PARTICULATE GEL FOR THE TREATMENT OF A BLEEDING IN THE SINUS OR NASAL CAVITY

Abstract

The invention relates to a gel comprising a first gelatin component and a second gelatin component in an aqueous medium, wherein the first gelatin component comprises gelatin particles comprising chemical cross-links and dehydrothermal cross-links; and the second gelatin component comprises a dissolved gelatin comprising chemical cross-links and at least one polysaccharide.

Claims

1. Gel comprising a first gelatin component and a second gelatin component in an aqueous medium, wherein the first gelatin component comprises gelatin particles comprising chemical cross-links and dehydrothermal cross-links; the second gelatin component comprises a dissolved gelatin comprising chemical cross-links and at least one polysaccharide.

2. Gel according to claim 1, wherein the gelatin is derived from a species selected from the group of pig, cow and horse.

3. Gel according to claim 1, wherein the chemical cross-links of the gelatin particles and/or the dissolved gelatin are derived from an aldehyde.

4. Gel according to claim 3, wherein the aldehyde is selected from the group of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, PEG-propionaldehyde, butyraldehyde, isobutyraldehyde, valeraldehyde, heptaldehyde, decanal, terephthaldehyde, crotonaldehyde, glutaraldehyde, glyoxal, PEG-dialdehyde, dialdehyde carboxymethyl cellulose and dialdehyde starch.

5. Gel according to claim 1, wherein the polysaccharide is selected from the group of xanthan, dextran, gellan, levan, curdlan, cellulose, cellulose derivatives, carboxymethylcellulose, hemicellulose, pullulan, starch, cellulose, agar, agarose, alginate, carrageenan, pectin, konjac, beta-mannan gum, carob gum, fenugreek gum, guar gum, tara gum, karaya gum, tragacanth gum, arabinoxylan gum, gellan gum, xanthan gum, agar-agar, chitosan, chitosan derivatives, hyaluronic acid and hyaluronic acid derivatives.

6. Gel according to claim 1, wherein the gel comprises a buffer solution having a pH in the range of 6.8-7.4.

7. Gel according to claim 1, wherein the particles of the first gelatin component have at least one dimension in the range of 50-750 μm, preferably in the range of 75-500 μm.

8. Method for preparing a gel according to claim 1, comprising preparing a first gelatin component by performing the steps of providing an aqueous composition comprising dissolved gelatin; then cross-linking the gelatin in the composition by treating the gelatin with a chemical cross-linking agent; then foaming of the aqueous composition to yield a foam; then lyophilizing the foam to yield a porous solid; then pulverizing the porous solid to yield a powder; then exposing the powder to dehydrothermal curing; then remoisturizing the powder to yield the first gelatin component; preparing a second gelatin component by performing the steps of providing an aqueous composition comprising dissolved gelatin; then cross-linking the gelatin in the composition by treating the gelatin with a chemical cross-linking agent; and adding a polysaccharide to the composition; mixing the first gelatin component with the second gelatin component to yield the gel.

9. Method according to claim 8, wherein the chemical cross-linking agent is an aldehyde, in particular an aldehyde selected from the group of formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, PEG-propionaldehyde, butyraldehyde, isobutyraldehyde, valeraldehyde, heptaldehyde, decanal, terephthaldehyde, crotonaldehyde, glutaraldehyde, glyoxal, PEG-dialdehyde, dialdehyde carboxymethyl cellulose and dialdehyde starch.

10. Method according to claim 8, wherein the powder of cross-linked gelatin is sieved over a plurality of sieves to yield a powder wherein the particles have at least one dimension that is in the range of 50-750 μm, preferably in the range of 75-500 μm.

11. Method according to claim 8, which method is followed by exposing the gel to a temperature in the range of 80-140° C. in particular in the range of 100-135° C.

12. Gel obtainable by the method of claim 8.

13. Gel of claim 1, for use in medical therapy.

14. Gel according to claim 1, for use in the treatment of a bleeding site, in particular a bleeding site in the nasal cavity or sinus cavity.

15. Method of treating a bleeding site of a human or an animal, comprising administering to the bleeding site an amount of the gel according to claim 1 effective to stop bleeding at the bleeding site.

16. Method according to claim 15, wherein the bleeding site is in the nasal or sinus cavity of the human or animal.

17. Method according to claim 15, wherein the amount effective to stop bleeding is in the range of 3-15 mL.

18. Use of a gel according to claim 1 for treating a bleeding site of a human or an animal.

19. A syringe (1) which includes an effective amount of a gel (2) according to claim 1 in order to stop bleeding at a bleeding site of a human or animal subject.

Description

EXAMPLES

Example 1: Preparation of Porous Gelatin Particles

[0078] In a large glass bottle, 75.00 g of gelatin (Pig skin, Type A, 285 bloom) were added to 1,175 g of demineralized water of 45° C., after which the gelatin was left to dissolve. Once fully dissolved, the solution was cooled to 35° C. After about one hour, 1.013 mL of a 37 wt. % formaldehyde solution in water was added. The gelatin was then left to cross-link for 3 hours.

