full issue - Association of Biotechnology and Pharmacy

Current Trends in Biotechnology and PharmacyVol. 5 (1) 972-981 January 2011. ISSN 0973-8916 (Print), 2230-7303 (Online)973to liposomes produced in the presence of ethanolcomprise of hydroalcoholic or hydro/alcoholic/glycolic phospholipids with high concentration ofalcohol may be upto 50 % (2, 6, 12, 13, 14).The ethosomal system consists ofphospholipids, ethanol and water (15) Thephospholipids with various chemical structureincludes phosphatidylcoholine (PC), hydrogenatedPC, phosphatidylethanolamine (PE), phosphatidylglycerol (PPG), phosphatidylinositol (PI),hydrogenated PC etc (16). The nonaqueous phaserange between 22 % to 70 %. The alcohol maybe ethanol or isopropyl alcohol. Dyes oramphiphilic fluorescent probe such as D – 289,Rhodamine – 123 , fluorescence isothiocynate(FITC), 6 – carboxy fluorescence are often addedto ethosomes for characterization study (3, 17,18).Effect of high alcohol concentration: Ethanolis an established permeation enhancer and isproposed that it fluidizes the ethosomal lipids andstratum corneum bilayer thus allowing the soft,malleable vesicles to penetrate the disorganizedlipid bilayer (8). The relatively high concentrationof ethanol (20 – 50 %) is the main reason forbetter skin permeation ability and is packed lesstightly than conventional vesicles but hasequivalent stability and better solubility of manydrugs (3,19). Moreover the vesicular nature ofethosomal formulation could be modified byvarying the components ratio and phospholipids(20). Ethanol confers a surface negative netcharge to the ethosome which causes the size ofvesicles to decrease. The size of ethosomalvesicles increase with decreasing ethanolconcentration (3).Advantages of ethosomes1. Enhanced permeation of drug molecules toand through the skin to the systemiccirculation (3, 14).2. Contrary to deformation liposomes,ethosomes improve skin delivery of drugsboth under occlusive and non-occlusiveconditions (22).3. Since composition and components ofethosomes are safe, they have variousapplications in pharmaceutical, veterinaryand cosmetic field.4. Better patient compliance.5. Better stability and solubility of many drugsas compared to conventional vesicles.7. Relatively smaller size as compared toconventional vesicles.Limitations of ethosomes1. Poor yield (23).2. In case if shell locking is ineffective thenthe ethosomes may coalescence and fallapart on transfer into water.3. Loss of product during transfer form organicto water media (24)Methods of preparation ethosomes: Ethosomescan be prepared by two very simple and convenientmethods that is hot method (Fig 1 and Fig 2) andcold method (Fig 3) (16, 17, 18, 25)Fig.1. General method for the preparation of ethosomesAbdul Wahid et al