TRANSFEROSOMES A Novel Approach to Trans Dermal Drug Delivery

TRANSFEROSOMES- a novel approach to transdermal drug delivery system.

Submitted By-S.M.SAIM.M.PharmKSOP.

WHY TRANSFEROSOMES ?

• Despite major research and development efforts in transdermal systems and the advantages of the routes, low stratum corneum permeability limits the usefulness of topical drug delivery.

• Avoidance of first pass metabolism.Predictable and extended duration of activity. Minimising undesirable side effects .

Utility of short half-life drugs. Improving physiological and

pharmacological response.Avoiding the fluctuation in drug levels.

Inter-and intra-patient variations.Provides patients convenience.

INTRODUCTION-• The term Transfersome and the underlying concept

were introduced in 1991 by Gregor Cevc.• A Transfersome carrier is an artificial

vesicle designed to be like a cell vesicle or a cell engaged in exocytosis, and thus suitable for controlled and, potentially targeted, drug delivery.

• In broadest sense, a Transfersome is a highly adaptable and stress-responsive, complex aggregate.

• Its an ultradeformable vesicle possessing an aqueous core surrounded by the lipophilic core.

• Elasticity is generated by incorporation of an edge activator in the lipid bilayer structure.

• Transfersomes overcome the skin penetration difficulty by squeezing themselves along the intracellular sealing lipid of stratum corneum.

[cont..]Vesicles are colloidal particles

having a water filled core surrounded by a wall of lipids and surfactants (amphiphiles) arranges in bilayer.

Hydrophilic drugs find a place in the internal aqueous environment while amphiphilic, lipophilic drugs get entrapped in the bilayered wall with electrostatic and/or hydrophobic forces.

Structure of a) conventional and b) ultra deformable vesicles-

ADVANTAGES-

1. These shows greater permeation of the drugs through the skin because of its flexible membranes.

2. These serves as carrier for both small and large molecular weight drugs.

3. In transferosomes percentage of the drug entrapment is more .

4. Protect the entrapped drug from atmospheric degradation.

5. These are biocompatible and biodegradable as they are prepared with natural phospholipids.

LIMITATIONS-

Transferosomes are chemically

unstable because of their oxidative

degradation.

Purity of natural

phospholipids is another

criteria militating against

adoption as drug delivery

vehicles.

Transfersomes formulations

are expensive.

TRANSFERSOMES V/S OTHER CARRIER SYSTEMS:

In its basic organization broadly similar to a liposome, the Transfersome  differs from conventional vesicle primarily by its "softer", more deformable, and better adjustable artificial membrane complex  lipid bilayer.

The extremely high flexibility of their membrane permits transfersomes to squeeze themselves even through pores much smaller than their own diameter.

Transferosomes are made up of a phospholipids component along with a surfactant mixture. The ratio of individual surfactants and total amount of surfactants control the flexibility of the vesicle.

The uniqueness of this type of drug carrier system lies in the fact that it can accommodate hydrophilic, lipophilic as well as amphiphilic drugs.

Method Advantage Disadvantage

Penetrationenhancers

Increase penetration through skin and giveboth local and systemic effect

Skin irritation Immunogenicity,only for low molecular weightdrugs

Physical methodse.g.iontophoresis

Increase penetration of intermediate sizecharged molecule

Only for charged drugs, transferefficiency is low (less than 10%)

Liposomes Phospholipid vesicle,biocompatible, biodegradable

Less skin penetration less stable

NiosomesProniosomes

Non-ionic surfactants vesicles,greater stability, Will convert into niosomein situ, stable

Less skin penetration easyhandling But will not reach up todeeper skin layer

Transfersome More stable, high penetration due to highdeformability,

None, but for some limitations

MECHANISM OF PENETRATION OF

TRANSFERSOMES: An ultradeformable and highly hydrophilic vesicle always

seeks to avoid dehydration;  Transfersome vesicle applied on an open biological surface, such as non-occluded skin, tends to penetrate its barrier and migrate into the water-rich deeper strata to secure its adequate hydration.

The mechanism for penetration is the generation of “osmotic gradient” due to evaporation of water while applying the lipid suspension (Transfersomes) on the skin surface.

The transport of these elastic vesicles is thus independent of concentration.

As the vesicles are elastic, they can squeeze through the pores in stratum corneum (though these pores are less than one-tenth of the diameter of vesicles).

During penetration through the stratum corneum, reversible deformation of the bilayer occurs.

Intracellular drug transportation may involve diffusion of vesicle lipid bilayer with the cell membrane like normal endocytosis.

Schematic diagram of the two microroutes of penetration-

Illustration of pore penetration at molecular level-

Diagrammatic Representation of The Stratum Corneum . The Intercellular And Transcellular

Routes of Penetration (Heather., 2005).

METHOD FOR PREPARATION OF TRANSFEROSOMES-Class Example Uses

Phospholipids Soya phosphatidyl choline,eggphosphatidyl choline,dipalmitoylphosphatidyl choline

Vesicles formingComponent

Surfactant Sod.cholate,Sod.deoxycholate,Tween-80,Span-80

For providingflexibility

Alcohol Ethanol,methanol As a solvent

Buffering agent Saline phosphate buffer (pH 6.4)

As a hydrating medium

Dye Rhodamine-123 Rhodamine-DHPEFluorescein-DHPE Nile-red

For CSLM study

The general method- Two steps-1) First, a thin film is prepared, hydrated and then brought

to the desired size by sonication.2) Secondly, sonicated vesicles are homogenized by

extrusion through a polycarbonate membrane.

