DANDRUFF AND OTHER SCALP DISEASES AND ITS METHOD OF

PREPARATION THEREOF

FIELD OF INVENTION

The field of invention is pharmaceutical formulations. More specifically, the invention describes an improved, water dispersible coal tar formulation for treatment of dandruff and other scalp diseases and its method of preparation thereof.

BACKGROUND OF THE INVENTION

Dandruff {Pityriasis capitis) is a global phenomenon usually associated with excessive shedding of dead skin cells from the scalp. The process of dying and flaking off of the skin cells in unusually large amount accompanied by redness and irritation is considered as dandruff. Skin oil commonly referred to as sebum or sebaceous secretions, metabolic by- products of skin micro-organisms (most specifically Malassezia sp yeasts) and individual susceptibility are the main causes for the problem of dandruff. The fungus Malassezia furfur (previously known as Pityrosporum ovale) is a major cause of dandruff. Although very rare but dandruff can also be a manifestation of an allergic reaction to chemicals in hair gels/sprays, hair oils.

Dandruff Treatment Shampoos: Traditionally, regular shampoos were used to get the symptomatic relief but their failure to provide proper treatment leads to the usage of OTC (over the counter) dandruff shampoos, which are classified on the basis of active ingredients as below:

Zinc pyrithione based e.g. Head & Shoulders®

Coal tar based e.g. Neutragena T®

Salicylic acid based e.g. Ion i 1 T®

Selenium sulphide based e.g. Selsun Blue®

Ketoconazole based e.g. Nizoral® Limitations:

• Short contact time: between the active agent and the scalp, as it is to be washed within 5 min. of application, due to which either the duration of treatment is prolonged from weeks to months or/and it is ineffective.

• Lack of efficacy: Despite the introduction of potent "anti-dandruff ingredients, the formulations are not effective, due to short contact time. Hence, there is dire need to prolong retention or contact of the drug with the affected area to improve efficacy.

Use of Coal tar for treatment of skin diseases

Coal Tar is also known as 'liquor carbonis detergens ' (LCD) and 'liquor picis carbonis '. Composition: Coal tars are complex combinations of hydrocarbons, phenols and heterocyclic oxygen, sulphur and nitrogen compounds. It is prepared during the production of coke and gas and these are the by-products of destructive distillation of coal. Over 400 compounds have been identified in coal tars, and as many as 10,000 may actually be present. Composition of coal tar varies with its origin and type of coal (e.g. lignite, bituminous or anthracite) used to make it.

Therapeutic use: Coal tar has been used for dermatological conditions for over 2000 years, when it was referred to "asphalt" by Dioscorides, a Greek physician and pharmacologist. More recently, therapeutic coal tar in dermatology was emphasized in 1681 by Bechar and Serle. It has been a very popular traditional treatment for various types of scalp disorders including dandruff, atopic dermatitis, seborrheic dermatitis and chronic stable plaque psoriasis. Tar is used mainly in the treatment of various scalp disorders either alone or in combination therapy with other medications, phototherapy, or both. According to the National Psoriasis Foundation and the USFDA, coal tar is a valuable, safe and inexpensive treatment option for millions of people with psoriasis and other scalp or skin conditions. Coal tar concentrations between 0.5% and 5% are safe and effective for psoriasis and no scientific evidence suggests that the coal tar in the concentrations seen in non-prescription treatments is (or is not) carcinogenic because there are too few studies and insufficient data to make a judgement.

Formulations based on coal tar: Both prescription and non-prescription preparations of coal tar are available and include cleansing bars, creams, gels, lotions, ointments, shampoos, and other topical solutions and suspensions. When used in topical medications, it is supplied in the form of Coal Tar Topical Solution USP (United States Pharmacopeia), which consists of a 20% w/v solution of coal tar in ethyl alcohol, with an additional 5% w/v of polysorbate 80 USP; this must then be diluted in an ointment base such as petrolatum.

Mechanism of action: Being a crude material and having a complex composition, the exact mechanism of action of coal tar is not known yet. But there are many theories which are thought to play a role in treating varied scalp diseases by coal tar. Coal tar belongs to a class of drugs known as keratoplasties. It works by causing the skin to shed dead cells from its top layer and slow down the growth of skin cells. This effect decreases scaling and dryness. Coal tar can also decrease itchiness from these skin conditions. Coal tar helps to decline the rapid proliferation of the skin cells and return to skin to a normal appearance.

