GB2527617A

GB2527617A - Wound dressing

Info

Publication number: GB2527617A
Application number: GB1418565.6A
Authority: GB
Inventors: Stephen Cotton
Original assignee: Brightwake Ltd
Current assignee: Brightwake Ltd
Priority date: 2014-05-14
Filing date: 2014-10-20
Publication date: 2015-12-30
Also published as: GB201418565D0; GB201408553D0

Abstract

A wound dressing comprising an absorbent body 110 that is laminated to, or is in intimate contact with, a perforated film 120 comprising one or more benefit agents e.g. manuka honey, wherein the film 120, in use, is exposed to a wound to which the dressing is applied, such that exudates from the wound passes through the perforations 125 in the film 120 and is absorbed by the absorbent body 110, and wherein the film 120 dissolves upon exposure to wound exudates, thereby releasing the one or more benefit agents. In another aspect a solid dissolvable film comprising a polymeric carrier material and from about 25% to about 75% w/w honey is described.

Description

Intellectual Property Office Application No. GB1418565.6 RTIVI Date:23 October 2015 The following terms are registered trade marks and should be read as such wherever they occur in this document: Activon (page 2) Algivon (page 2) Brightwake (page 2) Jeffamine (page 5) Cosmocil (page N, 23) Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo

I

This invention relates to a wound dressing, and in particular to a wound dressing comprising one or more benefit agents that, in use, are released into the wound to aid in wound healing or to provide some other therapeutic benefit.

BACKGROUND OF THE INVENTION

Different types of wound dressing are required to meet different clinical needs.

However, a common requirement for wound dressings is that they are able to absorb exudate from a wound. In addition, infrequent dressing changes are preferable as changing a dressing can aggravate a wound, as well as causing pain and/or discomfort for the patient.

Infection of wounds during the healing process is a major concern in healthcare and, as well as being a source of pain and distress to the patient, can be very expensive. Infection of a wound can greatly increase the length of a patient's stay in hospital. However, pre-emptive prescribing of antibiotics is not currently recommended due to the rising number of resistant strains of bacteria. It is therefore known to incorporate antimicrobial agents or other therapeutic benefit agents into a wound dressing.

One benefit agent that has been included in wound dressings is honey. Healing properties have long been associated with honey. Honey is a mixture of sugars, water and other active ingredients such as vitamin C, catalase and chrysin, that are thought to act as anti-oxidants. As such, honey has much greater activity than sugar alone.

In particular, certain honeys such as manuka honey, produced from the plant species Leptospermum scoparium, have been shown to have high anti-bacterial, non-peroxide activity which inhibits the growth of various species of bacteria. As such, honey can support wound healing through its anti-inflammatory action, its natural anti-bacterial properties, its debriding action and its stimulatory effect on granulaflon and epitheUalisation. In fact, honey has been shown to have considerable wound-and ulcer-heaUng capacity and strong antimicrobial capacity even in moist healing environments.

Honey dressings are known in which honey is simply impregnated into a fibrous mat. The mat may be a gauze-like material, or may be formed of a geHing fibre such as aiginate. Such dressings have been commerciafly available for many years, for instance under the trade names ACTR'ON and ALGIVON (Brightwake Ltd, Kirkby-in Ashfield, United Kingdom, w.advancis.co.uk). WhUst such IC) dressings are effective, release of honey from them may not occur in the manner that is desired. In particular, the honey may he washed out of the dressing and away from the wound by wound exudate more quickly than is desired. Also, honey is somewhat sticky and as a result the dressings are not as easy to handle for clinical staff as may be desired.

ICC

Another approach is described in WO0i/41776, which discloses putty-like compositions comprising honey and a gelling agent. Such compositions can be formed into sheets or moulded to complex shapes, eg for insertion into cavity wounds. Again, such dressings may be of benefit in certain situations, but they also suffer from disadvantages. The absorptive capacity of such dressings is very limited, and the release of honey may be lower than is desired, as a result of the phenomenon known as gel-blocking, in which wound exudate combines with gelling agent at the surface oF the dressing to form a layer of gel that prevents the release of honey from within the dressing.

Another form of wound dressing is disclosed in W0201 1/001181. This dressing comprises a dissolvable film that contains a small proportion typically around 4% w/w -of propolis, another known antimicrobial agent that is produced by bees.

The application of such a film directly to a wound to aid wound healing is described. The possibility of incorporating such a film into a composite wound dressing is also mentioned, as is the use of such material to form a sachet to hold superabsorbent material in a wound dressing, but no example of such a dressing construction is given.

It has now surprisingly been found that antimicrobial and other therapeutic benefit agents, notably honey, may be incorporated into solid dissolvable films at high concentrations and that such a film may be laminated to an absorbent body to provide a wound dressing that overcomes or substantially mitigates some or all of the above-mentioned andlor other disadvantages of the prior art.

SUMMARY OF THE INVENTION

Thus, according to a first aspect of the invention, there is provided a wound dressing comprising an absorbent body that is laminated to, or is in intimate contact with, a perforated film comprising one or more benefit agents, wherein the film, in use, is exposed to a wound to which the dressing is applied, such that exudate from the wound passes through perforations in the film and is absorbed by the absorbent body, and wherein the film dissolves upon exposure to wound exudate, thereby releasing the one or more benefit agents.

The wound dressing according to the invention is beneficial in that the absorbent body provides for good absorption of wound exudate, while the perforated film slowly dissolves as a result of contact with the wound exudate. Dissolution of the film releases the one or more benefit agents into the vicinity of the wound. This leads to a high and prolonged concentration of those agents at the wound site.

The perforations nonetheless permit the flow of wound exudate into the absorbent body, without the occurrence of gel-blocking or similar phenomena. Prior to use, the perforated film is dry, which may make the dressing easier to handle and apply. In addition, the film may be sufficiently thin that it does not significantly reduce the flexibility and conformability of the dressing.

According to another aspect of the invention, there is provided a method of treating a wound, which method comprises applying to the wound a wound dressing according to the first aspect of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Perforated film The perforated film preferably comprises a carrier material that is flexible at ambient temperature, and which dissolves at an appropriate rate in use, upon exposure to wound exudate. The carrier is preferably capable of forming conformable and flexible sheets that are sufficiently robust to maintain their integrity during normal use and handling. As the perforated film is placed in direct IC) contact with a wound, the carrier is most preferably free from toxic or allergenic substances. The carrier may be formed of a single substance, or may he a composite. The carrier is preferably a polymeric material.

The film may comprise up to 60% wlw carrier, but more corn..ionly the proportion of carrier material is up to 50% w/w, for instance from about 10% to about 60%, or from about 20% to about 50%, or from about 30% to about 50% w/w.

