Hemostatic powder

Abstract

The present disclosure provides a hemostatic powder for treatment of bleeding that includes an acid salt of a hydrophobically modified polymer and a carbonate salt, wherein said hemostatic powder foams and expands upon contact with an aqueous environment. The disclosure further provides a method of treating bleeding wounds in a patient in need thereof, wherein a hemostatic powder is applied to the bleeding wound and allowed to foam.

Description

HEMOSTATIC POWDERCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 519,302, filed August 14, 2023, the entire contents of which are hereby incorporated by reference in their entirety.STATEMENT OF GOVERNMENT RIGHTS

[0002] This invention was made with government support under contract W81XWH-21-1-0886 awarded by the Department of Defense. The government has certain rights in the invention.BACKGROUND OF THE INVENTION

[0003] Non-compressible hemorrhage remains the leading cause of preventable deaths among both civilian and military trauma patients. It accounts for 85% of all hemorrhage related deaths. The United States Department of Defense has recognized a longstanding need to develop a hemostatic device that is effective, safe, biocompatible, durable, easily applicable, and economical for treatment of non-compressible hemorrhage.

[0004] Only pipeline interventions for non-compressible hemorrhage exist; the standard-of-care is surgical intervention, with a very high risk of exsanguination before the patient is received in the operating room. Accordingly, there remains a need for products that can effectively stop non-compressible bleeding both initially on site and subsequently throughout the pre-hospital transfer period.BRIEF SUMMARY OF THE INVENTION

[0005] A hemostatic powder is disclosed. The hemostatic powder comprises an acid salt of a hydrophobically modified polymer such as chitosan and a carbonate salt. The hemostatic powder foams and expands upon contact with an aqueous environment (e.g., blood).

[0006] The present disclosure provides a method for inducing hemostasis in a patient in need thereof, the method comprising administering the hemostatic powder described herein to a bleeding wound of thepatient. The method in some embodiments is applied to a non-compressible hemorrhage, a surgical bleed, or a cavity wound, and which is optionally a non-compressible abdominal wound, a non-compressible wound within a closed abdominal cavity, and / or a trauma-induced bleeding wound, or which is optionally a cavity bleed, including a soft tissue bleed during surgery.

[0007] The present disclosure further provides a method of making the hemostatic powder described herein. The method includes the steps of (i) providing a hydrophobically modified polymer (e.g., hydrophobically-modified chitosan): (ii) forming an aqueous gel comprising at least the hydrophobically modified polymer and an organic acid; (iii) freeze-drying the aqueous gel and milling the freeze-dried gel to obtain a powder comprising the organic acid salt of tire hydrophobically modified polymer; and (iv) adding a carbonate salt. The method, in some embodiments, further comprises mixing into the powder fonnulation one or more of a free acid, gelatin, and porous particles.

[0008] Other aspects and embodiments of the present disclosure will be apparent from the following detailed description.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 shows how a powder according to the present disclosure, when applied to blood, produces an expanding foam that stops blood flow, as depicted via beaker inversion.DETAILED DESCRIPTION OF THE INVENTION

[0010] In various aspects and embodiments, the present invention provides hemostatic powder compositions and uses thereof (e.g., methods) for treating wounds, including surgical bleeds, cavity wounds and non-compressible hemorrhage. In various embodiments, the invention employs hydrophobically- modified polymer powders that convert to hemostatic foam when contacted with an aqueous environment (e.g., blood).