Benefits: Coal tar preparations are more effective and cheaper than most other available treatments for scalp psoriasis, including corticosteroids and calcipotriol and extend the length of remission without causing systemic side effects.

Limitations: Low penetration through skin thus low bioavailability, messy application and staining of clothes and skin during application. Due to viscous consistency, oily nature of coal tar based formulations and. presence of long, dense hair, it is difficult to apply these preparations to the scalp leading to reduced efficacy of the preparation. On application, the hair become messy and difficult to wash, further reducing patient compliance.

Improvements made to overcome limitations of coal tar based formulations:

• Topical lipid vesicles formulations- Development of topical lipid vesicles formulation of the drugs is a promising alternative to overcome the problems associated with conventional formulations as discussed earlier. Lipid vesicles were originated in 1965 by Bingham and the name given was "Bingham bodies" which play a major role in modelling biological membranes and in the transport and targeting of active agents. Consequently, a number of vesicular delivery systems such as liposomes, niosomes, sphingosomes, ethosomes, transferosomes and pharmacosomes were developed and used to improve therapeutic index of both existing and new drug molecules by encapsulating an active pharmaceutical ingredient inside the vesicular structure in one such system.

• Lipid emulsions- Lipid emulsions are suitable for drug delivery of lipophilic drugs. Thus these systems have the potential for an improved benefit/risk ratio of the topical drug therapy and have high degree of effectiveness in the treatment of diseases.

• Nano-emulsions- Nano-emulsions have several significant advantages including low skin irritation, powerful permeation ability, and high drug- loading capacity for the topical delivery when compared with other carriers.

Some of the commercially available coal tar based formulations are given in Table 1 below. All of these formulations contain coal tar solution which is a 20% w/v solution of coal tar in alcohol. Only one marketed formulation-LIPOTAR uses coal tar but that also contains alcohol (ethanol), which evaporates fast and has a drying effect on the skin.

Table 1: Commercially available coal tar based formulations

solution

Salicylic acid

Benzocaine

5 Psoriatrax Coal tar Shampoo solution

6 Denorex Coal tar Parachlorometaxylenol Shampoo solution

7 Galderma Coal tar Lauromacrogol 200, Shampoo

Ionil T solution Lauromacrogol 1 150, Ethanol and

Shampoo Salicylic acid Purified Water, Disodium Edetate

and Benzalkodnium Chloride

8 Neutrogena Coal tar Shampoo

T/Gel extract/

solution

Salicylic acid

Zinc

Pyrithione

9 DHS tar Coal tar Purified Water, TEA Lauryl Shampoo shampoo extract/solution Sulfate, Sodium Chloride, PEG-8

Distearate, Cocamide DEA,

Cocamide MEA, and Citric Acid

10 Cutar Coal tar Mineral Oil, Isopropyl Myristate, Lotion

emulsion solution Polysorbate 80, Sorbitan

Sesquioleate, Lanolin Alcohols

Extract, Methyl And Propyl

Parabens, Fragrance, Xanthan

Gum, Carbomer

1 1 Elta tar Coal tar Petrolatum, Paraffin, Mineral Oil, Cream

solution PVP Eicosene Copolymer,

polysorbate 90, alcohol

12 MG217 Coal tar Petrolatum, Cetyl Alcohol, Foam

Medicated solution Polysorbate 80, Microcrystalline

Tar Ointment Wax

13 Carbo-dome Coal tar Beeswax, white soft paraffin, Cream

solution light liquid paraffin, glycerol,

sodium lauryl sulphate, methyl-p- hydroxybenzoate and purified

water

14 Psorigel Coal tar Ethanol, fragrance, isopropyl Gel/Ointment solution alcohol, and polysorbate 80

15 Lipotar Coal Tar Tween, lecithin, paraffin, coconut Gel

Salicylic acid oil, ethanol

Note: Coal tar solution is ethanolic extract of coal tar

In the aforementioned table, all formulations except one, contain coal tar solution which is an ethanolic extract of coal tar (more than 80% v/v ethanol content). Formulations based on coal tar only (and not coal tar solution), contain ethanol and do not include water at all. In contrast, the composition of the present invention does not use coal tar solution at all. Instead it uses coal tar and water as its key ingredients. Such a composition of coal tar in which water is the major phase comprising more than 70% w/w of the said composition has not been disclosed in the prior art at all and is being disclosed for the first time.

