing a source of heparin having a known activity concentration and a source of at least one bulking agent. In certain aspects, the source of heparin may be either a dry or solution of a heparin salt, such as heparin salts chosen from lithium, sodium, calcium, or zinc. In certain aspects, the source of heparin is lyophilized heparin. In certain aspects, the source of the at least one bulking agent can be provided in either a dry or solution form. The source of heparin and the source of at least one bulking agent are combined in a predetermined ratio to obtain the desired activity concentration of heparin units per milligram. The method further comprising mixing the heparin component and the at least one bulking agent in solution until the source of heparin and the source of at least one bulking agent are dissolved in solution to form a heparin-bulking agent formulation. The method also comprises lyophilizing the heparin-bulking agent formulation for an initial period, wherein the formulation has been dried into a solid heparin-bulking agent composition following the primary period. The method further comprises grinding the heparin-bulking agent composition into a powder having a predetermined particulate size. In certain aspects, the method further comprises optionally drying the ground heparin-bulking agent composition for a second period of time. In another aspect, the heparin-bulking agent formulation can be spray dried into a holding chamber to provide a heparin-bulking agent composition, which can then be ground into a free-flowing powder. Alternatively, the heparin-bulking agent formulation can be spray dried instead of being lyophilized before the heparin-bulking agent composition is ground into a free-flowing powder. 
         [0028]    In certain aspects, the at least one bulking agent and heparin are provided in solution with a ratio of about 60% to about 97% by weight of solid content of the at least one bulking agent and about 3% to about 40% by weight of solid content of heparin, although other ratios greater or less than the foregoing ranges are contemplated herein. In certain aspects, the ratio of bulking agent to heparin solution is selected to produce about 1.5 mg of the dried, heparin-bulking agent composition in a powder form having the preferred activity concentration of heparin. The method can further comprise adding a quantity of a solvent, such as water (e.g., de-ionized water), to the heparin, bulking agent, heparin and bulking agent mixture, or heparin-bulking agent formulation to facilitate the dissolution of the bulking agent and heparin within solution. 
         [0029]    In another aspect, the method can further comprise freezing the heparin-bulking agent formulation for a freezing period at a predetermined temperature to obtain a frozen solid. For example, without being bound by limitation herein, the mixture can be frozen for at least 8 hours at about −80° C. The method can further comprise lyophilizing the frozen heparin-bulking agent formulation within a lyophilizer having a desired product and/or shelf. The bulking agent provided in the heparin-bulking agent composition provides enough mass to the composition, such that after the heparin-bulking agent composition is ground to a free-flowing powder, the free-flowing powder can be filled into a container, such as a blood collection container. The free-flowing powder also readily dissolves within a blood sample as the blood sample is introduced into the sample container containing the heparin-bulking agent composition temperature. In another aspect, the primary drying period can last a desired drying period of time, while an optional subsequent additional drying period can also be utilized for a desired period of time. 
         [0030]    A method of preparing a syringe, according to certain aspects of the present invention, comprises providing a syringe having a barrel and a quantity of an anti-coagulant comprising a heparin-bulking agent composition, the bulking agent chosen from mannitol, trehalose, raffinose and combinations thereof, wherein the heparin-bulking agent formulation is lyophilized into the heparin-bulking agent composition, which is ground into a free-flowing powder. The method further comprises dry-filling the free-flowing powder into the syringe barrel and sealing the barrel. In one aspect, the method can further comprise dry-filling the syringe barrel under an inert atmosphere (i.e., inert gas such as nitrogen, argon, and the like). 
         [0031]    A method of using a syringe loaded with an anti-coagulant, according to certain aspects of the present invention, comprises providing a syringe having a barrel loaded with the anti-coagulant, a plunger and a needle, wherein the anti-coagulant comprises a free-flowing powder of a heparin-bulking agent composition, the bulking agent chosen from mannitol, trehalose, raffinose and combinations thereof. The method further comprises pulling the plunger to create a vacuum within the barrel to pull a blood sample into the barrel, wherein the flow of blood into the barrel circulates and dissolves the anti-coagulant into the blood. Alternatively, the method further comprises allowing arterial blood to fill a syringe with a pre-set plunger position, wherein the flow of blood into the barrel circulates and dissolves the anti-coagulant into the blood. The method can further comprise placing the syringe or an aliquot of the blood sample having the dissolved anti-coagulant from the syringe into a blood analyzer for analysis. Alternatively, the plunger can be actuated to expel the blood sample and anti-coagulant mixture into a sample blank that is insertable into a blood analyzer for analysis. 
         [0032]    In certain aspects of the present invention, a blood collection container have a predetermined amount of a free-flowing powder of a heparin-bulking agent composition is capable of being dissolved within a blood sample of a patient in the blood collection container in less than about 10 seconds, in some aspects less than about 8 seconds, in some aspects less than about 6 seconds, in some aspects less than about 4 seconds, in some aspects less than about 2 seconds, in some aspects less than about 1 second, and in some other aspects about instantaneously. In certain aspects, a predetermined amount of a free-flowing powder of a heparin-bulking agent composition preloaded into a blood collection container is capable of being dissolved within a blood sample of a patient in the blood collection container in less than about 10 seconds, in some aspects less than about 8 seconds, in some aspects less than about 6 seconds, in some aspects less than about 4 seconds, in some aspects less than about 2 seconds, in some aspects less than about 1 second, and in some other aspects about instantaneously, without the need of agitating the blood collection container. 
         [0033]    The above summary of the various representative embodiments of the invention is not intended to describe each illustrated embodiment or every implementation of the present invention. Rather, the embodiments are chosen and described so that others skilled in the art can appreciate and understand the principles and practices of the invention. The figures in the detailed description that follow more particularly exemplify these embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]    The present invention can be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which: 
           [0035]      FIG. 1  is a flow diagram illustrating the formulation of an anti-coagulant using lyophilization according to certain aspects of the present invention. 
           [0036]      FIG. 2  is a flow diagram illustrating the formulation of an anti-coagulant using spray drying according to certain aspects of the present invention. 
           [0037]      FIG. 3  is a schematic view of a syringe loadable with an anti-coagulant according to certain aspects of the present invention. 
           [0038]      FIG. 4  is schematic view of the syringe depicted in  FIG. 3  illustrating filling the syringe with a free-flowing powder of the anti-coagulant. 
           [0039]      FIG. 5  is schematic view of the syringe depicted in  FIG. 3  illustrating the anti-coagulant powder loaded into the syringe and depressed to one end by depressing a plunger. 
           [0040]      FIG. 6  is a schematic view of the syringe depicted in  FIG. 3  illustrating drawing a blood sample into the syringe and dissolving the anti-coagulant powder within the blood sample. 
           [0041]      FIG. 7  is a schematic view of the syringe depicted in  FIG. 3  loaded with a blood sample containing the dissolved anti-coagulant. 
           [0042]      FIG. 8  is a schematic view of a syringe loadable with an anti-coagulant having a preset plunger with a filter tip for arterial blood samples according to certain aspects of the present invention, the arterial blood forcing air past the plunger filter tip until contacting the tip and plugging the filter; the heparin-bulking agent composition of the present invention dissolving as blood fills the syringe barrel. 
           [0043]      FIG. 9  is an SEM image of a free-flowing powder of a heparin-bulking agent composition of the present invention after a milling process, the bulking agent being mannitol. 
           [0044]      FIG. 10  is an SEM image of a free-flowing powder of a heparin-bulking agent composition of the present invention after a milling process, the bulking agent being trehalose. 
           [0045]      FIG. 11  is a water adsorption/desorption isotherm graph of a free-flowing powder of a heparin-bulking agent composition of the present invention after a milling process, the bulking agent being mannitol. 
           [0046]      FIG. 12  is a water adsorption/desorption isotherm graph of a free-flowing powder of a heparin-bulking agent composition of the present invention after a milling process, the bulking agent being trehalose. 
       
