FIELD OF THE INVENTION
The present invention pertains to the field of pharmaceutical formulations. More specifically it pertains to a novel topical pharmaceutical composition for treatment of all kinds of dermal corns and calluses.
BACKGROUND OF THE INVENTION
Corns (also called clavi) are specially-shaped calluses (a callus is defined as toughened area of skin which has become relatively thick and hard) of dead skin that usually occur on thin or glabrous (hairless and smooth) skin surfaces, especially on the top of toes or fingers. They can sometimes occur on the thicker palmar or plantar skin surfaces. Since the skin acts as the body's protector, corns form when the body attempts to protect the troubled area from more pressure by building up a mass of dead skin cells and secreting a hard substance called keratin. If there is constant stimulation of the tissues producing the corns, even after the corn is removed or the pressure surgically removed, the skin may continue to grow as a corn. Their hard waxy core bores down into the skin and pressure on the underlying tissue and nerves can cause extreme pain. Persons who have abnormal bone structure in their feet or certain types of arthritis tend to develop corns and calluses. Generally, those who avoid high-heeled or tight-fitting shoes should be able to avoid corns and calluses.
Prior art methods/compositions for treating corns and calluses
The treatment of corns and calluses begins by attacking the cause, preventing the friction and relieving the pressure on the area. In the past, various forms of therapy have been employed in the treatment of corns and calluses and they include the use of
• Orthopedic appliances
• Water soluble ointment based medications
• Surgical procedures
• Orthopedic appliances: These are plastic inserts that hold the foot straight, heel wedges, heel seats or cups, sole wedges which can be placed in regular shoes for treating corns and calluses. These appliances work by gradually straightening the
bones at the rear of the foot, eventually resulting in the formation of arch. There are several drawbacks to this method of approach like they are very costly, quite rigid and non adjustable. Sometimes they tend to be uncomfortable, painful and a physician may recommend surgery. While the novel composition of present invention provides the consumer with an effective, gentle and safe product that overcomes the above mentioned limitations of orthopedic appliances (The Complete Encyclopedia of Medicine and Health by Johannes P. Schade, Page No 375-376).
• Water soluble ointment based medications and devices: These include primarily "keratolytic agents" such as salicylic acid and resorcinol. Traditionally, "keratolytic agents" such as salicylic acid and resorcinol have been applied topically to the lesions to solubilize intercellular bonds resulting in desquamation of the thickened, hyperkeratotic tissues. Many other acid preparations are also available for reducing corns and calluses such as glacial acetic acid, lactic acid, salicylic acid, phenoxyacetic acid, zinc chloride, ascorbic acid, calcium pantothenate, cantharidin, podophyllum and bleomycin sulfate. Specially medicated plasters and devices in form of 'corn caps' containing chemicals that can dissolve the tissue (keratolytics) are used for treatment of corns. However, these medications and devices have certain limitations which are as follows:
1. Affect normal tissues also: The preparation is containing chemicals that are supposed to 'eat away' the corn but the chemical cannot tell what corn is and what is normal - this chemical will eat wherever it is applied.
2. Can cause ulceration: The formulations can be risky in healthy people; it can be very dangerous and risky in those with poor circulation and diabetes since it can cause ulceration of the skin. The use of "corn caps" in those who are at risk or have frail skin is not advisable as it can lead to development of ulcer (breakdown of the skin) which can become infected and lead to further complications.
3. Product related difficulties: Different sizes of caps are necessary depending on the size of the corn on the toes and these should not be used in cuts and burns.
In contrast, the novel topical pharmaceutical composition of the present invention comprising benzoin tincture /Compound benzoin tincture supersaturated with salicyclic acid does not suffer from such limitations. It offers the advantages of high penetration and eliminates offending lesions without affecting the healthy skin. It restores the normal lines and the natural texture of the skin. Also, this medication has been found advantageously to bring softening of the hard callous or corn tissues, thereby lessening the irritating impact of any bony prominences that may act against the involved tissues. It thus allows the use of conventional shoes as opposed to special orthopedic shoes which a person affected by corns may be forced to wear. Thus, even while the treatment is being performed, this novel topical composition relieves the painful symptoms of the corns by softening them.
