Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
  • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
  • A61L15/42—Use of materials characterised by their function or physical properties
  • A61L15/44—Medicaments
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
  • A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
  • A61L15/22—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons containing macromolecular materials
  • A61L15/225—Mixtures of macromolecular compounds
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2300/00—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices
  • A61L2300/20—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices containing or releasing organic materials
  • A61L2300/30—Compounds of undetermined constitution extracted from natural sources, e.g. Aloe Vera
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2300/00—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices
  • A61L2300/40—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices characterised by a specific therapeutic activity or mode of action
  • A61L2300/404—Biocides, antimicrobial agents, antiseptic agents
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2300/00—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices
  • A61L2300/60—Biologically active materials used in bandages, wound dressings, absorbent pads or medical devices characterised by a special physical form
  • A61L2300/606—Coatings
  • A61L2300/608—Coatings having two or more layers

Definitions

• This invention relates to wound dressings containing honey.
• honey possesses antimicrobial properties that make it suitable for use in treating a range of infections and skin disorders.
• This antimicrobial activity can be attributed to a number of factors, in particular the natural presence in honey of hydrogen peroxide (H 2 0 ), its high saccharide content (which tends to dehydrate bacteria by osmosis) and its relative acidity (normally around pH 4).
• H 2 0 hydrogen peroxide
• those honeys produced by bees that have fed on nectar from manuka blossom possess enhanced antimicrobial potency, due to the presence in such honeys of an as yet unidentified substance known simply as "unique manuka factor" (UMF).
• UMF unique manuka factor
• honeys also render honey suitable for use in the dressing of wounds, where it assists in preventing infection, the debridement of necrotic tissue, the deodorising of malodorous wounds and the minimisation of scar formation.
• an obvious problem associated with the use of honey in such circumstances is that it is a rather runny substance, with the result that the use of natural honey in a wound dressing is messy and impractical and the wound dressing has no absorbing capacity, so that on an exuding wound it rapidly becomes unevenly liquefied and runs off the wound. This also causes dilution of the antimicrobial effect.
• WO 01/41776 discloses a wound treatment composition comprising an adsorbent material for adsorbing moisture on or around a wound and a saccharide or polysaccharide or derivative thereof.
• WO 02/00269 published on 3 rd January 2002 also discloses a wound dressing comprising a honey composition and a base material and optionally further layers for adhesion.
• substantially liquid-impervious composite material still has a significant liquid-absorption capacity, together with a high degree of permeability to water vapour generally, being capable of achieving a 24-hour moisture-vapour transmission rate of at least 20g per 100cm 2 and a 24-hour total fluid handling capacity of at least 35g per 100cm 2 .
• the term "impervious” is used in relation to the composite structure in the sense that liquid water (or an aqueous liquid such as saline solution) does not penetrate all the way through the structure and emerge in the liquid phase at the opposite face.
• aqueous liquid such as saline solution
• the above-mentioned “Paddington Cup test” can serve as a test for this purpose, a composite being considered impervious if the liquid saline does not pass through it within 24 hours under that test.
• the composite material is therefore ideally suited for use as a moist wound dressing, which assists in the healing of exuding wounds, since it retains its structural integrity in moist conditions, is able to form a barrier to liquid water, and yet both absorbs liquid water and transmits substantial amounts of water vapour at a steady rate. Both liquid absorbency and vapour transmission can be important. Absorbed liquid will include other wound fluid components and wound debris, as well as water. Moisture vapour transmission is an on-going property of the dressing whereas liquid absorption (absorbency) is a property which attains a maximum level.
• the invention therefore provides, in one aspect, a wound dressing comprising: a wound-contacting layer composed of a mixture of honey and a moisture-absorbing agent; a water-permeable fabric backing layer; and an intermediate layer comprising water-permeable fabric impregnated with a mixture of honey and a moisture-absorbing agent.
• the wound dressings of the invention preferably are substantially impervious to liquid water but permeable to water vapour as manufactured, preferably even after sterilisation.
• wound-contacting and intermediate layer are in direct physical contact as are the intermediate layer and backing layer, although liquid and vapour contact is sufficient.
• the honey mixture in the wound- contacting and intermediate layers preferably forms a continuum, as does the fabric in the backing and intermediate layers.
• the wound-contacting layer and the intermediate layer preferably form a first continuous phase and the fabric layer and intermediate layer preferably form a second continuous phase, the first and second continuous phases overlapping to form the intermediate layer. This may be achieved, for example, by spreading the honey mixture over a layer of fabric and allowing the mixture only partially to impregnate the fabric before it sets. This structural integrity also assists in removal of a used dressing in one piece.
