INTRODUCTION:

Fungal infection of skin, hair and nail has been increased in worldwide. The progression of fungal infection can berapid and serious. The fungal infection mainly cause by various fungal species especially Candida albicans which grow and spread on skin surface, cause symptoms like itching, reddening, thickening of skin. Skin infections including onchocytosis, vaginal infection are major conditions which can be treated by Transdermal drug delivery system. Topical semisolid dosage form mostly used to treat topical fungal infection to avoid the systemic or other GIT irritations.

Topical treatment of fungal infections has several superiorities including, targeting the site of infection reduction of systemic side effects, high patient compliance. Different type of topical antifungal compounds has been used in the treatment of various skin infections, but they fail to penetrate deeply into stratum corneum layer and they remain into the stratum corneum layer which makes this system quite a failure skin acts as a major target but also act as barrier for topical drug delivery. The main function of skin is to give the protection from water loss. Physical protection is provided by outer most layer of skin. The skin consists of mainly three layers subcutaneous tissue, dermis, and epidermis. Stratum corneum is outermost layer of epidermis. It consists of 10-25 layers of dead, elongated, fully keratinized corneocytes, which embedded in matrix of lipid bilayers. Stratum corneum is main barrier to penetration through the skin. When topical formulation is placed on skin active drug is required to penetrate through the stratum corneum into viable tissue. The limiting factor for these processes is slow diffusion through the dead Horney layer of skin. To overcome stratum corneum barrier, various mechanism have been investigated, including use of chemical or physical enhancers. The examples of these enhancers are iontophoresis, sonophoresis, liposomes, niosomes, transferosomes and ethosome. In novel drug delivery systems, noninvasive lipid elastic vesicles are very useful in transdermal drug delivery system to increase penetration. Drug encapsulated in lipid vesicles prepared from phospholipids which transported into and across the skin. Lipid vesicles may serve as nontoxic penetration enhancer for drugs. Many chemical enhancers have been investigated e.g. liposome, niosome, transferosomes and ethosome. Liposome is unstable and poor skin permeation. Noisome also has poor permeability. To overcome problem of permeability recently introduced new vesicular carrier system i.e. ethosome

SKIN LAYER-

Fig. 1 Skin layer

ETHOSOME-

Ethosome are lipid elastic vesicles which contain phospholipids and relatively high concentration of alcohol. Ethosomes are non-invasive delivery carries which penetrate deep into skin layer. Ethosomes are soft, malleable in nature. Ethosomes are mainly used for drugs which are having low solubility and having high molecular weight. Ethosome shows synergistic effect because of combination of phospholipids and high concentration of ethanol in vesicular formulations they responsible for deeper distribution and penetration in skin lipid bilayer size of ethosome is vary from nanometers to microns.

Fig. 2 Ethosome vesicles

COMPOSITION OF ETHOSOME

Table no-1 List of materials used in ethosome.

Material	Examples	Uses
Phospholipid	Soya phosphatidyl choline Egg phosphatidyl choline Dipalmitylphosphatidyl choline Distearylphosphatidyl choline	Vesicles forming component
Polyglycol	Propylene glycol	As a skin penetration enhancer
Alcohol	Isopropyl alcohol, Ethanol	For providing the softness for vesicle membrane As a penetration enhancer
Cholesterol	Cholesterol	For providing the stability to vesicle membrane.
Vehicle	Carbopol 934	As a gel former

ADVANTAGES OF ETHOSOME-

1. Ethosome is soft and malleable in nature.

2. Ethosome contain nontoxic raw material so ethosome formulation is safe for use.

3. Ethosome has better stability and solubility as compared to conventional vesicles.

4. Ethosome facilitates delivery of large molecules as well as small molecules.

5. Ethosome is semisolid dosage form, producing high patient compliance

6. This system is passive and non-invasive in nature.

7. It enhances permeation of drug molecules to and through the skin to the systemic circulation.

8. It avoids first pass metabolism effects and their related side effects.

9. Ethosome drug delivery system can be applied widely in Pharmaceutical, veterinary, cosmetic fields.

10. Method of preparation of ethosome is simple as compared to other transdermal drug delivery system.

LIMITATIONS OF ETHOSOMES-

1. Poor yield.

2. In case if shell locking is ineffective then the ethosomes may coalescence and fall apart on transferinto water.

3. Loss of product during transfer from organic to water media.

MECHANISM OF DRUG PENETRATION^[3]-

Generally, Ethosomes are high fluidity of lipid layer low density layer; soft, malleable vesicles penetrate from layer and in deep layer it release drug. Basically ethosome, mechanism of penetration occurs into mainly two phases first is ethonolic effect and second is ethosome effect.