[0079] A gelatin foam was created using a Kenwood Chef premier mixer. The mixing bucket was charged with 1,250 g of the aqueous cross-linked gelatin solution as prepared above. After connecting the mixing bucket to the mixer, the the gelatin solution was whisked during 30 minutes using speed setting 6, yielding a foam with a density of 2.91 mL/g.

[0080] Three lyophilization plates were filled with 330-340 g of the foam as prepared above and loaded into a standard, plate based, freeze dryer that was pre-cooled to −40° C. After freezing for 3 hours, the lyophilization cycle was started. The material was then lyophilized during 64 hours yielding three dried gelatin sponges.

[0081] The dried gelatin sponges as prepared above were milled using a Retsch ZM 200 ultra centrifugal mill. The sponges were first pre-cut to roughly 0.5×0.5×1.0 cm and thereafter added to the mill in a continuous flow over the course of 5 minutes. The milling occurred at 18,000 rpm. In the first milling cycle, a 1.00 mm sieve was installed in the mill. The particles that passed this sieve were then subjected to a second cycle using a sieve of 0.50 mm. The particles that passed this sieve were then subjected to a third cycle using a sieve of 0.25 mm. The particles that passed this last sieve formed a white powder of porous gelatin particles.

[0082] The porous gelatin particles as prepared above were exposed to a dehydrothermal curing step. First, paper bags of 9×5×16.8 cm were each filled with 9.00 g of gelatin particles. The filled paper bags were placed up-right in an oven rack of a Binder forced convection oven that was pre-heated to 140° C. The porous gelatin particles were then cured during 6 hours at this temperature. After the curing, the porous gelatin particles were left to remoisturize in ambient air, after which they were ready for use in the preparation of the gels of the invention.

Example 2: Reference Gel

[0083] In a small plastic container, 1.00 g of the porous gelatin particles obtained according to the procedure of Example 1 was mixed with 9.00 g of phosphate buffered saline (pH 7.4). The resulting mixture was left to equilibrate for 6 hours. The obtained gel was mixed again before transferring it into a syringe. The filled syringe was steam sterilized using a standard steam sterilization cycle operating at 121° C. for 20 minutes.

Example 3: Gel of the Invention with Carboxymethyl Cellulose

[0084] A 2.0 wt. % carboxymethyl cellulose solution was prepared as follows. An amount of 0.20 g of carboxymethyl cellulose (700 kDa, degree of substitution 0.9) was mixed with 9.80 g of phosphate buffered saline (pH 7.4) in a small glass container. The mixture was then stirred for 2 hours to dissolve the carboxymethyl cellulose.

[0085] A 3.0 wt. % gelatin solution was prepared as follows. An amount of 0.754 g of gelatin (Pig skin, Type A, 285 bloom) was mixed with 24.25 g of phosphate buffered saline (pH 7.4) in a small glass container at 45° C. Once dissolved, 10 μL of a 37 wt. % formaldehyde solution in water was added. The gelatin solution was then left to cross-link for 18 hours.

[0086] In a small plastic container, 2.00 g of the 2.0 wt. % carboxymethyl cellulose solution were mixed with 6.00 g of the 3.0 wt. % cross-linked gelatin solution with the aid of a spatula. Then, 0.798 g of the porous gelatin particles of Example 1 were added to the plastic container and mixed with the solution. The resulting mixture was left to equilibrate for 6 hours. The created gel was transferred into a syringe and steam sterilized as described in Example 2.

Example 4: Gel of the Invention with Chitosan

[0087] A 2.0 wt. % chitosan solution was prepared as follows. An amount of 0.53 g of chitosan was mixed with 26.48 g of a 2.0 wt. % acetic acid solution in water in a small glass container. The mixture was then stirred for 1 hour to dissolve the chitosan.

[0088] A 1.5 wt. % gelatin solution was prepared as follows. An amount of 0.291 g of gelatin (Pig skin, Type A, 285 bloom) was mixed with 19.13 g of phosphate buffered saline (pH 7.4) in a small glass container at 45° C.

[0089] The dissolved chitosan and the dissolved gelatin were then mixed with each other in a 1 to 1 ratio. In a small plastic container, 19.0 g of the 2.0 wt. % chitosan solution were mixed with 19.0 g of the 1.5 wt. % gelatin solution. Under stirring, the resulting solution was warmed to 35° C., after which 10 μL of a 37 wt. % formaldehyde solution in water were added. It was then left to cross-link for 3 hours.

[0090] Then, 6.05 g of the chitosan/gelatin solution was mixed with 0.605 g of the porous gelatin particles of Example 1 in a plastic container. The resulting mixture was left to equilibrate for 6 hours. The created gel was transferred into a syringe and steam sterilized as described in Example 2.