• the invention therefore provides, in another aspect, a method of manufacturing a wound dressing, comprising the steps of: providing a layer of a water-permeable fabric material; providing a mixture of honey and a moisture-absorbing agent; spreading said mixture over said fabric layer; allowing a portion of said mixture to impregnate an upper sub-layer of said fabric layer; and allowing said mixture to set; thereby producing a dressing comprising a wound-contacting layer composed of a mixture of honey and a moisture-absorbing agent, a water-permeable fabric backing layer, and an intermediate layer comprising fabric impregnated with said mixture of honey and moisture-absorbing agent.
• the three-layer structure is well defined, with the wound- contacting layer being free (or substantially free) from fibres such as fabric fibres from the backing layer and the fabric backing layer being free (or substantially free) from honey.
• the thickness of the intermediate layer e.g. as formed by partial impregnation of the fabric backing layer by the honey mixture may, for example, be from 100 ⁇ m to 1,000 ⁇ m, preferably from 200 to 500 ⁇ m.
• the honey layer forms a substantially homogeneous solid phase gel sheet.
• the ratio of honey to moisture-absorbing agent in the wound-contacting layer needs to be controlled within certain limits.
• the weight ratio of moisture-absorbing agent to honey should be within the range from 1:2 or 1:3 to 1:14 and preferably in the range from 1:2 or 1:3 or 1:4 to 1:10.
• the preferred ratio of moisture-absorbing agent to honey has been found to be affected by irradiation, which is the preferred method for sterilising the wound dressings of the invention after manufacture and prior to use. Either gamma-irradiation or electron- beam irradiation can be used.
• the dressing can be irradiated by 25kGy or more, or by lower amounts sufficient to achieve sterilisation. Surprisingly, it has been found that the ability of the honey layer to absorb liquid is diminished substantially and to a similar degree by both gamma-irradiation and electron-beam irradiation, if the ratio of moisture-absorbing agent to honey is very low, i.e. in compositions containing a relatively low proportion of moisture-absorbing agent.
• the weight ratio of moisture-absorbing agent to honey is in the range from 1:2 or 1:3 or 1:4 to 1:5.
• the liquid absorbency is at least 15g per 100cm 2 after irradiation.
• the identity of the moisture-absorbing agent and its molecular weight will also affect the constitution of the honey mix, and the precise identity and molecular weight of the agent used for best results may easily be determined by experiment.
• the moisture- absorbing agent may be selected from those which are non-toxic and pharmaceutically acceptable. Suitable moisture-absorbing agents include alginate salts such as sodium alginate (e.g. KeltoneTM HVCR sodium alginate) and modified cellulose polymers such as carboxymethylcellulose (CMC), generally in powder form.
• the water-permeable fabric for the intermediate and backing layers is preferably a needled non-woven fabric, but woven fabric may also be used. It is preferably a calcium alginate fabric, but other fabric materials such as carboxymethylcellulose or polyester may be used. As mentioned above, the same fabric is preferably used for both layers.
• the fabric density is preferably in the range 100 to 200, for example 150 to 180 gsm (gm -), although use of a lighter or heavier fabric may be possible. However, with lighter weight fabrics, for example of 70 gsm or less, it may be more difficult to produce dressings substantially impervious to liquid.
• the amount of the mixture of honey and water-absorbing agent applied to the water- permeable fabric is desirably in the range 1000 to 5000 gsm (gm -2 ), preferably 1500 to 4500 gsm, more preferably 2200 to 4200 gsm, although lower or higher amounts may be used.
• the amount of the mixture is substantially below 1500 gsm, for example down to 1350 gsm or less, the dressings may not be substantially impervious to liquid.
• a particularly preferred dressing is composed of non-woven calcium : alginate fabric of 130-170 gsm, preferably about 150 gsm, impregnated with 2000-3000 gsm, preferably about 2500 gsm, of a mixture of sodium alginate and honey in a ratio by weight of 1:3 to 1:5, preferably about 1:4, so as to form a wound-contacting layer of the sodium alginate/ honey mixture, an intermediate layer of the fabric impregnated with the sodium alginate/ honey mixture and a backing layer of the fabric.
• the dressings may also include one or more active pharmaceutical components to augment or supplement the properties of the dressing, particularly those components whose activity supplements those of honey, so that the wound-contacting layer need not be composed solely of honey and the moisture-absorbing agent.
• active pharmaceutical components for example, an antimicrobial agent, or an antibiotic, or an anaesthetic, or an anti-inflammatory agent, or a wound-healing agent, or a skin-protective agent, or a substance intended to negate malodours, can be incorporated.
• Suitable antimicrobial agents include silver or silver- containing compounds, povidone iodine and substances or formulations which release hydrogen peroxide.
• Honey already contains an amount of glucose oxidase which acts in combination with glucose, also present in honey, to produce hydrogen peroxide.
