What are transferosomes?
A new drug carrier system called transferosomes contains phospholipids and edge activator. An edge activator i.e., a single chain of surfactants used to destabilize the lipid bilayer of the vesicles and increases the deformability of the bilayer by decreasing its interfacial tension. Functionally its deformability permits the penetration through the pores which are smaller than the droplet size. Transferosomes have been defined as specially designed vesicular particles consisting of at least one inner aqueous compartment enclosed by lipid vesicles, liposomes in morphology, but, functionally, transferosomes are suitably deformable to go through pores much smaller than their own sizes.
- Transferosomes have ability to deform which provides better penetration and reform to its original shape again.
- They can be used for both topical as well as systemic drug delivery.
- They have high entrapment efficiency.
- They act as a depot, releasing their contents gradually and slowly.
- They protect the drug from metabolic degradation.
- They are biocompatible and biodegradable as they are made from natural phospholipids.
- They can act as a carrier for low as well as high molecular weight drugs. E.g. sex hormone, anticancer.
Disadvantages or limitations
- Transferosomes formulations are expensive.
- Transferosomes are chemically unstable due to their predisposition to oxidative degradation.
Preparation of Transferosomes
Reverse Phase Evaporation method
Reverse Phase Evaporation involves removal of solvent from an emulsion by evaporation. Water in oil emulsion is formed by bath sonication of a mixture of two phases, and then the emulsion is dried to a semisolid gel in a rotary evaporator under reduces pressure. The next step is to bring about the collapse of certain portion of water droplets by vigorous mechanical shaking with a vortex mixture. In these circumstances, the lipid monolayer, which encloses the collapse vehicles contributed to adjacent vesicles to form the bilayer resulting in formation of transferosomes.
Ethanol Injection method
In this process, the aqueous solution containing drug is heated with stirring at a constant temperature. Ethanolic solution of phospholipids and EAs is injected in to aqueous solution dropwise. When the ethanolic solution comes in contact with the aqueous media the lipid molecules are precipitated and bilayered structure is formed. This process has advantages such as reproducibility, scale-up and simplicity.
Thin Film Hydration technique
A thin film can be prepared from phospholipids and surfactant by dissolving in volatile organic solvent. It is then evaporated above lipid transition temperature using rotary evaporator. The prepared film is hydrated with buffer by rotation at 60 rpm for 15 min at the corresponding temperature. The resulting vesicles will be swollen for 30 min at room temperature. Then the vesicles are sonicated for 5 min using a bath sonicator and we get the resultant transferosomes.
Mechanism of Action
The mechanism of action works by osmotic gradient process because of evaporation of water after applying the transferosomes on the surface of the skin. The transportation of these vesicles is independent of concentration. The trans-epidermal hydration gives driving force to the vesicles for transportation. The vesicles have elastic properties which help them to squeeze through the pores in to stratum corneum. When a Transferosomes vesicles are applied on an open biological surface, for e.g., non-occluded skin, it tends to penetrate its barrier and migrate in to the water-rich stratum to secure its adequate hydration. Reversible deformation of the bilayer occurs during penetration through the stratum corneum.
The mechanical properties and transport ability of a vesicle can be studied by measuring stress or deformation dependent vesicle bilayer elasticity and permeability changes. For the proper Transferosome vesicles, “Penetrability” increases non-linearly (usually sigmoid ally) with the flux driving force (head pressure).
1. Vesicle size distribution and zeta potential Vesicle size, size distribution and zeta potential .
2. Vesicle morphology Vesicle diameter can be determined using photon correlation spectroscopy or dynamic light scattering (DLS) method. Transferosomes vesicles can be visualized by TEM, phase contrast microscopy, etc. The stability of vesicle can be determined by assessing the size and structure of vesicles over time.
3. No. of vesicles per cubic mm This is an important parameter for optimizing the composition and other process variables.
4. Entrapment efficiency
5. Drug content .
6. Turbidity measurement
7. Penetration ability Penetration ability of Transferosomes can be evaluated using fluorescence microscopy.
8. In-vitro drug release In vitro drug release study is performed for determining the permeation rate. Time needed to attain steady state permeation and the permeation flux at steady state and the information from in vitro studies are used to optimize the formulation before more expensive in vivo studies are performed.
- Delivery of Insulin
- Carrier for other Proteins and Peptides.
- Transdermal Immunization
- Delivery of NSAIDS
- Delivery of Anesthetics
- Delivery of Anticancer Drugs