Drug – bio-affecting and body treating compositions – Effervescent or pressurized fluid containing – Organic pressurized fluid
Reexamination Certificate
1997-05-07
2001-02-13
Bawa, Raj (Department: 1619)
Drug, bio-affecting and body treating compositions
Effervescent or pressurized fluid containing
Organic pressurized fluid
C424S046000, C424S443000, C424S078020, C424S618000, C424S630000, C424S641000, C424S614000, C424S649000, C424S613000, C424S078070, C424S620000, C424S657000, C424S667000, C424S655000, C424S639000, C514S944000, C514S945000, C514S938000
Reexamination Certificate
active
06187290
ABSTRACT:
The present invention is concerned with a foamable formulation and the foam formed therefrom.
BACKGROUND OF THE INVENTION
A wide variety of gels, creams, ointments, lotions etc are available for application to a body surface. The exact content of such compositions generally depends upon the purpose of application which may be, for example, to clean a body surface, to promote healing of any wound or injury, to prevent an exposed area of the body from drying out, to prevent infection etc. In certain circumstances the composition may include an active ingredient which is administered to the patient by application of the composition.
One example of a commercially available gel in INTRASITE™ produced by Smith & Nephew Ltd. This hydrogel contains hydrated carboxymethylcellulose as its main ingredient, and is applied to wounds in gel form as a primary treatment in order to clean the exposed surface by aiding removal of cell debris, dirt etc. In addition to acting as a sloughing agent, the gel also keeps the wound from drying out, thereby promoting healing.
Another example of a gel suitable for use on a wound dressing is described in EP-A-0586260 of Courtaulds Fibres Ltd. The gel disclosed is an alginate gel having an alginate content of 2 to 11 percent by weight.
SUMMARY
Viewed from one aspect, the present invention provides a formulation for application to a body surface as a foam, said formulation comprising an active ingredient and a foamable, preferably physiologically acceptable, carrier. The active ingredient(s) may be present as an integral part of the formulation, or may be held separately to other ingredients of the formulation, being combined therewith during formation of the foam. Optionally, the formulation may also comprise a foaming agent (for example a surfactant) which is capable of promoting production of a foam structure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In one embodiment, the present invention provides a, physiologically acceptable (preferably pharmaceutically acceptable), foamable carrier and an active ingredient packaged separately thereto which is admixed with the foamable carrier during the foaming process.
The term “active ingredient” is used herein to refer to any agent which affects the metabolism or any metabolic or cellular process of the patient (including growth factors nutrients and living cells), promotes cleaning of the area to which it is applied (for example aids removal of a debris, dirt, bacteria, malodours and the like), combats infection, hypergranulation, inflanmation and/or aids healing.
The term “foamable carrier” refers to any ingredient which is compatible with the active ingredient and which is capable of forming a foam. Conveniently the foamable carrier does not affect the function of the active ingredient in a detrimental manner. Desirably the foamable carrier is non-irritant when maintained in contact with a body surface for several hours. The foamable carrier may be a gel, for example an alginate gel.
The foam produced may be maintained on the body area, to form a protective covering, for example over a wound. Additionally, the foam may deliver the active ingredient, preferably in a controlled release manner. In one embodiment the foam acts as a transdermal delivery system. The foam may be exposed to the atmosphere so that it dries into a coating, or may be covered by conventional dressings.
As an example, the foam may be used to treat dermatological conditions (including psoriasis, atopic and allergic eczema). It may be convenient in this embodiment for the foam to deliver an active ingredient normally used to alleviate such conditions, for example a steroid such as hydrocortisone.
In another embodiment the foam may be used to treat burns or scalds, including sunburn.
In another embodiment the foam may be applied cosmetically, and for example may include skin moisturising agents, nutrional agents and growth factors suitable to promote skin regeneration. A foam intended for cosmetic use may include colorants or pigments so that the foam may be applied to the skin as a cosmetic or to disguise any blemishes in the skin.
The foam may be used prophylactically. In particular a foam containing a UV blocking agent may be applied to exposed areas of the skin to protect it from the effects of the sun.
The formulation of the invention is applied to the body site of interest in the form of a foam and it is therefore essential that the composition undergoes a foaming process before application to the body. In the foaming process gas is forced into or is formed within the formulation to entrap small bubbles of gas therein, thereby forming the foam. Any suitably gas or gas producing system can be used to produce the foam. Mention may be made of butane and nitrous oxide, but other gases are also suitable. Conveniently the foam may be produced by conventional means such as by using aerosol technology.
The formulation according to the present invention may be stored in any convenient container until required. Generally, the container will be designed to preserve the sterile nature of the formulation. Conveniently the container will be provided with means to foam the composition when required.
Thus the present invention also provides an apparatus which produces a physiologically acceptable foam as described above. Generally, the foam will be produced from sterile ingredients.
Viewed from another aspect, the present invention provides a closed container, containing therein a formulation as described above, said container being capable of expelling said formulation in the form of a foam. For example, the container may be an aerosol canister, containing a pressurized gas which in use causes production of the foam. Alternatively, the gas may be produced by a chemical reaction when two different ingredients (for example contained in two portions of a sachet) are admixed together. In one embodiment the closed container has separate reservoirs for the foamable carrier and the active ingredient. Thus, the foamable carrier and the active ingredient are stored separately during storage and are admixed together in suitable proportions during the foaming process.
The present invention thus provides an apparatus to produce a foam for application to a body surface, from a formulation as defined above, said apparatus comprising:
a. a closed container having
i) a reservoir containing said foamable carrier;
ii) a reservoir containing said active ingredient; and
b. foaming means to produce a foam from said foamable carrier.
Optionally a foaming agent may be mixed with the foamable carrier.
Prior to the foaming process, the foamable carrier is preferably in the form of a gel. The gel may be sterilised and this is generally desirable where the foam is intended for medical use. Usually, sterilisation will take place by autoclaving the formulation, since this is currently the most economic means of achieving sterilisation. Autoclaving at temperatures of from 100° C. to 125° C. for under ½ hour is normally sufficient. Generally, the autoclaving process should be as mild as possible, whilst being sufficient to sterilise the formulation. For example, autoclaving at temperatures of about 121° C. for 15-20 minutes is acceptable. The autoclaved formulation may then be foamed when cool. It is also possible, however, to sterilise the formulation by other means, for example by &ggr;-irradiation or e-beam irradiation. It has been found that autoclaving the gel may cause the MW of the foamable carrier to be slightly reduced. Consequently it may be desirable to select a foamable carrier having a higher MW than that ultimately required.
The foam forms an air-tight cover around any wound or injury to which it is applied, and this prevents that area from drying out and may also combat infection. The advantages of applying a topical product in the form of a foam include:
1. Easy rapid application,
2. Conforms to surface irregularities,
3. Insulates the wound,
4. Cools the tissues,
5. Offers antibacterial action to prevent infection,
6. Biocompatibility with tissue,
Gilchrist Eilidh
Gilchrist Thomas
Bawa Raj
Giltech Limited
Ratner & Prestia
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