ETHOSOMES: A NOVEL VESICULAR CARRIER FOR TRANSDERMAL DRUG DELIVERY

 

About Authors:
Patel Chirag J*1, Prof. Satyanand Tyagi2, Patel Pinkesh1, Umesh Kumar1, Patel Jaimin1, Chaudhari Bharat1
1Department of Pharmaceutics, Maharishi Arvind Institute of Pharmacy, Mansarovar, Jaipur, Rajasthan, India-302020.
*Mr. Chirag Patel has published various Books, Research and Review articles. His academic works include 35 Publications (2 books was published in Lambert Academic Publishing, Germany & 8 Research Articles and 25 Review Articles was published in standard and reputed National and International Pharmacy journals)
2President & Founder, Tyagi Pharmacy Association (TPA) & Scientific Writer (Pharmacy), Chattarpur, New Delhi, India-110074.
*chirag.bangalore@gmail.com, +91-8000501871

ABSTRACT:
Transdermal drug delivery system is a type of convenient drug delivery system where drug goes to the systemic circulation through the protective barrier i.e. Skin. Skin acts as a major target as well as a principal barrier for topical / transdermal drug delivery. Vesicular system is one of the most controversial methods for transdermal delivery of active substances in that ethosome are the ethanolic phospholipids vesicles which are used mainly for transdermal delivery of drugs.  Ethosomes have higher penetration rate through the skin as compared to liposomes hence these can be used widely in place of liposomes. The increased permeation of ethosomes is probably due to its ethanolic content. Ethanol increases the cell membrane lipid fluidity which results in increased skin penetrability of the ethosomes. These ethosomes permeates inside the skin and fuse with cell membrane lipids and release the drug. Hot and cold methods are used for formulation of ethosomes. Characterizations of ethosomesinclude Particle size, Zeta potential, Differential Scanning Calorimertry (DSC),Entrapment efficiency, Surface tension activity measurement, Vesicle stabilityand Penetration Studiesetc.

Reference Id: PHARMATUTOR-ART-1571

INTRODUCTION
Transdermal drug delivery generated tremendous excitement and interest amongst major pharmaceutical companies in the 1980s and 90s. By the mid to late 1990s, the trend of transdermal drug delivery system merged into larger organizations. Over the year it has showed promising result in comparison to oral drug delivery system as it eliminates gastrointestinal interferences and first pass metabolism of the drug but the main drawback of TDDS is it encounters the barrier properties of the Stratum Corneum i.e. only the lipophilic drugs having molecular weight < 500 Da can pass through it [1].

Ethosomes are lipid vesicles containing phospholipids, alcohol (ethanol and isopropyl alcohol) in relatively high concentration and water.Ethosomes are soft vesicles made of phospholipids and ethanol (in higher quantity) and water. The size range of ethosomes may vary from tens of nanometers to microns (μ) [2]. ethosomes permeate through the skin layers more rapidly and possess significantly higher transdermal flux in comparison to conventional liposomes.Although, the exact mechanism for better permeation into deeper skin layers from ethosomes is still not clear. The synergistic effects of combination of phospholipids and high concentration of ethanol in vesicular formulations have been suggested to be responsible for deeper distribution and penetration in the skin lipid bilyers [2-5].     

To improve the permeation of drugs through the skin various mechanisms have been investigated, including use of chemical or physical enhancers, such as iontophoresis, sonophoresis, etc. Liposomes, niosomes, transferosomes and ethosomes also have been reported to enhance permeability of drug through the stratum corneum barrier. Permeation enhancers increase the permeability of the skin, so that the drugs can cross through the skin easily. Unlike classic liposomes, [6] that are known mainly to deliver drugs to the outer layers of skin, ethosomes can enhance permeation through the stratum corneum barrier [7, 8].Ethosomes can entrap drug molecule with various physicochemical characteristics i.e. of hydrophilic, lipophilic, or amphiphilic [9, 10].

The ethosomes more advantages when compared to transdermal and dermal delivery. It delivers large molecules such as peptides, protein molecules. Simple method for drug delivery in comparison to Iontophoresis and Phonophoresis and other complicated methods. Low risk profile- The technology has no large-scale drug development risk since the tox-icological profiles of the ethosomal components are well documented in the scientific literature. High pa-tient compliance as it is administrated in semisolid form (gel or cream) and various application in Pharmaceutical, Veterinary, Cosmetic field [2].

ADVANTAGES OF ETHOSOMAL DRUG DELIVERY
In comparison to other transdermal & dermal delivery systems
1.      Enhanced permeation of drug through skin for transdermal drug delivery.
2.      Delivery of large molecules (peptides, protein molecules] is possible.
3.      It contains non-toxic raw material in formulation.
4.      High patient compliance- The ethosomal drug is administrated in semisolid form (gel or cream) hence producing high patient compliance.
5.      The Ethosomal system is passive, non-invasive and is available for immediate commercialization.
6.      Ethosomal drug delivery system can be applied widely in Pharmaceutical, Veterinary, Cosmetic fields.
7.      Simple method for drug delivery in comparison to Iontophoresis and Phonophoresis and other complicated methods [2].

ETHOSOMES COMPOSITION[1]
The Ethosomes are vesicular carrier comprise of hydroalcoholic or hydro/alcoholic/glycolic phospholipid in which the concentration of alcohols or their combination is relatively high. Typically, Ethosomes may contain phospholipids with various chemical structures like phosphatidylcholine (PC), hydrogenated PC, phosphatidic acid (PA), phosphatidylserine (PS), phosphatidylethanolamine (PE), phosphatidylglycerol (PPG), phosphatidylinositol (PI), hydrogenated PC, alcohol (ethanol or isopropyl alcohol), water and propylene glycol (or other glycols). Such a composition enables delivery of high concentration of active ingredients through skin. Drug delivery can be modulated by altering alcohol: water or alcohol-polyol: water ratio. Some preferred phospholipids are soya phospholipids such as Phospholipon 90 (PL-90). It is usually employed in a range of 0.5-10% w/w. Cholesterol at concentrations ranging between 0.1-1% can also be added to the preparation. Examples of alcohols, which can be used, include ethanol and isopropyl alcohol. Among glycols, propylene glycol and Transcutol are generally used. In addition, non-ionic surfactants (PEG-alkyl ethers) can be combined with the phospholipids in these preparations. Cationic lipids like cocoamide, POE alkyl amines, dodecylamine, cetrimide etc. can be added too. The concentration of alcohol in the final product may range from 20 to 50%. The concentration of the non-aqueous phase (alcohol and glycol combination) may range between 22 to 70% (Table 1).

Table: 1 Different additive employed in formulation of Ethosomes [1]

Class

Example

Uses

Phospholipid

Soya phosphatidyl choline

Egg phosphatidyl choline

Dipalmityl phosphatidyl choline

Distearyl phosphatidyl choline

Vesicles forming component

Polyglycol

Propylene glycol

Transcutol RTM

As a skin penetration enhancer

Alcohol

Ethanol

Isopropyl alcohol

For providing the softness for vesicle membrane

As a penetration enhancer

Cholesterol

Cholesterol

For providing the stability to vesicle membrane

Dye

Rhodamine-123

Rhodamine red

Fluorescene Isothiocynate (FITC)

6- Carboxy fluorescence

For characterization study

Vehicle

Carbopol Ð934

As a gel former

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