Ethosomes: A Novel Vesicular Innovation to Enhance Transdermal Delivery of Drugs

 

Saloni Bhandari*

Bhupal Nobles’ College of Pharmacy, BN University, Udaipur (Raj.), 313001.

 

ABSTRACT:

Transdermal route of drug delivery is a promising substitute to oral-systemic delivery of drug substances. It offers several benefits such as avoidance of first pass metabolism, patience compliance, ease of application and so on. But along with these benefits, the major drawback is the barrier function of the skin which hinders the transdermal delivery of the drugs. Hence, ethosomes are useful in such conditions as they surpass the barriers of the skin. Ethosomes are the noninvasive delivery carriers that enable drugs to reach deep into the skin layers or the systemic circulation. They are made up of phospholipids, high concentration of ethanol and water. Ethosomes are able to encapsulate and distribute extremely lipophilic molecules through the skin, as well as cationic drugs, due to their unique structure and deliver them to the deep layers of the skin. Ethosomes have become an area of research interest, because of its enhanced skin permeation, improved drug delivery, increased drug entrapment efficiency etc. This review article provides an insight about the ethosomal systems, their mechanism of penetration into the skin, methods of preparation, evaluation and applications in the field of pharmacy.

 

 

 

INTRODUCTION:

Skin is the largest and most accessible organ of the body that accounts around 15% of total adult body weight. It is a possible route of drug administration for systemic effects. However, skin also acts as the most resistant barrier to drug penetration through stratum corneum, thereby restricting transdermal bioavailability of drugs. With the help of some novel carriers the skin barrier can be overcome to deliver drug molecules with different physicochemical properties to the systemic circulation.

 

The research for these novel carriers began with the synthesis of transdermal liposomes of triamcinolone, followed by synthesis of transferosomes (elastic/deformable liposomes) by Cevc and Blume in 1992, and further researches carried out by Touitou et al, which led to the discovery of a novel lipid vesicular system called “Ethosomes”. In addition to phospholipid and water, high concentrations of ethanol (30-50%) differentiate ethosomes from liposomes.

 

Composition of ethosomes:

The ethosomes are vesicular carrier systems consisting of hydro-alcoholic or hydro/alcoholic/glycolic phospholipid with relatively high alcoholic concentrations. Main components of ethosomes are phospholipids, ethanol (upto 45%), glycerol and water, which facilitate delivery of high concentration of active ingredients through skin. ^{4, 5}

 

Figure 1: Structure of Ethosome ⁶

 

Ethanol

Ethanol is an efficient penetration enhancer. ⁷ In ethosomes, role of ethanol is to provide the vesicles special dimensional characteristics size, ζ-Potential, and stability, prevention of clogging and increased permeability of the skin. Concen­trations of ethanol in ethosomes vary between ~10% –50%. ^{8, 9} Increasing the concentration of ethanol above the optimum level will result in the leaky bilayer, leading to a slight increase in vesicular size and decrease in entrapment efficacy, and a further increase will solubilize the vesicles.

 

High ethanol concentration in ethosomes shifts the vesicular charge from positive to negative, affecting the vesicular properties like stability and vesicle–skin interaction. ^[8,10] As the concentration of ethanol increases, negative charge of empty ethosomes also increases, which further prevents the aggregation of the vesicular system due to electrostatic repulsion. The concentration of ethanol should be optimized in an ethosomal preparation because entrap­ment efficacy will be minimum at low concentrations, and at very high concentra­tions ethosomal membrane will be more permeable because phospholipids can easily be dissolved in ethanol, resulting in a big reduction in entrapment efficacy. ^{1, 11}

 

Phospholipids:

Appropriate concentration as well as type of phospholipid used in ethosomal system is important as the presence of phospholipid affects the scale, the effectiveness of the trapping, ζ -Potential vesicular properties, stability, and penetration. ^[2] Generally, phospholipids are added in an ethosomal formulation in the concentration range of is 0.5%–5%. ^[12] Increasing the concentration of phospholipid slightly increases the vesicular size ^{[9, 13, 14]} and significantly increases entrapment efficiency. However, the relationship holds true only upto a certain concentration, whereby after that incre­ment in phospholipid concentration will have no effect on entrapment efficiency. ¹⁵