Suitable materials for use as, or in, the carrier include many natural or synthetic polymers. The carrier materials should be such that, in use and once applied to a wound, the carrier dissolves or otherwise breaks down over time, thereby releasing the one or more benefit agents into the wound environment.

In many embodiments, the carrier comprises a polymer with film-forming properties. A variety of suitable film-forming polymers may be used, provided that they are suitable for medical applications, for instance they are non-toxic and hiocompatible.

Most commonly, the carrier comprises just one polymer, which may be a film-forming polymer. Alternatively, the carrier may comprise a mixture of materials, one or more of which may be a film-forming polymer.

Most preferred carriers are soluble upon exposure to wound fluid. Use of such carriers facilitates the release of the benefit agent(s) into the wound space when the anfimicrobial material is in place. The most preferred substance for use as a carder is polyvinyl alcohol (PVA).

Other synthetic polymers that may be suitable for use in the antimicrobial material are biodegradable polyesters. Specific examples of such polymers are polylactic add and polyglycoUc add, and copolymers and blends thereof. Other examples include polycaprolactones and polyhydroxyalkanoates, such as polyhydroxybutyrate, polyhydroxyvalerate and polyhydroxyhexanoate.

IC) Further tUrn-forming polymers that may be suitable for use in the antimicrobial material are polysaceharides, and in particular basic polysaccharides.

One such film-forming basic polysaccharlde is chitosan, the (at least substantially) N-deacetylated derivative of chitin. Chitin is a naturally abundant mucopolysaccharide and is the supporting material of crustaceans and insects.

Chitin is readily obtainable from crustacean shells discarded in the food industry, and the preparation of chitosan from chitin is well known and documented.

Derivatives of chitosan may also be used. Chitosan may offer further benefits when used as the carder material. In particular, chitosan is known to swell when hydrated and so may absorb wound exudate. In addition, chitosan may itself exhibit useful antibacterial and haemostatic properties. Chitosan is also believed to be susceptible to attack by lysozyme, and this may be useful in providing a ready mechanism for biodegradation of the carrier material.

Examples of other synthetic polymers that may be suitable are aminated polymers such as aminated PEGs (including those sold under the trade name JEFFAMINE) and polyallylamines.

The carrier material is chosen such that it dissolves or otherwise breaks down over time, so that the benefit agent(s) are released from it. The material may be such that the film, at least in that part which is in contact with wound fluid, loses its integrity over a timescale of several minutes, for example up to 10, 30 or 60 minutes, eg 1 to 10 minutes or 10 to 60 minutes, or several hours, for example up to 6, 12 or 24 hours, eg I to 6 hours or 6 to 24 hours, or several days, for example uptol dayor2 days.

One or more additives may be included to improve the physical properties of the film. For instance, the incorporation of an additive may improve the flexibility and pliability of the film.

Typically, the perforated film has a thickness of from 2Opm to 5mm, but more commonly, the thickness of the film is from 100pm to 3mm, more typically 200pm to 2mm, eg about 0.5mm or about 1mm.

The perforated film may be manufactured in various ways. A currently preferred method of manufacture, which constitutes a further aspect of the invention, comprises the steps of: a) producing a fluid precursor composition comprising a carrier material, one or more benefit agents, and a liquid medium; and b) casting the precursor composition into a sheet; c) causing or allowing the precursor composition to at least partially solidify; and d) forming perforations in the at least partially solidified film.

In the currently preferred manufacturing method, the precursor composition most preferably contains about 20% to about 80% w/w of liquid medium. The liquid medium is employed in the precursor composition to aid in the mixing of the components and to enable the composition to be cast into the desired form prior to it being caused or allowed to solidify. The liquid medium is preferably non-toxic and non-allergenic, to prevent an adverse reaction when the film comes into contact with a wound. In the currently preferred manufacturing method, PVA is the preferred carrier, and water is the preferred liquid medium.

The precursor composition may be prepared by dispersing the carder material (eg PVA) and the one or more benefit agents in the liquid medium. The carrier material is preferably added to the flquid medium in finely dMded or powder form and the Uquid medium may be heated and/or agitated to aid dispersion.

In one embodiment, the precursor composition may he spread onto a substrate to form a layer of uniform thickness. The substrate may be a film, eq of paper or plastics material, that functions as a r&ease carrier from which the film is pe&ed or otherwise separated prior to incorporation into a wound dressing of the invention.

Once the precursor composition has been cast into the desired form, it is caused IC) or aVowed to sodify This process involves subjecting the precursor composition to different conditions depending on the nature of the carrier material. In particular, this may involve heating the precursor composition for a period of time in order to evaporate some or all of the liquid medium and/or cause the carrier material to set. For instance, the precursor composition may be heated in an oven at a temperature above ambient temperature but generally below about 100°C, eg between 40° and 70°C for a period of between 5 minutes arid 1 hour, eg 15-30 minutes. Heating of the precursor composition generally results in the loss by evaporation of any volatile components. The liquid medium will generally be at least partially aqueous, and heating wiU also result in the loss of much of the water that is present. Typically, the film has a water content of less than 20% w/w, more commonly less than 10%, eq 1 to 20% cr 1 to 10% w/w, for instance about 5% w/w.

The heating process may be carried out batchwise, but is preferably carried out as a continuous process, eq by transporting the precursor composition through an oven on a conveyor.

The method may involve the use of a manufacturing line that is able to continuously form the film. In one such method, a release carrier is fed onto a conveyor, preferably comprising one or more looped belts, which transports it along the manufacturing line. Suction may be applied from beneath the belts to hold the release carrier flat against the surface of the conveyor.

The precursor composition is preferably applied to the release carrier in a uniform layer. This may be carried out by applying the composition from the edge of a suitably formed blade that is positioned close to the release carrier passing beneath it on the conveyor. Following application of the layer of precursor composition, the product may be passed through an elongated oven.

Once the product has at east partially solidified, perforations are introduced into it.

Perforation may take place with the release liner in place, or the release liner may first be removed. In general] partially solidified' means in the context of the IC) invention solidified sufficiently for perforations to he formed that retain their integrity dudng subsequent further solidification of the film.

The primary purpose of the perforations is to permit fluid, notably wound exudate and the like, to pass through the film into the absorbent body. The perforations may, however, also provide for ease of removal of the dressing, improved flexibility and conformity, arid skin breathability.

