FORM 2
THE PATENT ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rulel3)
1. TITLE OF THE INVENTION:
"Topical Preparation"
2. APPLICANT
(a) NAME: CIPLA LTD.
(b)NATIONALITY: Indian Company incorporated under the Indian Companies ACT, 1956
(c) ADDRESS: 289, Bellasis Road, Mumbai Central, Mumbai - 400 008, Maharashtra, India.
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.


Technical field of the invention:
The present invention relates to a topical foam composition comprising a corticosteroid, its process of preparation and use thereof.
Background and prior art:
The corticosteroids are a class of compounds comprising steroid hormones secreted by the adrenal cortex. In pharmacological doses, corticosteroids are used primarily for their anti-inflammatory and/or immunosuppressive effects. Topical corticosteroids are effective in the treatment of corticosteroid-responsive dermatoses primarily because of their anti-inflammatory, antipruritic, and vasoconstrictive actions.
Psoriasis is one such inflammatory skin disorder that affects 1 to 3 percent of population throughout the world. The scalp is a favored site for psoriasis and sometimes may be the only site affected.
Scalp psoriasis is a frequent expression of the common skin disease; scaling and itching are the two major complaints. Topical treatments are the mainstay of the treatment of psoriasis of the scalp. The dosage forms as well as the active ingredient are relevant to the efficacy, tolerability and compliance of the preparation. Dosage forms can be shampoos, lotions, gels, foams, creams and more greasy ointments. Active ingredients generally used for the treatment are keratolytics, coal tar, dithranol, corticosteroids and vitamin D3 analogues. Nevertheless topical corticosteroids remain the most popular treatment of scalp psoriasis. The several corticosteroids are used for the treatment of scalp psoriasis.
U.S. Patent application. No. 4,070,462 discloses a steroid ointment having good efficacy. The effectiveness of this composition is believed to be due to the steroid being completely dissolved in the ointment. However, this ointment, like others, feels somewhat greasy when applied to the skin.

However, due to the undesirable consistency of these hydrophobic carriers, their use is limited. For instance, ointments containing white petrolatum, e. g., Vaseline petroleum jelly, as the carrier often form an impermeable barrier, so that metabolic products and excreta from the wounds to which they are applied are not easily removed or drained away. Furthermore, it is difficult for the active drug dissolved in the carrier to pass through the white petrolatum barrier layer into the wound tissue, so the efficacy of the drug is reduced.
US 4,489,071 provides a betamethasone dipropionate cream formulation in the form of water-in-oil emulsion, through out which the steroid was dispersed and claimed the efficacy was similar to, the ointment of U.S. Pat. No. 4,070,462
In addition, ointments and creams often do not create an environment for promoting respiration of the wound tissue and it is not favorable to the normal respiration of the skin.
Their main disadvantage is in their sticky feeling, which remains so long after treatment is over. This decreases the patient compliance drastically. Therefore there is a strong need for providing a topical formulation that omits all the disadvantages of the above mentioned pharmaceutical preparations and yet retains the beneficial therapeutic properties of the drug combination.
US 6,126,920 claims a method of treating skin diseases by employing a pharmaceutical foaming composition comprising of betamethasone valerate as the corticosteroid used in amounts of 0.01 to 1.0% w/w along with buffering agent to stabilize the active isomer of the corticosteroid active substance in the complex foamable composition. The patent also claims that the formulation can be used for the treatment of skin diseases inter alia scalp psoriasis.