[0011] Hydrophobically modified chitosan (HM-C) has been proposed for the treatment of non- compressible hemorrhage by being delivered from a double barrel syringe as a gel, which converts into afoam upon a reaction initiating in the mixing tip. See US 2021 / 0353501, which is hereby incorporated by reference in its entirety. However, given the large volumes that might be required to treat a severe cavity bleed or non-compressible hemorrhage, a double-barrel syringe platform is not practical for many embodiments. The present application provides HM-C in a powder fonn, to achieve wetting in vivo and ultimate tamponade effect by the expanded, biocompatible material. Removing water from the system, and introducing the material in the abdominal cavity, largely as chitosan-acid salts, result in a material that expands into a foam structure upon wetting in blood. For example, upon contact with an aqueous environment, such as blood, the hydrophobically-modified polymer powder produces a stable foam (due to the production of CO2) that will expand in a body cavity and produce a gel or '’artificial clot” and / or seal with blood cells. See US Patent No. 10,179,145, which is hereby incorporated by reference in its entirety. The character and density of the hydrophobic grafts allow for the tuning of foam properties. In some embodiments, the hydrophobic modifications comprise or consist essentially of linear hydrocarbon groups, which in embodiments have a variable size.

[0012] In some embodiments, the foaming action of the powder enables expansion of the material inside a body cavity (e.g.. ‘‘expansion phase”), and during this expansion, the foam adheres and attaches to tissue in the body cavity, resulting in a halting of the bleeding during the expansion phase. In accordance with embodiments of the invention, varying the hydrophobic chain length and density of the hydrophobic grafts, allows for tuning of the foam properties, including for production of a stable foam that does not quickly dissipate.

[0013] In one aspect, a hemostatic powder is disclosed. The hemostatic powder comprises an acid salt of a hydrophobically modified polymer (such as chitosan) and a carbonate salt, wherein said hemostatic powder foams and expands upon contact with an aqueous environment. The hydrophobically-modified polymer acid salt, in some embodiments, is an organic acid salt. The organic acid salt, in some embodiments, is selected from a salt of succinic acid, citric acid, glycolic acid, acetic acid, fumaric acid,malic acid, glutaric acid, oxaloacetic acid, lactic acid, and pyruvic acid, and combinations thereof. The hemostatic powder may also comprise one or more free organic acids (e.g., citric acid).

[0014] In embodiments, the polymer is a cationic polymer, such as chitosan.

[0015] In some embodiments, the hydrophobic groups comprise linear (saturated) hydrocarbon groups (or “grafts”) of from about C6 to about C l 8, or are from about C8 to about Cl 8. In some embodiments, the hydrophobically-modified polymer has hydrocarbon grafts of at least two different sizes attached to the polymer backbone. For example, the hydrocarbon grafts can comprise at least a first hydrocarbon chain length of from C8 to C12. which supports hemostatic properties, and at least a second hydrocarbon chain length of from C14 or greater (e.g., C14 to C18), which provides improved blood gelling properties and foam integrity. In some embodiments, the second chain length is C16 or C18. In still other embodiments, hydrophobic grafts are limited to one or more C12 to C18 hydrocarbon grafts (e.g., one or more of Cl 2, C14, and C16).

[0016] In embodiments, the hydrophobically-modified polymer has hydrocarbon grafts of at least three different sizes attached to the polymer backbone. In some embodiments, the hydrophobic grafts comprise a combination of the following linear, saturated, hydrocarbon grafts: (a) grafts of Cl to C6 in length; (b) grafts of C8 to C12 in length; and (c) grafts of C14 to C18 in length. This combination of hydrocarbon grafts can provide strong blood gelling properties while also producing a stable foam and while increasing the biodegradation rate of the material inside the body.

[0017] In various embodiments, the hydrophobically-modified polymer (e.g., chitosan) has a grafting density from about 1% to about 50% of the available functional groups on the polymer backbone. In some embodiments, particularly with regard to hm-chitosan and grafts in the range of C8 to C 18. the hydrocarbon groups have a grafting density of about 0.1% to about 10% substitution of available amines (e.g.. about 0.5% to about 5% substitution of available amines, or about 0.5% to about 3%). In embodiments, the hydrophobically modified chitosan comprises grafts in the range of Cl to C6 (e.g.. C2) at a density of from about 10% to about 40%, such as from about 20% to about 40%. In an exemplary embodiment, thehydrophobically-modified polymer is chitosan modified with from about 0.5% to about 2% C16 linear hydrocarbon grafts. In embodiments, the HM-C comprises from about 20% to about 90%. or from about 40% to about 90%, or from about 50% to about 90%, or from about 60% to about 90% free amines.