• Surgical procedures: These involve removal of the corns and calluses by 'cutting away' using surgical blades etc. However, as the 'root' of the corn is not removed, the surgical procedures do not offer a permanent solution and the corns and calluses keep on growing. While the novel composition of present invention removes the corn and calluses permanently and no reoccurrence at the same point (Redmond A et ah. Effect of scalpel debridement on the pain associated with plantar hyperkeratosis. J Am Podiatr Med Assoc, 89(10): 515-9).
Compositions available in the market: A number of corn and callus removal compositions are available in the market, but none of them disclose the novel composition of the present invention. Some of the corn and callus removal compositions are briefly mentioned below in Table 1:
Table 1:

(Table Removed)
Patents in the prior art are briefly reviewed as below:
US Patent 4824865 discloses that 2-hydroxyoctanoic acid, 2-ketooctanoic acid and their C2 to C6 alkyl esters are useful in treating callous-forming disorders notably palmar and plantar hyperkeratosis including corns. It offers the advantage of having wide spectrum of activity in the successful treatment of skin disorders, painless and the response to treatment is more rapid. However it suffers from the limitations that pH and amount of composition employed should be kept within defined limits. The patent does not disclose the novel topical pharmaceutical composition of the present invention comprising Benzoin tincture/Compound benzoin tincture supersaturated with salicylic acid.
US Patent 5686083 discloses a topical composition for treating corns and calluses which comprise a 4 carbon a-keto acid like a-ketobutyric acid, its corresponding salts or esters in combination with a pharmaceutically acceptable carrier. The pharmaceutically acceptable carrier may be a liquid such as propylene glycol, petrolatum, ethanol, acetone, dimethyl sulfoxide (DMSO), and the like. There can be added conventional adjuvants, conventional penetration enhancers, conventional buffers, preservatives, hydrophilic emulsifiers, lipophilic emulsifiers, sun-screening agents, perfumes, emollients, deodorants etc. It offers the advantages of faster removal of corn and calluses and can be taken in various delivery forms like salves, lotions, plaster devices, collodion-type vehicles, suspensions, ointments, sprays, bandages etc. However it suffers from the limitations of affecting the normal tissues besides the affected part i.e. the tissue which has hardened, forming a corn. The patent does not disclose the novel topical pharmaceutical composition of the present invention comprising Benzoin tincture/Compound benzoin tincture supersaturated with salicylic acid.
US Patent 3514515 discloses a preparation containing a salt of thioglycolic acid as the active ingredient, along with an inert vehicle like propylene glycol or hydrophilic ointment base for arresting and eliminating corns and calluses from parts of the human body. It offers the advantages of maintaining the irritated tissues in a soft and resilient state over a period of time, thereby lessening the irritating impact of the painful corns and
calluses. However it suffers from the limitations of affecting the normal tissues. The patent does not disclose the novel topical pharmaceutical composition of the present invention comprising Benzoin tincture/Compound benzoin tincture supersaturated with salicylic acid.
US Patent 4012508 discloses an ointment for topical use comprising a small amount of a cortical steroid intimately mixed with aspirin in a suitable carrier such as petroleum jelly wherein about 45 to 125 parts of the steroid per million parts of the aspirin are present in the mixture. It offers the advantages that the ointment can be applied to corns, calluses, planter's and seed warts and various other forms of skin disorders. However it suffers from the limitations that remission of the disorder is slow and frequently incomplete. Even the widespread uses of steroids become limited due to severe contraindications without medical supervision. The patent does not disclose the novel topical pharmaceutical composition of the present invention comprising Benzoin tincture/Compound benzoin tincture supersaturated with salicylic acid.
US Patent 0053289 discloses a kit comprising an AM (morning) treatment system and a PM (evening) treatment system stored within the box. The AM treatment system comprises a plurality of AM foam bandages each having a medicated foam pad of hydrocolloid. The PM treatment system comprises a plurality of PM foam protective covers and a plurality of PM medicated non-woven patches impregnated with salicylic acid. It offers the advantages that kit limits the migration of the salicylic acid to healthy skin. However it suffers from the limitations that the PM foam protective covers need to be cut from the foam roll in various shapes, sizes and sealed. Even the kit is very complex and treatment cycle also takes a very long time. The patent does not disclose the novel topical pharmaceutical composition of the present invention comprising Benzoin tincture/Compound benzoin tincture supersaturated with salicylic acid.