US20050069499 refers to a foamable composition comprising atleast one corticosteroid active ingredient, a non CFC propellant and an acceptable carrier configured to generate a quick breaking foam, the composition being devoid of buffer. The said composition instead makes use of weak acids as preferred pH adjusting agents.
Although the foam compositions referred to in above is a better dosage form than the other dosage forms mentioned in the prior art, it has been observed that these foam products have higher isomeric impurity content that is not desirable.
The present invention thus aims to exclude all the above disadvantages and provide a dosage form that provides an improved delivery of active, and has lower impurity profile, has decreased inconvenience and irritation, and increased ease of use for the patient.
Object of the invention:
It is therefore the object of the present invention to provide for topical foam composition comprising corticosteroids that is a quick-break foam composition.
It is another object of the present invention to provide for a topical foam formulation comprising one or more corticosteroids or their salts, solvates, prodrugs, derivatives, esters, polymorphs or enantiomers thereof, quick-break foaming agent; a propellant; and Hydrochloric acid and other suitable pharmaceutically acceptable excipients.
It is yet another object of the present invention to provide for a topical foam formulation having a lower impurity profile.
It is yet another object of the present invention to provide for a method of manufacturing the topical foam composition.
It is a further object of the present invention to provide for a topical foam composition for the treatment of skin and its related disorders such as eczema, infantile eczema, atopic

dermatitis, dermatitis herpetiformis, contact dermatitis, seborrheic dermatitis, neurodermatitis, psoriasis and intertrigo.
Summary of the invention:
According to the present invention there is provided a topical foam composition comprising one or more corticosteroids or thein salts, solvates, prodrugs, derivatives, esters, polymorphs or enantiomers thereof, quick-break foaming agent; a propellant; and Hydrochloric acid and other suitable pharmaceutically acceptable excipients.
According to the present invention there is also provided method for preparation of the formulation.
According to the present invention there is also provided a method for the treatment of skin and its related disorders such as eczema, infantile eczema, atopic dermatitis, dermatitis herpetiformis, contact dermatitis, seborrheic dermatitis, neurodermatitis, psoriasis and intertrigo using the pharmaceutical foam composition.
Detailed Description:
Foaming preparations are more advantageous over other pharmaceutical dosage forms
such as creams, ointments, sprays, lotions or liquid preparations. Foams use a propellant
(pressurized gas) and a surfactant in addition to the drug to help create smooth, creamy
foam. When one shakes the can, liquid propellant is mixed with the water based liquid
concentrate. Then, when the can is inverted and product is dispensed, the pressure of the
vapour propellant pushes the mixture of liquid propellant and liquid concentrate out of
the can. The liquid propellant then quickly evaporates, creating foam. The foam makes it
easy to apply the drug to the hair because in the foaming state it can be spread very thinly
to the entire area of the scalp. :•
Another benefit of foam is that its foamy state is not runny and thus will stay where it is put. Yet another advantage of foam is that its application provides a larger surface area being less viscous, hence better activity. Therefore, overall foams achieve better patient

compliance. In addition if silicon is added as a conditioner to the foam, it will give additional styling property to the formulation. Also if any styling polymers are added to the said formulation it can function as a medicament as well as a hair styling foam so that the patient in addition to getting the medical benefits from the formulation can derive cosmetic benefit from the formulation.
Since the package is sealed, there is no danger of contamination of the unused portion of the medication. Irritation produced by the application of an ointment or cream over an abraded area of the skin is reduced and sometimes eliminated by aerosolized foam. Hair foam preparations are more economical, since they can be applied easily as a thin layer with no wastage. This may result in faster absorption and more efficient use of medication. In case of a spray, the application of a spray composition to specific areas is difficult, whereas the foam can be dispensed to a suitable open receptacle and then applied to an affected area of a patient's scalp.
Various corticosteroids or their salts, solvates, prodrugs, derivatives, esters, polymorphs or enantiomers thereof can be used. Preferably corticosteroids that can be used for treatment of psoriasis may comprise alclometasone dipropionate, amcinonide, beclamethasone dipropionate, betamethasone benzoate, betamethasone dipropionate, betamethasone valerate, budesonide, clobetasol propionate, clobetasone butyrate, desonide, desoxymethasone, diflorasone diacetate, diflucortolone valerate, flumethasone pivalate, fluclorolone acetonide, fluocinolone acetonide, fluocinonide, fluocortin butyl, fluocortolone preparations, flupredmdene acetate, flurandrenolone, halcinonide, hydrocortisone, hydrocortisone acetate, hydrocortisone butyrate, methylprednisolone acetate, mometasone furoate, triamcinolone acetonide, and pharmacologically effective mixtures thereof.In the addition to the above mentioned drugs, the various other salts, solvates, prodrugs, derivatives,esters, polymorphs or enantiomers of the specific drugs mentioned above and other corticosteroids are to be considered to be covered within the scope of this invention. However it has been found important to stabilize the active isomer of the corticosteroid active substance in the complex foamable composition,