Examples of some phospholipids used in ethosomal systems- Phospholipon 90G, 90H, 80H, Dipalmitoylphosphatidylcholine (DPPC), Phosphatidylethanolamine (PE), l-α Phosphatidylcholine (PC), DPPG (1,2-dipalmitoyl-sn-glycero-3-phosphatidylglycerol), DOTAP (1,2-dioleoyl-3-trimethylammonium-propane [chloride salt]), Phospholipon50. ¹

 

Cholesterol:

Incorporation of cholesterol molecules into the ethosomes enhances the entrapment efficiency as well as the stability of the drugs. Several studies have shown that use of cholesterol increases the vesicle size. In a study conducted by López-Pinto et al the ethosomal size increased from 136±42 nm to 230±27 nm when 25.87 mM of cholesterol was used in the formulation. ^[16] The concentration of cholesterol is generally about 3%, but in some formulations it was used up to 70% of the total phospholipid concentration in the formulation. ¹²

 

Dicetyl phosphate:

Dicetyl phosphate is used in the concentration ranging between 8% and 20% of the total phospholipid concentration, to prevent vesicle aggregation and improve the formulation stability. ³ Studies conducted by Maestrelli et al showed that the ethosomal vesicles incorporated with dicetyl phosphate exhibited sharp neg­ative ζ-potential. ¹⁷

 

Stearylamine:

Stearylamine being a positively charged agent when added to ethosomal preparation causes a great increase in vesicular size and decrease in entrapment efficiency, and change in the ζ-potential charge from negative to positive which cause aggregation of the vesicles in one week. Due to its small molecular weight (296.5 Da), Stearylamine easily penetrates the skin. ^{1, 3}

 

Propylene glycol [PG]:

PG is generally used as penetration enhancer in formulation of binary ethosomes in a concentration between 5-20%. Addition of PG affects the vesicle size, entrapment efficiency, permeation, stability, and causes a reduction in particle size. A significant reduction in particle size was observed from 103.7±0.9 nm to 76.3±0.5 nm when the concentration of PG was increased from 0% to 20 % v/v. PG is additionally suggested to reinforce ethosome stability by increasing the viscosity and antihydrolysis property. ^{18, 19}

 

Isopropyl alcohol:

The influence of Isopropyl alcohol on the entrapment effi­ciency and skin permeation of a diclofenac-loaded ethosomal system was studied by Dave et al. he prepared Three types of formulations: classical ethosomes with 40% ethanol, binary ethosomes con­taining 20% Isopropyl alcohol and 20% ethanol, and a vesicular system solely with 40% Isopropyl alcohol. He observed that the vesicular system containing 40% Isopropyl alcohol had better entrapment efficiency (95%) than the binary ethosomes (83.8%). However, on contrary to the better entrapment efficiency this system had the lowest (83.2%) in vitro drug release in 8 hours when compared with the binary ethosomes (85.4%) and classical ethosomes (93%). ^{1, 3}

 

Table 1: Composition of Ethosomes ²⁰

Classes	Types	Concentration (%)	Uses
Alcohol	Ethanol	20-50%	Efficient permeation enhancer
Other alcohols Glycols	Isopropyl alcohol (IPA) Propylene glycol (PG)	5-20%	In the preparation of ethosomes along with ethanol, efficient permeation enhancers
Phospholipids	Phospholipon 90G, 90H, 80H Lipoid S100, S75, S75-3, E80 Soya phosphatidylcholine (SPC50)	0.5-10%	Vesicle forming agents
Cholesterol	Cholesterol	0.1-1%	Provide vesicular stability and rigidity

 

Advantages of ethosomes ^21-24

Ethosome enhances permeation of drugs as well as molecules with different physicochemical properties, hydrophilic and lipophilic molecules, peptides, proteins and other macromolecules through skin for dermal, transdermal and intracellular delivery.

 

The ethosomal composition are generally recognized as safe (GRAS), non-toxic and approved for pharmaceutical and cosmetic use.

 

Low risk profile as the toxicological profiles of ethosomal constituents are well documented in scientific literatures.

 

Passive and non-invasiveness of ethosomes makes them suitable for immediate marketing.