    
    
       [0047]    While the present invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION 
       [0048]    The present invention is directed to a heparin-bulking agent composition as an anti-coagulant, the composition having a heparin component and at least one bulking agent component. In some aspects, the heparin-bulking agent composition is provided in a free-flowing powder form. 
         [0049]    In certain aspects, the heparin component may be a heparin salt such as lithium, sodium, calcium, zinc or combinations thereof. The one or more bulking agent components are selected to be non-reactive with the components within a blood sample to avoid impacting the blood gas analysis. 
         [0050]    In certain aspects, the bulking agent component is a water soluble material. Such water soluble materials that are suitable to be a bulking agent component include a sugar alcohol, a carbohydrate such as a monosaccharide, a disaccharide, a trisaccharide, a polysaccharide, a water-soluble polymer, or combinations thereof. In certain aspects, the bulking agent can be, but is not limited to, a monosaccharide alcohol, a α1-1 disaccharide, a α1-6, β1-2 trisaccharide, an α1-β2 disaccharide, an β1-4 disaccharide, a polyvinylpyrollidone, or combinations thereof. In certain aspects, the bulking agent is chosen from mannitol, trehalose, raffinose, sorbitol, sucrose, lactose, polyvinylpyrollidone, and combinations thereof. In some aspects, the bulking agent is the monosaccharide alcohol D-Mannitol. In some aspects, the bulking agent is the monosaccharide D-Sorbitol. In some aspects, the bulking agent is the α1-β2 disaccharide Sucrose. In some aspects, the bulking agent is the β1-4 disaccharide α-Lactose. In some aspects, the bulking agent is the α1-1 disaccharide D(+) Trehalose dehydrate. In some aspects, the bulking agent is the α1-6, β1-2 trisaccharide D-Raffinose pentahydrate. In some aspects, the bulking agent is a polyvinylpyrollidone. In some aspects, the bulking agent is one or more of the monosaccharide D-Sorbitol, the α1-β2 disaccharide Sucrose, the β1-4 disaccharide α-Lactose, the α1-1 disaccharide D(+) Trehalose dehydrate, the α1-6, β1-2 trisaccharide D-Raffinose pentahydrate, and polyvinylpyrollidone. 
         [0051]    In certain aspects of the present invention, a method of making an anti-coagulant formulation comprises providing a source of heparin with a known activity concentration and a source of at least one bulking agent. In certain aspects, the source of heparin may be either a dry or solution of a heparin salt, such as heparin salts chosen from lithium, sodium, calcium, or zinc. In certain aspects, the source of heparin comprises lyophilized heparin. In certain aspects, the source of the at least one bulking agent can be provided in either a dry or solution form. The source of heparin and the source of at least one bulking agent are combined in a predetermined ratio to obtain the desired activity concentration of heparin units per milligram. The heparin component and the at least one bulking agent are then mixed in solution until the source of heparin and the source of at least one bulking agent are dissolved in solution to form a heparin-bulking agent formulation. The heparin-bulking agent formulation is then either lyophilized or spray dried to form a heparin-bulking agent composition. The heparin-bulking agent composition can undergo further processing, such as being ground to provide the heparin-bulking agent as a free-flowing powder. 
         [0052]    In certain aspects of the present invention, the heparin-bulking agent formulation contains one or more additives that do not substantially affect the activity of the heparin component. Such additives may include a buffering agent, a stabilizer, or combinations thereof. In certain aspects, the heparin-bulking agent formulation contains calcium acetate, as heparin has an affinity for calcium that depletes a blood sample of the calcium giving false low values of the calcium content in a blood sample of a patient. Thus, the calcium component already loaded in the heparin composition by virtue of the calcium acetate allows an accurate reading of a patient blood sample to be obtained. The one or more additives may be added to the heparin component, the bulking-agent component, or to a solution of the heparin component and bulking-agent component. The one or more additives may be added as a solution or a solid material. The one or more additives may comprise less than about 10% by total solid content of the heparin-bulking agent formulation and also the resulting heparin-bulking agent composition after lyophilization or spray drying, in some aspects less than about 8%, in some aspects less than about 6%, in some aspects less than about 4%, in some aspects less than about 2%, in some aspects less than about 1%, and in some other aspects there is no additive in the heparin-bulking agent formulation. 
         [0053]    Referring now generally to the figures, particularly the lyophilization flow-diagram in  FIG. 1  and the spray drying flow-diagram in  FIG. 2 , methods of preparing a heparin-bulking agent composition, which comprises a heparin component and a bulking agent component, comprise providing a source of heparin having a known activity concentration and a source of at least one bulking agent  10 . Both the heparin component and the at least one bulking agent component can be provided as dry components. The heparin component and the at least one bulking agent component can also both be provided in solution. The heparin component can also be provided in solution while the at least one bulking agent component is provided as a dry component, or the heparin component can be provided as a dry component while the at least one bulking agent component is provided in solution. 
         [0054]    After the heparin component and the bulking agent component(s) are provided, the heparin component and the bulking agent component(s) are then combined, mixed together, and/or dissolved in solution  12  to provide a heparin-bulking agent formulation. In the situation where either the heparin component, the bulking agent component(s) and/or both the heparin component and the bulking agent component(s) are provided in solution, the solution of the component provided in solution may serve as the solvent to dissolve the heparin and the one or more bulking agents in solution. 
         [0055]    In certain aspects, a desired quantity of heparin by weight is determined and measured (by weight or volume) to which a desired amount of at least one bulking agent is determined and measured (by weight or volume) and added before the heparin component and bulking agent component(s) are dissolved in solution  12 . In certain aspects, the heparin component may be provided as a raw heparin powder, such as lyophilized heparin, or in solution, and the bulking agent component(s) may be provided as a dry component or in solution, before being combined, mixed together and dissolved  12  in a solvent, such as water. One of ordinary skill in the art will appreciate that the heparin component and the bulking agent component(s), whether as a solution or in dry form, may be combined together in either order. For instance, one or more bulking agent components in dry granular form may be provided into a heparin solution, a raw heparin powder may be provided into a solution of one or more bulking agent components, the heparin and the one or more bulking agent components may be provided in dry form and added to a measured volume of solvent such as water, or the like. 
