Ethosomes: Composition, Types, and Mechanism

• Ethosomes are ethanolic liposomes.
• They were developed in 1997.
• Ethosomes are a non-invasive delivery system.
• They enable drugs to reach deep skin layers and/or systemic circulation.
• Soft vesicles are novel carriers for enhanced delivery through the skin.
• Ethosome vesicles vary in size from 30nm to a few microns.

Composition of ethosomes

• Phospholipids like soya phosphatidyl choline, egg phosphatidyl choline, dipalmityl phosphatidyl choline, and distearyl phosphatidyl choline are used as vesicle-forming components.
• Polyglycols like propylene glycol and transcutol are skin penetration enhancers.
• Alcohols like ethanol and isopropyl alcohol provide softness to the vesicle membrane.
• Cholesterol provides stability to the vesicle membrane.

Types of ethosomes

• Classical ethosomes
• Binary ethosomes
• Transethosomes

Mechanism of Action

• Drug absorption happens in two phases.
• Ethanol Effect: Ethanol acts as a penetration enhancer through the skin.
• The mechanism of ethanol's penetration enhancing effect is well known.
• Ethanol penetrates intercellular lipids, increases cell membrane fluidity, and decreases the density of the lipid multilayer of the cell membrane.
• Ethosomes Effect: Increased cell membrane lipid fluidity is caused by the ethanol, resulting in increased skin permeability.
• Ethosomes permeate easily inside the deep skin layers, fuse with skin lipids, and release drugs into the deep layer of the skin.

Advantages and Disadvantages

Pros

• Enhance permeation of the drug through the skin.
• Low risk as the safety of components is well-documented in scientific studies.
• Easy and cost-effective to manufacture without complex technical requirements.

Cons

• Poor yield.
• If shell locking is ineffective, ethosomes may coalesce.
• There can be a loss of product during transfer from organic to water media.

Cold Method of Preparation

• Mix phospholipid, drug, and other lipid materials.
• Dissolve in ethanol in a covered vessel with vigorous stirring at room temperature (RT).
• Add propylene glycol at 40°C during stirring.
• Heat the mixture up to 30°C.
• Add water at 30°C.
• Stir for 5 minutes in a covered vessel.
• Reduce size by sonication or extrusion.
• Store under refrigeration.

Hot Method of Preparation

• Disperse phospholipid in water at 40°C.
• Mix ethanol and propylene glycol at 40°C.
• Mix the organic phase with the aqueous phase.
• Add the drug dissolved in a suitable solvent (water or ethanol depending on solubility).

Application

• Delivery of antiviral drugs
• Topical delivery of DNA
• Transdermal delivery of hormones
• Delivery of antigen-loaded drugs
• Delivery of NSAIDs
• Widely used in cosmoceuticals

Commercially Available Ethosomal Formulations

• Decorin cream is used for anti-aging and hyperpigmentation.
• It's developed by Genome cosmetics of Pennsylvania, US.
• Nanominox is used as a hair growth promotor.
• Developed by Sinere, Germany

Future Prospective

• Further research will allow better control over drug release in vivo, making therapies more efficient for physicians.
• Special emphasis is given to the skin delivery of proteins and other macromolecules and for transcutaneous immunization.

Ethosomes are ethanolic liposomes used for non-invasive drug delivery, reaching deep skin layers and systemic circulation. Their composition includes phospholipids, polyglycols, and alcohols. There are three types: classical, binary, and transethosomes.