Prior art patents

Dandruff and scalp diseases such as seborrheic dermatitis and pruritis represent widespread cosmetic problems. Methods for the treatment of dandruff and seborrheic dermatitis and pruritis are known in the art. Among the most common treatment regimens are washing with shampoos containing chloroxylenol, pyridinethione heavy metal salts including zinc, cadmium, magnesium, tin, aluminum and zirconium; salts such as zinc pyrithione, sulfur, selenium sulfide, salicylic acid, piroctone olamine also known as octopirox; hexachlorophene, resorcinol, coal tar, coal tar extracts, coal tar solutions, ketoconazole, alkali metal salts and ammonium salts of low molecular weight huminates with a mean molecular weight of 1000 with a range of 300 to 1500, and certain cationics such as cetyldimethylbenzylammonium bromide followed by rinsing, as disclosed in U.S. Pat. Nos. 4,470,982, 5,494,675, 5,641 ,480, 5,730,965 and 6,294, 186, each of which is incorporated herein by reference. Cooling sensates have also been added in compositions for the treatment of dandruff and other scalp diseases. Use of cooling sensates such as menthol and menthyl lactate is disclosed in U.S. Pat. No. 6,294, 186, cited above.

US Patent No. 6075017 A discloses a composition for the treatment of dandruff. The same is a synergistic combination of a cytotoxic agent and an antifungal agent. The cytotoxic agent is selected from the group consisting of coal tar and zinc pyrithione and the antifungal agent is an antifungal imidazole.

US Patent No. 6319392 B l discloses a coal tar extract with reduced aromatic hydrocarbon content, method for obtaining same and dermatological and cosmetic compositions based on the same.

US 4178373 A discloses a coal tar gel composition for topically treating skin conditions, especially psoriasis and eczema which contains as an essential ingredient coal tar in a gel base. None of the prior art compositions or marketed formulations based on coal tar/coal tar solution discloses the composition of the present invention which comprises coal tar, water and emulsifiers as the major ingredients. Further, ethyl alcohol has been eliminated from the composition. Ethyl alcohol owing to its fast evaporation led to drying of the skin.

Limitations of Coal Tar

Though coal tar is already an established ingredient for treatment of scalp infections, it suffers from several disadvantages, particularly lack of aqueous dispersibility and messiness. Topical formulations containing coal tar as the active ingredient are extensively employed in the treatment of skin disorders, such as dermatitis. To be therapeutically effective, the active ingredient must be in a molecular dispersion to facilitate desired percutaneous absorption which is particularly important in achieving a therapeutic response for the management of psoriasis or eczema. Unfortunately, coal tar is practically insoluble in water.

Certain organic solvents and solubilizers have been found to be good solvents for various fractions of coal tar. However, they have been found to be undesirable for commercial applications for reasons such as their high volatility and low boiling points, their disagreeable odour and their untoward skin reaction.

Incorporation of coal tar in an alcoholic gel base suffers from the limitation that such compositions have a drying effect on the skin and result in the production of denatured protein. Furthermore, various water-soluble emulsifiers and oil liquids or emollients have been suggested for use in preparing creams or lotions. However, because of the undesirably low solubility of the coal tar in such vehicles, higher levels of these materials in topical products are required thereby increasing their cost and also adversely affecting their cosmetic appearance.