ETHANOLIC EFFECT-

In this phase, ethosome vesicles contain ethanol in relatively high concentration. Ethanol acts as permeation enhancer and it fluidizes the lipid bilayer. Also it decreases density of lipid multilayer.

ETHOSOME EFFECT-

Ethosome is soft and malleable vesicles. Vesicles easily penetrate from lipid layer because of its decreasing density and increase fluidity. Ethosome vesicles are penetrate deep into skin layer it fuse with lipid layer

Fig. 3 Mechanism of drug penetration

METHOD OF PREPARATION OF ETHOSOME-:

Ethosomes can be prepared by two methods, one is hot method and other method is cold method.

Cold method:

This is the most common method for the preparation of ethosome formulation. In covered vessels phospholipids, drug and lipid materials are dissolved in ethanol with vigorous stirring. In this mixture propylene glycol or other polyol is added during stirring. This mixture is heated to 30⁰C in water bath. At same time water is heated in separate vessels at 30⁰c. Then water is added in previous mixture, which is then stirred for 5min. incovered vessel. Vesicles size of formulation is decreased by using sonication or extrusion method.

Mixture is dissolved in ethanol in covered vessel.

Propylene glycol or other polyol is added

Water is added at same temperature (300c)

Stir for 5 min. in vessels ad size reduction achieve by using sonication or extrusion

Fig-4 Flow chart for procedure of cold method.

Hot method:

In this method disperse phospholipids dissolved in water by heating in a water bath at 40 ⁰C until a colloidal solution is obtained. In a separate vessel ethanol and propylene glycol are mixed properly and this mixture is heated up to 40⁰C. At equal temperature, add the organic phase into the aqueous phase. Drug is dissolved in water or ethanol depending on its solubility. The vesicle size of ethosomal formulation can be decreased to the desire extent using probe sonication or extrusion method.

Fig: 5 Flow chart for procedure of hot method.

CHARACTERIZATIONS OF ETHOSOMES^[9]:

1. VESICLE SHAPE-

Ethosomes can be easily visualized by using transmission electron microscopy (TEM) and by scanning electron microscopy (SEM).

2. VESICLE SIZE AND ZETA POTENTIAL-

Particle size of the ethosomes can be determined by dynamic light scattering (DLS) and photon correlation spectroscopy (PCS). Zeta potential of the formulation can be measured by Zeta meter.

3. TRANSITION TEMPERATURE-

The transition temperature of the vesicular lipid systems can be determined by using differential scanning calorimeter (DSC).

4. DRUG ENTRAPMENT-

The entrapment efficiency of ethosomescan be measured by the ultracentrifugation technique.

5. SURFACE TENSION MEASUREMENT-

The surface tension activity of drug in aqueous solution can be measured by the ring method in a Du Nouy ring tensiometer.

6. DRUG CONTENT-

Drug content of the ethosomes can be determined using UV spectrophotometer. This can also be quantified by a modified high performance liquid chromatographic method.

7. STABILITY STUDIES-

The stability of vesicles can be determined by assessing the size and structure of the vesicles over time. Mean size is measured by DLS and structure changes are observed by TEM.

8. SKIN PERMEATION STUDIES-

The ability of the ethosomal preparation to penetrate into the skin layers can be determined by using confocal laser scanning microscopy (CLSM).

APPLICATION OF ETHOSOME-

1. Delivery of anti-viral drugs-

Oral administration of antiviral drug is associated with strong side effects. To overcome this side effects and also to increase permeation of drugs through skin ethosome drug delivery system are used. Zidovudin and Acyclovir have oral side effects and also poor skin penetration. This problem is avoided by using ethosome drug delivery system.