 

Ethosomes has varied applications in Pharmaceutical, Biotechnology, Veterinary, Cosmetic and Nutraceutical fields.

 

The ethosomal drug is delivered in a semi-solid form (gel or cream) thereby, increasing the patient compliance.

 

Ethosomes are relatively cheap and easy to manufacture without any complicated technical investments.

 

Ethosomes enhances drug permeability across/through the skin, thereby targeting the drug to reach the desired site in the skin or to the blood.

 

Higher drug entrapment efficiencies.

 

Excellent stability over long periods.

 

Alcohol in the system acts as natural preservative.

 

The ethosomal vector has been shown to be capable of augmenting intracellular delivery of both molecules that have affinity towards water and lipids, and to escalate the permeation of an antibiotic peptide.

 

Disadvantages of ethosomes ²²

Allergic reaction can be triggered in patients sensitive to ethanol or any of the ethosomal components.

 

Ethosomal carriers can only be applied for transdermal use.

 

Due to flammability of ethanol, special care should be taken during planning, application, transport and storage.

 

Poor yield.

 

Drug should possess a suitable HLB value to achieve microcirculation of the dermal and to obtain access to circulation.

 

Skin irritation or dermatitis due to excipients and penetration enhancers of drug delivery systems.

 

Due to improper shell locking, ethosomes can coalesce and fall apart when transferred to water.

 

Types of ethosomes ^{1, 3, 20}

1.     Classical ethosomes:

Classical ethosomes are the modification of liposomes, consisting of high ethanol concentration (~45% w/w), phospholipids and water. Classical ethosomes as compared to liposomes exhibits improved skin permeation and stability profiles. The molecular weight of drugs caught in traditional ethosomes varies between 130.077 Da to 24 kDa.

 

2.     Binary ethosomes:

Zhou et al came up with the concept of binary ethosome, by adding a different form of alcohol to the classical ethosomes. Propylene glycol (PG) and isopropyl alcohol (IPA) are the most widely used alcohols in binary ethosomes.

 

3.     Transethosomes:

Song et al in 2012 synthesized the latest generation of ethosomal systems and named them as transethosomes. Along with the basic components of classical ethosomes, a penetration enhancer or an edge activator (surfactant) is incorporated in its formula. Transethosomes combines the advantages of classical ethosomes and deformable liposomes (transfersomes) in one formula. Transethosomes with molecular weights ranging from 130.077 Da to 200–325 kDa have been reported to entrap drugs.

 

Examples of edge activators: Tween 60, 80, 20 Span 80, 60, 40, 20, Cremophor RH-40.

Examples of penetration enhancers: Oleic acid, L-Menthol, Dimethyl sulfoxide, SPACE (skin penetrating and cell entering peptide).

 

Figure 2: Types of Ethosomes ^[1]

 

Mechanism of penetration of ethosomes

Exact mechanism of action of ethosomes is still not clear but the main action is attributed to the large concentration of ethanol which contributes in disruption of skin lipid bilayers; thus, when incorporated into a vesicle membrane, vesicles are capable of penetrating the stratum corneum, along with the effect of ethanol on the structure of the stratum corneum, the ethosome itself also can interact with the stratum corneum barrier. ^[3] The absorption of drug occurs due to the two following effects:

1.     Ethanol effect- Ethanol works through the skin by increasing the permeability of skin. Intercalation of the ethanol into intercellular lipids increases the lipid fluidity and reduces the density of the lipid multilayer of cell wall. ^[25]

2.     Ethosome effect- The presence of ethanol in the formulation enhances the lipid fluidity in the cell membrane leading to increased permeability of the skin. Due to the malleability and fusion of ethosomes with skin lipids they penetrate very quickly into the deep layers of the skin, where they fuse and release the drugs into the deep layer of the skin. ^{[3, 25, 26]}

 

Figure 3: Mechanism of Action of Ethosomes ²⁷

 

Method of preparation of ethosomes

There are four basic methods for preparation of ethosomes. They are-

1.     Cold method

2.     Hot method

3.     Classical mechanical dispersion method

4.     The ethanol injection–sonication method

Cold and hot methods are most commonly employed for preparing ethosomes.

