Degradable haemostat composition

Abstract

The present invention relates to a fibrous haemostat composition that is able to safely gradually and fully degrade in a human or animal body within about 30 days and so can be utilized by physicians to stem a flow of blood and promote healing both after as well as during surgical procedures.

Claims

1. A haemostat composition comprising a chitosan salt or a chitosan derivative and a physiologically acceptable acid, wherein the haemostat composition is in a fibrous form, the physiologically acceptable acid is present in an amount of between about 20% and about 70% by weight of the haemostat composition, and wherein complete degradation of the haemostat composition in a human or animal body occurs after more than about 4 days but less than about 30 days.

2. A haemostat composition according to claim 1, wherein complete degradation of the haemostat composition occurs after more than about 7 days but less than about 30 days.

3. A haemostat composition according to claim 1, wherein the physiologically acceptable acid is present in an amount of between about 25% and about 65% by weight of the haemostat composition.

4. A haemostat composition according to claim 3, wherein the physiologically acceptable acid is present in an amount of between about 30% and about 60% by weight of the haemostat composition.

5. A haemostat composition according to claim 1, wherein the physiologically acceptable acid comprises an organic acid and/or an inorganic acid.

6. A haemostat composition according to claim 5, wherein the organic acid comprises a carboxylic acid.

7. A haemostat composition according to claim 6, wherein the carboxylic acid is selected from formic acid, acetic acid, ascorbic acid, halogen acetic acids, propanoic acid, propenoic acid, lactic acid, succinic acid, acrylic acid, glyoxylic acid, pyruvic acid or a hydroxy propionic/butanoic acid, and combinations of any two or more thereof.

8. A haemostat composition according to claim 7, wherein the carboxylic acid is selected from lactic, acetic and succinic acids, and combinations of any two or more thereof.

9. A haemostat composition according to claim 8, wherein the carboxylic acid is lactic acid.

10. A haemostat composition according to claim 5, wherein the inorganic acid comprises one or more of hydrochloric acid and/or sulphuric acid.

11. A haemostat composition according to claim 1, wherein the haemostat composition comprises a chitosan salt.

12. A haemostat composition according to claim 1, wherein the chitosan salt comprises one or more salts selected from chitosan acetate, chitosan lactate, chitosan succinate, chitosan malate, chitosan acrylate, chitosan formate, chitosan ascorbate, chitosan fluoroacetate, chitosan chloroacetate, chitosan propanoate, chitosan glyoxylate, chitosan pyruvate, chitosan sulphate or chitosan chloride.

13. A haemostat composition according to claim 12, wherein the chitosan salt comprises chitosan lactate.

14. A haemostat composition according to claim 1, wherein the haemostat composition has an absorption of less than 20 g/g.

15. A haemostat composition according to claim 1, wherein the composition is made without subjecting the composition to any heat treatment after the composition has been dried.

16. A haemostat composition according to claim 1, wherein the fibres have a minimum average length of about 3 mm and a maximum length of about 500 mm.

17. A haemostat composition according to claim 16, wherein the fibres have a length of between about 10 mm and about 76 mm.

18. A haemostat composition according to claim 1, wherein the fibres have a diameter of no more than 100 microns.

19. A haemostat composition according to claim 1, wherein the molecular weight of the chitosan used for the preparation of the haemostat composition is less than about 500,000.

20. A haemostat composition according to claim 1, wherein the viscosity of the chitosan used for the preparation of the haemostat composition is from about 40 to about 200 cps when measured at 20? C.

21. A haemostat composition according to claim 1, wherein the particulate haemostat composition is in the form of a textile fabric or a pad.

22. A haemostat composition according to claim 1, wherein the haemostat composition is sterilised.

23. A haemostat composition according to claim 1, further comprising one or more components selected from pharmaceutical agents; wetting agents; colouring agents; processing aids; bulking agents; absorbent polymers; antimicrobial agents; growth factors; cytokines; agents which absorb agents which delay healing, and/or another haemostat component.

Description

DETAILED DESCRIPTION

Examples

Method

(1) The total absorbency of the haemostat composition of the invention is determined using simulated wound fluid, serum and lysozyme solution. This is undertaken by determining the maximum absorbency of the materials by slowly adding fluid to the materials until no more can be absorbed. The amount of fluid absorbed is calculated from the wet weight minus the dry weight.

(2) Using the total absorbency volume for the material to be tested, this volume of lysozyme solution, simulated wound fluid or serum is decanted into a clean sealable beaker.

(3) The haemostat composition is added into the solution (the solution volume being greater than the maximum absorbency of the haemostat composition), ensuring that the weight of product is not greater than the absorbency potential for the volume of fluid within the beaker.

(4) The haemostat composition and solution are sealed and incubated at 37? C. (i.e. body temperature) for up to 30 days.

(5) At each time point the solution is visually assessed to determine whether and to what degree the haemostat composition has degraded.

(6) It is to be noted that at maximum absorbency at day 1, the degradation time is quicker than if the same volume of solution is applied gradually over a 5 day period.

(7) The haemostat composition is considered to have completely degraded if the viscosity of the lysozyme solution, simulated wound fluid or serum falls below 10 cps as measured at 20? C. on a Brookfield viscometer, measured by setting the viscometer to spindle 64 and setting the spindle speed to 10 rpm, or if the fluid in the beaker becomes optically clear with no particles or insoluble matter visible to the human eye.

(8) The degradation data is provided in Table 1.

(9) TABLE-US-00001 TABLE 1 Testing/Examples Days to full degradation Sample SWF Lysozyme solution Chitosan/Viscose/Acid >30 days >30 days blend Celox gauze >30 days >30 days Chitosan nonwoven with >30 days >30 days 10% Acid Chitosan nonwoven with 1 day 4 days 35% Acid Chitosan nonwoven with 1 day 1 day 55% Acid

(10) In the examples in Table 1, a chitosan nonwoven fabric, 135 gsm, was coated with the designated quantity of a lactic acid solution, dried, and then sterilised under gamma irradiation.

(11) It can therefore be seen that the fibrous haemostat compositions according to the invention degrade effectively over a desired period of between 1 and 30 days in conditions designed to replicate those that would be encountered in the human or animal body, and would be able to safely remain in the human or animal body post-surgery to aid in reducing and preventing incidences of re-bleeding and promoting healing, before completely degrading and being excreted from the body naturally.

(12) It is of course to be understood that the present invention is not intended to be restricted to the foregoing examples which are described by way of example only.