[0018] In some embodiments, the acid salt of a hydrophobically-modified polymer is prepared by freeze- dr ing and milling a hydrophobically-modified polymer organic acid solution. The composition prior to frcczc-drying and milling comprises an organic acid that is present at a molarity of about 0.25 M to about 2.0 M. The composition prior to frcczc-drying and milling comprises from about 0.5 \vt% to about 2.5 wt% of hydrophobically modified polymer, such as from about 1.0 \\t% to about 2.5 wt%.

[0019] The hydrophobically modified polymer is a hydrophobically-modified cationic polymer, such as chitosan Chitosan is the common name of the linear, random copolymer that consists of -( 1 -4)-linked D- glucosamine and N-acetyl-D-glucosamine. The molecular structure of chitosan is a linear backbone linked with glycosidic bonds. Chitosan is the major component of crustacean shells such as crab, shrimp, krill and crawfish shells. Additionally, chitosan is the second most abundant natural biopolymer after cellulose. Commercial chitosan samples are typically prepared by chemical de-N-acetylation of chitin under alkaline conditions. Depending on the source of the natural chitin (extracted from shells) and its production process, chitosan can differ in size (average molecular weight Mw) and degree of N-acetylation (%DA). While the poor solubility of chitosan in water and in common organic solvents restricts its applications, reactive amino groups in the chitosan backbone make it possible to chemically conjugate chitosan with various molecules and to modulate its properties for use as a hemostatic product.

[0020] In various embodiments, the degree of deacetylation of chitin may range from about 40-100%, or in some embodiments, from 60 to 100%, or from 40 to about 90%, or from 50 to about 100%, which determines the charge density. The structure of chitosan (deacetylated) is depicted in Formula 1 :Formula 1

[0021] These repeating monomeric units include a free amino group, which makes molecules or compounds containing chitosan or its derivatives readily reactive. The hydrophobic modification of the chitosan backbone is through the association of an amphiphilic compound with the amino group, such that the hydrophobic tail of the amphiphilic compound is bound with the hydrophilic backbone structure. For determination of grafting density, the degree of acetylation is assumed to be about 85%.

[0022] In various embodiments, the biopolymer is a hm-chitosan, which may be prepared according to International PCT Application No. PCT / US 18 / 25742, which is hereby incorporated by reference in its entirety.

[0023] In some embodiments, the molecular weight of the polymer (e.g., chitosan) ranges from about 25,000 to about 1,500.000 grams per mole. In various embodiments, the molecular weight of the polymer ranges from about 40,000 to about 500,000 grams per mole, or from about 50,000 to about 250,000 grams per mole, or from about 50,000 to about 100,000 grams per mole. In some embodiments, the polymer is a low molecular weight chitosan (e.g., having an average molecular weight of less than about 150,000 grams per mole, or less than about 100,000 grams per mole). As used herein, the term “molecular weight” means average molecular weight. Methods for determining average molecular weight of polymers include low angle laser light scattering (LLS) and Size Exclusion Chromatography (SEC). In performing low angle LLS, a dilute solution of the polymer, typically 2% or less, is placed in the path of a monochromatic laser. Light scattered from tire sample hits the detector, which is positioned at a low angle relative to the laser source. Fluctuation in scattered light over time is correlated with tire average molecular weight of thepolymer in solution. In performing SEC measurements, again a dilute solution of polymer, typically 2% or less, is injected into a packed column. The polymer is separated based on the size of the dissolved polymer molecules and compared with a series of standards to derive the molecular weight.

[0024] Chitosans can be hydrophobically modified by reaction of alkyl (or aryl) aldehydes with primary amine groups along the chitosan backbone in a 50 / 50 (v / v)% of aqueous 0.2 M acetic acid and ethanol. After reaction, the resulting Schiff bases, or imine groups, arc reduced to stable secondary amines by dropwise addition of the reducing agent sodium cyanoborohydride.

