JPH039761A - Hemostatic material for treatment of external injury - Google Patents

Abstract

PURPOSE: To obtain a hemostatic treating material for trauma by coating a fibrous substrate with an aqueous dispersion of a pharmaceutically allowable alginate and drying the coated substrate. CONSTITUTION: A treating material for trauma consists of a fibrous substrate having a discontinuous coating of a pharmaceutically allowable alginate on a surface. The alginate is useful in the treating material for trauma because of its hemostatic property. The alginate is preferably coated on a substrate in a dry weight of 1-30g/m<2> . A preferable fabric to be used as the treating material for trauma is 100% polyester malefreece with a weight range of 100g/m<2> -200g/m<2> . Polyester has a tendency to resist against wet disintegration, so that it is formed into an elastic pad providing protection of the trauma by cushioning. The coating of the alginate may consist of any pharmaceutically allowable cationic alginate such as sodium, calcium, potassium and ammonium alginates or mixture thereof. Sodium and calcium alginates as well as mixture thereof are preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to hemostatic wound dressing materials, and more particularly to fibrous wound dressing materials coated with alginate. The invention further provides wound dressing materials made of such materials and methods for their manufacture.

To summarize the invention, the wound dressing material consists of a fibrous substrate, such as a needle-stitched fleece, having a discontinuous coating of pharmaceutically acceptable alginate on the surface.

Alginates have been recognized as useful in trauma dressing materials because of their hemostatic properties. US Pat. No. 2,512,616 recognizes that alginate exists in a variety of physical forms, but indicates that the fibrous form is preferred for use in surgical dressing materials. Alginates in a loose woolly form similar to woven gauze or cotton wool have been particularly recognized as useful.

British Patent No. 629,419 discloses a hemostatic surgical material formed by impregnating cotton gauze or other fibrous material with a relatively large amount of insoluble alginate.

GB 1329693 also discloses a surgical dressing material that includes alginate as a hemostatic agent. In this case, the alginate may be used, for example, with polyvinyl acetate/polyvinylpyrrolidine copolymer, sodium carboxymethyl cellulose, polyethylene oxide, poly(
(galactose methacrylate), poly(galactose acrylate), methyl vinyl ether and maleic anhydride copolymers or allantoin polygalacturonic acid. Such water-soluble polymers are obviously used to cast or spread the alginate in the form of a film, sheet or block of hemostatic material. The membrane, sheet or block gradually dissolves in contact with the wound or burn, releasing the alginate, which is then liberated and exhibits its hemostatic properties.

GB 1,329,693 further describes casting an alginate/water soluble polymer mixture onto a sheet of PvC or, in some embodiments, onto a sheet of Polywebnet 909 (Smith and Nehew). It also discloses that it is possible. The latter is a wound release layer widely used in wound dressing materials.

The allowance material proposed in each of the above UK patents is not believed to be commercially available. Currently, alginate is
It is available for use in wound treatment in two major forms: as a fiber filling and as a powder spray.

Commercially available alginate fiber fillings are generally used in relatively large quantities (generally greater than 100j7/m2 of wet-spun fibers) and are therefore expensive. Needle stitching to increase the integrity of the filling is even more costly.

For example, as described in British Patent No. 1254534,
Alginate powder sprays may be a convenient way to quickly apply hemostasis to the wound surface.

However, the use of such sprays does not provide protection against wounds and therefore cannot be considered as a replacement for conventional wound dressing materials.

In accordance with the present invention, a wound dressing material is provided comprising a fibrous substrate having a discontinuous coating of pharmaceutically acceptable alginate deposited on the surface.

By applying the alginate coating directly to the surface of the fibrous substrate, a very large alginate surface area relative to its weight can be achieved. This is advantageous in that, unlike the dressing disclosed in GB 132,963, the alginate rapidly contacts and reacts with the blood from the wound to which the dressing is to be applied. Therefore, effective hemostasis can be achieved with relatively modest amounts. alginate or alginate blend) from 1 to 30. ? /m' dry weight, -
Layer preferably! It is preferred to coat the substrate in an amount of 1 M/m"-202/m", most preferably 87/m".