         [0056]    In certain aspects, the at least one bulking agent and heparin are dissolved  12  in solution with the bulking agent component comprising about 60% to about 97% of the heparin-bulking agent mixture by weight of the solid content while the heparin component comprising about 3% to about 40% of the heparin-bulking agent mixture by weight of the solid content, although other ratios greater or less than the foregoing ranges are contemplated herein based upon the respective activity of the heparin component. For example, the bulking agent component may be provided in an amount of about 11 grams while the heparin component is provided in an amount of about 4 grams. 
         [0057]    In certain aspects, the method can further comprise an optional solubility step  14 , in which a quantity of water (e.g., de-ionized water) is added to the heparin-bulking agent mixture to facilitate the dissolution of the bulking agent and/or heparin into the heparin-bulking agent solution mixture. The amount of water can vary, although in certain aspects the amount of water is added such that there is about 10% to about 25% by weight solid content, and in some other aspects about 10% to about 20% by weight solid content, of the heparin and bulking agent(s) in solution for a subsequent lyophilization process according to the method illustrated in the flow diagram of  FIG. 1 . 
         [0058]    As illustrated in  FIG. 1 , after the desired heparin-bulking agent formulation in solution is obtained, the method can further comprise a freezing step  16  in which the heparin-bulking agent formulation in solution is cooled to temperatures below about −26° C., in some instances below about −28° C., in some instances below about −30° C., in some instances below about −32° C., and in some other instances below about −35° C. for the mixture to achieve complete solidification. In some aspects, the heparin-bulking agent formulation in solution achieves complete solidification in less than about 1 hour, in some instances less than about 45 minutes, in some instances less than about 30 minutes, in some instances less than about 20 minutes, in some instances less than about 15 minutes, and in some instances less than about 10 minutes. In some instances, the heparin-bulking agent formulation in solution can be frozen to a state of complete solidification at a temperature of about −26° C. to about −80° C. for a freezing period of time of about 10 minutes to about 8 hours. 
         [0059]    The method further comprises a primary drying step  18  in which the frozen heparin-bulking agent formulation is lyophilized for a primary period of time. For example, without being bound by limitation, the mixture can be placed within the condenser chamber of a lyophilizer having a temperature of about −50° C. and a system pressure of about 950 mBar absolute for a primary period of about 48 hours. One of ordinary skill in the art will appreciate that other lyophilization temperatures, pressures and periods of time can be utilized and are contemplated herein. For example, in some aspects, the heparin-bulking agent formulation undergoes a lyophilization cycle in which the heparin-bulking agent formulation is exposed to more than one freezing temperature of about −10° C. to about −80° C. for different periods of time, which may also occur under chamber pressure or pressures ranging from about 1 mTorr to about 250 mTorr. 
         [0060]    In certain aspects, the solidified heparin-bulking agent formulation is dried to produce a heparing-bulking agent composition having a moisture content less than about 10%, in some aspects less than about 7.5%, in some aspects less than about 5%, in some aspects less than about 2.5%, and in some further aspects less than about 1.5%, during the primary drying step  18 . 
         [0061]    The method may further comprise a grinding step  20 , in which the lyophilized heparin-bulking agent composition is removed from the drying container and ground into a powder. The lyophilized heparin-bulking agent composition can be ground using known milling processes, such as a mortar and pestle, ball mill, hammer mill, cryogenic grinding, cryo-milling, or the like grinding methods for providing a powder with desired particle size so as to allow efficient and accurate powder filling using current powder filling technology. 
         [0062]    In certain aspects, the method further comprises an optional second drying step  22  in which the powder is dried for a second period of time. In the optional second drying step  22 , the heparin-bulking agent composition can be dried at ambient temperature on a shelf dryer. For instance, without being bound by limitation, the second period of time can comprise about 24 hours, although shorter and longer periods of time are contemplated herein. In one aspect, the moisture content of the heparin-bulking agent composition powder following the second drying step  22  can be less than about 10%, in some aspects less than about 7.5%, in some aspects less than about 5%, in some aspects less than about 2.5%, and in some further aspects less than about 1.5%. 
         [0063]    Alternative to the lyophilization process, as shown in the flow diagram of  FIG. 2 , after the desired heparin-bulking agent formulation in solution is obtained, the method can further comprise spray drying  19  the heparin-bulking agent formulation using a standard spray drying system. For instance, without being bound by limitation, the heparin-bulking agent formulation in solution is spray dried using a spray dryer equipped with a two fluid atomizing nozzle, standard drying chamber, and standard solids separation cyclone. 
         [0064]    The method may further comprise a grinding step  20  in which the spray dried heparin-bulking agent mixture is further ground using known milling processes, such as a mortar and pestle, ball mill, hammer mill, cryogenic grinding, cryo-milling, or the like grinding methods for providing a powder with desired particle size so as to allow efficient and accurate powder filling using current powder filling technology. 
         [0065]    Whether the heparin-bulking agent powder composition is prepared using the lyophilization process illustrated in  FIG. 1  or the spray drying process illustrated in  FIG. 2 , the method can further comprise a filling step  24  in which a container is dry filled with the dried powder using current powder filling technology. 
         [0066]    In certain aspects, as shown in  FIGS. 3-7 , the container in the dry-filling step may be a syringe  30  having a barrel  32 , a needle  34  and a plunger  36 . The barrel  32  defines an internal volume  38  for receiving the heparin-bulking agent composition  46  in a powder form and a blood sample. The barrel  32  further comprises a first opening  40  at one of the internal volume  38  and a second opening  42  at the opposite end of the internal volume  38 . As depicted, the needle  34  is fitted to the first opening  40  and the plunger  36  is insertable into the second opening  42  to draw and expel material through the needle  34  into and out of the internal volume  38 . The description of the syringe  30  is not intended to be limiting, but to assist in the description the loading of the syringe  30  with the free-flowing powdered heparin-bulking agent composition. 
         [0067]    As shown in  FIGS. 4-5 , the powdered composition  46  can be dry filled through the second opening  42  into the internal volume  38 . The plunger  36  can then be inserted into the second opening  42  and depressed, as shown in  FIG. 5 , to remove any unused volume within the internal volume  38 . 