US Patent 4588590 discloses an improved nail polish composition containing an effective amount of at least one corrosive agent for treating corns, calluses and warts. It has the advantage of reducing the moisture exchange between the skin and the
environment, relatively inexpensive and generally affordable by the public. However it suffers from the limitations that the selected nail polish should form an occlusion over the affected area when dry. The patent does not disclose the novel topical pharmaceutical composition of the present invention comprising Benzoin tincture/Compound benzoin tincture supersaturated with salicylic acid.
EP Patent 0658108 discloses a medicament that contains an effective amount of at least one saturated (alpha)-hydroxy fatty acid having 12 to 22 carbon atoms, salts or esters. The medicament can be in the form of a liquid preparation or a medicated device which contains the saturated (alpha)-hydroxy fatty acid. It has the advantage of providing compounds which can rapidly penetrate corn and callus tissues to facilitate rapid softening or loosening for removal from the body. However it suffers from the limitations of affecting the normal tissues. The patent does not disclose the novel topical pharmaceutical composition of the present invention comprising Benzoin tincture/Compound benzoin tincture supersaturated with salicylic acid.
In contrast to the patents of the prior art, the novel topical composition of the present invention is very simple, economical and easy to formulate. All the ingredients of the novel composition are easily available commercially. It is found to be very effective in the removal of corns and calluses without affecting the normal skin and possesses synergistic effect. It does not allow the accidental washing off or dispersal of the liquid formulation.
US Patent 6303140 discloses a plaster preparation comprising a synthetic rubber, a reinforcing agent based on silica or random styrene-butadiene, copolymer; a tackifier, salicylic acid and pharmaceutically acceptable salt or ester. The patent does not disclose the novel topical composition of the present invention. It offers the advantage of providing a medicated plaster which is efficacious and can release the active ingredient into the skin at a sufficient rate to treat or remove warts, corns and calluses. However it suffers from the following limitations:
• Contains rubber which is an 'allergen': Many individuals are allergic to synthetic rubbers and government regulatory agencies have responded by mandating that medical devices containing synthetic rubber must bear label warnings of possible allergic sensitization.
• Stability problems: Corn remover plasters reported in the prior art patent are subject to a phenomena known as "cold flow" in which during storage the plaster or polymeric component tends to ooze out or extrude beyond the edge of the medicated disk.
So the corn plaster composition reported in the prior art patent does not have adequate properties for adhering to the site of application on the skin. While the composition of present invention has high penetration power and allow sustained release of the active ingredient without accidental washing off or dispersal in addition to a long time adherence to the affected area.
Thus the methods or compositions reported in prior art need the entire treatment cycle to be completed and do not ensure that the healthy and unaffected areas of skin close by to the affected corn area remain healthy and the medication does not affect healthy tissues of the skin. The medication continues to burn the corn affected as well as unaffected close by areas continuously. The inventors of present invention developed a faster acting corn remover composition containing Benzoin tincture/Compound benzoin tincture supersaturated with salicylic acid which prevents damage to the corn or callus adjoining normal tissues.
Although both the compounds are individually known for their properties yet the synergistic combination of both as described in the present invention is nowhere reported in prior art to the best of inventor's knowledge. The composition of present invention is very simple, effective and possesses synergistic effect. It provides the consumer with an effective, gentle and safe product that can be easily stored and used when required.
OBJECTS OF THE INVENTION
The invention has the following objects:
1. To disclose a novel topical pharmaceutical composition possessing synergistic effect which is very simple, cost effective, safe and having higher efficacy than the compositions existing in prior art.
2. To disclose a novel topical pharmaceutical composition which provides maximum comfort to the user and minimal damage to healthy skin while effectively removing painful corns and calluses.
3. To disclose a faster acting novel topical pharmaceutical composition which can rapidly penetrate into the corns and calluses to facilitate softening or loosening for their easy removal from the affected body parts.
SUMMARY OF THE INVENTION
The present invention provides a novel, synergistic topical pharmaceutical composition for the treatment of dermal corns and calluses which is very simple, cost effective, safe and efficacious. It provides faster removal of corns, eliminates the offending lesions without affecting the healthy skin and brings the softening of the corn tissues.