otherwise the complex interactions within the foamable composition may result in the instability of the more active isomer.
The preferred corticosteroids according to the present invention are betamethasone and clobetasol.
Betamethasone and clobetasol are synthetic, medium potency, corticosteroids for topical dermatological use. They have anti-inflammatory, anti-pruritic and vasoconstrictive properties. The mechanism of anti-inflammatory activity of topical steroids, in general is unclear. However, corticosteroids are thought to act by the induction of phospholipase A2 inhibitory proteins. Phospholipase A2 is responsible for release of arachidonic acid from membrane phospholipids. Potent mediators of inflammation like prostaglandins and leukotrienes are synthesized from arachidonic acid.
The betamethasone may preferably be used in its salt/ester form such as valerate, hydrochloride, phosphate, salicylate, sodium phosphate, valero acetate, dipropionate, etc. The preferred salt form is betamethasone valerate. The clobetasol may preferably be selected from its salts, solvates, prodrugs, derivatives, esters, polymorphs or enantiomers thereof. The preferred salt/ester of clobetasol is clobetasol propionate.
Preferably the drug may be used in the concentration of 0.025% w/w to 0.5% w/w as topical application.
In view of the complexity of the composition, it has been found that in order to ensure stability of the active isomer of the corticosteroid in the composition and thus to ensure delivery of the most active isomer to the epidermis, it necessary to achieve a desired pH and maintain the same throughout the shelf life. For example incase of Betamethasone, Betamethasone-21-valerate is one of the major impurity of the active drug, betamethasone -17-valerate and this impurity needs to be controlled, since the impurity Betamethasone-21 valerate is less active than the therapeutic drug, Betamethasone 17 valerate. The more the impurity the less will be the therapeutically effective drug

available for use. Thus a product that decreases the less active Betamethasone 21 valerate is always desired. Foams in the prior art use buffering agents containing a mixture of a weak acid and the salt of the corresponding weak acid or simply weak acids to overcome the problem of impurities. But the inventors of the present invention have now surprisingly found that the use of a strong acid like hydrochloric acid (HC1) stabilizes the 17-valerate configuration of the betamethasone valerate over the less active 21-valerate configuration, thus producing a composition which efficaciously delivers active to the epidermis and inturn reduces the less active impurity, betametasone 21 valerate to a large extent. The impurity is basically due to the alkaline hydrolysis when the drug is exposed to an aqueous environment and hence an acidic environment is required. The used pH adjusting agent is the source of a respective anion, such that the desired pH is achieved and maintained throughout the shelf life. Thus the present invention provides a foam composition that has a lower impurity profile. Accordingly the present invention provides a topical foam preparation comprising one or more corticosteroids, quick-break foaming agent; a propellant; Hydrochloric acid and other suitable pharmaceutically acceptable excipients.
In order to ensure stability of the more active form of the corticosteroid in the composition and thus to ensure delivery of the most active form of the corticosteroid to the epidermis, there is a need of a pH adjusting agent like Hydrochloric acid for suitably adjusting the pH. It is desirable generally to adjust the pH of the composition to preferably pH 3.0-6.0, more preferably to pH 3.0-5.0 To this end the pH adjusting agent may preferably be present in an amount of 0.01-1.0% w/w, more preferably 0.05-0.2% w/w. The use of the pH adjusting agent according to the present invention limits the impurity betamethasone-21-valerate preferably to;less than 4% by weight of the active; more preferably to less than 3% by weight of the active; most preferably to 2% by weight of the active. Suitably, this means when the composition is stored controlled at room temperature at 25°C and about 60% relative humidity for a period of at least 24 months
The composition according to the present invention, when applied to the skin site (after foaming) as foam, is a thermophobic (heat sensitive) quick-break foam. On application to