 

1.     Cold method:

This is most widely accepted method for preparing ethosomes and was introduced by Touitou in 1996. ^[28] If required, process can also be carried out under nitrogen environment. ^[14] It is a two step procedure. In step I, organic phase is prepared by dissolving phospholipid and other lipid material into ethanol in a closed vessel by heating at 30^˚C with continuous stirring. ^[22] The aqueous phase (water, buffer solution or normal saline) is added to the organic phase, drop wise, at a constant rate of 175 or 200 μL/min. The mixture is stirred at a speed of 700–2,000 rpm using a magnetic stirrer for 5-30 minutes. Based upon physicochemical properties of drug, drug is either dispersed in organic or in aqueous phase. ^[1] The obtained suspension is cooled to room temperature, followed by adjusting the vesicle size with the help of sonication or extrusion. The prepared ethosomes are stored in refrigerator (temperature 5^˚C). ²⁹

 

2.     Hot method:

In hot method, phospholipid is dispersed in water and heated at 40^˚C till a colloidal suspension is formed. In another beaker, ethanol and propylene glycol are mixed and also heated to 40^˚C. Ethanol is dropwise added to the phospholipid dispersion with vigorous stirring using a magnetic stirrer. ^{[29, 30]} Depending upon the hydrophilic/hydrophobic properties of drug, it is either dissolved in aqueous or organic medium. Desired vesicle size is obtained by using probe sonication or extrusion. ^[22]

 

3.     Ethanol injection-sonication method:

This method is based on slow injection of the organic phase containing phospholipid dissolved in ethanol to the aqueous phase, utilizing a syringe system, at a flow rate of 200 μL/min, followed by homogenization with an ultrasonic probe for 5 minutes. ^{1, 3, 13, 15}

 

Characterization

1.     Vesicle shape-

Vesicular shape of ethosomes is identified using electron microscopy. The vesicles seems to be imperfectly round shape with a diameter of 300-400mm. Transmission electron microscopy [TEM] and scanning electron microscopy [SEM] techniques are used. ^{22, 31}

 

2.     Vesicle size and zeta potential:

Smaller the size of the ethosomes, larger is the efficiency of drug delivery to the targeted site. Vesicles are of nanometer to micrometer range. ^[29] Vesicle size is estimated by dynamic light scattering (DLS) using a computerized inspection system and photon correlation spectroscopy (PCS). ^{[5, 32, 33]} Zeta potential is determined by using Zeta meter or Zeta sizer. The unit of Zeta potential is denoted by Milli Volts. ^33-36

 

3.     Transition temperature-

Differential scanning calorimetry [DSC] technique is used to determine the transition temperature of ethosomal system. ^[27]

 

4.     Drug entrapment efficiency and drug content-

Entrapment efficiency is a parameter for determining the prolong release of the ethosomally encapsulated drug. It is determined by using ultracentrifugation, column centrifugation method and fluorescence spectrophotometry and dialysis method. ^{[2, 37, 38]} Mathematically, it is determined by using the following formula;

EE (%) = Dt – Ds x 100

                     Dt

EE is the entrapment efficiency, Dt is the theoretical amount of drug added and Ds is the amount of drug detected only in the supernatant. ^[3] UV spectroscopy or HPLC is used to identify the drug content in ethosomes. ^[22] Vesicles’ lysis is carried out by solvents like isopropylalcohol, methanol, etc. ^[39]

 

5.     Permeation distinctiveness-

The synergistic effect between the lipids, skin, vesicles and ethanol is known to enhance the penetration of ethosomes, which can be explained by following two effects;

A.   Push effect: Escalation in thermodynamic action caused due to the vaporization of ethanol.

B.    Pull effect: Ethanol reduction of the barrier properties of the dermatological tissue by ethanol resulting in an increase penetration of drug molecules. ^{2, 3}

 

