Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Web – sheet or filament bases; compositions of bandages; or...
Patent
1997-03-31
1998-12-29
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Web, sheet or filament bases; compositions of bandages; or...
424 7801, 424 7803, 424 7806, 424445, 424446, A61K 3174, A61L 1516
Patent
active
058537490
DESCRIPTION:
BRIEF SUMMARY
This application is a 35 USC 371 of PCT GB95/01804 filed Jul. 31, 1995.
This invention relates to a gel wound dressing material, and to techniques for preparing and using such a material.
It is desirable to control the condition of a wound to encourage the healing process by maintaining it sufficiently moist so as to absorb or to eliminate the formation of dry crusty tissue in the vicinity of the wound, while also absorbing materials exuded from the wound, including dead leucocytes, epidermal and dermal cells. At the same time, it is desirable to prevent access to the wound of agents, whether bacterial or fungal, which can lead to infection. Examples of wounds to which these factors are relevant are ulcers, traumatic and surgical wounds, and burns, and tissue donor sites.
Traditionally, wounds have been encouraged to heal by placing a gauze material over the wound. More recently, however, it has been proposed to apply a gel material over the wound. A suitable gel material is disclosed in U.S. Pat. No. 4,226,232. It comprises a hydrolysed copolymer of starch-and an acrylonitrile. The polymer is prepared in gel form by mixture with water, to an extent which gives the copolymer an appropriate viscosity which enables it to be manipulated as a gel, especially when applying it to a wound and while it is applied to the wound. Modified such materials are disclosed in U.S. Pat. No. 4,302,369, in which the polymer is converted to its aluminium salt to increase its ability to absorb solutions with a high ionic strength.
Appropriate properties for a gel, for use as a wound dressing include a viscosity that makes the material capable of being manipulated before administration to a wound and then applied appropriately over the area of the wound, and an ability to absorb exudate from the wound. The need to be able to manipulate a gel material for a wound dressing conveniently has to be balanced with the ability of the gel to absorb additional liquid; the mixture of the polymer with water to confer the gel viscosity on the polymer will result in a reduction of the ability of the polymer to absorb liquid.
The present invention provides a gel-wound dressing in which the polymer component comprises a copolymer of a starch and a monounsaturated carboxylic acid or an ester or salt thereof.
Accordingly, in one aspect, the invention provides a gel wound dressing which comprises: carboxylic acid or an ester or salt thereof; and
The dressing material may further comprise a preservative or other additive.
The dressing of the invention has the advantage that it can be provided as a gel, and therefore be manipulated conveniently before application to a wound and while it is so applied, with an ability to absorb fluids which can be at least comparable with gel wound dressings based on other polymer systems. The dressing can also provide appropriate moisture levels to minimise the risk of a wound drying out during the healing process, which can itself give rise to complications in the healing process in terms of the formation of crusty tissue. The dressing material of the invention can be made with a viscosity which is at least about 100 kcps, preferably at least about 125 kcps, for example at least about 160 kcps. The viscosity can be arranged to be not more than about 300 kcps, more preferably not more than about 275 kcps, for example not more than about 250 kcps. The viscosity of the dressing material is measured on a Brookfield RVF viscometer with a helipath stand, using a T-bar D spindle at 4 rpm.
The viscosities referred to above can be attained according to the present invention while maintaining a high ability to absorb exuded materials from the wound as can be demonstrated by means of a saline absorption test. That test comprises dispersing 2 g of the dressing material in 20 ml of 0.9% aqueous NaCl solution. The dispersion is decanted into a 50 ml measuring cylinder. Once the dispersion has settled, the position of the phase separation is noted from which the fluid absorption capacity can be calculated. It has been found that
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patent: 4226232 (1980-10-01), Spence
patent: 4302369 (1981-11-01), Elmquist
patent: 4781919 (1988-11-01), Liebowitz
patent: 5505718 (1996-04-01), Roe et al.
Abstract-JP3141229 -"Composition and Drug for Treating Wound", Jun. 1991.
Page Thurman K.
Scimat Limited
Shelborne Kathryne E.
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