• honey-containing wound-contacting layer, intermediate layer and fabric backing layer may be produced by mixing the honey and water-absorbing agent batchwise or continuously in appropriate proportions, for example in an extruder such as a twin-screw extruder, for an appropriate period until a mixture is formed, extruding the mixture at an appropriate temperature and calendering the extruded mixture in contact with the fabric backing layer so as to achieve partial impregnation of the backing layer by the mixture.
• the mixing may be carried out for from 2 to 60 minutes, a mixing period of 10 minutes or more being preferred to induce some degree of set in the mixture.
• the mixing temperature is preferably in the range 40 to 50°C
• a final heat treatment to set the honey may be desirable. At heat setting temperatures of about 80°C setting occurs in less than 1 minute but at 50°C setting can take up to 30 minutes.
• an adhesive layer may be attached to or formed integrally with the fabric backing layer. Conveniently, the adhesive layer may extend laterally outwardly beyond the periphery of the wound-contacting layer and is provided with adhesive material on such outward extension of its surface oriented towards the wound-contacting layer.
• the adhesive layer may thereby be caused to adhere to an area of the skin of a patent to whom the dressing is supplied surrounding a wound to be treated, while the honey layer is brought into contact with the wound.
• the adhesive layer is disposed in a window-frame-type arrangement around the periphery of the fabric backing sheet, leaving at least a substantial portion of the fabric backing sheet uncovered, i.e. not overlain by the adhesive layer. This arrangement has the advantage of allowing the wound dressing to "breathe", thus permitting moisture absorbed in the honey layer to be transpired to the atmosphere.
• Fig 1 is a diagrammatic representation of an embodiment of wound dressing according to the invention.
• Fig 2 is a scanning electron microgram of a cross-section of a wound dressing manufactured according to the invention.
• FIG 1 illustrates the basic structure of an embodiment of wound dressing 10 according to the invention, in which a fabric backing layer 12 is partially impregnated with a mixture of honey and sodium alginate to form an intermediate layer 16, with the remainder of the honey/ alginate mixture forming a wound-contacting layer 14.
• a flexible adhesive fabric 18 is attached to the periphery of the underside of the fabric layer 12 and is provided on its upper surface with an adhesive substance suitable for adhering the dressing to the patient's skin.
• the adhesive fabric 18 is mounted to the fabric backing layer 12 in a window-frame-type arrangement, leaving a central hole 20, through which water vapour absorbed into the dressing is able to transpire.
• a test sample of a composite three-layer structure according to the invention was manufactured by the following procedure. 50g of honey was warmed to 50°C and added to lOg of KeltoneTM HVCR sodium alginate powder (viscosity 600-900 cP 1.25% aq. solution at 25°C on spindle 3 of an LV Brookfield viscometer at 60 rpm). The mixture was stirred for 10s and transferred to a petri dish. A disc of 150 gsm (gm- 2 ) calcium alginate fabric was placed on top of the honey/ sodium alginate mixture, followed by a closely fitting support member. The assembly was then inverted and placed under pressure to spread the honey/ sodium alginate mixture evenly over the fabric carrier, and heated at 50°C for 1 hour.
• KeltoneTM HVCR sodium alginate powder viscosity 600-900 cP 1.25% aq. solution at 25°C on spindle 3 of an LV Brookfield viscometer at 60 rpm.
• the mixture was stirred for
• the assembly was then cooled and the resulting composite product removed.
• the sample was prepared for electron microscopy by immersion in liquid nitrogen and cut with a scalpel to produce a suitable cross-sectional surface, which was then coated with gold/ palladium and analysed under a Hitachi S4000 field emission scanning electron microscope operating at 2kV.
• the resulting electron microgram appears as Fig 2 and clearly reveals a distinct three-layer structure comprising (from left to right in the figure) honey layer, honey/ fibre impregnated layer, and fabric backing layer.
• Products were made with a honey sheet having a 1:4 sodium alginate: honey ratio and with (a) 150 gsm calcium alginate needled fabric and 1350 gsm honey sheet, and (b) 70 gsm calcium alginate needled nonwoven fabric and 2500 gsm honey sheet, and these were gamma sterilized at 25kGy. They were subsequently tested using the Paddington Cup test and, after 24 hours, showed leakage of liquid through to the back of the dressing, i.e. they were not impervious to liquid, due to the "thinness" of the product, i.e. low honey level or low fabric density.
• the extruded sheet of honey mixture was 1.2mm thick and was laid onto a support paper and then passed through calender rolls, heated to 55°C by circulating water, with a gap set to produce the required final thickness of material.
• calender rolls Prior to passing the extruded material through the calender rolls, 150gsm calcium alginate needled nonwoven fabric, together with a backing release paper, was placed directly against the honey mixture. The action of the calender rolls was to achieve partial impregnation of the alginate fabric with the honey mixture.
• a twin-screw extruder having a series of temperature zones down its length can be fed with sodium alginate powder together with downstream addition of honey at one or more injection points and mixing and heating to a series of temperature points carried out to produce a consistent mixture at a high temperature, for example of 75- 80°C, so that it would start to gel immediately on extrusion, and fed to forming and calendering equipment similar to that already described in Example 5.
• Optimisation of the temperature profile enables the final heat treatment to set the honey mixture to be omitted.