[0025] Alternatively, fatty acid anhydride chemistry may be used for hydrophobic modification of chitosan, resulting in amide bonds with the chitosan polymer and the hydrocarbon chains. While hydrolysis of amide bonds is generally known to occur in the presence of dilute acids, which acts as a catalyst for the reaction between the amide and water, the amide bonds formed between chitosan and alkyl anhydrides are shelf stable, even in the presence of dilute acids. Accordingly, the modified polymers may be prepared using a one-pot synthesis, without the need for harsh reagents, including reducing agents. The materials can be precipitated following the reaction and dried for processing.

[0026] In embodiments, the hydrophobically modified polymer is a hydrophobically modified chitosan, which is optionally a hydrophobically modified low molecular weight chitosan. The hydrophobically modified chitosan comprises one or more hydrocarbon groups attached to the polymer’s backbone through amide linkages, optionally wherein the hydrocarbon groups comprise one or more of C8 to Cl 8 hydrocarbon groups (as described). The hydrophobically modified polymer, in some embodiments, comprises at least 1% graft density of hydrocarbon groups in the range of C8 to C18 with respect to available backbone functional groups (amines), optionally wherein the graft density of hydrocarbon groups in the range of C8 to Cl 8 is from 1% to about 15%, or from about 2% to about 10%, or from about 3 to about 7%, with respect to available backbone functional groups (e.g.. amines). An exemplary hydrophobically-modified chitosan according to this disclosure is a low molecular weight chitosan having about 5% C8 grafts (with respect to available backbone amines).

[0027] The hemostatic powder comprises from about 10 wt% to about 60 wt%, or from about 10 wt% to about 55 wt%, or from about 10 wt% to about 50 wt%. or from about 10 wt% to about 45 wt%. or from about 15 wt% to about 50 wt%, or from about 15 wt% to about 45 wt%. or from about 20 wt% to about 30 wt% of the hydrophobically modified chitosan acid salt. In some embodiments, the carbonate salt is a salt selected from sodium, potassium, calcium, or magnesium, and which is optionally selected from sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, calcium carbonate, and magnesium carbonate. Tire hemostatic powder, in some embodiments, comprises about 40 wt% to about 80 wt%, or from about 45 wt% to about 80 wt%, or from about 55 wt% to about 80 wt%, or from about 60 wt% to about 80 wt%, or from about 50 wt% to about 75 wt% of carbonate salt.

[0028] The hemostatic powder may also include porous polymeric particles, optionally comprising polyacrylic acid. An exemplary polyacry lic acid porous particle and process for producing the same is described elsewhere herein. The hemostatic powder, in some embodiments, comprises from about 15 wt% to about 30 wt% of such particles. In some embodiments, the hemostatic powder also includes gelatin, optionally comprising from about 0.2 wt% to about 1.0 wt% of gelatin.

[0029] A hemostatic powder, of an exemplary embodiment, comprises (a) a freeze-dried and milled organic acid salt of low molecular weight hydrophobically modified chitosan (as described), (b) sodium bicarbonate (in an amount as described), and (c) porous polymeric particles (as described), wherein said hemostatic powder foams and expands upon contact with an aqueous environment. In some embodiments, the aqueous environment is a bleeding wound. The hemostatic powder in some embodiments comprises (a) from about 10 wt% to about 45 wt% of low molecular weight hydrophobically modified chitosan succinic acid salt; (b) from about 40 wt% to about 80 wt% of sodium bicarbonate; and (c) from about 10 wt% to about 30 wt% of porous particles comprising polyacrylic acid. In embodiments, the hemostatic powder further comprises citric acid, for example, about 10 wt% free citric acid. In embodiments, the hemostatic powder further comprises about 0.5 wt% gelatin.

[0030] In some embodiments, the hemostatic powder is contained in a syringe dispenser. The hemostatic powder comprises from about 10 g to about 150 g of tire hemostatic powder in a syringe dispenser.