Example 5: Gel of the Invention with Guar Gum

[0091] A 2.66 wt. % guar gum solution was prepared as follows. An amount of 0.27 g of guar gum was mixed with 9.83 g of phosphate buffered saline in a small glass container. The mixture was then stirred for 40 hours to dissolve the guar gum.

[0092] A 3.0 wt. % gelatin solution was prepared according to the procedure as described in Example 3, with the difference that the gelatin solution was left to cross-link for 2 hours instead of 18 hours.

[0093] In a small plastic container, 10.0 g of the 2.66 wt. % guar gum solution were mixed with 3.35 g of the 3.0 wt. % cross-linked gelatin solution during stirring for 2 hours. Then, 0.626 g of the porous gelatin particles of Example 1 were added to the plastic container and mixed with the solution. The resulting mixture was left to equilibrate for 6 hours. The created gel was transferred into a syringe and steam sterilized as described in Example 2.

[0094] Then, 6.364 g of the guar gum/gelatin solution was mixed with 0.626 g of the porous gelatin particles of Example 1 in a plastic container. The resulting mixture was left to equilibrate for 6 hours. The created gel was transferred into a syringe and steam sterilized as described in Example 2.

[0095] Water Absorption Test Method

[0096] The water absorption capacity of the prepared gels was analyzed using the following standardized absorption method.

[0097] An amount of 1.00 g of gel was weighted into a container and a 4-fold excess of demineralized water was added. The container was closed off and the gel was mixed with the demineralized water by vortexing the container for 15 seconds. The gel was then left to absorb the water for 2 hours.

[0098] Excess demineralized water was removed as the supernatant resulting from centrifugation using an Eppendorf (5810) centrifuge at 4,000 rpm for 15 minutes followed by letting the container stand during 15 minutes. The total amount of water absorbed was determined by subtracting the amount of removed water from the initial amount of excess water that was added. The total water absorption of the gel was calculated as the percentage of the initial starting weight of the tested gel.

[0099] Occlusion Test Method

[0100] The sealing/barrier formation capabilities of the prepared gels were assessed with the following standardized occlusion test.

[0101] A glass test tube of 7 mL having an inner diameter of 1 cm and one opening was used to mimic the dimensions of the nasal cavity. The test tube was charged with 4.00 g of water followed by 1.00 g of gel, the water and the gel in tube being separated by a small amount of air. The gel was applied in such a way that the opening of the test tube was completely sealed with gel and that the gel levelled with the opening of the test tube (no protrusion of gel from the opening). After its sealing with gel, the test tube was turned 180°, i.e. with the opening downwards. The test tube was inspected regularly for signs of leakage through the gel during 1 hour. When there were no signs of leakage at that time, the tubes were shaken by slowly lifting them 10-15 cm with the opening still oriented downwards, followed by one quick movement to bring the tube back in the original position. The time or the amount of shakes (when the seal survived the initial hour) required for the seal to break were recorded.

[0102] Dynamic Viscosity Test Method

[0103] The dynamic viscosity of the prepared gels was analyzed using a Discovery Hybrid Rheometer (HR-2) from TA Instruments. A parallel plate system was used, wherein both plates are made of stainless steel with the top (rotating) plate having a diameter of 40 mm. Measurements were performed with a gap height of 500 μm in between the plates with a controlled temperature of 32° C.

[0104] Roughly 1 mL of gel was placed on the lower plate. The top plate was first lowered to a trim height wherein excess gel that was expelled was removed. The top plate was then lowered to the measurement height and the gel was left to rest for 3 minutes. After this resting period, the measurement was started whereby the shear rate was increased from 5 to 250 1/s over the course of 4 minutes. All dynamic viscosity data were obtained at a shear rate of 10 1/s.

[0105] Results of the Tests

[0106] The water absorption, the occlusion and the dynamic viscosity were measured for the reference gel (Example 2) and the gels of the invention (Examples 3-5). The results are displayed in Table 1.

TABLE-US-00001 TABLE 1 Water absorption, occlusion and dynamic viscosity of the gels. Water Dynamic absorption viscosity Gel (%) Occlusion (Pa .Math. s) Example 2: Reference 29 45 minutes 19.4 Example 3: CMC 99 1 hour, 3 shakes 21.1 Example 4: Chitosan 117  1 hour, 5 shakes 21.8 Example 5: Guar 39 1 hour, >15 shakes 29.0

CONCLUSIONS

[0107] In the above experiments, gels of the invention were compared to a reference gel. All the gels comprise gelatin particles comprising chemical cross-links and dehydrothermal cross-links, but the reference gel differs in that it does not comprise a dissolved gelatin comprising chemical cross-links and at least one polysaccharide.

[0108] The experiments demonstrate that gels of the invention all have an improved water absorption, provide a better occlusion and have a higher dynamic viscosity than the reference gel.

[0109] The improved water absorption indicates that the gel is more effective in the treatment of haemostasis at a wound or bleeding site, since it can absorb more blood. Further, when applied in a body cavity (e.g. to treat epistaxis), the gel provides a better (i.e. stronger and longer lasting) sealing of the bleeding site.