BRIEF DESCRIPTION OF THE DRAWINGS
NIL - No drawings attached.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a novel topical pharmaceutical composition for treatment or removal of corns and calluses which can obviate the drawbacks of existing compositions viz. complexity, less efficacy, high cost etc.
NOVELTY ASPECT OF INVENTION
The present invention discloses a novel topical pharmaceutical composition comprising Benzoin tincture/Compound benzoin tincture supersaturated with salicylic acid for the treatment of corns and calluses. It is very simple, having synergistic effect and high

efficacy and the same has not been disclosed anywhere in the prior art to the best of inventor's knowledge.
INVENTIVE STEP
The inventive step of the invention lies in developing a topical pharmaceutical composition which is a simple, inexpensive faster acting corn and callus remover. This is achieved by supersaturating Benzoin tincture/Compound benzoin tincture with salicylic acid at room temperature which is nowhere disclosed in prior art methods. After considerable research effort, the inventors developed the present product which is quite efficacious in the treatment of painful corns and calluses, easy to formulate and quite inexpensive.
INDUSTRIAL APPLICATION
The present invention can easily be manufactured on Industrial scale, as a pharmaceutical composition for the removal of corns and calluses. It provides the consumer with an effective, gentle, more economical and safe product that can be easily stored and used as needed.
DETAILS OF THE INVENTION
Ingredients
1. Benzoin tincture or Compound benzoin tincture
2. Salicylic acid
Although both the compounds are individually known for their properties as described below yet the combination of both as a novel topical pharmaceutical composition for the treatment of corns and calluses is nowhere reported in prior art to the best of inventor's knowledge.
Benzoin tincture is a pungent solution of benzoin resin in alcohol. The composition of Benzoin tincture is as follows: Benzoin-10% and Alcohol -90%
Compound benzoin tincture (Friar's Balsam) : It comprises Benzoin (10%), storax or liquid amber resin (8%), aloe (2%), tolu balsam (4%), and alcohol (75% to 83%).
(Ref: SUDHENDU SEKHAR SEN GUPTA (1976) KGHOSH'S Pharmacology Materia Medica and Therapeutics (23rd edition) Publisher Hilton and Co., Calcutta pp Page -
571)
Benzoin tincture has mucosal protectant and antiseptic properties. It work as a mucosal protectant for recurring sores and blisters. Compound benzoin tincture has antiseptic, mild styptic(anti haemorrhagic agent ) aromatic inhalant and topical protectant properties . It work as topical protectant and mild styptic for intact skin as a protective dressing . It acts as inhalant by relieving nasal congestion and soothes bronchitis.
Salicylic acid is a white crystalline powder or needle-shaped crystals with sweetish taste. It is slightly soluble in water but soluble in acetone, ether, alcohol, boiling water, benzoin and sparingly soluble in chloroformbenzene. It is having the chemical formula of C6H4 (OH) COOH and melting point of 158°C.
Salicylic acid has analgesic, antipyretic and keratinolytic properties. It is a key ingredient in many skin-care products for the treatment of acne, psoriasis, calluses, corns and warts. It works as keratolytic agent by causing the cells of the epidermis to shed more readily, opening clogged pores and neutralizing bacteria within, preventing pores from clogging up again by constricting pore diameter and allowing room for new cell growth. It is also used as an intermediate of dyes, insecticides, pharmaceutical, pesticides and other chemical compounds.
Mechanism of action of the synergistic composition of the present invention
The composition of the present invention which comprises a solution of benzoin tincture or compound benzoin tincture supersaturated with salicyclic acid exhibits synergistic effects. The tincture acts as a 'carrier' of salicyclic acid, thus promoting localized faster penetration right upto the root of the corn, enabling faster corn removal. Secondly, the
tincture helps localize the composition to the 'application area' owing to thick and viscous nature which forms a 'coating' on the corn after drying, thus preventing the composition of the present invention from spreading to the surrounding tissues and affecting normal cells. The components of the present invention, individually are not as effective in corn removal as when present together in the composition prepared according to the process of the present invention i.e synergistic effect is exhibited.
