Title:  Aerosol ointment compositions for topical use

United States Patent:  6,214,318

Assignee:  OMS Holdings LLC (New York, NY)

Filed:  March 30, 1999

Aerosol compositions are provided that enhance the therapeutic action of ointments by producing, upon topical application thereof, a sustained cooling effect that provides fast relief form pain and itching as well as a tendency to shrink swollen, inflamed tissue. The compositions contain oils, thickening agents for the oils, and propellant. Aqueous solutions, therapeutic ingredients and various adjuvants may also be present. The specific propellant and the proportion used are selected to provide a deposit with a temperature of about -5^oC. to about +5^oC. In this temperature range, the deposit is cold enough for the required therapeutic effect, but not so cold as to cause pain or tissue damage. The choice and proportion of thickening agents used are selected to provide a deposit that does not flow or spread. Were the deposit to spread, it would present a large surface area from which propellant present in the deposit would evaporate rapidly. By avoiding spreading, the propellant evaporates more slowly and the cooling effect is more sustained.

SUMMARY OF THE INVENTION

The present invention relates to an aerosol composition consisting essentially of the ingredients of an ointment-liquefied propellant composition which when expelled from an aerosol container onto damaged tissue provides a cold ointment which exerts a therapeutic effect on said tissue in contact therewith.

The cooling effect provided by the expelled composition of this invention is controlled so as to provide relief of pain for a desirable period of time but not too cold to cause discomfort or tissue damage.

Thus, an object of this invention is to provide a therapeutic ointment composition which when expelled from an aerosol container is cold enough to provide a cooling effect for pain relief but not too cold as to cause discomfort to damaged tissue to which the ointment is applied, said ointment also exerting a therapeutic effect on damaged tissue in contact therewith.

A further object is an ointment that can deliver appropriate medication as well as a cooling effect where it is applied.

Another object of the invention is to provide a cold ointment for the temporary relief of hemorrhoids which when applied to the swollen inflamed tissue provides a cooling effect and quickly relieving pain and itching as well as effecting shrinking of swollen inflamed tissue.

A still further object of the invention is an ointment for the treatment of sunburn.

Another object of the invention is a cold anti-itch ointment as well as one that provides relief from arthritic pain.

Another object of the invention is an antifungal ointment.

An object of this invention is an antibacterial ointment.

An additional object of the invention is to provide a cold ointment that is initially unctious, but dries to leave a deposit that is neither greasy nor oily.

More particularly, the present invention relates to novel aerosol compositions that enhance the therapeutic action of an ointment by instantly producing, upon topical application thereof, a sustained cooling effect which provides fast relief from pain and itching as well as a tendency to shrink swollen, inflamed tissue in advance of the slower action of any medication present in the ointment, said aerosol composition consisting essentially of from about 10 to about 60 percent by weight of ointment ingredients and from about 40 to about 90 percent by weight of liquefied propellant that is predominantly a non-polar propellant, i.e., at least about 80% by weight of the non-polar propellant and where the sum of the ointment ingredients and the propellant equals 100 percent by weight of the composition.

In another embodiment, applicants' invention is directed to a therapeutic aerosol composition for topical use consisting of (a) from about 10 to about 60 percent by weight of the ingredients of an ointment and (b) from about 40 to about 90 percent by weight of liquefied propellant, where at least about 80 percent by weight of the liquefied propellant is a non-polar propellant or mixture of non-polar propellants selected from the group consisting of a hydrocarbon propellant and a fluorocarbon propellant and the sum of ingredients from (a) and (b) equals 100 percent by weight of the composition, the composition when expelled from an aerosol device containing the composition depositing as an ointment having a solid or semi-solid consistency and a temperature between about -5^oC. and +5^oC.