In one group of presently preferred embodiments of the invention, the film is formed with a regular array of perforations. Typically, such perforations are circular and have a diameter of from 5Opm to 10mm, more commonly from 1mm to 5mm. Other shapes of perforation may alternatively be used, eg square perforations or elongated slits The perforations may be produced by mechanical cutting, eg using a rotary or reciprocating cutting die.

A currently preferred method of forming the perforations, however, involves the application of high frequency mechanical vibrations in a similar manner to ultrasonic welding technology. This method involves contacting perforating elements with the coated or uncoated film and subjecting the film, at least in the regions contacted with the perforating elements, to high frequency mechanical vibrations.

The application of high frequency mechanical vibrations to the film brings about the generation of localised heat by friction, which leads to softening of the material, thereby facilitating puncturing of the material by the perforating elements.

The high frequency mechanical vibrations are preferably applied to the material using a device of the type commonly used in ultrasonic welding. These devices are typically used to weld thermoplastic or fine metal components by applying high frequency mechanical vibrations to such components as they are held together under pressure. This combination of mechanical vibration and pressure results in the generation of heat by friction, allowing the generation of heat to be localised to the points at which the material is held under pressure. The use of ultrasonics is of particular advantage in the medical industry because it does not introduce potential contaminants into the material. The use of ultrasonics is advantageous compared to the direct application of heat to the material because it is highly controllable and may be switched off instantaneously without any residual effect.

Excess or residual heat is undesirable because it may damage the film or cause it to deform. Also, the effects of ultrasonics can be restricted to a very limited part of the material without altering the properties of the surrounding regions.

The film is generally held between the perforating elements and a sonotrode, by which the high frequency vibrations are applied. The perforating elements preferably take the form of a plurality of projections extending from a support, such that the tips of the perforating elements contact the film. The sonotrode may then be applied to the other side of the material so as to hold the film under pressure between the sonotrode and the support, compressing the film between the sonotrode surface and the projections at the points at which it is in contact with the tips of those projections. The generation of heat by friction is thereby localised to the points of the film that are in contact with the tips of the perforating elements.

The perforating elements may then pass through the film at these points.

producing perforations. The perforating elements thereby serve to compress the film against the sonotrode at the desired points, localising the generation of heat to the points at which they contact the film, followed by perforation of the film at those points.

The perforating elements most preferably pierce the film as soon as possible following contact with the sonotrode. It is therefore desirable to apply a force to the film to facilitate passage of the perforating elements through it. This may be done by applying suction, by holding the film under tension against the perforating elements, or by applying a mechanical force directly to the film.

The support from which the perbrating elements extend preferably takes the form of a roller with the perforating elements extending from its circumferential surface.

Such a roller will typically have a diameter of between 5cm and 50cm, more commonly between 10cm and 30cm. The film may be fed on and off the roller and make contact with the sonotrode continuously, improving throughput. The sonotrode must therefore apply high frequency mechanical vibrations to the material continuously. It is therefore necessary to supply the high frequency mechanical vibrations to the sonotrode using a continuous pulsating generator, rather than an intermittent pulsating generator, both of which are commonly used

in the field of ultrasonics.

Generally, operation of the sonotrode for continuous periods will, unless appropriate measures are put in place to maintain the temperature of the sonotrode at a substantially constant level, result in the generation of heat and an increase in the temperature of the sonotrode. This can lead to thermal expansion of the sonotrode, which may reduce the clearance between the sonotrode and the perforating elements. It may therefore be desirable or necessary for the sonotrode to be cooled during operation, eg by the application of a cooling fluid, most commonly chilled air.

The film on which the process is carded out is typically in the form of an elongate strip with a width that generally does not exceed 200mm, although the use of strips with greater widths is possible. However, sonotrodes having a width of greater than about 200mm are less effective at applying high frequency mechanical vibrations to a material. Therefore, in order to perforate strips of film material having widths in excess of 200mm, a number of sonotrodes posifloned adjacent to one another may be used.

The tUrn is preferably fed past the perforating &ements at a rate of at least 0.1 metres/second and up to 1.0 metres/second. Typicafly, the film may be fed through the apparatus at a rate of between 0.2 and 0.8 metres/second, or between 0.3 and 0.6 metres/second.

Alternatively, the tUrn may be laminated to an absorbent body prior to forming the perforations. n this case the film may be manufactured as set out above up to the point at which the film would he perforated. The film is then aminated to the absorbent body prior to being perforated. PreferaHy the film is laminated to the absorbent body by the application of heat and pressure. The perforations may then subsequently be formed through both the film and absorbent body of the resulting laminate.

Perforating both the film and the absorbent body may result in a dressing which is more breathable and also allows for easier passage of wound exudate away from the wound.

The perforations in the laminate may be formed by similar processes to those discussed above in relation to the perforation of the film itself, ie by mechanical cutting or by application of high frequency mechanical vibrations.

Preferably the perforations are formed by application of high frequency mechanical vibrations. Forming the perforations in this way compresses the film and the absorbent body between the sonotrode and the support. The resulting laminate may have a quilted appearanceS Benefit agents The perforated film comprises one or more benefit agents. By benefit agent in the context of this invention is meant any material that has a therapeutically beneficial effect at the wound site to which a dressing of the invention is applied.

For example, benefit agents may be (without limitation) antimicrobial agents, antiseptic agents, antifungal agents, antkinflammatory agents, and/or haemostatic agents.

Preferably, the one or more benefit agents indude at east one antimicrobial agent.

Preferably, the one or more benefit agents include honey. Honey has long been known to be effective in treating wounds, with records of such use dating from at IC) least 2000 years ago. More recently, research has shown honey to have potent antimicrobial, antifungal and antiinflammatory properties, and to be able to stimulate lymphocytic and phagocytic activity within the body. FLirther, honey has been demonstrated to assist in the debridement of necrotic tissue, and to stimulate the growth of new tissue. In terms of its antibacterial activity, honey has been reported to have an antibacterial effect on more than sixty species of bacteria, including aerobes arid anaerobes, arid both Gram-positive and Gramnnegative bacteria. In particular, honey has been shown to be effective against antibiotic resistant strains of bacteria including MRSA.

Without wishing to be bound by theory, it is believed that the antibacterial activity of honey is partly due to the release of low levels of hydrogen peroxide, a well known antimicrobial agent. As the production of hydrogen peroxide is stimulated by diluLion of the honey (eg by wound exudate), honey has the distinctive property of becoming more active on dilution, rather than less.

Many studies have shown that the maintenance of a moist wound environment aids in wound healing. However, a moist environment also promotes the growth of bacteria, and the prevention of infection is therefore a serious concern. The addition of honey to a wound dressing thus enables the wound to be kept moist whilst inhibiting bacterial growth and reducing the likelihood of infection.