[0031] In other aspects, the present disclosure provides a method for inducing hemostasis in a patient in need thereof, comprising administering the hemostatic powder described above to a bleeding wound of the patient. The method in some embodiments is applied to a non-compressible hemorrhage, a surgical bleed, or a cavity wound, and which is optionally a non-compressible abdominal wound, a non-compressible wound within a closed abdominal cavity, and / or a trauma-induced bleeding wound, or which is optionally a cavity bleed, including a soft tissue bleed during surgery.

[0032] Blood gelation of the compositions disclosed herein can be evaluated using dynamic rheology, by performing a time-to-gelation evaluation. For example, dynamic time sweeps after foams are mixed with blood at equal volume. For treating severe bleeds, it is important to understand how quickly a hemostatic material can halt blood flow. Hm-chitosan solution and blood can be added to the rheometer stage sequentially. An oscillatory shear can then be actuated as quickly as possible to achieve the best representation of time-to-gelation. G’ and G” are then recorded as a function of time, i.e., a '‘time sweep.” Any time at which G’ becomes higher than G” indicates a time-to-gelation point at which the material began acting more like an elastic solid, rather than a viscous liquid.

[0033] Tissue adhesion plays an important role for hemostatic materials which attempt to seal damaged tissue against a pressurized blood flow. The hydrophobic grafts on hm-chitosan are expected to attach and anchor onto fatty tissue and thereby improve adhesion to tissue relative to unmodified chitosan. This can be evaluated, for example, by examining the adhesion of solid foams to a bovine tissue using an automated strain-gauge. Based on rheological results, the number of grafted hydrophobes per chitosan chain are believed to be correlated with tissue adhesion.

[0034] As an exemplary means of testing tissue-material interaction, an adhesion test can be designed and developed from a standard tissue adhesion test. For example, foams can be tested with an Instron machine, which involves placing a foam sample between a cover plate and loading platform. The foam can be mixedwith 0.25 ml of bovine blood to coincide with in vivo large animal models. A 200 mm2PVC adhesion surface area can be brought into contact with the blood-foam mixture and loaded at a rate of 10 N / s to 10 N or 50 kPa and held for 3 minutes. The adhesion-testing surface is then pulled away at a rate of 1 mm / s, and the adhesion strength (kPa) can be determined by the maximum force divided by the contact surface area.

[0035] In other aspects, the disclosure provides a method of making the hemostatic powder described herein. In embodiments, tire method comprises the following steps of (i) providing a hydrophobically modified polymer (e.g., a hydrophobically-modified chitosan as described); (ii) forming an aqueous gel comprising at least the hydrophobically modified polymer and an organic acid (including an organic acid as described); (iii) freeze-drying the aqueous gel and milling the freeze-dried gel to obtain a powder comprising the organic acid salt of the hydrophobically modified polymer; and (iv) adding a carbonate salt, and optionally other materials as described herein. The method, in some embodiments, further comprises mixing into the powder formulation one or more of a free acid, gelatin, and porous particles.

[0036] In one embodiment, the hemostatic powder comprises particles comprising polyacrylic acid. The particles can be manufactured by a procedure for synthesizing porous gels involving a series of steps carried out as follows. Initially, a foam is generated by employing a dual-barreled syringe (DBS). One barrel of the syringe contains an acidic solution that includes monomers (acrylic acid and acrylamide), a cross-linker (N,N'-methylene-bis-acrylamide). and a stabilizer (hmC). The other barrel holds a basic solution containing a photoinitiator (lithium phenyl-2.4.6-trimethylbenzoylphosphinate) dissolved in sodium bicarbonate. When these solutions come into contact at the mixing tip of the syringe, a chemical reaction occurs:R-COOH + NaHCO3 R-COONa + CO2 (g) + H2O (3.1)

[0037] This reaction releases carbon dioxide (CO2) gas in the form of bubbles. These bubbles are stabilized by the HM-C present in the acidic solution, resulting in the fonnation of a stable foam. The foam is then spread evenly in a container and exposed to UV light at room temperature for a duration of two (2) minutes.The UV light triggers the photopolymcrization of the monomers, leading to the creation of a cross-linked polymer network around the gas bubbles.