         [0068]    As shown in  FIG. 6-7 , during use of the syringe  30  containing the powdered heparin-bulking agent composition  46 , the plunger  36  can be pulled to create a vacuum within the internal volume  38  and draw a blood sample into the internal volume  38 . The flow of the blood sample into the internal volume  38  agitates the powdered heparin-bulking agent composition  46  and dissolves the heparin-bulking agent composition  46  into the blood sample to form a heparin-blood composition  48 , the heparin-bulking agent composition  46  used as an anti-coagulant. 
         [0069]    Referring now to  FIG. 8 , the syringe  30  containing a free-flowing powder of the heparin-bulking agent composition  48 , the plunger  36  can be provided at a preset position and contain a special filter  44  thereon. Thus, when arterial blood is provided into the internal volume  38 , wherein the arterial blood forces air past the plunger filter tip  44  until the arterial blood contacts the tip of the plunger thereby plugging the filter  44 . The flow of the arterial blood into the internal volume  38  also dissolves the heparin-bulking agent powder composition  46 , which serves as an anti-coagulant, to form a heparin-blood composition  48 . 
         [0070]    As provided by the foregoing syringe embodiments, the powdered heparin-bulking agent composition can be provided in any type of blood sample container where an anti-coagulant is desired, including, but not limited to, such as a blood sample collection tube, a syringe, a vacuum tube, and the like. 
         [0071]    In certain aspects, the blood collection container, such as a syringe, contains about 0.5 mg to about 5 mg of the free-flowing, powdered heparin-bulking agent composition, in some other aspects about 1.0 mg to about 3.0 mg, in some other aspects about 1.5 mg to about 2.0 mg, although other amounts greater or less than the foregoing ranges and subranges being contemplated herein. In another aspect, the heparin-bulking agent composition within the respective system has a moisture content less than about 10%, in some aspects less than about 7.5%, in some aspects less than about 5%, in some aspects less than about 2.5%, and in some further aspects less than about 1.5%. 
         [0072]    A range of the particle size distribution between the X 10  and the X 90  values of the powdered heparin-bulking agent composition may be less than about 320 microns, in some aspects less than about 300 microns, in some aspects less than about 270 microns, and in some other aspects less than about 250 microns. The powdered heparin-bulking agent composition may have a particle size distribution with respect to the X 10  and the X 90  values that is in the range between about 4 microns to about 400 microns, in some aspects about 8 microns to about 390 microns, in some aspects about 10 microns to about 380 microns, in some aspects about 15 microns to about 350 microns, in some aspects about 35 microns to about 280 microns, and still in some other aspects about 40 microns to about 380 microns. 
         [0073]    In certain aspects of the present invention, the heparin-bulking agent composition in a free-flowing powder has a particle size distribution X 10  value greater than about 4 microns, in some aspects greater than about 8 microns, in some aspects greater than about 10 microns, in some aspects greater than about 15 microns, in some aspects greater than about 25 microns, and in some aspects greater than about 30 microns. In some aspects, the powdered heparin-bulking agent composition has a particle size distribution X 10  value in the range of about 4 microns to about 40 microns, in some aspects about 4 microns to about 35 microns, in some aspects about 4 microns to about 30 microns, in some other aspects about 8 microns to about 32 microns, in some aspects about 8 microns to about 18 microns, in some aspects about 10 microns to about 18 microns, and in some other aspects about 25 microns to about 40 microns. 
         [0074]    In certain aspects of the present invention, the powdered heparin-bulking agent has a particle size distribution X 90  value less than about 400 microns, in some aspects less than about 390 microns, in some aspects less than about 350 microns, in some aspects less than about 340 microns, in some aspects less than about 320 microns, in some aspects less than about 300 microns, in some aspects less than about 280 microns, and in some other aspects less than about 260 microns. In some aspects, the powdered heparin-bulking agent composition has a particle size distribution X 90  value in the range of about 260 microns to about 400 microns, in some aspects about 260 microns to about 280 microns, in some aspects about 280 microns to about 400 microns, in some other aspects about 280 microns to about 320 microns, in some aspects about 280 microns to about 340 microns, in some aspects about 250 microns to about 320 microns, and in some other aspects about 300 microns to about 320 microns. 
         [0075]    In certain aspects of the present invention, the powdered heparin-bulking agent composition has a particle size distribution X 50  value in the range of about 80 microns to about 140 microns, in some aspects about 80 microns to about 100 microns, in some aspects about 85 microns to about 95 microns, in some aspects about 120 microns to about 140 microns, and in some other aspects about 125 microns to about 135 microns. 
         [0076]    With respect to a syringe loaded with a heparin-bulking agent composition of the present invention, at least a portion of the barrel of the syringe is pre-loaded with the free-flowing powdered anti-coagulant, the syringe having a plunger and a needle. The plunger of the syringe is pulled to create a vacuum within the barrel to pull a blood sample into the barrel, wherein the flow of blood into the barrel circulates and dissolves the anti-coagulant into the blood. Alternatively, arterial blood may be allowed to fill a syringe pre-loaded with the free-flowing powdered anti-coagulant, the syringe having a pre-set plunger position, wherein the flow of blood into the barrel circulates and dissolves the anti-coagulant into the blood. The syringe, or an aliquot of the blood sample having the dissolved anti-coagulant from the syringe, may be placed into a blood analyzer for analysis. Alternatively, the plunger can be actuated to expel the blood sample and anti-coagulant mixture into a sample blank that is insertable into a blood analyzer for analysis. 
       WORKING EXAMPLES 
     Example 1 
       [0077]    The effect of lyophilization on the heparin-bulking agent formulation was tested by combining 60 ml of heparin solution containing about 2556 mg of heparin with about 7274 mg of bulking agent, wherein the bulking agent was sucrose, mannitol, trehalose or raffinose. 60 ml of de-ionized water was added to the heparin-bulking agent mixture to fully dissolve the bulking agent. The heparin-bulking agent mixture was then lyophilized for about 48 hours at about −50° C. in a lyophilizer having a system pressure of about 950 mBar absolute. The lyophilized heparin-bulking agent composition was then ground into a powder before being dried at ambient temperature for about 24 hours. The resulting heparin-bulking agent compositions in a dried powder form were evaluated for yield (weight), residual moisture and flow-ability characteristics. 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Bulking Agent 
                 Yield (g) 
                 [WT] % Residual Moisture 
               