Honey is produced worldwide from many different floral sources, and its antibacterial activity varies with the source of the honey and the processing it has undergone. For example, lotus honey in India is reputed to be good for eye diseases, whereas manuka honey, a monofioral honey produced from poflen from the manuka bush, is known for its antiseptic properties. The manuka plant is part of the genus Leptospermum, and honeys produced from plants of this genus, such as manuka or jellybush honey, are known for their particularly strong anti-bacterial properties. Preferably. the honey used in the present invention is produced from plants of the genus Leptospermum. More preferably, the honey is manuka honey orjellybush honey.

IC) Where the perforated film incorporates honey, it has been found that the honey may he incorporated into the film at surprisingly high concentrations. In particular, honey may account for more than 25%, more than 35% or more than 45% w/w of the film, and up to 55%, 65% or 75% w/w of the film, The honey content of the film may therefore be from about 25%, 35% or 45% to about 55%, 65% or 75% w/w, for instance from about 25% to about 75%, from about 35% to about 65%, or from about 45% to about 55% w/w.

Solid films comprising honey in combination with a carrier material are believed to be novel, and represent a further aspect of the invention. In a further aspect, the invention thus provides a solid, dissolvable film comprising a polymeric carrier material and from about 25% to about 75%, from about 35% to about 65%, or from about 45% to about 55% W/W honey. The honey is preferably manuka honey or jellybush honey, and the carrier is preferably polyvinyl alcohol. Such films may be of utility in the treatment of wounds, more generally than in the perforated and laminated form of the first aspect of the invention.

Another antimicrobial agent that may be incorporated into the perforated film is silver. Despite metallic silver being relatively unreactive, ionic silver has been shown to have antimicrobial activity and has been previously used in wound dressings, In use, posftively charged silver ions bind to negatively charged sites on proteins and nucleic acids in bacteria. This causes a number of effects, including alteration of the protein structure, rupture of the cell wall and/or cell death. It is believed that silver ions have multiple attack sites, interacting with a number of different functional groups in bacteria, including thiS groups, carboxylates, phosphates, indoles and amines. This makes the development of bacterial resistance to silver unusual.

The incorporation of silver into the film results in the sustained release of low concentrations of silver ions over time. Such a slow release has been shown to stimulate healing and inhibit the growth of micro-organisms. My suitable method or form of silver known in the art may be used in the present invention. For example, the silver may be in the form of silver sulphadiazine.

Another antimicrobial that may be incorporated into the film is polyhexamethylene biguanide (PHMB; also known as polyaminopropyl biguanide). PHMB is available as a 20% aqueous solution under the trade name COSMOCIL® CQ from Arch Personal Care Products, 70 Tyler Place, South Plainfield, NJ 07080, USA.

Further antimicrobials that may be incorporated into the film include plant essential oils having known antimicrobial activity. For instance, where manuka honey is used, the antimicrobial activity may be enhanced by the additional inclusion in the film of a small proportion of manuka oil.

In general, although antimicrobial agents such as silver, PHMB or an essential oil may be incorporated into the film at high concentrations, relatively low concentrations are found in practice to be sufficient. Thus, such an antimicrobial agent is typically present at a level of between 0.1 and 10% wlw, more typically between 0.1 and 5% w/w, more commonly between 0.1 and 2% w/w.

More than one antimicrobial agent is preferably present in the film, to provide activity against a wide range of micro-organisms. As noted above, honey is preferably used, and is preferably present at high concentration. In addition to honey, it is preferred that at least one, and preferably two or more, further antimicrobial agents are present, selected from PHMB, silver and plant essential oils.

Films comprising manuka honey, PHMB and optionally also manuka oil are particularly preferred. In such films, the concentrations of manuka honey, PHMB and essential oil may be as set out above.

Alternatively, or in addition to, antimicrobial agents, the perforated film may incorporate other benefit agents, which may be selected from antifungal agents, antiviral agents, anti-inflammatory agents, and haemostatic agents.

Absorbent body The wound dressing according to the invention comprises an absorbent body, which is laminated to, or is in intimate contact with, the perforated film. Preferably, the film is laminated to the absorbent body.

Any suitable absorbent material may be used in the wound dressing.

The absorbent body may comprise a foam, a gelling material, a superabsorbent material, or a combination of these components.

Where the absorbent body comprises a foam, the foam may be any suitable foam known in the art. Usually, the foam is an open-celled foam. Preferably, the foam is a hydrophilic foam. More preferably, the hydrophilic foam is a polyurethane foam. Most preferably, the foam is an open-celled polyurethane foam. The open cellular structure of the foam allows exudate from a wound to pass through it, as well as to be absorbed by it. The foam typically has a thickness of 0.5mm to 10mm, preferably from 1mm to 7mm, or from 2mm to 7mm, and the foam most preferably has a thickness of about 2mm, about 3mm, about 4mm or about 5mm.

The absorbent material may alternatively comprise a gelling material. By "gelling material" is meant in relation to the invention a material that is capable of absorbing aqueous fluid, such as wound exudate, and which on absorbing liquid becomes gel-like, moist and slippery. The gelling material is preferably in the form of a non-woven pad or a knitted structure. The gelling material may have an absorbency of at least 2 grams 0.9% saline solution per gram of material, as measured by the free swell absorbency test (ie dispersing a known dry weight of material in the test liquid (saline) for sufficient time for the material to absorb liquid, removing the excess liquid by vacuum filtration, and measuring the increase in weight of the fibre). The absorbency may be considerably higher, eg at least 5g/g, or at least lOg/g, or at least lSgIg, or at least 25g/g.

The gelling material may be any suitable gelling material known in the art, including pectin, alginate, materials made from alginate and another polysaccharide, chitosan, hyaluronic acid, other polysaccharide materials or materials derived from gums, or chemically-modified cellulosic materials, eg carboxymethyl cellulose (CMC). The gelling material may be a combination or blend of different gelling materials.

Where the absorbent body is a non-woven pad or knitted structure, it may be formed using fibres or yams of both gelling and non-gelling material. Typical non- gelling material is cellulosic fibres, eg of tencel or lyocell. The gelling and non-gelling fibres or yams may be separate, for instance where non-gelling yams are used to reinforce a structure of gelling yam, or gelling and non-gelling fibres may be blended in a single yam. Suitable blended yams of this type are disclosed in Currently preferred gelling fibres are alginate fibres and pectin fibres.

In other embodiments of the invention, the absorbent body may comprise a superabsorbent material. tmSuperabsorbent material" in the context of the present invention means a material that is capable of absorbing many times its own mass of water (eg up to 200, 300, 400, 500 or more times its own mass of water).