Accordingly, in view of the above considerations, it is seen that a need exists for a suitable composition in which a sufficient amount of coal tar can be solubilised so that it may be employed in a topical formulation, while being dermatologically beneficial, stable and pharmaceutically acceptable. The present formulation meets the need of such a composition. The composition of the present invention is an improved coal tar based formulation which comprises coal tar, water and emulsifiers as the major ingredients. It has been able to overcome the limitations of existing formulations in an innovative manner by introduction of ingredients which enable formation of emulsion with lotion like consistency. The formulation is thus a lipid based coal tar formulation with acceptable consistency, washability, enhanced penetrability and retention on the scalp and skin. Salicylic acid is used in the formulation to remove excessive dead tissue from the skin. Although the use of coal tar and salicylic acid has been disclosed in prior art, nothing in the prior art discloses or suggests, the unexpected and unobvious advantages obtained as a result of using emulsifiers such as lecithin and tween in combination with coal tar and other anti-dandruff substances in an aqueous phase. The combination of these elements in a personal care product provides the following benefits for a substantial period of time post-use:

i. Enhanced efficacy in treatment of dandruff and diseases of the scalp.

ii. Enhanced patient compliance due to ease of application and water

dispersibility, which enables easy washing of hair.

iii. No irritation of skin due to absence of ethanol or any other fast drying alcohol base.

iv. No offensive or unpleasant odour of coal tar.

v. Non-greasy and dose not leave sticky residue after application.

vi. Reduced frequency of application and overall duration of treatment.

vii. Improved general appearance of patient.

viii. Reduced side effects due to reduction in the doses of the active ingredients used.

SUMMARY OF THE INVENTION

The invention pertains to an improved, water dispersible coal tar formulation and its method of preparation thereof. The formulation comprises coal tar, water and emulsifiers as the major ingredients. It offers distinct advantages of enhanced efficacy in treatment of diseases of scalp, enhanced patient compliance due to ease of application, reduced frequency of application and overall duration of treatment, improved general appearance of patient and reduced side effects due to reduction in the doses of the active ingredients used. Owing to elimination of ethyl alcohol from the composition, drying of skin is considerably reduced. Further, the composition of the present invention being water dispersible, is easy to wash and does not stain the clothes. DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an improved, water dispersible, coal tar and salicylic acid, lipid-based, oil-in-water type emulsion, with the consistency of a lotion, processes for preparing the same and methods of use and treatment. This has been achieved by incorporation of one or more emulsifiers from about 4% to about 18% by weight, based on said composition and presence of aqueous phase as the major phase in the said composition which contains coal tar at concentration of about 1 to about 4% by weight. The composition contains one or more emulsifiers selected from the group consisting of lecithin, sorbitan monoester (Span) and polyethoxylated sorbitan monoester (Tween).

Key ingredients of the novel composition of the present invention and their role/function are described below in Table 2:

Table 2: Key ingredients of the improved coal tar formulation and their functions

The improved formulation of the present invention offers the following advantages not offered by existing commercially available formulations or prior art compositions:

i. Enhanced efficacy in treatment of diseases of scalp.

ii. Reduced side effects due to reduction in the doses of the active ingredients used.

iii. No offensive or unpleasant odour of coal tar.

iv. Not greasy and dose not leave sticky residue after application.

v. Reduced frequency of application and overall duration of treatment.

vi. Improved general appearance of patient.

vii. Enhanced patient compliance due to ease of application and water

dispersibility, which enables easy washing.

Novelty - The novelty of the present invention lies in incorporation of emulsifiers into the composition along with coal tar and water, resulting in an improved, water- dispersible, coal tar formulation not disclosed in the prior art or in commercially available formulations.

Inventive Step- The inventive step of the present invention lies in incorporation of emulsifiers into the composition along with coal tar and water, resulting in an improved, water- dispersible, coal tar formulation. Unlike prior art compositions, the formulation of the present invention is easy to apply and wash away, does not stain clothes, and has higher efficacy and reduced side-effects. This has been made possible by use of specific ingredients in specific ratios as given in Table 2 and incorporation of emulsifiers into the composition. Industrial application- Formulation of the present invention can be manufactured on industrial scale and has applications in the treatment of various skin diseases, including scalp related skin problems like dandruff, seborrheic dermatitis and psoriasis.

The following examples illustrate an improved coal tar based formulation and its various embodiments. The same are for illustrative purposes only and may not be construed as limiting in nature. Example 1

An improved formulation based on ingredients as shown in Table 2 is described below:

Table 2: Improved Coal Tar Formulation

The method of preparation of the formulation is given below:

Step 1 : Heat and melt the components of oil phase as per the concentrations given above and mix them by gentle stirring.