Table 2: Characterization of Ethosomes ^39-44

S. No.	Parameter	Importance	Method
1.	Size and shape	Determine skin penetration	SEM, TEM, DLS
2.	Zeta potential	Stability of vesicles	Zeta Meter
3.	Entrapment efficiency	Suitability of method	Ultracentrifugation
4.	Drug content	Important in deciding the amount of vesicle preparation to be used	UV, HPLC
5.	Stability studies	To determine the shelf life of vesicle formulation	SEM, TEM, HPLC
6.	In vitro dissolution	Determine the drug release rate from vesicle	Franz diffusion cell
7.	Skin permeation	Determines rate of drug transport through skin	Confocal laser scanning microscopy (CSLM)

 

Evaluation of ethosomes ^{3, 22, 4, 46}

1.     Filter Membrane Vesicles Interaction Study by Scanning Electron Microscopy:

A small volume of vesicle suspension (0.2 mL) is applied to filter membrane of 50 nm pore size and is kept in diffusion cells in such a manner that the upper side of the filter is exposed to the air, whereas the lower side is in contact with phosphate buffer saline solution (pH 6.5). After 1 hour filters are removed and prepared for SEM analysis by fixation at 4°C in Karnovsky’s fixative overnight followed by dehydration with graded ethanol solutions (30%, 50%, 70%, 90%, 95%, and 100% v/v in water). At the end, filters are coated with gold and examined in SEM.

 

2.     Stability Study:

Stability study is performed by storing the vesicles at 4°C ± 0.5°C. Vesicle size, zeta potential, and entrapment efficiency of the vesicles was measured after 180 days.

 

3.     Vesicle-Skin Interaction Study by TEM and SEM:

Ultra-thin sections cut (Ultracut, Vienna, Austria) from the animal skin are mounted on formvar coated grids and examined under TEM. For SEM analysis, dehydrated skin sections are mounted on stubs using an adhesive tape and coated with gold palladium alloy using a fine coat ion sputter coater. The sections are examined under scanning electron microscope.

 

Applications:

Applications of ethosomes as a carrier system: ^{47- 51}

·       Pilosebaceous targeting

·       Transdermal delivery

·       Delivery of HIV drugs

·       Topical delivery of DNA

·       Transdermal delivery of hormones

·       Delivery of antibiotics

·       Transcutaneous delivery

·       Delivery of anti arthritis and anti-parkinsonism drugs

 

Table 3: Applications of Different Ethosomal Preparations ⁶

Formulation	Rationale of ethosomal delivery	Application	Route of admin.
5- Amniolevulinic acid ethosome	Significantly improved the delivery of ALA in the inflammatory skin.	Anti psoriasis	Topical
Erythromycin ethosome	Ethosomal erythromycin was highly efficient in eradicating S.aureus- induced intradermal infections.	Anti bacterial	Topical
Isoeugenol ethosome	Chemicals (allergen) in vesicular carrier system can enhance the sensitizing capacity.	Allergen	Topical
Matrine ethosome	Improves the percutaneous permeation.	Anti- inflammatory	Topical
Methotrexate ethosome	Ethosomes showed favorable skin permeation characteristics.	Anti- pyretic	Topical
Minoxidil ethosome	Enhance the penetration and accumulation of minoxidil in the skin by pilosebaceous targeting.	Hair growth promoter	Topical
Testosterone ethosome	Testosterone ethosomes for enhanced transdermal delivery.	Steroid hormone	Topical
Fluconazole ethosome	Enhances the skin permeation.	Antifungal	Topical
Acyclovir ethosome	Binary combination of the lipophilic drug ACV-C16 and the ethosomes synergistically enhanced ACV absorption into the skin.	Anti viral	Topical

 

CONCLUSION:

Ethosomes appears to be providing new opportunities in transdermal drug delivery by overcoming epidermal barrier to a significant extent. Ethosomes are mainly composed of multiple, concentric layers of flexible phospholipid bi -layers, with large amounts of ethanol (20-45%), glycols and water. Their unique structure makes them an efficient novel vesicular carrier for encapsulating and delivering highly lipophilic molecules such as testosterone, cannabinoids and ibuprofen, as well as hydrophilic drugs like clindamycin phosphate, buspirone hydrochloride into the skin. They have been studied for the transdermal and intradermal delivery of peptides, steroids, antibiotics, prostaglandins, antivirals and anti-pyretics. Ethosomes are easy to incorporate into various pharmaceutical formulations such as gels, creams, emulsions and sprays. Therefore, ethosomal preparations offer a promising future in the successful delivery of bioactive agents to the intradermally / transdermally.