Although it should be appreciated that the absorbent body of the present invention may comprise any superabsorbent material, preferred superabsorbent materials are polymeric superabsorbent materials and include alginate, polyacrylate (le a salt of polyacrylic acid), polyacrylamide copolymers, ethylene maleic anhydride copolymer, carboxymethylcellulose, polyvinylalcohol copolymers, polyethylene oxide and starch-grafted copolymers of polyacrylonitrile.

Many such superabsorbent materials may be used in particulate form. In such cases, the particles may be incorporated into a carrier material, for instance by being encapsulated between two layers of carrier material, eg tissue paper or the like.

An alginate superabsorbent may be sodium or calcium alginate. The alginate superabsorbent is preferably in the form of a non-woven mat.

The most preferred superabsorbent material is sodium polyacrylate polymer.

Sodium polyacrylate polymer is a solid crystalline material, and is preferably incorporated into a layer in the form of particles encapsulated between two layers of carrier material, such as tissue paper. A specific example of a suitable material is Gelok® 14040S/S manufactured by Gelok Intemational Corporation.

Dressings in which the absorbent body comprises a foam, particularly an open-celled foam, eg an open-celled polyurethane foam, are presently preferred, The absorbent body may comprise a combination of one or more components.

For instance, the absorbent body may comprise two layers of absorbent materials.

By way of example, the absorbent body may comprise a foam layer that is laminated to the perforated film, and a superabsorbent layer bonded to the reverse side of the foam layer. In such cases, the foam layer is preferably an open-celled polyurethane foam, and the superabsorbent layer comprises a sodium polyacrylate polymer, for example Gelok® 140408/S manufactured by Gelok International Corporation.

The perforated film is preferably laminated to the absorbent body.

Lamination of the perforated film to the absorbent body may be brought about by any suitable means, provided that the perforations in the film are not occluded and passage of wound exudate into the absorbent body is not otherwise significantly inhibited or impaired.

In order to laminate the perforated film to the absorbent body, one or both of the juxtaposed surfaces of those components may be coated with a suitable adhesive, and the two components then pressed together.

Alternatively the two components may be laminated by applying both heat and pressure to the layered components. The two components are typically passed through a pair of heated rollers which compress the layers together. This method of laminating is preferred where the two components are laminated prior to forming the perforations. Rather than perforating the film before laminating it to the absorbent body, both components of the laminate may then be perforated after the laminating process has occurred.

Where the film is perforated before being laminated to the absorbent body, the two components are preferably laminated using a fusible web material. Such materials are typically of synthetic fibres that melt when heated. When the fusible web is placed between the perforated film and the absorbent body and heated, the melting action of the web causes it to fuse the film and absorbent body together.

Fusible web is available in various weights, and in general a lightweight material is preferred, to minimise any risk of the perforations becoming occluded by melted web.

Individual pieces of perforated film and of absorbent material, both having the dimensions necessary for incorporation into a dressing of the invention, may be bonded together using adhesive or fusible web. However, it will be appreciated that more commonly an oversized sheet of perforated film will be bonded to a sheet of absorbent material, and then individual pieces of bonded material will be cut from the sheets, for incorporation into dressings.

Dressing formats Wound dressings according to the invention may comprise only the absorbent body and perforated film. When applied to a wound, with the perforated film in contact with the wound, such a simple dressing may be held in place by a secondary dressing or by means of adhesive tapes or the like.

More commonly, however, the wound dressing of the invention is a composite dressing comprising additional components. Thus, the dressing typically comprises an adhesive skin contact layer that provides for attachment of the dressing to the pen-wound skin, and a backing layer that is normally impermeable IC) to liquids hut permeable to gas and moisture vapour.

Skin contact layer The surface of the dressing that, in use, is applied to the pen-wound skin may carry an adhesive. ft is generally preferable that the adhesive that is used is one that is non-adherent and permits the wound dressing to be removed relatively easily and without causing trauma to the wound and surrounding skin. Thus, the adhesive may be, for instance, a hydrocolloid adhesive, a polyurethane adhesive, a hydrogel or, most preferably, a silicone adhesive, particularly a silicone gel.

Silicone adhesives offer numerous advantages. Most preferably, the silicone adhesive is in the form of a sflicone ge of the type generaUy referred to as a soft silicone'.

Soft silicone adhesives are particularly suiterJ for use as skin contact layers in wound dressings. They are soft, tactile and conformable, and exhibit good adhesion to dry skin but low adherence to an underlying wound. Thus, the dressing can be applied to a wound and subsequently removed without causing trauma to the wound. Silicone gels are adhesive but do not leave residue on a surface/substrate when removed, SiUcone gels suitable for use as skin contact materials in the present invention may be carried on a layer of melt-blown non-woven material. eg a sheet of melt-blown polyurethane (MBPU), as described in W02007/1 13597.

ri such cases, the reverse side of the MBPU may be coated with an adhesive, eq an acryhc adhesive, to affix the siHcone gel/MBPU laminate to overlying components of the dressing, eq to the perforated film and/or a backing layer of the form described below.

In use of the dressing of the present invention, it is necessary that the perforated film is exposed to the wound site. Thus, in certain embodiments, the dressing has a border format, in which the adhesive that provides for fixation of the dressing is provided only around the periphery of the dressing, and does not cover the perforated film. Nonetheless, the adhesive skin contact layer may overlap to some extent with the perforated film, provided that the majority of the perforated film is exposed to the wound. In other words, the skin contact layer may be provided with a single, generally central opening, through which the perforated film is exposed to the wound in use.

In other embodiments, the skin contact adhesive may also extend across the perforated film, so that the adhesive layer overlies and contacts the wound itself, rather than just the surrounding healthy skin. In such cases, however, it is necessary that the part of the skin contact layer that does overlie the perforated film is provided with substantial openings, so that a substantial proportion of the perforated film is exposwJ to the wound. In such cases, it is also particularly important that the skin contact adhesive is one that exhibits low adherence, so that removal of the dressing does not cause undue trauma to the wound.

Backing layer The wound dressing according to the inventbn may comprise a backing layer, which forms a baffler between the wound and the surrounding atmosphere. Any suitable material known in the art may be used for the backing layer.

The backing layer will generally be impermeable to wound exudate and other liquids, but is preferably permeable to air and moisture vapour. In particular, the backing layer preferably exhibits a relatively high moisture vapour transmission rate (MVTR). The MVTR of the backing layer may be at least 300g1m2124h, more suitably at least 500g/m2124h and preferably at least 700g1m2124h at 37°C and 100% to 10% relative humidity difference.