[0038] After the polymerization process, the resulting gel contains a network structure that encapsulates the gas bubbles. To achieve the desired porous gel, tire material undergoes a drying process under ambient conditions. This drying process involves solvent exchange with ethanol followed by air drying. Tire final product is a solid material with a sponge-like texture, which is subsequently ground down to a fine powder.

[0039] In embodiments, the foam is prepared using a monomer composition of about 18.75 wt % acrylic acid (AAc), about 6.25 wt % acrylamide (AAm), and about 0.375 wt % N,N'-methylene-bis-acrylamide (BIS). Additionally, about 0.5 wt % of HM-C is employed as a foam stabilizer. The HM-C stabilizer can include a combination of C16 anhydride at about 2 mol %, C12 anhydride at about 5 mol %, and CIO anhydride at about 10 mol %. As a result, a total of 17% of the amines present in chitosan underwent functionalization with hydrophobic (alkyl) chains through reactions with anhydrides in such embodiments. The wavelength of the UV light emitted falls within the range of 320 to 400 nanometers.

[0040] As used herein, the term "about " means ±10% of a reference value.

[0041] Other aspects and embodiments of the invention will be apparent to the skilled artisan from this disclosure.

[0042] The invention will be further described in the following examples, which do not limit the scope of the invention described in the claims.EXAMPLESExample 1: Hydrophobically-Modified Chitosan Powder Produces Expanding Hemostatic FoamWhen Contacted With Blood

[0043] The use of hmC powder that produces an expanding foam was evaluated as a hemostatic material, i.e., whether effective at stopping bleeding. To examine this ability, experiments were conducted in vitro. A simple beaker-inversion test served as an indicator in this regard.

[0044] In brief, the hmC was produced as a chitosan acid salt by freeze drying hmC aqueous gels. Specifically, a low molecular weight chitosan modified with a C8 chain length graft at 5% graft density was produced (which is low molecular weight chitosan, with 5% of C8 hydrocarbon tails grafted to the biopolymer backbone via free amines). Tire hmC was dissolved at 1.8 wt%, in water with dilute acid (this gel is referred to as the “salt prep gel”). 0.5 M of succinic acid was used for this example. The resulting gel was a thick, clear, but flowing gel, which could be frozen and then placed into the freeze dryer for removal of water via sublimation at low pressures. This process resulted in a solid, porous pad out of the freeze dryer, which was then crushed into a fine powder through the process of milling and sieving, thus producing a hydrophobically-modified chitosan-succinate salt. The hm-chitosan-succinate salt was shown to dissolve about 100 times faster in water, relative to the same hm -chitosan.

[0045] The hm-chitosan-succinate salt was formulated with free bicarbonate and free polyacrylic acid (PAA) particles in order to produce a hmC powder. The formulation pennutations are summarized in the following Table 1 :

[0046] The expansion of foam produced by the powder in the beaker was measured over time. Volume of powder expansion was measured as ultimate expansion volume calculated by (Vfmai- Vinitiai) / Vinitiai x 100% conducted in a large graduated cylinder. The hmC formulations at a ratio 1 :20 powder to citrated blood, by volume, were combined in this experiment. Tire results are shown in the following Table 2:

[0047] In addition, the hmC powders were shown to form firm clots with minimal mixing in blood at 20: 1 Blood:Powder ratio: and the foamed clots were stable for over 20 minutes. When placed in powder dispensers to obtain expansion data, the above-identified powders were shown to achieve greater than 20 x expansion (Figure 1). The beaker container was also inverted to show that the produced foam exhibited sufficient properties to hold back the blood, where the produced foam mechanically acts like a robust clot (Figure 1). The hmC powder was also assessed by a visual blood gelation score with the following criteria:Visual Blood Gelation Scale0 = freely flowing, no gelation at all1 = still freely flowing, slight increase in viscosity2 = still freely flowing, significant increase in viscosity3 = mild gelation, initial gelation, quickly followed by flowing; does not hold weight upon tapping the vial4 = moderate gelation, gel holds weight for significant period of time, even with tapping the vial: flows again within 1 hour of gelation5 = strong gelation, gel holds weight for significant period of time, even with tapping the vial; holds weight for greater than 3 hours after initial gelation