Surprisingly, such levels of alginate provide significant trauma relief, resulting in a separate trauma relief layer (
For example, there is no need for perforated plastic films or plastic nets of the type commonly used in wound dressing materials).

The substrate can be any suitable material suitable for use as a scratch contact absorbent. The trauma contact absorbent layer may be of woven, knitted or non-woven construction and may be comprised of any suitable fibers. Cotton, rayon, acrylic, polypropylene and polyester fibers are examples of suitable fiber types and can be used alone or in mixtures.

The surface of the fibrous substrate can, if desired, be made delaminated, for example by thermal calendering of the surface fibers, especially in the case of heat-fusible fibers. Of course, if such thermal calendering is used, it must not be carried out to such an extent that the fibrous nature of the substrate is completely lost.

A preferred fabric for use in the wound dressing material of the present invention is 100% polyester malifleece (Ma 1iN
eece) (Radachick). Polyester tends to resist wet decay better than rayon, thus providing an elastic pad that provides some protection by cushioning scratches.

Alginate coatings can be made by e.g. sodium alginate,
It can be comprised of any pharmaceutically acceptable cationic alginate, such as calcium, potassium and ammonium or mixtures thereof. Sodium and calcium alginate and mixtures thereof are preferred.

The hemostatic effect of 100% sodium alginate can be increased by replacing some of the sodium ions with calcium ions.

7.2% calcium based on the weight of sodium alginate is required for complete replacement of sodium ions by calcium. However, much lower levels of ion exchange, e.g. 1-3 by weight of alginate
% calcium, preferably 1.5-2.5% calcium by weight, a suitable gel results.

Since it is undesirable to form a continuous film of alginate on the substrate, there is no need to include a film-forming water-soluble polymer in the alginate coating. In fact, it is preferred that the alginate coating contains only less than 40% by weight of other polymers, preferably less than 15% by weight of the layer. It is particularly preferred that less than 5% by weight of other polymers be included in the alginate coating, as the presence of other polymers may interfere with the hemostatic effect of the alginate.

In the absence of significant amounts of film-forming polymers, alginate tends to become powdery and therefore the coating of alginate in the wound care material of the invention is made of, for example, ethylene. Preferably it also contains a plasticizer, such as glycol, propylene glycol or hexylene glycol, or an alkyl citrate or a suitable mixture thereof. A preferred plasticizer is glycerin (propane-1,2,3-triol). The plasticizer may represent 0-80% by weight of the coating, preferably 10-70% by weight. It is particularly preferred that the plasticizer is present in the coating in an amount of 30 to 60% by weight.

The alginate coating may optionally contain other additives such as preservatives, analgesics or other drugs, preferably less than 5% by weight, preferably less than 2% by weight. It may be contained in an amount of less than 1% by weight.

Other additives may be desirable, for example as processing aids. For example, when a sodium/calcium alginate coating is required, the concentration of sodium alginate in the presence of calcium ions may be reduced by the inclusion of pH-adjusting materials such as gluconolactone or adipic acid/sequestering agents (e.g., sodium citrate). Immediate gel formation of viscous aqueous solutions can be prevented. Such materials are generally used in amounts of 1 to 10% by weight, preferably 2.5 to 7.5% by weight. Preservatives can also be added to improve the resistance of the alginate to microbial attack. Examples of suitable preservatives are Metasol D3T (Merck), Parasebut (Methylparaben) (Roma Chemical) and Hypronopol (2-7'Roma2,2-nitropropane-1,3-diol) (Boots Limited). . Typical ranges for the amount of preservative are 0.1-5.0% by weight, preferably 0.1% by weight.
It is 25-1.0%.

When applying an alginate coating to a fibrous substrate in accordance with the present invention, individual fibers near the surface of the substrate are at least partially coated.

A very thin film of alginate can also be formed between adjacent fibers near the point of intersection. Discrete films or layers of alginate on the surface of the substrate should be avoided in order not to reduce the permeability of the substrate to the substrate (eg, air and water vapor). Coating methods suitable for achieving such distribution include knife-over roll, Meyer rod, screen printing and reverse roll coating. Reversed roll coating is particularly suitable, even on substrates with varying and non-uniform surfaces, by making it possible to apply a controlled amount of material to a given area of the substrate.