The backing layer is most preferably a plastics film having the desired characteristics. The backing layer may be a polyurethane film.

The backing layer may be larger in size than the perforated film and absorbent body, such that it extends beyond the edge of the film and absorbent body on one or more sides. Preferably, the backing layer extends beyond the edge of the film and absorbent body on all sides, forming a border around the film and absorbent body, and is bonded to the peripheral region of the skin contact layer.

Release finer Where the skin contact layer carries an adhesive, or where the perforated film is tacky (for instance where it contains honey), the dressing will generally be supplied with a releasable liner on its underside. The releasable liner may cover the adhesive portions of the wound dressing prior to use, and be removed from the dressing immediately before application of the dressing to the wound. This reduces the risk of contamination of the wound dressing and facilitates handling of the dressing.

Such releasable liners are commonly used on wound dressings known in the art, and suitable materials which can be employed in the present invention will be familiar to the skilled worker. For example, the releasable liner may be of a suitable plastics sheet or a siliconised paper or the like.

The releasable liner may be a single sheet which covers the underside of the wound dressing, or may be formed of two or more sheets. The releasable liner may further comprise a tab to enable the liner to be easily removed from the dressing before use. In particular, where the releasable liner is formed of two or more parts, the parts may either overlap or abut and extend outwards from the wound dressing, thus providing an easy method for removal of the releasable liner.

An embodiment of the invention will now be described in greater detail, by way of illustration only, with reference to the following Example and the accompanying drawings, in which Figure 1 is a plan view of a first embodiment of a wound dressing according to the invention; Figure 2 is an underside plan view of the wound dressing of Figure 1, with release liners removed; Figure 3 is a cross-sectional view (not to scale) along the line Ill-Ill in Figure 1; Figure 4 is a schematic representation, not to scale, of apparatus used to produce perforations in a film forming part of the dressing of Figures 1 to 3; and Figure 5 is a plan view of a second embodiment of a wound dressing according to the invention.

Example

Dissolvable antimicrobial film Ingredients: PVA 43%w/w Manuka honey 50% Manuka oil 1% Cosmocil 1% Water 5% A precursor composition is produced by dispersing the PVA, Manuka honey, Manuka oil and Cosmocil in appropriate proportions in an excess of hot (100°C) water.

The precursor composition is spread onto a temporary substrate (a plastics or paper sheet) and dried in an oven at 45-65°C for 20 minutes, to the desired final water content of 5% w/w. This process may be carried out by spreading the precursor composition on a continuous band of substrate that is conveyed through an elongate oven.

After drying, a regular array of perforations is introduced into the film (still carried on its substrate). Apparatus 10 by which the perforations are introduced into the film is depicted schematically in Figure 4, in which the film/substrate is denoted 2.

The perforating apparatus consists of a perforating roller 12 which is a cylindrical barrel having a multitude of fiat-tipped, pin-like perforating elements 13 projecting from the circumferential surface, and a sonotrode 14 which, in operation, applies high frequency mechanical vibrations to the film 2. The perforating roller 12 and sonotrode 14 are configured such that when the perforating roller 12 is rotated, the tips of the perforating elements 13 pass close to the surface of the sonotrode 14.

The diameter of the perforating roller 12 is approximately 20cm, and the perforating elements 13 have a length of approximately 5mm.

In operation, the film 2 is drawn past a guide roller 16 into the nip between the perforating roller 12 and the sonotrode 14. The points at which the hIm 2 contacts the tips of the perforating elements 13 of the perforating roller 12 are compressed against the surface of the sonotrode 14. The high frequency mechanical vibrations produced by the sonotrode 14 generate high levels of friction at the points where film 2 is compressed, causing heating of the film 2 at these points.

The material of the film 2 melts at those points were such heating occurs, allowing the perforating elements 13 to pass through the film 2, thereby formiig perforations.

The perforated film 2 is drawn off the perforating roller 12 via a second guide roller 18. The second guide roller 18 is positioned such that the film 2 remains in contact with the surface of the perforating roller 12 after passing through the nip between the perforating roller 12 and the sonotrode 14. This means that the locally heated material of the film 2 cools somewhat before being drawn off the perforating roller 12 and the perforating elements 13 are withdrawn from the perforations that have been formed, so that the the integrity of the perforations is maintained.

Chilled air from a chiller unit 15 is blown through the sonotrode 14 via a conduit 17. The flow of chilled air is controlled to maintain the temperature of the sonotrode 14 substantially constant, and hence prevent thermal expansion of the sonotrode 14 that would otherwise reduce the clearance between the sonotrode 14 and the tips of the perforating elements 13.

The film 2 is drawn off the perforating roller 12 at a rate of approximately 0.3 metres/second. The perforated film 2 may be taken up on a roller (not shown) for storage or may pass directly to further processing stations.

The perforations are circular, with diameter approximately 1.5mm, and are formed in a regular array across the full extent of the film 2, with separations of approximately 5mm.

After the film has been formed and perforated, it may be bonded to an absorbent material, eg an open-celled foam, for instance by means of a fusible web interposed between the film and the absorbent material. Appropriately sized pieces of the laminated product may then be cut out and incorporated into a wound dressing, for instance the wound dressing shown in Figures 1 to 3, as described below.

Referring now to the Figures 1 to 3, a wound dressing according to the invention is generally designated 100. The dressing 100 is rectangular in overall shape, with rounded corners. As depicted in the drawings, the dressing 100 has overall dimensions of approximately 25cm x 10cm, but it will be understood that the shape and dimensions of the dressing may vary widely, depending for instance on the size and nature of the wound to be dressed and the part of the body to which the dressing is to be applied.

Figure 1 is a plan view of the dressing 100 from above, ie from the non-wound- facing side. The structure of the dressing 100 is more evident from the cross-sectional view of FigureS (in which the thickness of the various components is depicted on an exaggerated scale) and the underside plan view (with release liners removed) of Figure 2.

As can be seen most clearly in FigureS, the dressing 100 comprises an absorbent foam pad 110 that is laminated at its underside (as viewed in Figure 3) to a perforated honey-containing film 120. The film 120 may be a dissolvable antimicrobial film prepared as described in the Example above. The foam pad 110 and film 120 are both substantially rectangular and are of identical length and width. They have been bonded together by means of a fusible web, as described above.

The dressing further comprises a skin contact layer 130 in the form of a sheet of MBPU that is impregnated with and coated on its underside (as viewed in Figure 3) with a silicone gel non-adherent adhesive. The skin contact layer 130 is of greater length and width than the pad 110 and film 120, such that it forms a border around the periphery of the dressing 100.