[0048] When tested, the hmC powder exhibited the following results (Table 3):

[0049] These results show that foam produced by the hmC powder of the present application is advantageous for hemostatic purposes.Example 2: Hydrophobically-Modified Chitosan Powder Produces Foam That Stops Bleeding In Vivo

[0050] Tire hemostatic powder referenced in Example 1 above was tested in Yorkshire swine. A control (low molecular weight unmodified chitosan acid salt (1.8 wt% unmodified chitosan with 1 M succinic acid freeze-dried, 60 wt% free bicarbonate, and 20 wt% free PAA porous particles) was also performed. A non- compressible injury model was implemented under the following conditions: reproducibly lethal within 30minutes, closed-cavity, using a cutting wire instrumented to create severe injury in both hepatic and portal veins and medial lobes of the liver.

[0051] Specifically, the experiment design included performing lethal injury to swine liver with the abdominal cavity closed. 10 minutes after injury, the hmC powder was applied (Mean Arterial Pressure (MAP) falls to 15-25 mmHg). Lactated Ringer’s Solution (LRS) was given at a rate of 165 mL / min, with a maximum of 10L LRS administered. The LRS was started when MAP <65 mm Hg and LRS stopped when MAP > 65 mmHg: and restarted when MAP < 60 mmHg). Blood lab draws were made at 0,10, 30, 60, 90, 120. 150 and 180 min. Tire primary endpoint was animal survival at 3 hours, and the secondary endpoint was the presence of adverse events during the treatment period and average resuscitation volume.

[0052] Hie hmC powder reproducibly (n=6) and consistently (83% of subjects treated) demonstrated survival of surgically injured subjects at 3 hours without adverse events (the expansion of the foam is “soft” mechanically, and results in no lesions or constrictions). The controls utilizing unmodified chitosan were used in this study, and in contrast to the hmC powder, the control chitosan foams showed no ability to halt hemorrhage in the swine injury model.

Claims

CLAIMSWhat is claimed is:

1. A hemostatic powder, comprising an acid salt of a hydrophobically modified polymer and a carbonate salt, wherein said hemostatic powder foams and expands upon contact with an aqueous environment.

2. Tire hemostatic powder of claim 1, wherein the acid salt is an organic acid salt.

3. The hemostatic powder of claim 2, wherein the organic acid is selected from succinic acid, citric acid, glycolic acid, acetic acid, fumaric acid, malic acid, glutaric acid, oxaloacetic acid, lactic acid, and pyruvic acid.

4. Tire hemostatic powder of claim 1, further comprising one or more free organic acids, which is optionally citric acid.

5. The hemostatic powder of any one of claims 1 to 4, wherein the acid salt of a hydrophobically - modified polymer is prepared by freeze-drying and milling a hydrophobically-modified polymer organic acid solution.

6. Tire hemostatic powder of claim 5, wherein the composition prior to freeze-drying and milling comprises an organic acid that is present at a molarity of about 0.25 M to about 2.0 M.

7. The hemostatic powder of claim 6, wherein the composition prior to freeze-drying and milling comprises from about 1.0 wt% to about 2.5 wt% of hydrophobically modified polymer.

8. The hemostatic powder of any one of claims 1 to 7, wherein the hydrophobically modified polymer is a hydrophobically modified chitosan.

9. The hemostatic powder of claim 8, wherein the hydrophobically modified polymer is a hydrophobically modified chitosan, which is optionally a hydrophobically modified low molecular weight chitosan.

10. The hemostatic powder of claim 9, wherein the hydrophobically modified chitosan comprises one or more hydrocarbon groups attached to the polymer’s backbone through amide linkages, optionally wherein the hydrocarbon groups comprise one or more of C8 to Cl 8 hydrocarbon groups.