               
                   
                   
               
             
             
               
                   
                 Sucrose 
                 9.21 
                 Not Determined 
               
               
                   
                 Mannitol 
                 9.31 
                 2.7% 
               
               
                   
                 Trehalose 
                 7.57 
                 3.3% 
               
               
                   
                 Raffinose 
                 7.88 
                 3.3% 
               
               
                   
                   
               
             
          
         
       
     
         [0078]    All four formulations dried easily with mannitol having the best appearing cake and lowest bulk density, trehalos and raffinose having the freest flowing powder, and sucrose producing a slightly glassy cake after drying. 
       Example 2 
       [0079]    The effect of spray drying on the heparin-bulking agent formulation was tested by combining 200 ml of heparin solution containing about 8520 mg of heparin with about 24240 mg of bulking agent and mixed until the bulking agent is dissolved into the heparin solution. The bulking agent was selected from sucrose, trehalose, raffinose and mannitol. The heparin-bulking agent mixture was then successfully spray dried at different sprayer inlet temperatures ranging from about 115° C. to about 175° C., sprayer outlet temperatures ranging from about 50° C. to about 65° C., heparin-bulking agent mixture feed rates of about 6 ml/min to about 9 ml/min, while obtaining the following residual moisture of the dried heparin-bulking agent mixture. 
         [0000]                                                [WT] % Residual Moisture           Bulking Agent   Spray dried                           Mannitol   3.9%           Trehalose   8.2%           Raffinose   7.7%                        
These results demonstrate that the heparin-bulking agent composition can be spray dried and were not optimized for a final low or otherwise desired residual moisture content. In certain aspects, the final particulate size of the dried heparin-bulking agent formulation can be controlled by adjusting the droplet size exiting the sprayer nozzle. The droplet size can be adjusted such that milling of the dried heparin formulation to the desired particulate size for the powder is not necessary or otherwise an optional step. In certain aspects, the final particulate size can be controlled by altering the milling speed and passing the milled particulates through a sieve screen. In certain aspects, the dried heparin formulation can be milled at 2000 RPM and passed through a 0.050 mm screen to provide a consistent particulate size without clumping.
 
       Example 3 
       [0080]    1.5 mg of the powdered heparin-bulking agent mixtures with different bulking agents were loaded into a syringe  30  for evaluating the differences between the flowability and dissolution characteristics when the powder is formed by lyophilization or spray dried. A surrogate blood buffer solution was introduced into the syringe at a rate approximating the flow rate of blood collected from an artery. 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
               
               
                   
                   
                 Dry Filing 
                 Dissolution 
               
               
                 Bulking Agent 
                 Drying Method 
                 Characteristics 
                 Characteristics 
               
               
                   
               
             
             
               
                 Mannitol 
                 Lyophilized 
                 Acceptable fill 
                 The formulation can 
               
               
                   
                   
                 characteristics 
                 initially form clumps 
               
               
                   
                   
                   
                 that dissolve with 
               
               
                   
                   
                   
                 minor agitation 
               
               
                 Mannitol 
                 Spray Dried 
                 Acceptable fill 
                 Small amounts of 
               
               
                   
                   
                 characteristics 
                 floating clumps of the 
               
               
                   
                   
                 (product light 
                 formulation can form 
               
               
                   
                   
                 dusting, light 
               
               
                   
                   
                 static) 
               
               
                 Raffinose 
                 Lyophilized 
                 Acceptable fill 
                 The formulation 
               
               
                   
                   
                 characteristics 
                 dissolves with minor 
               
               
                   
                   
                   
                 agitation 
               
               
                 Raffinose 
                 Spray Dried 
                 Acceptable fill 
                 Large amounts of 
               
               
                   
                   
                 characteristics 
                 floating clumps of the 
               
               
                   
                   
                   
                 formulation can form 
               
               
                 Trehalose 
                 Lyophilized 
                 Acceptable fill 
                 Small amounts of 
               
               
                   
                   
                 characteristics 
                 floating clumps of the 
               
               
                   
                   
                   
                 formulation can form 
               
               
                 Trehalose 
                 Spray Dried 
                 Acceptable fill 
                 The formulation 
               
               
                   
                   
                 characteristics 
                 easily dissolves 
               
               
                   
                   
                 (product can 
               
               
                   
                   
                 clump into 
               
               
                   
                   
                 semi-solid 
               
               
                   
                   
                 slug 
               
               
                   
                   
                 formations) 
               
               
                   
               
             
          
         
       
     
         [0081]    The heparin-bulking agent powdered compositions using raffinose and trehalose as the bulking agent were further evaluated for shelf-life using an accelerated shelf-life protocol to simulate real time shelf life. To conduct the accelerated shelf-life analysis, the stability of the powdered samples was determined using Anti-Factor IIa test methodology following the USP Monograph with guidance for using elevated temperature to simulate real time following ASTM F1980 standard testing at a conditioning temperature of 50° C. Material from pre-gamma, T=0 equivalent year, T=1 equivalent year, T=3 equivalent year and T=5 equivalent year were analyzed for anti-Factor IIa testing, which as shown in the following tables show no real trending. 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
                   
               
               
                   
                 Trehalose - Lyophilized 
                 Trehalose - Spray Dried 
               
               
                   
                 Anti-Factor IIa (units/mg) 
                 Anti-Factor IIa (units/mg) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Pre-gamma 
                 45 
                 44.1 
               