Method of preparation
Salicylic acid in powder form is directly added to Benzoin tincture/Compound benzoin tincture until the supersaturation of solution is achieved. Super saturation procedure is performed for three days at room temperature while occasionally stirring the solution. Then resulting solution is kept as such for one day at room temperature to allow ripening
The criticality of the novel composition lies in being able to bring about synergistic effects which offer three distinct advantages as follows:
1. Enhanced efficacy: It increases the efficacy of the preparation owing to synergistic effect. This is a faster acting corn remover composition containing salicylic acid as the active ingredient and Benzoin tincture/Compound benzoin tincture as a vehicle in which the active ingredient is administered. The vehicle act as a inert medium which add bulk to the formulation without interfering with the active ingredient and confer a suitable consistency to the resulting preparation to facilitate its application. The Benzoin tincture/Compound benzoin tincture compound of new preparation helps in deep penetration of the active compound and ensures long and sustained release of the same without accidental dispersal or washing off.
2. Reduction of undesirable side-effects: The benzoin tincture/compound benzoin tincture on drying forms a protective coat which prevents 'spreading' of the salicyclic acid to surrounding normal tissues, thus preventing undesirable side-effects.
3. Simplicity of formulation: Both the ingredients are easily available commercially. The innovation lies in being able to formulate them into an efficacious composition which is effective in removal of corns and calluses.
Method of use: A little dab of preparation is applied directly to the small circumscribed area of the enucleated corns preferably with help of cotton swab or 'cotton ear buds' which are easily available commercially. It is applied daily, preferably at night so that after application, the affected area remains undisturbed. The composition is applied in continuation for 15-20 days. The duration of the application and treatment is not restrictive and can vary depending upon the severity of the corn and stage of development. In case of corns and calluses which are small and at initial stages of development, treatment can be short, lasting a few days, while for deep seated older corns, the affected person will have to apply the composition for longer duration, till the corn softens and 'leaves' its seat, permitting removal. As a precautionary measure, the composition should not touch the normal unaffected skin or tissue and should be directly applied only on the corn or callus.
The novel composition was successfully used in several patients and found to be remarkably efficacious, painless and economical for removal of corns and calluses. It was found to eliminate corns and calluses without affecting the healthy skin, restoring the natural texture of the skin and preventing recurrence at the same point. Also, it was advantageously able to soften corn tissues, thereby lessening the irritating impact of any bony prominence. Thus, the present invention provides a faster acting corn and callus remover composition which is very simple, effective and possesses synergistic effect.
Advantageously, the novel composition of the invention can take any of the following delivery forms: salves, lotions, plaster devices, collodion-type vehicles, suspensions, ointments, creams, gels, sprays, bandages, patches or other appropriate topical vehicles or delivery devices. It provides the consumer with an effective, gentle and safe product that can be easily stored and used as needed.
In the above detailed description of the invention, a novel composition for treating corns and calluses has been disclosed with particular reference to the preferred forms thereof. Deviations to the same can easily be carried out by those skilled in the art once the basic concept is understood and hence must be regarded as within the scope of the present invention which is not intended to be limiting.

I CLAIM:
1. A novel composition for treatment of corns and calluses wherein the same comprises tincture of benzoin supersaturated with salicylic acid.
2. A novel composition for treatment of corns and calluses wherein the same comprises compound benzoin tincture supersaturated with salicylic acid.
3. A process for the preparation of the composition of claim 1 or claim 2 comprising

- Taking a solution of tincture of benzoin or compound benzoin tincture.
- Adding salicyclic acid with continuous stirring at room temperature till supersaturation is achieved

4. The composition of claim 3 wherein supersaturation is carried out optimally for a period of three days, with occasional stirring.
5. The composition of claim 3 or claim 4 wherein after supersaturation the composition is kept at room temperature for at least one day for ripening.
6. The composition of claim 1 or claim 2 wherein after addition of excipients it can have any of the following delivery form such as salve, lotion, plaster device, collodion-type vehicle, suspension, ointment, cream, gel, spray, bandage, patch or other appropriate topical vehicle or delivery device.
7. The composition of claim 1 or claim 2 and a method for its preparation thereof as described substantially herein with reference to the detailed description.