2. Topical delivery of DNA-

Skin acts as excellent protective barrier and also immunologically active and able to express genes. Ethosome is used for topical delivery of DNA molecules to express genes in skin cells. Touitou et.al.^[19]In their study encapsulated the GFP-CMV- driven transfecting construct into ethosome formulation. Topically applied ethosomes GFP-CMV- driven transfecting construct enabled efficient delivery and expression of genes in skin cells. Ethosome could be used as carriers for gene therapy applications.

3. Transdermal delivery of hormones-

Oral administration of hormones is associated with GIT problem also it has low oral bioavailability. Skin permeation of testosterone ethosome has better permeation than marketed patch of testosterone.

4. Delivery of antibiotics-

Oral or conventional oral therapy of antibiotics has several side effects. To avoid this oral side effects topical drug delivery system is better choice but it possess low permeability to deep skin layers. Ethosome contain antibiotics can be used to overcome side effects and also it increases permeability through skin.

5. Delivery of Problematic Drug molecules-

A large biogenic molecule such as peptides or protein is difficult for oral delivery. Non-invasive delivery of proteins is a better option for overcoming the problems associated with oral delivery. Touitou investigated the effect of ethosome insulin delivery in lowering blood glucose levels (BGL) in vivo in normal and diabetic SDI rats.

6. Delivery of anti-Parkinsonism agent-

Dayan and Touitou^[19] prepared ethosome formulation of psycholractive drug trihexyphenidyl HCl. Ethosome-THP formulation indicated better skin permeation. Its use for better management of Parkinson disease.

Table no.-2 Example of drug molecules used in ethosome drug delivery.

Sr.no.	Drug	Category	Application(s)
1	Ciclopiroxolamine	Antifungal drug	For treatment of cutaneous candidiasis infection
2	Amphotericin-B	Antifungal drug	Treatment of topical fungal infection.( Leishmaniasis)
3	Miconazole	Imidazole antifungal drug	For treatment of fungal infection.
4	Ketoconazole	Antifungal drug	Treatment of topical fungal infection.
5	Clotrimazole	Antifungal drug	For treatment of fungal infection of candida species.
6	Azidothymidine	Antiviral agent	For treatment acquired immune deficiency syndrome
7	Tizanidine HCl	Muscle relaxant drug	Used to treatmuscle spasms
8	Finasteride	Anti-androgens	For treatment of benign prostatic hyperplasia and androgenetic alopecia.
9	Indinavir sulfate	Antiviral drug	For treatment of HIV-1 infection.
10	Ketoprofen	Non-steroidal anti-inflammatory drug	For treatment of musculoskeletal pain
11	Tetrandrine	Antiathritis	For treatment of arthritis.
12	Acyclovir	Antiviral drug	For treatment of Herpes labialis.
13	Insulin	Anti-diabetics	For treatment of Diabetes.
14	Repaglinide	Anti-Diabetic drug	For treatment of Diabetes.
15	Testosterone	Hormones	For treatment of male hypogonodism.
16	Erythromycin	Antimicrobial	Efficient healing of S.aureus.
17	Diclofenac	NSAID	Used inboth acute and chronic inflammation
18	Cavamax W₇	Anti-psoriatic drug and anti vitiligo	For treatment of chronic immunological disorders.
19	Cromolyn Sodium	Ant allergic drug	For treatment of allergic exercise induced asthma and food allergy.
20	Piroxicam	NSAID	For treatment of pain and inflammatory disorders.
21	Ligustrazine	Antioxidant	For treatment of angina pectoris
22	Tacrolimus	Immunosupressor.	For treatment of atopic dermatitis.

CONCLUSION:

Conventional Formulations are used across the world for treating fungal infections, these formulation have limitations in term of therapeutic efficacy stability and safety profiles. Topical antifungal drug were unstable to penetrate deeply across the stratum corneum and make these system quite a failure in case of topical as transdermal care of fungal infection. These drawbacks can be overcome by ethosome drug delivery system. Liposome, transferosomes cannot pass through stratum corneum. Ethosome is novel vesicular systems which are best alternatives to liposome as it is having high penetration rate through stratum corneum barrier. Ethosome initiated a new area in vesicular research for Transdermal drug delivery for provide better permeation.

REFERENCES:

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Received on 22.02.2015 Accepted on 05.03.2015

Research J. Topical and Cosmetic Sci. 6(1):Jan.–June 2015 page 32-37

DOI: 10.5958/2321-5844.2015.00005.9