               
                 T = 0 
                 45 
                 46.4 
               
               
                 T = 1 
                 38.8 
                 44.6 
               
               
                 T = 3 
                 43.1 
                 39.4 
               
               
                 T = 5 
                 42.4 
                 40.7 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
                   
               
               
                   
                 Raffinose - Lyophilized 
                 Raffinose - Spray Dried 
               
               
                   
                 Anti-Factor IIa (units/mg) 
                 Anti-Factor IIa (units/mg) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Pre-gamma 
                 44.6 
                 53.4 
               
               
                 T = 0 
                 43.5 
                 42.4 
               
               
                 T = 1 
                 46 
                 44.8 
               
               
                 T = 3 
                 44.1 
                 38.5 
               
               
                 T = 5 
                 46.7 
                 45.9 
               
               
                   
               
             
          
         
       
     
       Example 4 
       [0082]    In the following example, a first heparin-bulking agent composition contains D-mannitol as the bulking agent (referred to in this example for ease of reference as “heparin-mannitol composition”), and a second heparin-bulking agent composition contains α,α-Trehalose as the bulking agent (referred to in this example for ease of reference as “heparin-trehalose composition”). 
         [0083]    With respect to the preparation of the heparin-mannitol composition, 61.5 grams of a lyophilized lithium salt of heparin and 163.5 grams of D-mannitol were combined together, to which 1000 mL of purified water and 6.14 grams of a calcium acetate stock solution (the calcium acetate stock solution comprising 0.100 grams of calcium acetate dissolved in 100 ml of purified water) were added. The calcium acetate is added to the formulation to negate any effect the heparin activity may have on the calcium analysis of a blood sample, including artificially low calcium values. The combined components were stirred until dissolved in solution and then the solution was brought to volume by adding purified water to equal 1500 ml of a prepared heparin-mannitol formulation. 
         [0084]    With respect to the preparation of the heparin-trehalose composition, 61.51 grams of lyophilized lithium salt of heparin and 180.59 grams of α,α-Trehalose were combined, to which 1000 mL of purified water and 6.15 grams of the calcium acetate stock solution were added. The combined components were stirred until dissolved in solution and then the solution was brought to volume by adding purified water to equal 1500 ml of a prepared heparin-trehalose formulation. 
         [0085]    Once the heparin-bulking agent formulations were prepared, the respective heparin-bulking agent formulations underwent a lyophilization cycle process, which includes pre-chilling the lyophilizer to 4° C. at an ambient temperature, adding 1500 mL of the respective heparin-bulking agent formulation into a disposable lyophilization tray and placed into the pre-chilled lyophilizer, and then running a programmed lyophilization cycle on the heparin-bulking agent formulation that includes ramp and hold steps at various pressures, temperatures and periods of time. In particular, the heparin-mannitol formulation underwent a lyophilization cycle process provided in Table 6. 
         [0000]                                                                                                                                                      TABLE 6                   Lyophilization Cycle Process of Heparin-Mannitol Formulation                Temperature (° C.)                    Time   Shelf   Product -   Product -   Pressure (mTorr)            Step   Process   (hr)   Set   Start   End   Start   Beginning   End                    1   Load   0.5   +4.0   —   +3.5   Ambient   Ambient   Ambient       2   Ramp   1.0   −40   +3.5   −42.1   Ambient   Ambient   Ambient       3   Hold   1.0   −40   −42.1   −42.1   200   Ambient   183       4   Ramp   1.0   −10   −42.1   −36.5   200   183   188       5   Hold   15   −10   −36.5   −35.3   200   188   188       6   Hold   15   −10   −35.3   −19.9   100   188   90       7   Ramp   2.0   +25   −19.9   −0.8   0   90   97       8   Hold   4.5   +25   −0.8   +15.2   0   97   14            Cycle time   40                    
Similarly, the heparin-trehalose formulation underwent a lyophilization cycle process provided in Table 7.
 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
             
           
               
                 TABLE 7 
               
             
             
               
                   
               
               
                 Lyophilization Cycle Process of Heparin-Trehalose Formulation 
               
             
          
           
               
                   
                 Temperature (° C.) 
                   
               
             
          
           
               
                   
                 Time 
                 Shelf 
                 Product - 
                 Product - 
                 Pressure (mTorr) 
               
             
          
           
               
                 Step 
                 Process 
                 (hr) 
                 Set 
                 Start 
                 End 
                 Start 
                 Beginning 
                 End 
               
               
                   
               
             
          
           
               
                 1 
                 Load 
                 0.5 
                 +4.0 
                 — 
                 +3.9 
                 Ambient 
                 Ambient 
                 Ambient 
               
               
                 2 
                 Ramp 
                 1.0 
                 −40 
                 +3.9 
                 −30.1 
                 Ambient 
                 Ambient 
                 Ambient 
               
               
                 3 
                 Hold 
                 0.5 
                 −40 
                 −30.1 
                 −38.1 
                 200 
                 Ambient 
                 184 
               
               
                 4 
                 Ramp 
                 1.0 
                 −10 
                 −38.1 
                 −31.1 
                 200 
                 184 
                 184 
               
               
                 5 
                 Hold 
                 18 
                 −10 
                 −31.1 
                 −14.5 
                 200 
                 184 
                 185 
               
               
                 6 
                 Ramp 
                 2.0 
                 +25 
                 −14.5 
                 ~+10 
                 0 
                 185 
                 193 
               
               
                 7 
                 Hold 
                 6 
                 +25 
                 ~+10 
                 +10.6 
                 0 
                 193 
                 17 
               
             
          
           
               
                 Cycle time 
                 31.5 
               
               
                   
               
             
          
         
       
     