Preferably, the alginate is applied to the substrate as a viscous aqueous or substantially aqueous liquid.

The viscosity of the aqueous suspension of the alginate composition can be adjusted to suit the coating method used, but for reverse roll coatings 2000 cp to 30.0 OOC1)%
Preferably a viscosity in the range 3000 cp - 3000 cp is suitable. Adjustment of the roll gap and casting ratio determines the amount of coating material applied to the substrate, as is known in the coating art.

For reverse roll coating, the gap between the doctor roll and applicator roll is generally 0.075-0.45
mm, preferably 0.10-0.30 mm, e.g. O
, 15 to 0.20 mm.

The casting ratio (i.e. the ratio of the circumferential speed of the applicator roll to the circumferential speed of the packing roll) is - generally 0.8:
l-1,7: 1. - layer preferably l:1-1.5:
l, for example t, 2. :i.

Evaporation of the aqueous phase can be achieved by any suitable means, for example by passage through a temperature controlled oven. The oven should be 100-150°C, for example 1.
Temperatures of 10-140°C are suitable. Gradual increases in oven temperature can also be used if desired. Drying generally takes 1 to 10 minutes; drying typically takes 2 to 5 minutes.

The alginate-coated wound dressing materials of the present invention have a substrate permeability of at least 5
Preferably, it has a gas permeability (defined below) of 0%. More preferably, the gas permeability of the coated material is between 60 and 98% of that of the uncoated material, and between 75 and 9%.
5%, for example 85 to 92.5%, is also preferred.

The term "gas permeability" means the permeability of the wound dressing material to cyclohexane vapor (not water vapor), which is inert to the alginate and does not cause swelling of the alginate.The test method is as follows: as follows: 10 m4 of cyclohexane are placed in a 4 cm diameter cylindrical test cell, which is then closed with a layer of test material.The cell is placed in a steam shelf at 25 °C and the rate of loss of cyclohexane vapor is It is determined by weighing the cell periodically (eg, every hour over a period of 5 hours).The transmittance is conveniently expressed in units of cyclohexane loss/m'/24 hours.

Generally, the trauma dressing material of the present invention has a cost of 2,500 to 20,000
2/m'/24 hours, -layer preferably 4000~l
It has a gas permeability of 50,002/m"/24 hours. Particularly preferred is 5,000 to 10,000/m"/24 hours.
”/24 hour gas permeability.

The wound dressing material of the present invention is suitable for use in a variety of forms. For example, they can be used alone (secured in place by bandages, adhesive tape, or other suitable means) or they can be formed into a composite dressing. Indeed, the materials of the present invention can be used advantageously in situations where absorbent wound care pads are commonly used. They are particularly suitable for use as post-surgical dressing materials.

Composite dressings, including dressings of the present invention, generally consist of a fibrous pad with an alginate coating on one surface and a backing material bonded to the opposite surface. The backing material may be porous or non-porous, and materials that are impermeable to water but permeable to water vapor are particularly suitable. Such materials include, for example, cast polyurethane films. Alternatively, the backing material may be e.g.
It can be a perforated plastic film, such as those commonly used in first aid materials.

Composite wound dressings comprising the wound dressing materials of the present invention are generally supplied sterile in a germ-resistant outer package. Such an outer envelope is similar to a pouch consisting of two overlapping layers of glass film that are heat-sealed around the perimeter.
It can be of any general form.

Sterilization can be accomplished by conventional means, such as autoclaving, gamma irradiation, and ethylene oxide treatment.

The invention is further illustrated by the following examples.

Example 1 An alginate composition having the following formulation was prepared by simple mixing of the listed ingredients: % wt/wt Sodium alginate I, 96 Calcium orthophosphate 0.17 Glufunolactone
0.17 glycerin
1.34 Pronopol 0.02
Water 96.
34 The ratio of calcium to sodium ions in this formulation is 46.6153.4.