 

REFERENCES:

1.      Abdulbaqi IM, Darwis Y, Khan NA and Khan RA. Ethosomal Nanocarriers: The Impact of Constituents and Formulation Techniques on Ethosomal Properties, In vivo Studies, And Clinical Trials. International Journal of Nanomedicine. 2016; 11: 2279–2304.

2.      Monisha C, GNK Ganesh, Mythili L and Kayalvizhi Radhakrishnan. A Review on Ethosomes for Transdermal Application. Research J. Pharm. and Tech. 2019; 12(7): 3133-3143.

3.      Jadhav KP, Kundan A, Kapadnis K, Shinkar D, Pathan V and Jadhav A. Ethosomes as Novel Drug Delivery System: A Review. Int. J. Pharm. Sci. Rev. Res. 2000; 62(1): 173-182.

4.      Meesa Rajender, et al, Ethosomes as Novel Drug Delivery Carriers – A Review, Indo Am. J. P. Sci, 2016; 3(12): 1639-1643.

5.      Garg V, Singh H, Bimbrawh S, et al. Ethosomes and Transfersomes: Principles, Perspectives and Practices Current Drug Delivery. 2017; 14: 613-633

6.      Wadher KJ, Shital D, Pounikar SD, Trivedi SS and Umekar MJ. Ethosome: A Novel Vesicular Carrier International Journal of Innovative Research and Advanced Studies (IJIRAS) 2018; 5(7): 13-20.

7.      Finnin BC and Morgan TM. Transdermal Penetration Enhancers: Applica­tions, Limitations, and Potential. J Pharm Sci. 1999; 88(10): 955–958.

8.      Touitou E, Dayan N, Bergelson L, Godin B, Eliaz M. Ethosomes- Novel Vesicular Carriers for Enhanced Delivery: Characterization and Skin Pen­etration Properties. J Control Release. 2000; 65(3): 403–418.

9.      Puri R and Jain S. Ethogel Topical Formulation For Increasing The Local Bioavail­ability Of 5-Fluorouracil: A Mechanistic Study. Anticancer Drugs. 2012; 23(9): 923–934.

10.   Rao Y, Zheng F, Zhang X, Gao J and Liang W. In vitro Percutaneous Per­meation and Skin Accumulation of Finasteride Using Vesicular Ethosomal Carriers. AAPS Pharmscitech. 2008; 9(3): 860–865.

11.   Dayan N and Touitou E. Carriers for Skin Delivery of Trihexypheni­dyl Hcl: Ethosomes Vs Liposomes. Biomaterials. 2000; 21(18): 1879–1885.

12.   Limsuwan T and Amnuaikit T. Development of Ethosomes Containing Mycophenolic Acid. Procedia Chem. 2012; 4: 328–335.

13.   Liu X, Liu H, Liu J, et al. Preparation of a Ligustrazine Ethosome Patch and its Evaluation In vitro and In vivo. Int J Nanomedicine. 2011; 6: 241–247.

14.   Paolino D, Lucania G, Mardente D, Alhaique F and Fresta M. Ethosomes for Skin Delivery of Ammonium Glycyrrhizinate: In vitro Percutaneous Permeation through Human Skin and In vivo Anti-Inflammatory Activity on Human Volunteers. J Control Release. 2005; 106(1–2): 99–110.

15.   Zhaowu Z, Xiaoli W, Yangde Z and Nianfeng L. Preparation of Matrine Ethosome, its Percutaneous Permeation In vitro and Anti-Inflammatory Activity In vivo in Rats. J Liposome Res. 2009; 19(2): 155–162.

16.   López-Pinto JM, González-Rodríguez ML and Rabasco AM. Effect of Choles­terol and Ethanol on Dermal Delivery from DPPC liposomes. Int J Pharm. 2005; 298(1): 1–12.

17.   Maestrelli F, Capasso G, Gonzalez-Rodriguez ML, Rabasco AM, Ghelardini C and Mura P. Effect of Preparation Technique on the Properties and In vivo Efficacy of Benzocaine-Loaded Ethosomes. J Liposome Res. 2009; 19(4): 253–260.