11. Tire hemostatic powder of any one of claims 8 to 10, wherein the hydrophobically modified polymer comprises at least 1% graft density of hydrocarbon groups in the range of C8 to C 18, with respect to available backbone functional groups, optionally wherein the graft density of the hydrocarbon groups is from 1% to about 15%, or from about 2% to about 10%, with respect to available backbone functional groups.

12. Tire hemostatic powder of any one of claims 1 to 11, comprising from about 10 wt% to about 60 wt%, or from about 10 wt% to about 55 wt%, or from about 10 wt% to about 50 wt%, or from about 10 wt% to about 45 wt%, or from about 15 wt% to about 50 wt%, or from about 15 wt% to about 45 wt%, or from about 20 wt% to about 30 wt% of the hydrophobically modified polymer acid salt.

13. The hemostatic powder of any one of claims 1 to 12. wherein the carbonate salt is a salt selected from sodium, potassium, calcium, or magnesium, and which is optionally selected from sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, calcium carbonate, and magnesium carbonate, and combinations thereof14. The hemostatic powder of claim 13, comprising from about 40 wt% to about 80 wt%, or from about 45 wt% to about 80 wt%, or from about 55 wt% to about 80 wt%. or from about 60 wt% to about 80 wt%, or from about 50 wt% to about 75 wt% of carbonate salt.

15. Tire hemostatic powder of any one of claims 1 to 14, further comprising porous polymeric particles, optionally comprising porous particles comprising polyacrylic acid.

16. The hemostatic powder of claim 15. comprising from about 15 wt% to about 30 wt% of said porous particles.

17. The hemostatic powder of any one of claims 1 to 16, further comprising gelatin, optionally comprising from about 0.2 wt% to about 1.0 wt% of gelatin.

18. A hemostatic powder, comprising (a) a freeze-dried and milled organic acid salt of low molecular weight hydrophobically modified chitosan, (b) sodium bicarbonate, and (c) porous polymeric particles, wherein said hemostatic powder foams and expands upon contact with an aqueous environment.

19. The hemostatic powder of claim 18. comprising:(a) from about 10 wt% to about 45 wt% of low molecular weight hydrophobically modified chitosan succinic acid salt;(b) from about 40 wt% to about 80 wt% of sodium bicarbonate;(c) from about 10 wt% to about 30 wt% of porous particles comprising polyacrylic acid.

20. The hemostatic powder of claim 18 or 19, further comprising about 10 wt% free citric acid.

21. The hemostatic powder of claim 18 or 19, further comprising about 0.5 wt% gelatin.

22. The hemostatic powder of any one of claims 1 to 21 , wherein the aqueous environment is a bleeding wound.

23. The hemostatic powder of any one of claims 1 to 22, wherein the powder is contained in a syringe dispenser.

24. The hemostatic powder of claim 23, comprising from about 10 g to about 150 g of the hemostatic powder.

25. A method for inducing hemostasis in a patient in need thereof, comprising administering the hemostatic powder of any one of claims 1 to 24 to a bleeding wound of the patient.

26. The method of claim 25, wherein the wound is a non-compressible hemorrhage, a surgical bleed, or a cavity wound, and which is optionally a non-compressible abdominal wound, a non-compressiblewound within a closed abdominal cavity, and / or a trauma-induced bleeding wound, or which is optionally a cavity bleed, including a soft tissue bleed during surgery.

27. A method of making the hemostatic powder of any one of claims 1 to 22, comprising:(i) providing a hydrophobically modified polymer;(ii) forming an aqueous gel comprising at least the hydrophobically modified polymer and an organic acid;(iii) freeze-drying the aqueous gel and milling the freeze-dried gel to obtain a powder comprising the organic acid salt of the hydrophobically modified polymer; and(iv) adding a carbonate salt.

28. The method of making of claim 27, further comprising mixing into the powder formulation one or more of a free acid, gelatin, and porous particles.

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