CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to LJK provisional application No. 0817486.4 entitled "Delivery System" filed on 24 September 2008.

FIELD OF THE INVENTION

The invention relates to a liquid delivery system.

In particular the invention relates to a transdermal medicament delivery system for the controlled delivery of a liquid to a selected area of skin of a patient.

BACKGROUND OF THE INVENTION

Current transdermal systems deliver actives by loading adhesives, foams or fibres with active ingredients. Current systems are not compatible with all actives and all delivery media.

Many actives for drug delivery systems are required or it is beneficial at least, if the active is in aqueous solution. The active in aqueous solution can be transported through skin pores and into deep tissue. What is often required is a delivery system which when applied to the skin will deliver a consistent dose of liquid to the skin, without the need for specific user input.

Current drug delivery systems are not compatible with all actives and delivery media. The actives and delivery media can bind to the adhesives, foams or fibres of current delivery systems, preventing release to the skin. The present invention allows the active and delivery system to be delivered directly to the skin at a steady rate. SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a liquid delivery system comprising; (i) a non-porous wall member; and

(ii) a porous wall member, wherein said wall members define a liquid retaining chamber, wherein said porous wall member has a substrate-contacting surface and wherein upon contact with said substrate the liquid egresses through the pores.

In embodiments of the invention the liquid delivery system consists of a non- porous wall member and a porous wall member, as illustrated in Figure 1. In this embodiment of the invention the peripheral edges of the two wall members are sealed together. Sealing techniques include, but are not limited to; heat sealing, ultrasonic welding, radio-frequency welding and adhesives.

In an alternative embodiment of the invention the liquid delivery system is substantially triangular, having two wall members which are non-porous and third wall member which is porous, wherein the porous wall member contacts a substrate.

In an alternative embodiment of the invention the liquid delivery system is substantially square, having three wall members which are non-porous and fourth wall member which is porous, wherein the porous wall member contacts a substrate.

In an alternative embodiment of the invention the liquid delivery system is substantially rectangular, having three wall members which are non-porous and fourth wall member which is porous, wherein the porous wall member contacts a substrate. In the alternative embodiments of the invention as outlined above, the peripheral edges of the wall members are sealed in a similar manner as to that of the embodiment disclosed in Figure 1.

The porous wall member is such that it will hold a liquid throughout the manufacture, storage and transport of the liquid delivery device, but will release liquid upon contact with a substrate. Liquid from the liquid retaining chamber can flow across the porous wall member at a desired steady rate to the substrate with which the porous wall member is in contact.

The pore size may vary from about 1 μm to 500 μm, more particularly from 1 - 100//m, or from 50-100/ym, or from 100-150μm, or 100-250μm, or 100-500μm, or 250-500/ym, and can be varied and optimised depending on what flow rate is required.

The non-porous wall member may comprise of a film or other flexible material but could also be inflexible in some embodiments.

The porous wall member may comprise a porous film.

The porous wall member may comprise a double-layered porous material, which can for instance be formed by the co-extrusion of two materials. The first material being substantially hydrophobic and the second material being substantially hydrophilic. The orientation of the double-layered material (i.e which material forms the substrate-contacting surface (outer surface) and which material forms the liquid-contacting surface (inner surface) is dependent on the affinity of the retained liquid for water.

It is envisaged that currently known manufacturing processes and materials may be used to make the porous and non-porous films. Different weights of films may be used to make the porous and non-porous films. During manufacture a non-porous safety cover layer or film may be adhered to the porous wall member to ensure liquid does not escape, during manufacture and transport of the product. Prior to use the safety cover/layer is removed.

The liquid delivery system can be referred to as a pouch or sachet, similar to those used in the detergent industry, but differing in that the liquid is not discharged from the system by means of the degradation of the wall members.

The liquid delivery system can be simply held in place on the substrate by the user until a sufficient discharge of liquid has been achieved.