the skin, the composition is initially in the form of a mousse-like foam. The quick-break foam slowly breaks down at the skin temperature to liquid to allow the alcohol and active substance to saturate the treatment site. Such a system provides enhanced penetration of the alcohol and active substance through the epidermis.
The Quick-break foam/quick break foaming agent preferably comprises an aliphatic alcohol, water, a fatty alcohol and a surface active agent.
It must be noted that, as used in this specification and the appended claims, the singular forms "a," "an" and "the" may also include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to" an aliphatic alcohol" also includes a combination of two or more aliphatic alcohols
In the quick-break foaming agent, the fatty alcohol may comprise preferably atleast one fatty alcohol having between 10 and 22 carbon atoms for example, one or more of but not limited to cetyl alcohol , stearyl alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, cetostearyl alcohol or mixtures thereof, The fatty alcohol may preferably be present in a range of 0.5 to 4.0 % w/w. The preferred fatty alcohol is cetyl alcohol and stearyl alcohol.
The aliphatic alcohol may preferably comprise one or more of but not limited to methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohols or mixtures thereof. Ethanol has been found to be particularly preferred. The aliphatic alcohol may preferably be present in a range of 40 to 60% w/w
Surface active agents utilised in the quick-break foaming agent may preferably comprise one or more of but not limited to polysorbates, ethoxylated sorbitan stearate, ethoxylated sorbitan palmitate, ethoxylated sorbitan oleate1, ethoxylated sorbitan nonyl phenol ethoxylates and fatty alcohol ethoxylates, and mixtures thereof, for example, Polysorbate 60(Tween 60), Polysorbate 80 (tween 80), Polysorbate 20 (tween 20). The surface-active agent enhances the fatty alcohol solubility in the system and enhances foam formation.

Preferably the surface-active agent may be present in a range of 0.1 to 1.0% w/w. Preferably the surface active agent is Polysorbate 60 (Tween 60) or Polysorbate 80(Tween 80).
The water may be added in quantities as per requirement but may preferably be added in an amount of 10 to 40% by weight of the composition.
The propellant used may be chosen from conventional aerosol propellants. Preferably the propellant may comprise, one or more of propane, butane, dichlorodifluoro methane, dichloro tetrafluoro ethane, octafluoro cyclobutane, isobutene, isopentane, n-pentane and mixtures thereof. It is necessary to. select a propellant most compatible with the entire system. It is particularly preferred that the propellant be present in amounts preferably of 3-30% w/w, more preferably 3-10% w/w, more preferably 4 to 8% w/w. Preferably the propellant is propane/butane.
The present invention may optionally comprise a suitable humectant. The humectant may preferably comprise one or more of but not limited to guanidine, urea, glycolic acid, glycolate salts, ammonium glycolate, quaternary alkyl ammonium glycolate, aloe vera, polyhydroxy alcohol, sorbitol, glycerol, hexanetriol, propylene glycol, butylene glycol, hexylene glycol, a hex-ylene glycol derivative, polyethylene glycol, a sugar, a starch, a sugar derivative, a starch derivative, alkoxylated glucose, monoethanolamine or mixtures thereof.
Any other suitable ingredient that does not affect the quick breaking foam quality may also be included in the present formulation.
Preparation of the composition may be effected by conventional means so as to produce a homogeneous solution of fatty alcohol(s) (wax) in an alcohol/water base. The relative proportions of the fatty alcohol(s), water/aliphatic alcohol and propellant are conveniently controlled according to conventional means so as to provide a homogeneous clear solution and so as to allow the formation of suitable quick-break foam. Generally