         [0086]    With respect to the heparin-mannitol composition, the phase transition temperature acquired from a resistance graph suggests that cooling to below temperatures of at least −23° C. would be required for achieving solidification during freezing. Observations under the microscope suggest cooling to below temperatures of at least −18° C. would be required for achieving solidification. Since, visual observations under the freeze drying microscope are more accurate, it is recommended that the material be cooled to temperatures below −18° C. to achieve complete solidification. 
         [0087]    The electrical resistance graph notes changes at −23° C. during warming. LT-DSC indicated that a glass transition occurred at −32° C. Observations under the microscope revealed the formation of voids at temperatures as low as −30° C. Also, darkened bands, followed by glistening, were observed along the top edge of the sample at temperatures of −49° C. However, it appeared that these darkened areas and glistening did not affect nor prevent continued drying of the sample. Thus, product temperatures should be maintained at or below a range of −32° C. to −34° C. for complete drying with retention of the structure established during the freeze and the absence of collapse. 
         [0088]    With respect to the heparin-trehalose composition, the phase transition temperature acquired from a resistance graph suggests that cooling to below temperatures of at least −26° C. would be required for achieving solidification during freezing. Observations under the microscope also suggest cooling to below temperatures of at least −26° C. would be required for achieving solidification. Therefore, it is recommended that the material be cooled to temperatures below −26° C. to achieve complete solidification. 
         [0089]    The electrical resistance graph notes changes at −26° C. during warming. LT-DSC indicated a glass transition occurred at −32° C. Observations under the microscope revealed void formation beginning at temperatures as low as −31° C. Also, areas of darkened material were observed along the top edge of the sample at temperatures of −49° C. In addition, small glistening areas were observed near the darkened material at temperatures of −43° C. However, it appeared that these darkened areas and glistening did not affect nor prevent continued drying of the sample. Thus, product temperatures should be maintained at or below a range of −33° C. to −35° C. for complete drying with retention of the structure established during the freeze and the absence of collapse. 
         [0090]    After lyophilizing the heparin-bulking agent formulations to form the respective heparin-mannitol composition and heparin-trehalose composition, the lyophilization trays were removed from the lyophilizer, the solid cake was removed and weighed. The lyophilized heparin-mannitol composition weighed 230.97 grams, which resulted in a yield from the 1500 ml of about 15.40%. The lyophilized heparin-trehalose composition weighed 231.04 grams, which resulted in a yield from the 1500 ml of about 15.40%. 
         [0091]    The lyophilized heparin-bulking agent compositions were then ground using hammer mill processing. It was determined that hammer mill processing utilizing a 0.050″ screen at speed of about 2000 rpm for about 2 to about 3 minutes provided free-flowing powder granules having a consistent particle size for both compositions. The heparin-mannitol composition after milling weighed 195.36 grams, which resulted in a yield after milling of about 13.02%. The heparin-trehalose composition after milling weighed 204.81 grams, which resulted in a yield after milling of about 13.65%. 
         [0092]    Both the heparin-mannitol and the heparin-trehalose compositions underwent moisture content analysis using the Karl Fischer process. The average moisture content of two samples of the free-flowing, powdered heparin-mannitol composition was about 5.2%, while the average moisture content of three samples of the free-flowing, powdered heparin-trehalose composition was about 6.3%. 
         [0093]    Samples of the heparin-mannitol composition and heparin-trehalose composition were also placed on a microbalance to determine the weight gain of the samples at a percentage of relative humidity. The resulting adsorption/desorption isotherm graphs of the heparin-mannitol composition is shown in  FIG. 11  and that of the heparin-trehalose composition is shown in  FIG. 12 . These isotherms illustrate that the heparin-trehalose composition has a greater rate of adsorption than the heparin-mannitol composition, with both heparin-bulking agent compositions having about 50% weight change at about 95% relative humidity. 
         [0094]    Both the heparin-mannitol composition and the heparin-trehalose composition were tested for dissolution time as pre-sterile material and post-sterile material in both gamma and electron beam (E-beam) methods at 40 kGy. A laboratory device that simulates the force of arterial blood entering a syringe was used with Hanks Buffer as the liquid. The heparin-bulking agent formulations were frozen on the lyophilizer shelf. The dissolution results are summarized in Table 8. 
         [0095]    The results as provided in Table 8 illustrate that the pre-lyophilization freezing yielded an acceptable dissolution characteristic for the heparin-trehalose composition, but not for the heparin-mannitol composition. As a result, a second pre-lyophilization freezing method was tested for the heparin-mannitol formulation, which included freezing the liquid solution of the heparin-mannitol formulation on dry ice in an insulated chamber. It was observed that the rate of freezing was much quicker than freezing the formulation on the lyophilizer shelf. An X-ray powder diffraction and crystallinity of the heparin-mannitol compositions (lyophilizer shelf freezing and dry ice freezing) resulted in the heparin-mannitol composition frozen by the dry ice method with a greater percentage of crystallinity. In some instances the pre-lyophilization freezing temperature is at least −70° C. In particular, the heparin-mannitol composition prepared by freezing the formulation on the lyophilizer shelf resulted in about 70% crystalline to 29% amorphous, while the heparin-mannitol composition prepared by freezing the heparin-mannitol composition using dry ice resulted in about 78% crystalline to 22% amorphous. The subsequent dissolution test yielded an instantaneous dissolution of the heparin-mannitol composition that underwent a lower temperature of pre-lyophilization solidification using dry ice. 
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 8 
               
             
             
               
                   
               
               
                 Dissolution Testing Results. 
               
             
          
           
               
                   
                   
                 Lyophilized 
                   
               
               
                   
                 Lyophilized Heparin 
                 Heparin 
                 Pre-Lyophilization 
               
               
                   
                 with Mannitol 
                 with Trehalose 
                 Freezing 
               
               
                   
                 Bulking Agent 
                 Bulking Agent 
                 (Heparin- Mannitol 
               
               
                   
                 Dissolution 
                 Dissolution 
                 Bulking Agent) 
               
               
                   
                 time (s) 
                 time (s) 
                 Dissolution time (s) 
               
               
                   
                   
               
             
          
           
               
                 Pre-sterile 
                 39 
                 6.5 
                 Instantaneous (&lt;1) 
               
               
                 Gamma 
                 &gt;60 
                 3.2 
                 Instantaneous (&lt;1) 
               
               
                   
                 (or did not dissolve) 
               
               
                 E-beam 
                 &gt;40 
                 5.2 
                 Instantaneous (&lt;1) 
               
               
                   
               
             
          
         
       
     
         [0096]    The stability of the heparin activity post-sterilization was also analyzed for the heparin-bulking agent compositions. In this analysis, both compositions were subjected to 40 kGy using both gamma and E-beam methods. Accelerated shelf life following ASTM F1980 at a conditioning temperature of 55° C., which uses the Q10=2 (which means that for every 10° C. rise in temperature, the rate of chemical reactions generally doubles) was conducted for a simulated four years. There was no statistical difference between pre-sterile and post sterile using both gamma and E-beam. Results provided in Table 9 (heparin-mannitol composition) and Table 10 (heparin-trehalose composition) are reported in International Units of heparin/mg using the Anti-factor IIa assay method. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 9 
               
             
             
               
                   
               
               
                 Stability of Heparin Activity Post-Sterilization: Heparin-Mannitol 
               
               
                 Composition 
               
               
                 Lyophilized Heparin with Mannitol Bulking Agent 
               
             
          
           
               
                   
                 Electron Beam 
                 Gamma 
               
             
          
           
               
                   
                 Test 1 
                 Test 2 
                 Avg. 
                 Test 1 
                 Test 2 
                 Avg. 
               