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• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Veterinary Medicine (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
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• Animal Behavior & Ethology (AREA)
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• Materials For Medical Uses (AREA)
• Medicines Containing Material From Animals Or Micro-Organisms (AREA)
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Related Child Applications (1)

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Cited By (10)

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Citations (4)

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• 2001
  • 2001-12-03 GB GB0128936A patent/GB2382527A/en not_active Withdrawn
• 2002
  • 2002-12-02 AT AT02804300T patent/ATE439149T1/de not_active IP Right Cessation
  • 2002-12-02 NZ NZ545248A patent/NZ545248A/en not_active IP Right Cessation
  • 2002-12-02 CA CA2469033A patent/CA2469033C/en not_active Expired - Lifetime
  • 2002-12-02 WO PCT/GB2002/005441 patent/WO2003047642A1/en not_active Ceased
  • 2002-12-02 ES ES02804300T patent/ES2333112T3/es not_active Expired - Lifetime
  • 2002-12-02 JP JP2003548896A patent/JP2005511146A/ja active Pending
  • 2002-12-02 AU AU2002365662A patent/AU2002365662B2/en not_active Expired
  • 2002-12-02 US US10/497,445 patent/US20050033213A1/en not_active Abandoned
  • 2002-12-02 EP EP02804300A patent/EP1450871B1/en not_active Expired - Lifetime
  • 2002-12-02 DE DE60233343T patent/DE60233343D1/de not_active Expired - Lifetime
• 2008
  • 2008-04-23 US US12/108,421 patent/US8303551B2/en not_active Expired - Fee Related

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