speaking the fatty alcohol(s), surface-active agent, aliphatic alcohol and humectant (if present) are preferably mixed together with the corticosteroid active substance to produce an "Alcohol Phase". An "Aqueous Phase" is preferably produced by mixing the pH adjusting agent like hydrochloric acid and water. These phases are then mixed, preferably in the final container, in the required amounts. The propellant is then added under pressure to produce the composition according to the invention.
The composition of the present invention may be contained in and dispensed from a container capable of withstanding the pressure of the propellant gas and having an appropriate valve/nozzle for dispensing the composition as foam under pressure.
The present invention further provides a method of treating a skin disease susceptible to treatment with corticosteroid active substances, said method comprising administering topically to a patient in need thereof, an effective amount of a foamable pharmaceutical composition according to the present invention.
The composition of the present invention may be used in treating skin diseases that are conventionally treated with corticosteroid active substances. Thus, the composition may be used in the treatment of, inter alia, eczema, infantile eczema, atopic dermatitis, contact dermatitis, seborrhoeic dermatitis, neurodermatitis, psoriasis and intertrigo. The composition is especially useful in the treatment of scalp psoriasis in human subjects
It will be readily apparent to one skilled in the art that varying substitutions and modifications may be made to the invention disclosed herein without departing from the scope and spirit of the invention. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be falling within the scope of the invention.

The following examples are for the purpose of illustration of the invention only and are not intended in any way to limit the scope of the invention.
Example 1

SL. No: Ingredients % w/w
1. Betamethasone valerate 0,12
2. Cetyl Alcohol 1.80
3. Stearyl Alcohol 0.80
4. Propylene Glycol 3.00
5. Tween 60 0.50
6. Ethanol 55.00
7. 0.1N HC1 Qs
8. Distilled water qs
9. Propellant Propane/Butane 5.00
Procedure:
Preparation of alcoholic phase:
1. Ethanol was taken in clean and dry container.
2. cetyl alcohol and stearyl alcohol were added to it and stirred.
3. To above solution propylene glycol and tween 60 were added and stirred to get a clear solution.

4. To this the drug was added to obtain a clear solution. Preparation of aqueous phase:
5. In a clean and dry container water was taken.
6. To it 0.IN HC1 was added and stirred to get pH 3
The canisters were then filled by addition of weighed qty of alcoholic phase and aqueous phase, followed by crimping of the valve and filling of the propellant.

Example 2

SL. No: Ingredients % w/w
1. Betamethasone valerate 0.12
2. Cetyl Alcohol 1.10
3. Stearyl Alcohol 0.50
4. Propylene Glycol 2.00
5. Tween 60 0.50
6. Ethanol 60.00
7. 0.1N HCl Qs
8. Distilled water qs
9. Propellant; Propane/Butane 5.00
Procedure:
Preparation of alcoholic phase:
1. In clean and dry container ethanol was taken.
2. To it cetyl alcohol and stearyl alcohol were added and stirred.
3. To above solution propylene glycol and tween 60 were added and stirred to get a clear solution.

4. To this the drug was added to obtain a clear solution. Preparation of aqueous phase:
5. In a clean and dry container water was taken.
6. To it 0. IN HC1 was added and stirred to get pH 3
The canisters were then filled by addition of weighed qty of alcoholic phase and aqueous phase, followed by crimping of the valve and filling of the propellant.
Example 3

SL. No: Ingredients % w/w
1. Clobetasol propionate 0.05

2. Cetyl Alcohol 1.10
3. Stearyl Alcohol 0.50
4. Propylene Glycol 2.00
5. Tween 60 0.50
6. Ethanol 60.00
7. 0.1N HC1 Qs
8. Distilled water qs
9. Propellant: Propane/Butane 5.00
Procedure:
Preparation of alcoholic phase:
1. In clean and dry container ethanol was taken.
2. To it cetyl alcohol and stearyl alcohol were added and stirred.
3. To above solution propylene glycol and tween 60 were added and stirred to get a clear solution.

4. To this the drug was added to obtain a clear solution. Preparation of aqueous phase:
5. In a clean and dry container water was taken.
6. To it 0. IN HC1 was added and stirred to get pH 4
The canisters were then filled by addition of weighed qty of alcoholic phase and aqueous phase, followed by crimping of the valve and filling of the propellant.
Example 4

SL. No: Ingredients % w/w
1. Clobetasol propionate 0.05
2. Cetyl Alcohol 1.80
3. Stearyl Alcohol 0.80
4. Propylene Glycol 3.00
5. Tween 60 0.50
6. Ethanol 55.00 .