Alternatively securing means, for example adhesive tape placed over the liquid delivery system can be used to temporarily secure the system to the substrate.

In other embodiments of the invention the liquid delivery system can be moved across a substrate so as to distribute the liquid over a wider area than the surface area of the substrate-contacting surface.

A handle means may be provided on the liquid delivery system for ease of use.

It is envisaged that the liquid delivery device can be used in medical/surgical applications.

For example, the substrate is skin and the liquid is an antiseptic solution, such as iodine solution, used in surgical preparation techniques.

For example, the substrate is skin and the liquid is a topical antibiotic.

For example, the substrate is skin and the liquid comprises a medicament. The liquid delivery system can thereby facilitate the transdermal delivery of the medicament. According to a second aspect of the invention there is provided a medical dressing comprising a liquid delivery system according to claim 1.

In a specific embodiment of the invention, the medical dressing comprises;

i) a liquid delivery device according to the first aspect of the invention; ii) a securing means, for securing the liquid delivery device to the skin.

The securing means may be in the form of a strip of adhesive tape.

The securing means may be in the form of an adhesive-coated filmic dressing which is placed over the upper surface of the liquid delivery device and which secures the device to the skin. An island dressing is thus formed.

The dosing i.e rate of release of the liquid from the liquid retaining chamber across the porous side or film to the skin can be controlled by optimising the pore size in the porous film.

It is further envisaged that the liquid delivery device can be used in non- medical/surgical applications in which a liquid is contacted with a substrate. For example, in cleaning applications. The liquid could be a cleaning agent, such as a disinfectant or a polish.

According to a third aspect of the invention there is provided a liquid delivery device or medical dressing as substantially herein described with reference to the accompanying Examples and Figures 1 , 2, 3 or 4.

The invention will now be described as way of example only by the following example and drawings Fig 1 shows a dressing of the present invention.

Fig 2 shows a dressing of the present invention on the skin (arm) of a patient. Fig 3 shows another embodiment of the present invention with heat sealed joins. Fig 4 shows a fluid reservoir with covering/holding layer. Fig 5 shows another embodiment of the present invention.

The porous film used in the reservoir may be a 46 gsm (grams per square metre) 2 layer (co-extruded) net (available from Smith & Nephew Extruded Films, CE46 ^® . The outer layer may be HDPE (High density polyethylene). The inner layer is LLDPE/EVA, (Linear Low Density Polyethylene/Ethylene Vinyl Acetate).

The nonporous film may be a 30 gsm PU (polyurethane) film.

The dressing itself may be a medical adhesive coated 30 gsm PV film on a PE (Polyethylene/ PET polyethylene Terephtalate) carrier. The adhesive liner may be a poly coated siliconised paper.

Figure 1 shows a dressing (10) of the present invention having a non-porous wall member (1 ) and a porous wall member (2) enclosing a fluid reservoir (3).

Figure 2 shows a dressing (10) of the present invention with porous (2) and non-porous (1 ) wall members on a patients arm (4). Liquid from the fluid reservoir (3) wicks upon contact with the skin of the patients arm (4), from the fluid reservoir to the skin of the patient (4).

Another design embodiment is shown in Figure 3 with a non-porous wall member (1) and porous wall member(2) heat sealed together at the sides (5) and with an active (6) present in the fluid reservoir (3). The present invention may also include a place on dressing (20) as shown in Figure 4 where a fluid reservoir (3) enclosed by a porous wall layer (2) is placed on the skin (4) of a user and covered by a non-porous layer.

The present invention may also include more complex designs such as a construct type dressing (30) as shown in Figure 5. Here the embodiment may have an occlusive film carrier (7) over a PU film (8) with adhesive (9). The PU film (8) may have the adhesive (9) on its inner/skin-facing side to adhere itself and to hold in place the fluid reservoir (3) containing an active (6). The fluid reservoir having a non-porous film side (1 ) and porous side/film (2) with the selectively porous side facing the skin (4) of a patient.