18.   Zhang JP, Wei YH, Zhou Y, Li YQ and Wu XA. Ethosomes, Binary Etho­somes and Transfersomes of Terbinafine Hydrochloride: A Comparative Study. Arch Pharm Res. 2012; 35(1): 109–117.

19.   Li G, Fan Y, Fan C, et al. Tacrolimus-Loaded Ethosomes: Physicochemical Characterization and In vivo Evaluation. Eur J Pharm Biopharm. 2012; 82(1): 49–57.

20.   Nidhi Nainwal, Sunil Jawla, Ranjit Singh and Vikas Anand Saharan. Transdermal Applications of Ethosomes-A Detailed Review. Journal of Liposome Research. 2018; DOI: 10.1080/08982104.2018.1517160

21.   Pawar P, Kalamkar R, Jain A and Amberkar S. Ethosomes: A Novel Tool for Herbal Drug Delivery, International Journal of Pharmacy and Pharmaceutical Research. 2015; 3(4): 191-202.

22.   Aggarwal D and Nautiyal U. Ethosomes: A review. International Journal of Pharmaceutical and Medicinal Research. 2016; 4(4): 354-63.

23.   Transdermal Delivery of Ciclopirox Olamine via Ethosomal and Liposomal Carrier, Research Journal of Pharmacy and Technology. 2011; 4(8):1207–11.

24.   Fan C, Li X, Zhou Y, Zhao Y, Ma S, Li W et al. Enhanced Topical Delivery of Tetrandrine by Ethosomes for Treatment of Arthritis. Biomed Res Int. 2013.

25.   Tiwari RK, Chauhan NS and Yogesh HS. Ethosomes: A Potential Carries for Transdermal Drug Delivery. Int. J. Drug Dev. and Res. 2010; 2(2): 448-452.

26.   Heeremans JLM, Gerristen HR, Meusen SP, et al. The Preparation of Tissue Type Plasminogen Activator (T- PA) Containing Liposomes: Entrapment Efficacy and Ultracentrifugation Damage. Journal of Drug Targeting. 1995; 3: 301.

27.   Pakhale NV, Gondkar SB and Saudagar RB. Ethosomes: Transdermal Drug Delivery System, Journal of Drug Delivery and Therapeutics. 2019; 9(3): 729-733.

28.   Touitou E. Inventor and Assignee. Compositions for Applying Active Substances to or through the Skin. United States Patent US 5540934 A. 1996 Jul 30.

29.   Mishra KK, Kaur CD, Verma S, et al. Chapter 2: Transethosomes and Nanoethosomes: Recent Approach on Transdermal Drug Delivery System. 32-54. Intechopen. http://dx.doi.org/10.5772/intechopen.81152

30.   Ashoniya S and Meenakshi C. Ethosomes as Vesicular Carrier for Enhanced Transdermal Delivery of Ketoconazole – Formulation and Evaluation. J Pharm Cosmetol. 2011; 1(3): 1–14.

31.   R.B. Saudagar, S. Samuel. Ethosomes: Novel noninvasive carrier for Transdermal Drug Delivery. Asian J. Pharm. Tech. 2016; 6(2): 135-138. doi: 10.5958/2231-5713.2016.00019.2

32.   Maghraby GM, Williams AC and Barry BW. Oestradiol Skin Delivery from Ultra Deformable Liposomes: Refinement of Surfactant Concentration, International Journal of Pharmaceutics. 2000: 63-74.

33.   Roge Ashish B, Sakhare Ram S, Bakal RL, Channawar MA, Bakde BV, Gawande SR , Chandewar AV. Ethosomes: Novel Approach in Transdermal Drug Delivery System. Research J. Pharma. Dosage Forms and Tech. 2010; 2(1): 23-27.

34.   Mahmood S, Mandal UK and Chatterjee B. Transdermal Delivery of Raloxifene HCl via Ethosomal System: Formulation, Advanced characterizations and Pharmacokinetic Evaluation. Int J Pharm. 2018; 542(1–2): 36–46.