The skin contact layer 130 has a central opening 133 that is generally rectangular and of slightly smaller dimensions than the film 120 and pad 110, so that the skin contact layer 130 overlaps the edges of the film 120, but the majority of the wound-facing (ie lower, as viewed in Figure 3) surface of the film 120 is exposed.

The upper surface of the skin contact layer 130 carries an acrylic adhesive, by means of which the edges of the film 120 are adhered to the periphery of the central opening 133 in the skin contact layer 130.

The dressing is completed by a porous polyurethane backing layer 140 and a three-part release liner I 50a-c. The backing layer 140 constitutes the upper surface of the dressing 100. It covers the foam pad 110 and is secured to the border regions of the skin contact layer 130 by means of the acrylic adhesive on the upper surface of the latter. The backing layer 140 may also be adhered to the upper surface of the foam pad 1101 but in general it is preferred that the backing layer 140 and foam pad 110 are not so adhered, in order to better provide for swelling of the foam pad 110 during use, as it absorbs wound exudate.

The release liner comprises three overlapping sheets I 50a-c of suitable material that are folded to form tabs by which the sheets I 50a-c may be pulled away to expose the skin contact layer 140 immediately prior to application of the dressing 100.

As can be seen in Figures 2 and 3, the film 120 is formed with a regular array of perforations 125. For clarity, these are depicted on a somewhat enlarged scale; in reality the perforations 125 have a diameter of approximately 1.5mm and they are separated by approximately 5mm.

As can also be seen in Figures 2 and 3, the border regions of the skin contact layer 130 are also formed with perforations 135. These perforations 135 serve to increase the breathability of the border regions of the dressing, and so reduce the likelihood of macoration of the healthy pen-wound skin to which the dressing 100 is adhered. The perforations 135 may be formed during manufacture of the skin contact layer 130, in an analogous manner to the way that the perforations 125 are formed in the film 120. Some of the perforations 135 are also shown as hidden detail in Figure 1. If the backing layer 140 were of transparent material, the perforations 135 would be visible through it, across the full extent of the border region of the dressing 100.

The dressing may be manufactured by the following general method.

First, the MBPUtsUicone gel composite used to form the skin contact layer 130 is produced in the manner described in W02007/1 13597. In genera! terms, this involves applying siHcone go! precursors to a sheet of meltblown polyurethane (MBPU), the underside of which carries a coating of acrylic adhesive and a temporary protective backing, eg of plastics film or paper. Once the silicone gel precursors have cured, to produce a hydrophobic silicone gel, a temporary cover, again of plastics film or paper material, is applied to the gel. Perforations corresponding to the perforations 125 are then formed in the composite, and large openings that will constitute the central opening 133 of the skin contact layer 130 referred to above are cut out.

In a separate operation, a laminate of the foam that is used to form the pad 110 and the perforated film 120 is produced by bonding sheets of foam and perforated film material together, as described above. Individual pieces of the desired shape and size are then cut out to form the laminated pad 110 and film i 20.

The pieces of laminated pad 110 and film 120 are then positioned on a sheet of breathable polyurethane film (which will form the backing layer 140 of the finished dressing 100). The temporary protective backing is removed from the underside of the MBPU to expose the acrylic adhesive and the MBPU/silicone gel composite is applied to Lhe polyurethane film with the large openings in registration with the pieces of laminated pad 110 and film 120. Finally, the temporary protective cover is removed from the silicone gel and replaced with appropriately formed release liners 150a-c, arid individual dressings 100 are punched out and sterile-packaged.

Sterilisation may be carried out by any suitable means, eg with the use of gamma irradiation or ethylene oxide.

In use, a dressing 100 is removed from its packaging and the release liners 150a-c are peeled off. The dressing 100 is then applied to a wound, with the exposed film 120 overlying the wound and the surrounding silicone gel of the skin contact layer 130 being attached to the periwound skin. Exudate from the wound is able to pass through the perforations 125 end is absorbed by the foam pad 110. At the same time, however, contact between wound exudate and the film 120 causes the film to gradually dissolve. As it does so, the antimicrobial components of the dressing 100 (eg manuka honey, manuka oil and PHMB) are released into the wound site.

Figure 5 shows a second embodiment of a wound dressing according to the invention, designated 200.

The dressing 200 is similar to the laminate described above in that it comprises an absorbent foam pad that is laminated to a honey-containing film 201. However, in this embodiment the perforations 202, shown on a portion of the dressing of Figure 5, pass through the whole dressing 200. The film 201 may be a dissolvable antimicrobial film prepared as described in the Example above but the perforations are not introduced until after the film 201 is laminated to the foam pad. The foam pad and unperforated film are first bonded together by applying heat and pressure, eg by passing the layered foam and unperforated film through a pair of heated rollers. A regular array of perforations 202 is subsequently introduced into the laminate as a whole, ie through the film 201 and the foam, by compressing the laminate between a sonotrode and a substrate and applying high frequency mechanical vibrations. Apparatus by which the perforations are introduced into the film is similar to that depicted schematically in Figure 4. The laminate is introduced into the apparatus 10 in place of the film/substrate 2.

As the perforations 202 in the dressing 200 are formed by compressing the absorbent foam pad and the film, the dressing remains compressed at the point at which the perforations are introduced. This results in a quilted appearance with the uncompressed areas of the foam pad forming peaks 203 between the perforations 202 in the laminate as illustrated by the lines 203 in Figure 5.

The dressing of Figure 5 may be applied directly to a wound or altematively, pieces of the laminated product may be cut out and incorporated into a wound dressing, for instance in pace of the aminate in the wound dressing shown in Figures 1 to 3