This composition was coated with a reversible roll onto the surface of a Malifleece P/175/15 fabric consisting of 100% polyester fibers weighing 175.9/m''. The coating conditions were 27327
m2, which gave a dry coating weight of 1 oLj/m'' after drying in an oven increasing the temperature from 110°C to 1300°C over 5 minutes.

Scanning electron microscopy showed that the alginate coating formed a very thin film between the individual fibers with very little effect on the overall porosity of the fabric. This can be clearly seen from Figures 1 and 2.3, which are micrographs at 13x, 31x and 67x magnification, respectively.

The coated material was found to be highly effective as a wound dressing material. Not only was a small amount of alginate found to provide effective hemostasis, but it also demonstrated significantly improved relief of dressing material from trauma compared to uncoated malignant fleece cloth.

Example 2 The composition described in Example 1 above was prepared as lcl? /m” on two samples of polyester Mari7 rease of 1507/m2. In the first case it was applied to the smooth surface of the fabric, while in the second case Alginate was applied to the opposite, less dense surface.

The gas permeability of both samples and the uncoated malifleece fabric was determined by the test method described above. The results are shown below: Sample gas permeability uncoated fabric
104001/m”/24 hours coated on smooth surface I; cloth 76009/m
” / Cloth coated on a less dense surface for 24 hours 78
002/m"/24 hours Example 3 Example 2 above was repeated using a hydrophobic polyester knitted fabric. Coating conditions were chosen to achieve a coverage of 12,027 m2 on a smooth surface. ζ, when applying to a raised surface, the same coating conditions are 25.?/
It is believed that the different structure of the raised surface also caused a lower uptake of the alginate solution from the applicator roll.

Sample M-weight uncoated cloth 98001/m”
/ Cloth coated on smooth surface for 24 hours 5400
．． ? / m”/24 hours Cloth coated on raised surface 49002/ m2/24 hours This example
It has been shown that a coat weight as high as 02/m2 +71 can be applied to a hydrophobic polyester knitted fabric while preserving 50% of the gas permeability of the fabric.

Although the invention has been described above merely by way of example, it should be understood that many modifications may be made within the scope of the invention.

The main features and aspects of the present invention are as follows.

11 A wound dressing material comprising a fibrous substrate having a discontinuous coating of a pharmaceutically acceptable alginate on its surface.

2. Trauma dressing material according to item 1 above, wherein the alginate is selected from calcium, sodium, potassium and ammonium alginate and mixtures thereof.

3. The wound dressing material according to 1 or 2 above, wherein the alginate is present on the surface of the substrate in an amount of 52/m'' to 20.?/m''.

4. A wound dressing material according to items 1 to 3 above, wherein the coating comprises 10 to 70% by weight of a plasticizer thereon.

5. The wound dressing material according to 1 to 4 above, wherein the coating includes a preservative, an analgesic or a pH regulator thereon.

6. The coating consists of a mixture of sodium alginate and calcium with a ratio of calcium ions to sodium ions of 20:80 to 80:20.
Injury treatment materials described in 5.

7. The trauma dressing material according to any of j to 6 above, wherein the substrate is a woven fabric, a knitted fabric, or a nonwoven fabric.

8. The wound dressing material as described in 1 to 7 above, wherein the substrate is made of cotton, rayon, acrylic, polypropylene or polyester fibers or a mixture thereof.

9. A composite trauma dressing material comprising the trauma dressing materials described in I to 8 above.

10. A method for producing a wound dressing material according to item 1 above, which comprises coating a fibrous substrate with an aqueous dispersion of a pharmaceutically acceptable alginate, and drying the coated substrate.

[Brief explanation of drawings]

Figures 1, 2 and 3 are 13x, 31x and 6x, respectively.
Figure 2 is a scanning electron micrograph of the alginate coating of Example 1 at 7X magnification. Procedural amendment form) October 31, 1999

Claims (1)

[Claims] 1. A wound dressing material consisting of a fibrous substrate having a pharmaceutically acceptable discontinuous coating on its surface. 2. A wound care material according to claim 1, comprising coating a fibrous substrate with an aqueous dispersion of a pharmaceutically acceptable alginate and subsequently drying the coated substrate. manufacturing method.