Barrier cream

Details Barrier cream Barrier cream

2000-07-20

2001-10-30

Page, Thurman K. (Department: 1615)

Drug, bio-affecting and body treating compositions

Topical body preparation containing solid synthetic organic...

Skin burn or open wound treatment

C424S070100, C424S078020, C424S401000, C424S059000

Reexamination Certificate

active

06309631

ABSTRACT:

This invention relates to barrier creams. More particularly, the present invention relates to barrier creams which are useful in protecting a user from burns during exposure to heat.
Traditional barrier creams place a passive barrier between the skin and the environment which prevents the access of chemicals generally to the surface of the skin. More recently, creams have been developed which contain an active ingredient which prevents a chemical from having an effect on the skin, for example by denaturing the chemical.
Additionally, creams are known which protect the skin from the adverse effects of ultraviolet light or sunlight in order to prevent sunburn. However, at present there are no creams available which prevent or minimise the damage caused to skin by burning as a result of exposure to heat per se, particularly heat from explosive events, or to infra-red light. In particular, there are no protective or barrier creams available which prevent burns in a military or accident scenario. In military scenarios it is known that up to 10% of all casualties may suffer burns, the incidence of burns may even rise as high as 40-60%.
It has long been the case that burns are generally prevented by the use of protective clothing, and materials are available which offer a high degree of protection from flame burns. Even lightweight materials are able to provide some measure of protection against flash burns. However, areas such as the hands and face are extremely vulnerable and are often not protected by clothing. For example, the loss of manual dexterity experienced by wearing protective gloves can be quite substantial, as can the impairment of the field of vision from wearing protective headgear. For these reasons, it is often the case that workers in potentially hazardous environments who find protective gloves and headgear particularly cumbersome will not wear them when the perceived risk of danger is low, with the result that incapacitating burns may arise in the event of an incident. In such situations it is desirable to provide an alternative method of burns protection.
In this respect the present inventors have developed a barrier cream for use in mitigating at least high flux, radiated and convected heat from reaching a surface to which the cream is applied.
Accordingly, the present invention provides a barrier cream for the mitigation of burns, the cream comprising a base cream and at least one of a melt additive and a reflective additive.
The present inventors have found that such additives are effective in increasing the time taken for radiated and convected heat to reach a surface to which the cream has been applied. Where the cream is applied to skin, the potential for burn injuries, particularly from explosive effects, is reduced.
The cream of the present invention is preferably applied to the skin. However, it may also be applied to fabrics, particularly clothing, or even to instruments which are sensitive to heat. Where the cream is applied to fabric, it may be applied to one or both sides of the fabric or may be impregnated through the fabric or its fibres.
The present inventors have found that barrier creams offering reflective protection are useful in the prevention of burns, particularly where the cream is able to reflect infra-red radiation. However, the present inventors have found that a cream comprising both reflective additive(s) and melt additive(s) gives better protection to the user.
In this respect the present invention further provides a barrier cream for the prevention of burns, particularly flash burns, the cream comprising a base cream, a melt additive and a reflective additive.
Preferably, the reflective additive reflects infra-red radiation.
The base cream is preferably a pharmacologically acceptable base cream, for example a proprietary base cream such as an aqueous cream, a zinc based cream or an oil based cream, for example a glycerol based cream.
Where the surface to be protected is skin, then it is highly desirable that the melt additive is non-toxic, moreover it should be non-irritant or hypoallergenic.
Preferably, the melt additive has a latent heat of fusion of at least 50 Jg
−1
. The latent heat of fusion should be as high as possible in order to provide optimum protection against thermal attack; preferably at least 150 Jg
−1
and ideally at least 200 Jg
−1
. However, the choice of the melt additive is also, in part, determined by its other properties such as solubility in the base cream, viscosity and melting point.
Conveniently, the melt additive has a melting point below 55° C., preferably below 50° C. Ideally, the melting point is above 40° C.
Preferably, the melt additive comprises an alkali metal salt, alcohol, fat or wax, more preferably a fatty acid or derivative, for example, a fatty acid ester.
In a most preferred embodiment, the melt additive is selected from the group comprising methyl 4-(hydroxymethyl) benzoate, 4-phenylbutyric acid, 1-4-benzodioxan-6-carboxaldehyde, methyl 4-methoxybenzoate, 4-methylbenzhydrol and methyl 7-oxooctadecanoate, cetyl alcohol or sodium thiosulphate. Of these, methyl 7-oxooctadecanoate and cetyl alcohol are preferred because of their high latent heat of fusion (222.3 and 244.1 Jg
−1
respectively), giving them a great ability to absorb heat without becoming hot, thus rendering them useful in the prevention of burns.
The reflective additive preferably comprises a salt of a transition metal, preferably a titanium or iron salt. In preferred embodiments, the salt may be selected from the group comprising zinc and titanium oxide, zinc plus a mixture of titanium and iron (III) oxide, titanium dioxide, iron (III) oxide, titanium oxide and iron (III) oxide, magnesium silicate and carbon black. Ideally, the reflective additive is able to reflect radiation at infra red and visible wavelengths.
It is preferred that the barrier cream comprises 5-75% w/w of the at least one of the melt additive and reflective additive (i.e. the summed weight of the melt additive and reflective additive is 5-75% of the total weight of the barrier cream). It is further preferred that the cream comprises 0-25% w/w of the melt additive, most preferably 10-20%. It is preferred that the cream comprises 0-50% w/w of the reflective additive, most preferably 10-50%. However, the preferred and most preferred concentrations of both the reflective additive and melt additive depend on the nature of the cream base. In the case of a zinc cream, it is preferred that the cream comprises 5-40% w/w of the at least one of the melt additive and reflective additive. It is most preferred that a zinc cream comprises 5-20% w/w of the reflective additive and 0-20% w/w of the melt additive. In the case of an oil based cream, it is preferred that the cream comprises 35-75% w/w of the at least one of the melt additive and reflective additive. It is most preferred that an oil based cream comprises 35-55% w/w of the reflective additive and 0-20% w/w of the melt additive.
Ideally, the cream has a longevity of application, that is, is resistant to inadvertent removal by abrasion against clothing and the like and is preferably waterproof, not only to water arising from perspiration but to immersion in water.
In a preferred embodiment the cream may comprise a colouring additive according to the intended purpose of the cream. For example, for military applications one may select a brown/green colouring additive so that the cream may be used in the place of a conventional camouflage cream.


REFERENCES:
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patent: 5427771 (1995-06-01), Grollier et al.
patent: 5486353 (1996-01-01), Billia et al.
patent: 5695747 (1997-12-01), Forestier et al.
patent: 5811082 (1998-09-01), Ahlnäs et al.
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patent: 2217987A (1989-11-01), None
patent: 2243781A (1991-11-01), None
patent: WO 96/28136 (1996-09-01), None
patent: 98/01107 A1 (1998-01-01), None

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