7. 0.1NHC1 Qs
8. Distilled water qs
9. Propellant: Propane/Butane 5.00
Procedure:
Preparation of alcoholic phase:
1. In clean and dry container ethanol was taken.
2. To it cetyl alcohol and stearyl alcohol were added and stirred.
3. To above solution propylene glycol and tween 60 were added and stirred to get a clear solution.

4. To this the drug was added to obtain a clear solution. Preparation of aqueous phase:
5. In a clean and dry container water is taken.
6. To it 0.IN HC1 was added and stirred to get pH 4
The canisters were then filled by addition of weighed qty of alcoholic phase and aqueous phase, followed by crimping of the valve and filling of the propellant.
Example 5

SL. No: Ingredients % w/w
2. Betamethasone valerate 0.12
3. Cetyl Alcohol 1.80
4. Stearyl Alcohol 0.80
5. Propylene Glycol 3.00
6. Tween 60 0.50
7. Ethanol 55.00
8. 0.1NHC1 Qs
9. Distilled water qs
10. Propellant: Propane/Butane 30.00

Procedure:
Preparation of alcoholic phase:
1. Ethanol was taken in clean and dry container.
2. cetyl alcohol and stearyl alcohol were added to it and stirred.
3. To above solution propylene glycol and tween 60 were added and stirred to get a clear solution.

4. To this the drug was added to obtain a clear solution. Preparation of aqueous phase:
5. In a clean and dry container water was taken.
6. To it 0.IN HCl was added and stirred to get pH 3
The canisters were then filled by addition of weighed qty of alcoholic phase and aqueous phase, followed by crimping of the valve and filling of the propellant.
Comparitive Stability data of the composition of the present invention w.r.t. prior art composition
Prior art compositon containing a buffer Vs. composition of the present invention.
In this experiment, the stability of the prior art composition containing a buffer as a pH adjusting agent was evaluated against the invention of the present invention containing HCl as the pH adjusting agent. Both the compositions were kept on stability and the data is tabulated below. Following is the result.

Composition containing a buffer as a pH adjusting agent Composition containing HCl as the pH adjusting agent

Initial 40°C 75%RH/3M Initial 40°C 75%RH/3 M
Betamethasone base (%) 0.05 0.06 0.06 0.12

Betamethasone 21 Valerate (%) 2.06 3.80 0.05 1.48
% Single max 0.16 0.06 0.22 0.28
% Total impurity 2.86 4.54 0.79 2.60
Thus it can be seen that use of HCl as the pH adjusting agent lowers the impurity to a very large extent.
Compositions containing various acids as pH adjusting agents Vs composition containing HCl as pH adjusting agent according to the present invention.
In this experiment various compositions containing different acids was evaluated against the invention of the present invention containing HCl as the pH adjusting agent. All the compositions were subjected to Forced degradation at 121°C for 30 min and 60 min. The results so obtained are given below
Compositions :

S.No Ingredients (%w/w) I (according to present invention) II Ill IV
1. Betamethasone valerate 0.12 0.12 0.12 0.12
2. Propylene glycol 2.0 2.0 2.0 2.0
3. Ethanol 55.0 55.0 55.0 55.0
4. Distilled water Qs to 95% Qs to 95% Qs to 95% Qs to 95%
5. Hydrochloric acid Qs to pH
3.52,4.05,4.38 ,4.95
6. Citric acid Qs to pH
3.89,4.50,5.
08,5.30
7. . Phosphoric acid Qs to pH
3.54,4.69, 5.16
8. Tartaric acid - - Qs to pH 3.58 -