               
                   
                   
               
             
          
           
               
                 Pre-sterile 
                 41.8 
                 41.3 
                 41.6 
                 41.8 
                 41.3 
                 41.6 
               
               
                 T = 0 
                 39.3 
                 39.8 
                 39.6 
                 41.9 
                 41.1 
                 41.5 
               
               
                 T = 1 
                 40.9 
                 40.6 
                 40.8 
                 41.1 
                 40.9 
                 41.0 
               
               
                 T = 2 
                 39.6 
                 39.4 
                 39.5 
                 41.1 
                 41.2 
                 41.2 
               
               
                 T = 3 
                 41.6 
                 41.8 
                 41.7 
                 41.4 
                 41.6 
                 41.5 
               
               
                 T = 4 
                 41.0 
                 42.0 
                 41.5 
                 41.1 
                 41.1 
                 41.1 
               
               
                   
               
             
          
         
       
     
         [0000]                                                                                              TABLE 10                   Stability of Heparin Activity Post-Sterilization: Heparin-Trehalose       Composition       Lyophilized Heparin with Trehalose Bulking Agent                Electron Beam   Gamma                Test 1   Test 2   Avg.   Test 1   Test 2   Avg.                        Pre-sterile   41.4   41.1   41.3   41.4   41.1   41.3       T = 0   42.1   41.4   41.8   39.2   41.4   40.3       T = 1   42.2   41.6   41.9   41.8   41.6   41.7       T = 2   41.4   41.2   41.3   43.4   43.0   43.2       T = 3   41.2   41.7   41.5   40.9   41.4   41.2       T = 4   42.0   41.9   41.9   41.8   42.2   42.0                    
These results demonstrate that there is no significant change in the reactivity of the anti-coagulants having either a mannitol bulking agent or a trehalose bulking agent over the simulated time period of 4 years.
 
         [0097]    The particle size distributions of the powdered heparin-mannitol composition and the powdered heparin-trehalose composition were also determined, the particle size distribution values summarized in Table 11. 
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 11 
               
             
             
               
                   
               
               
                 Particle Size Distribution 
               
             
          
           
               
                   
                   
                   
                 X 90    
               
               
                   
                 X 10  (microns) 
                 X 50  (microns) 
                 (microns) 
               
               
                   
                   
               
             
          
           
               
                 Heparin-Mannitol Samples 
                 — 
                 — 
                 — 
               
               
                 T = 0 Gamma 
                 9.62 
                 91.58 
                 276.82 
               
               
                 T = 0 E-beam 
                 10.79 
                 97.99 
                 279.11 
               
               
                 Pre-Sterile 
                 16.58 
                 104.74 
                 279.11 
               
               
                 Heparin-Trehalose Samples 
                 — 
                 — 
                 — 
               
               
                 T = 0 Gamma 
                 31.40 
                 129.61 
                 318.92 
               
               
                 T = 0 E-beam 
                 39.24 
                 156.26 
                 388.83 
               
               
                 Pre-Sterile 
                 33.57 
                 123.44 
                 281.94 
               
               
                   
               
             
          
         
       
     
         [0098]    As provided by the data in Table 8, the heparin-mannitol composition was capable of being ground such that at least 90% of the particulates were less than about 280 microns, the median value was about 90 microns to about 105 microns, and at least 10% of the particulates were less than about 20 μm. Similarly, the heparin-trehalose composition was capable of being ground such that at least 90% of the particulates were less than about 390 microns, the median value was about 120 microns to about 160 microns, and at least 10% of the particulates were less than about 40 μm. Further, the range between the X 10  and the X 90  values was relatively narrow being less than about 270 microns for the heparin-mannitol composition and less than about 350 microns for the heparin-trehalose composition. One of ordinary skill in the art will appreciate that the heparin-bulking agent compositions can be ground using various different grinding processes with desired particle sizes and/or particle size ranges being achieved.  FIG. 9  is an SEM image at 520× of a sample of the powdered heparin-mannitol composition after the milling process to form a free-flowing powder, with the bar scale being 230 microns.  FIG. 10  is an SEM image at 475× of a sample of the heparin-trehalose composition after the milling process to form a free-flowing powder, with the bar scale being 250 microns. 
         [0099]    The bulk density and the tapped density of the powdered heparin-mannitol composition and the powdered heparin-trehalose composition were also determined, the bulk density being the powder in the virgin state as poured while the tapped density measuring the density of the powder after 500 and 750 drops or taps to determine the settling and packing characteristics. The tapped density is a simulation of the change in density of the powdered anti-coagulant compositions from normal movement and settling. The bulk density and tapped density of the heparin-bulking agent compositions are summarized in Table 12. 
         [0000]                                                TABLE 12                   Bulk Density and Tapped Density                Lyophilized Heparin with   Lyophilized Heparin with           Mannitol Bulking Agent   Trehalose Bulking Agent           Density (gm/cc)   Density (gm/cc)                        Initial density   0.221   0.429       After 500 taps   0.276   0.573       After 750 taps   0.276   0.614                    
These results demonstrate that the powdered heparin-mannitol composition only had a 20% change in density from the bulk density to the tapped density after 500 taps. The powdered heparin-trehalose composition is almost twice as dense as the powdered heparin-mannitol composition, and the powdered heparin-trehalose composition continued to pack even after 750 taps.
 
         [0100]    The fillability of the powdered heparin-mannitol composition and heparin-trehalose composition were also tested using a hand volumetric powder filler manufactured by M&amp;) Perry in Corona, Calif. Both the powdered heparin-mannitol composition and the heparin-trehalose composition were free-flowing such that the powders filled easily and accurately. The fillability of the powdered heparin-trehalose composition was most effective at environments having less than about 5% relative humidity, where the composition absorbed minimal amounts of moisture. 
         [0101]    While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and described in detail. It is understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.