35.   Jaiswal PK, Kesharwani S, Kesharwani R and Patel DK. Ethosome: A New Technology used as Topical and Amp; Transdermal Delivery System. J Drug Deliv Ther. 2016; 6(3):6–17.

36.   Garg BJ, Garg NK, Beg S, Singh B and Katare OP. Nanosized Ethosomes-Based Hydrogel Formulations of Methoxsalen for Enhanced Topical Delivery against Vitiligo: Formulation Optimization, In vitro Evaluation and Preclinical Assessment. J Drug Target. 2016; 24(3): 233–46.

37.   Mbah C, Builders P, Nzekwe I, Kunle O, Adikwu M, and Attama A. Formulation and In vitro Evaluation of pH-Responsive Ethosomes for Vaginal Delivery of Metronidazole. Journal of Drug Delivery Science and Technology. 2014; 24(6): 565-571.

38.   Kadam NV, Mahajan VR. Ethosomes: A Novel Drug Carrier. Res. J. Topical and Cosmetic Sci. 2013; 4(1): 84-91.

39.   Touitou E. Compositions for Applying Active Substances to or Through the Skin, US Patent: 5538,934,19.

40.   Fry DW, White JC and Goldman ID. Rapid Secretion of Low Molecular Weight Solutes from Liposomes without Dilution, Analytical Biochemistry 1978; 90: 809-815.

41.   New RC. Preparation of liposomes and Size Determination, In: Liposomes A Practical Approach, New RRC (Ed.), Oxford University Press Oxford 1990: 36-3.

42.   Cevc G, Schatzlein A and Blume G. Transdermal Drug Carriers: Basic Properties, Optimization and Transfer Efficiency in case of Epicutaneously Applied Peptides, Journal of Controlled Release 1995; 36: 3-16.

43.   Berge V, Swartzendruber VB and Geest J. Development of an Optimal Protocol for the Ultrastructural Examination of Skin by Transmission Electron Microscopy, Journal of Microscopy 1997; 187(2):125-133.

44.   Toll R, Jacobi U, Richter H, Lademann J, Schaefer H and Blume U. Penetration Profile of Microspheres in Follicular Targeting of Terminal Hair Follicles, Journal of Investigative Dermatology 2004; 123: 168-176.

45.   Pratima NA and Tiwari S. Ethosomes: A Novel Tool for Transdermal Drug Delivery, International Journal of Research in Pharmacy and Sciences. 2012; 2(1):1-20.

46.   Celia C, Cilurzo F, Trapasso E, Cosco D, Fresta M and Paolino D. Ethosomes and Transfersomes Containing Linoleic Acid: Physicochemical and Technological Features of Topical Drug Delivery Carriers for the Potential Treatment of Melasma Disorders, Biomedical Microdevices. 2011; 6: 105-111.

47.   Patel A, Sharma RK, Trivedi M. Ethosomes: A Novel Tool for Transdermal Drug Delivery. Research J. Pharm. and Tech. 2013; 6(8): -841.

48.   Maxwell A, Priya S. Nanosized Ethosomes – A Promising Vesicular Drug Carrier for Transdermal Drug Delivery. Research J. Pharm. and Tech 2019; 12(2):876-880. doi: 10.5958/0974-360X.2019.00150.1

49.   Jose J, Shetty S, Sandeep DS, Nayak P. Ethosomes as a Promising Delivery Carrier for Herbal Drugs: Recent Developments. Research J. Pharm. and Tech 2018; 11(7): 3197-3200. doi: 10.5958/0974-360X.2018.00587.5 https://rjptonline.org/AbstractView.aspx?PID=2018-11-7-86

50.   Singh Shikha Y., Aher Smita S., Saudagar Ravindra B. Ethosomes –Novel Drug Delivery System. Research J. Topical and Cosmetic Sci. 2015; 6(1): 7-14.

51.   Kesharwani R, Patel DK, Sachan A, Kumar V, Mazumdar B. Ethosomes: A Novel Approach for Transdermal and Topical Drug Delivery. Research J. Topical and Cosmetic Sci. 2015; 6(1): 15-20. doi: 10.5958/2321-5844.2015.00003.5

 

Received on 15.09.2021         Modified on 16.11.2021

Accepted on 31.12.2021   ©AandV Publications All Right Reserved