,4.04 ,4.65& 5.15
All the samples were subjected to Forced degradation at 121°C for 30 min and 60 min.
Results:
• From the analysis it was observed that Impurity Betamethasone -21 - Valerate was found to be same in all the samples at initial.
• The Impurity Betamethasone -21- Valerate (At 121°C /60min) was found to be increased to
34.23% at pH 5.3 with citric acid, 14.87% at pH 5.16 with phosphoric acid, 4.21% at pH 5.3 with hydrochloric acid, 13.44% at pH 5.15 with tartaric acid.
• The single max unknown impurity was found to have no significant increase at
forced degradation.
Thus it is seen that least increase in impurity is seen in pH adjustment with HCI. Hence pH adjustment with hydrochloric acid is most preferred since a composition using this will have the least impurity and higher amount of the active drug, thereby making available more of active drug to the affected area. .,

We claim,
1. A topical foam composition comprising one or more corticosteroids or their salts,
solvates, prodrugs, derivatives, esters, polymorphs or enantiomers thereof; a
quick-break foaming agent, a propellant and Hydrochloric acid and other suitable
pharmaceutically acceptable excipients.
2. The topical foam composition as claimed in claim 1 having a pH in the range of 3.0 to 6.0.
3. The topical foam composition as claimed in claim 2 having a pH in the range of 3.0 to 5.0.
4. The topical foam composition as claimed in any of the claims 1 to 3, wherein the Hydrochloric acid is present in an amount from 0.01 to 1.0% w/w;
5. The topical foam composition as claimed in claim 4, wherein the Hydrochloric acid is present in an amount in the range of 0.05 to 0.2% w/w.
6. The topical foam composition as claimed in claim 1, wherein the corticosteroid is a topically effective corticosteroid selected from the group consisting of alclometasone dipropionate, amcinonide, beclomethasone dipropionate, betamethasone benzoate, betamethasone dipropionate, betamethasone valerate, budesonide, clobetasol propionate, clobetasone butyrate, desonide, desoxymethasone, diflorasone diacetate, diflucortolone valerate, flumethasone pivalate, fluclorolone acetonide, fluocinolone acetonide, fluocinonide, fluocortin butyl, fluocortolone, fluprednidene acetate, flurandrenolone, halcinonide, hydrocortisone, hydrocortisone acetate, hydrocortisone butyrate, methylprednisolone acetate, mometasone furoate, triamcinolone acetonide, and pharmacologically effective mixtures thereof.
7. The topical foam composition as claimed in claim 1, wherein the corticosteroid is betamethasone or its salts, solvates, prodrugs, derivatives, esters, polymorphs or enantiomers thereof
8. The topical foam composition as claimed in any of the preceding claims, wherein the corticosteroid is selected from betamethasone valerate, betamethasone

hydrochloride, betamethasone phosphate, betamethasone salicylate, betamethasone sodium phosphate, betamethasone valero acetate, betamethasone dipropionate.
9. The topical foam composition as claimed in claim 8, wherein the corticosteroid is betamethasone valerate.
10. The topical foam composition as claimed in claim 1, wherein the corticosteroid is Clobetasol or its salts, solvates, prodrugs, derivatives, esters, polymorphs or enantiomers thereof
11. The topical foam composition as claimed in claim 10, wherein the corticosteroid is clobetasol propionate.
12. The topical foam composition as claimed in any of the preceding claim, wherein the corticosteroid is present in an amount from 0.025 to 0.5% w/w.
13. The topical foam composition as claimed in claim 1, wherein the quick-break foaming agent comprises an aliphatic alcohol, water, a fatty alcohol and a surface active agent.
14. The topical foam composition as claimed in claim 13, wherein the aliphatic alcohol is present in an amount corresponding to 40. to 60% by weight of the composition
15. The topical foam composition as claimed in any of the claims 13 or 14, wherein the aliphatic alcohol comprises one or more of methanol, ethanol, isopropyl alcohol, butyl alcohol, or mixtures thereof.
16. The topical foam composition as claimed in any of the claims 14 or 15, wherein the aliphatic alcohol is ethanol.
17. The topical foam composition as claimed in claim 13, wherein the water is present in an amount in the range of 10 to 40% by weight of the composition..
18. The topical foam composition as claimed in claim 13, wherein the fatty alcohol is present in an amount corresponding to 0.5 to 4% by weight of the composition
19. The topical foam composition as claimed in any of the claims 13 or 18, wherein the fatty alcohol comprises atleast one fatty alcohol having between 10 and 22 carbon atoms