Preferably, the ointment ingredients constitute from 35 to 100 percent by weight of an oil phase and from 0 to about 65 percent by weight of an aqueous phase based on the weight of the ointment ingredients and the oil phase of the ointment does not flow below about 35^oC. The oil phase includes ingredients selected from the group consisting of oils, and oil soluble ingredients, the oil soluble ingredients including adjuvants, topical therapeutic agents, oil soluble emulsifiers, and thickening agents for the oils and oil soluble ingredients, where the oils and oil-soluble ingredients are soluble in the propellant. The aqueous phase includes water, water-soluble emulsifying agents and may also include topical therapeutic agents, humectants and alcohols.

Also, the present invention relates to a novel method for enhancing the therapeutic effect of a solid or semi-solid ointment which consists of dissolving and/or dispersing:

(a) from about 10 to about 60 percent by weight of an ointment that contains an oil phase and may contain an aqueous phase in the form of an emulsion, where the oil phase of the ointment does not flow below about 35^oC., in

(b) about 40 to about 90 percent by weight of a liquefied propellant that is at least 80 percent non-polar propellant in an aerosol container, whereby a solid or semi-solid deposit is formed when a portion of the composition is expelled and this deposit placed in contact with injured tissue it provides instant relief from pain and itching as the result of its sustained cold, thereby enhancing the performance of the ointment with its slower action medications.

The compositions used in the practice of this invention consist essentially of an ointment, i.e., a solid or semisolid component, dissolved and/or dispersed in a liquefied propellant in a suitable aerosol container. The product is expelled from the aerosol container either as a deposit confined to a small area or as a spray covering a wider area, depending on the application. Thus, to relieve hemorrhoids the deposit should be confined to a small area, while to relieve sunburn a wider area is likely to be more convenient.

The expelled therapeutic composition for this invention will feel cold due to the evaporation of the propellant. A substantial portion of the propellant that is expelled should initially be part of the deposit, so that there is a continuing cooling action as the propellant gradually evaporates. It is also important that the deposit have a comparatively high density and that it be applied thickly.

The temperature of the expelled deposit should be initially in the range of about -5^oC. to about +5^oC. In this range the deposit can have the therapeutic effects that are the objects of this invention while not being so cold as to cause pain or tissue damage. Suitable liquefied nonpolar propellants that can be used in aerosol compositions of this invention to obtain a deposit falling within this temperature range include the hydrocarbon propellants, e.g., n-butane, isobutane and propane; the fluorocarbon propellants, e.g., 1,1-difluoroethane; and mixtures of these liquefied nonpolar propellants.

It has now been found that n-butane is the preferred propellant for use in the compositions of this invention. n-Butane has a vapor pressure of 17 p.s.i.g. and a boiling point of -0.5^oC. and will tend to maintain the deposit at about that temperature. If the deposit gets much cooler, further cooling by evaporation will slow substantially. The deposit will remain in the required temperature range until the proportion of n-butane in the deposit has become quite low. If a significant amount of liquefied propellant remains with the deposit when it reaches the substrate, the temperature of the deposit will approximate the boiling point of the propellant. Once it reaches that temperature, the rate of evaporation will slow and absorption of heat from the substrate will prevent it from falling much lower. One reason for preferring n-butane is that a deposit containing it is not likely to become objectionally cold. In contrast, isobutane with a boiling point of -11.7^oC. is likely to be unpleasantly cold, if the deposit contains a significant amount of liquefied isobutane.

A related reason for preferring n-butane is that it has a lower vapor pressure than the more widely used liquefied propellants: isobutane and propane. The lower vapor pressure assures that less propellant will be lost through evaporation as the exudate travels from the aerosol valve to the substrate upon which it is to be deposited.

However, for those products that are likely to be used at lower ambient temperatures, where n-butane does not provide sufficient pressure to expel the composition properly, it is advantageous to combine n-butane with a lesser amount of a higher vapor pressure propellant, e.g., isobutane, propane, 1,1-difluorethane or dimethyl ether.