Claims

Claims 1. A wound dressing compdsing an absorbent body that is laminated to, or is in intimate contact with, a perforated film comprising one or more benefit agents, wherein the film, in use, is exposed to a wound to which the dressing is apphed, such that exudate from the wound passes through perforations in the film and is absorbed by the absorbent body, and wherein the film dissolves upon exposure to wound exudate, thereby releasing the one or more benefit agents.
2. A wound dressing according to Claim 1, wherein the perforated film comprises a carrier material.
3. A wound dressing according to Claim 2, wherein the film comprises from about 10% to about 60% w/w carder materiaLICC
4. A wound dressing according to Claim 3, wherein the film comprises frori about 30% to about 50% w/w carrier materiaL
5. A wound dressing according to any preceding claim, wherein the carrier is a polymeric material.
6. A wound dressing according to Claim 5, wherein the polymeric material is a film-forming polymer.
7. A wound dressing according to any of Claims 2 Lo 6, wherein the carrier is soluble upon exposure to wound fluid.
8. A wound dressing according to Claim 7, wherein the carrier loses its integrity over a timescale of 1 to 10 minutes or 10 to 60 minutes.
9. A wound dressing according to Claim 7. wherein the carrier loses its integrity over a timescale of 1 to 6 hours or 6 to 24 hours.
10. A wound dressing according to Cim 7, wherein the carrier loses its integrity over a timescale of up to 1 day or 2 days.
11. A wound dressing according to any of Claims 2 to 10, wherein the carrier is polyvinyl alcohoL
12. A wound dressing according to any of Claims 2 to 10, wherein the carrier is a polysaccha ride.IC)
13. A wound dressing according to any preceding daim, wherein the perforated film has a thickness of from 2Opm to 5mm.
14. A wound dressing according to Claim 13, wherein the perforated film has a thickness of from 200pm to 2mm.ICC15. A wound dressing according to any preceding daim, wherein the benefit agents include at east one antimicrobial agent.16. A wound dressing according to any preceding claim, wherein the benefit agents include honey.17. A wound dressing according to Claim 16, wherein the honey content of the film is from about 25% to about 75% w/w.18. A wound dressing according to Claim 17, wherein the honey content of the film is from about 45% to about 55% w/w.19. A wound dressing according to Claim 15, wherein the at least one antimicrobial agent is silver.20. A wound dressing according to Claim 15, wherein the at least one antimicrobial agent is polyhexamethylene biguanide.21. A wound dressing according to Claim 15, wherein the at least one antimicrobial agent is a plant essential oil having known antimicrobial actMty.22. A wound dressing according to any of Claims 19 to 21 wherein the antimicrobial agent is present in the film at a level of between 0.1 and 10% wlw.23. A wound dressing according to Claim 15, wherein the benefit agents comprise honey and at least one further antimicrobial agent selected from PHMB, silver and plant essential oils.24. A wound dressing according to Claim 23, wherein the benefit agents comprise manuka honey and PHMB.25. A wound dressing according to any preceding claim, wherein the film is laminated to the absorbent body.26. A wound dressing according to Claim 25, wherein the components are laminated using a fusible web material.27. A wound dressing according to any preceding claim, wherein the absorbent body comprises a foam.28. A wound dressing according to Claim 27, wherein the foam is an open-celled polyurethane foam.29. A wound dressing according to any of Claims I to 26, wherein the absorbent material comprises a gelling material.30. A wound dressing according to any of Claims I to 26, wherein the absorbent material comprises a non-woven pad or knitted structure.31. A wound dressing according to any of Claims I to 26, wherein the absorbent material comprises a superabsorbent material.32. A wound dressing according to Claim 31 wherein the superabsorbent material is sodium polyacrylate polymer.33. A wound dressing according to any preceding claim, wherein the film is laminated to the absorbent body, and perforations extend through both the film and the absorbent body.34. A wound dressing according to any preceding dairn, wherein the dressing IC) further comprises an adhesive skin contact layer.35. A wound dressing according to Claim 34, wherein the adhesive is a soft silicone adhesive.36. A wound dressing according to Claim 35, wherein the soft sflicone adhesive is carried on a layer of rneltThlown nonwoven material.37. A wound dressing according to any of Claims 34 to 36, wherein the adhesive is provided with a single opening, through which the perforated film is exposed to the wound in use.3$. A wound dressing according to any preceding claim, wherein the dressing further comprises a backing layer with a moisture vapour transmission rate of at least 300g/m2724h at 37°C and 100% to 10% relative humidity difference.39. A wound dressing according to Claim 38, wherein the backing layer extends beyond the edge of the film and absorbent body on one or more sides.40. A wound dressing according to Claim 39, wherein the backing layer extends beyond the edge of the film and absorbent body on all sides, forming a border around the film and absorbent body.41 A wound dressing according to any preceding dairn, wherein the dressing is suppUed with a releasable liner on its underside.42. A wound dressing according to Claim 41, wherein the releasable Uner comprises two or more two or more parts that overlap.43. A wound dressing according to Claim 1, wherein the perforated film comprises polyvinyl alcohol, manuka honey! and manuka oil and/or PHMB; IC) the absorbent body comprises an open-celled polyurethane foam; and the dressing further comprises a soft silicone skin contact adhesive and a polyurethane film backing layer.44. A wound dressing substantiaUy as hereinbefore described and as illustrated in the accompanying Figures Ito 3.45. A solid, dissolvable film comprising a polymeric carrier material and from about 25% to about 75% w/w honey.46. A film according to Claim 45, comprising from about 45% to about 55% w/w honey.47. A film according to Claim 45 or Cairn 46 for use in the treatment of wounds, 48. A wound dressing according to Claims l6to 18 orafilm according to Claims 45 to 47, wherein the honey is manuka honey orjellyhush honey.49. A film according to any one of Claims 45 to 48, which is laminated to an absorbent body.50. A film according to Claim 49, wherein the absorbent body is a foam.51. A film according to Claim 49 or Caim 50, wherein the film is perforated.52. A fUm according to Claim 51, wherein perforations in the film extend also through the absorbent body.53. A method of manufacturing a perforated fUm for use in a dressing according to Claim 1 comprising the steps of: a) producing a fluid precursor composition comprising a carrier material, one or more benefit agents, and a liquid medium; and b) casting the precursor composition into a sheet; IC) c) causing or allowing the precursor composition to at least partiafly solidify; and d) forrTling perforations in the at least partially solidified film.54. The method according to Claim 53, wherein the precursor composition contains about 20% to about 80% w/w of a liquid medium.55. The method according to Claim 54, wherein the liquid medium is water.56. The method according to Claim 53, wherein the precursor composition is spread onto a substrate to form a uniform layer.57. The method according to Claim 56, wherein the substrate functions as a release carrier.58. The method according Lo Claim 53, wherein to cause the precursor composition to at least partially solidify the precursor composition in step c) is heated.59. The method according to Claim 58, wherein the precursor is heated to between 40°C and 70°C for a period of between 5 minutes and 1 hour.60. The method according to Claim 55, wherein the final water content of the film is less than 20% w/w.61 The method according to Claim 53, wherein the film is formed in a confinuous process.62. The method according to Claim 53, wherein the perforations are produced by contacting perforating elements with the film and subjecting the film to high frequency mechanical vibrations.63. The method according to any one of Claims 53 to 62, further comprising the IC) step of laminating the film to an absorbent body.64. The method of Claim 63, wherein the film is laminated to the absorbent body after the perforations have been formed in the film.65. The method of Claim 63, wherein the film is laminated to the absorbent body before the perforations are formed in the Film.