20. The topical foam composition as claimed in claim 19 wherein the fatty alcohol comprises one or more of cetyl alcohol, stearyl alcohol, lauryl alcohol, myristyl alcohol, and palmityl alcohol, or mixtures thereof.
21. The topical foam composition as claimed in any of the claims 18,19 or 20, wherein the fatty alcohol is a mixture of cetyl alcohol and a stearyl alcohol.
22. The topical foam composition as claimed in claim 13, wherein the surface active agent is present in an amount 0.1 to 1.0 % by weight of the composition.
23. The topical foam composition as claimed in any of the claims 13 or 22, wherein the surface active agent comprises one or more of polysorbates, ethoxylated sorbitan stearate, ethoxylated sorbitan palmitate, ethoxylated sorbitan oleate, nonyl phenol ethoxylates, fatty alcohol ethoxylates, or mixtures thereof,
24. The topical foam composition as claimed in claim any of the claims 22 or 23, wherein the surface active agent is polysorbate 60 or polysorbate 80.
25. The topical foam composition as claimed in claim 1 wherein the propellant is present in amounts of3-30% w/w.
26. The topical foam composition as claimed in claim any of the claims 1 or 25 wherein the said propellant comprises one or more of propane, butane, dichlorodifluoro methane, dichloro tetrafluoro ethane, octafluoro cyclobutane, isobutene, isopentane, n-pentane or mixtures thereof.
27. The topical foam composition as claimed in any of the claims 25 or 26, wherein the propellant is propane/butane
28. A pharmaceutical product comprising the topical foam composition of claim 1 contained within a container capable of withstanding the pressure of the propellant and having a valve or nozzle for dispensing the foamable composition as a foam under pressure.
29. The topical foam composition as claimed in any of the claims 1 to 28 further comprising a humectant.
30. The topical composition as claimed in claim 29 wherein the humectant comprises one or more of guanidine, urea, glycolic acid, glycolate salts, ammonium glycolate, quaternary alkyl ammonium glycolate, aloe vera, polyhydroxy alcohol, sorbitol, glycerol, hexanetriol, propylene glycol, butylene glycol, hexylene glycol,

a hexylene glycol derivative, polyethylene glycol, a sugar, a starch, a sugar derivative, a starch derivative, alkoxylated glucose, monoethanolamine or mixtures thereof.
31. The topical foam composition as claimed in any of the claims 1 to 30 having the having a lower impurity profile.
32. The topical foam composition as claimed in any of the claims 1 to 31, which contains Betamethasone-21-valerate less than 4% by weight of the active.
33. The topical foam composition as claimed in any of the claims 1 to 31, which contains Betamethasone-21-valerate less than 3% by weight of the active.
34. The topical foam composition as claimed in any of the claims 1 to 31, which contains Betamethasone-21-valerate less than 2% by weight of the active.
35. The topical foam composition as claimed in any one of claims 32 to 34 wherein the composition has been stored at about 25°C and about 60% relative humidity
36. A method of preparation of a topical foam composition as claimed in any of the claims 1 to 35, which process comprises mixing the alcoholic and aqueous phases in the final container in the required amounts and charging the container with propellant.
37. The method as claimed in claim 36, wherein the alcoholic phase comprises fatty alcohol(s), surface-active agent, aliphatic alcohol and optionally humectant
38. The method as claimed in claim 36 wherein the aqueous phase pH adjusting agent, hydrochloric acid and water.
39. The use of a hydrochloric acid to stabilise a topical foam composition comprising corticosteroids.
40. The topical foam composition as claimed, in claim 1 for use in the treatment of skin diseases.
Dated this 20th day of December 2005

Dr. Gopakumar G. Nair
Agent for the Applicant