However, higher vapor pressure (lower boiling point) propellants can be used under conditions when little if any liquefied propellant remains with the deposit when it reaches the substrate so that the temperature of the deposit is in the required range of -5^oC. to +5^oC. This can be done by reducing the percent propellant in the composition. A beneficial feature is that the higher the vapor pressure (lower the boiling point) of the propellant, the greater the tendency to flash off before reaching the substrate. Nonetheless, in general, the higher vapor pressure propellants are not as effective as n-butane, the preferred propellant.

The distance of the spray path as well as the characteristics of the package play a role in determining how much propellant will be lost as the exudate travels to the substrate upon which it will be deposited. It is evident that the longer the spray path, the more propellant will be lost by evaporation before reaching the substrate and the less propellant will be available for sustained cooling. It has also been found that restrictions in the delivery system also promote early evaporation of propellant by reducing the flow rate of the exudate.

However, with some compositions a restricted delivery system is beneficial, since it results in a heavier-bodied deposit. Also, where layering of the composition occurs within the container, it is advantageous to employ a capillary dip tube, i.e., a dip tube with an inside diameter of 1 mm., to minimize the amount of separated material that is released after first shaking the container. Shaking is not effective in mixing material that is in the dip tube.

The dynamic physical characteristics of the composition play an important role in determining the amount of propellant in the deposit and the amount of time it will remain in the deposit to provide sustained cooling. The aerosol compositions of this invention consist of the ingredients of an ointment that generally contains a thickening agent in a solution of an oil, and often one or more medicinal ingredients, dispersed and/or dissolved in an appropriate propellant so that the expelled deposit is initially in the range of about -5^oC. to about +5^oC. As product is expelled there is some loss of propellant accompanied by cooling of the exudate. If the deposit had been a liquid rather than an ointment, it would have spread rapidly whereby expiration of the propellant would occur too quickly and one would not obtain the desired sustained cooling effect. The compositions of this invention deposit as solids or semi-solids. The thickness of the deposit helps to provide sustained therapeutic cooling.

It has been found that the oil phase of the ointment should have a flow temperature that is at least about 35^oC.; otherwise, the deposit will liquefy readily and not provide sufficient cooling. It is advantageous that the flow temperature of the oil phase of the ointment not exceed about 60^oC., otherwise manufacture becomes more difficult.

The preferred compositions contained in an appropriate aerosol container in accordance with this invention contain from about 10 to about 60 percent by weight of the ingredients of an ointment and from about 40 to about 90 percent by weight of a propellant that is at least 80% by weight n-butane. Also preferred are aerosol compositions of this invention that consist essentially of from about 50% to about 75% by weight of a non-polar propellant or mixture of non-polar propellants and 25% to 50% by weight of ingredients of an ointment.

Claim 1 of 29 Claims

We claim:

1. A therapeutic aerosol composition for topical use consisting of:

(a) from about 10 to about 60 percent by weight of the following ingredients:

oils selected from the group consisting of mineral oils, vegetable oils, silicone oils and synthetic oils;

thickening agents for the oils in an amount sufficient to thicken the oils to a non-flowable state below about 35^oC., said thickening agents being selected from the group consisting of mineral waxes, animal and vegetable waxes, synthetic waxes, polymers and metallic soaps; and

optionally ingredients selected from the group consisting of an aqueous solution, adjuvants, topical therapeutic agents and emulsifiers, and

(b) from about 40 to about 90 percent by weight of liquefied propellant, where at least about 80 percent by weight of the liquefied propellant is a non-polar propellant or mixture of non-polar propellants selected from the group consisting of hydrocarbon and fluorocarbon propellants, and the sum of (a) and (b) equals 100 percent by weight of the composition, the composition when expelled from an aerosol device depositing as an ointment having a solid or semi-solid consistency containing a substantial proportion of said propellant, whose evaporation is restrained by the solid or semi-solid nature of the deposit, thereby upon topical application producing a sustained cooling effect at a temperature between about -5^oC. and +5^oC.

____________________________________________
If you want to learn more about this patent, please go directly to the U.S. Patent and Trademark Office Web site to access the full patent.