Step 2: Prepare Carbopol and Poloxamer solutions as per the concentration separately and mix into the mixture prepared at Step 1.

Step 3: Add Tween into this mixture.

Step 5: Maintain temperature of oil and aqueous phase at 70 ± 5 °C.

Step 6: Add oil phase in aqueous phase under continuous stirring and mixing.

Step 7: Keep temperature at 70 ± 5°C till formation of homogenous dispersion.

Step 8: Allow the temperature of formulation to come down to room temperature under constant stirring and mixing. The formulation formed is stable. This particular embodiment offers the advantage of high concentration of aqueous phase wherein the coal tar is dispersed uniformly in the aqueous phase.

Example 2

In another embodiment, the improved coal tar formulation is in form of a gel due to presence of a gelling agent such as HPMC (Table 3). To keep the skin soft, an oil such as oleic acid is also included in the composition.

Table 3: Improved Coal Tar Formulation

The method of preparation of the formulation is given below:

Step 1 : Heat and melt the components of oil phase.

Step 2: Mix the melted ingredients.

Step 3: Prepare HPMC solution and add tween into this.

Step 4: Maintain temperature of oil and aqueous phase at 70 ± 5°C.

Step 5: Add oil phase in aqueous phase under continuous stirring and mixing.

Step 6: Keep temperature at 70 ± 5°C till formation of homogenous dispersion.

Step 7: Allow the temperature of formulation to come down to room

temperature under constant stirring and mixing.

Step 8: Transfer the obtained formulation in suitable container. Example 3

In another embodiment, the improved coal tar formulation has the following composition (Table 4). In this particular embodiment, the formulation offers the advantages of having almond oil in place of oleic acid. Almond oil provides better nourishment to the skin.

Table 4: Improved Coal Tar Formulation

The method of preparation of the formulation is given below:

Step 1 : Heat and melt the components of oil phase.

Step 2: Mix the melted ingredients.

Step 3: Prepare Carbopol and Poloxamer solutions separately and mix.

Step 4: Add Tween into this mixture.

Step 5: Maintain temperature of oil and Aqueous phase at 70 ± 5°C.

Step 6: Add oil phase in aqueous phase under continuous stirring and mixing.

Step 7: Keep temperature at 70 ± 5 °C till formation of homogenous

dispersion.

Step 8: Allow temperature of formulation to come down to room temperature under constant stirring and mixing. Example 4

In another embodiment, the improved coal tar formulation has the following composition (Table 5). In this particular embodiment, the formulation offers the advantages of having methyl salicylate and canthradin oil for their analgesic, counterirritant and hair growth enhancing action, respectively. Additionally, these agents are also useful in masking the unpleasant odor of coal tar.

Table 5: Improved Coal Tar Formulation

The method of preparation of the formulation is given below:

Step 1 : Heat and melt the components of oil phase.

Step 2: Mix the melted ingredients.

Step 3: Prepare HPMC and Poloxamer solutions separately and mix.

Step 4: Add Tween into this mixture.

Step 5: Maintain the temperature of oil and aqueous phase at 70 ± 5 °C

Step 6: Add oil phase in aqueous phase under continuous stirring and mixing. Step 7: Keep temperature at 70 ± 5 °C till formation of homogenous

dispersion.

Step 8: Allow the temperature of formulation to come down to room

temperature under constant stirring and mixing.

From the above it is clear that the basic innovation lies in the combination of specific ingredients comprising coal tar, water and emulsifiers in specific concentrations, due to which the formulation offers the distinct advantages not offered in the prior art or the existing formulations available commercially. It offers distinct advantages of enhanced efficacy in treatment of diseases of scalp, enhanced patient compliance due to ease of application, reduced frequency of application and overall duration of treatment, improved general appearance of patient and reduced side effects due to reduction in the doses of the active ingredients used. Owing to elimination of ethyl alcohol from the composition, drying of skin is considerably reduced. Further, the composition of the present invention being water dispersible is easy to wash and does not stain the clothes.

The invention thus comprises an improved, water dispersible coal tar formulation in which coal tar, water and emulsifiers are the major ingredients. Variations in the formulation can easily be carried out by those skilled in the art, once the basic concept is understood and such embodiments should be regarded as within the scope of the present invention.