All phospholipids and surfactants are dissolved in organic solvent. Any lipophilic drug could also be Incorporated in these organic solvent. Then prepare thin film using rotary evaporator then keep under vacuum for 12 hrs, after that hydrate it with buffer (pH 6.5) at 60 rpm.

To prepare small vesicles, resulting LMVs were sonicated at room temperature.

The sonicated vesicles were homogenized by manual

extrusion 10 times through a sandwich of 200 and 100 nm polycarbonate membrane.

Flow diagram for preparation of Transferosome-

Preparation of lipid film

Hydration

Homogenisation

Sonication

CHARACTERIZATION OF TRANSFERSOMES:

The characterization of transfersomes is generally similar to liposomes, niosomes and micelles.

1) Entrapment Efficiency2) Vesicle Diameter3) Number of Vesicle per cubic mm4) Confocal Scanning Laser Microscopy (CSLM) Study5) Vesicle Shape & Type6) Degree of Deformability or Permeability

Measurement7) Turbidity Measurement8) Surface Charge and Charge Density9) Penetration Ability10) Drug Content11) In Vitro Drug Released12) In Vivo Fate of Transfersomes & Kinetics of

Transfersomes Penetration

Entrapment Efficiency-The entrapment efficiency is expressed as

the percentage entrapment of the drug added.

Entrapment efficiency was determined by first separation of the unentrapped drug by use of minicolumn centrifugation method.

After centrifugation, the vesicles were disrupted using 0.1% Triton X-100 or 50% n-propanol.

The entrapment efficiency is expressed as: Entrapment efficiency= (amount

entrapped/ total amount added)×100.

Vesicle Diameter-

Vesicle diameter can be determined using photon correlation spectroscopy or dynamic light scattering (DLS) method.

Samples were prepared in distilled water, filtered through a 0.2 mm membrane filter and diluted with filtered saline and then size measurement done by using photon correlation spectroscopy or dynamic light scattering (DLS) measurements.

Number of Vesicle per cubic mm-

Non-sonicated transfersome formulations are diluted five times with 0.9% sodium chloride solution.

Haemocytometer and optical microscope can then be used for further study.

The Transfersomes in 80 small squares are counted and calculated using the following formula:

Total number of Transfersomes per cubic mm = Total number of Transfersomes counted × dilution factor × 4000

Confocal Scanning Laser Microscopy (CSLM) Study-

In this technique lipophilic fluorescence markers are incorporated into the transfersomes and the light emitted by these markers used for following purpose:

1) For investigating the mechanism of penetration of transfersomes across the skin.

2) For determining histological organization of the skin (epidermal columns, interdigitation),shapes and architecture of the skin penetration pathways.

3) For comparison and differentiation of the mechanism of penetration of transfersomes with liposomes, niosomes and micelles.

Penetration Ability-

Penetration ability of Transfersomes can be evaluated using fluorescence microscopy.

In Vivo Fate of Transfersomes- After penetration of Transfersome through the

outermost skin layers, transfersomes reach the deeper skin layer, the dermis.

From this latter skin region they are normally washed out, via the lymph,into the blood circulation and through the latter throughout the body, if applied under suitable conditions.

Transfersomes can thus reach all such body tissues that are accessible to the subcutaneously injected liposomes.

In Vitro Drug Released-

The information from in-vitro studies are used to optimize the formulation before more expensive in vivo studies is performed.

For determining in vitro drug release ,beaker method is used in which transferosomes suspension is incubated at 32*c using cellophane membrane and the samples are taken at different times and then detected by various analytical techniques (U.V., HPLC,HPTLC) .

The free drug is separated by minicolumn centrifugation, then the amount of drug release is calculated.

APPLICATION OF TRANSFERSOME- Transfersomes as drug delivery systems have the

potential for providing controlled release of the administered drug and increasing the stability of labile drugs.

Transferosomes have been widely used as a carrier for the transport of proteins and peptides. Proteins and peptide are large biogenic molecules which are very difficult to transport into the body, when given orally they are completely degraded in the GI tract. These are the reasons why these peptides and proteins still have to be introduced into the body through injections.

The bioavaibility obtained from transferosomes is somewhat similar to that resulting from subcutaneous injection of the same protein suspension.

Insulin is generally administered by subcutaneous route that is inconvenient. Encapsulation of insulin into transferosomes (transfersulin) overcomes these entire problems..

[cont…] Transferosomes have also been used as a carrier for

interferons, for example leukocytic derived interferone-α (INF-α) is a naturally occurring protein having antiviral, antiproliferive and some immunomodulatory effects.

Another most important application of transferosomes is transdermal immunization using transferosomes loaded with soluble protein like integral membrane protein, human serum albumin, gap junction protein.

Transferosomes have also used of the delivery of corticosteroids.

Application of anaesthetics in the suspension of highly deformable vesicles, transferosomes, induces a topical anesthesia, under appropriate conditions, with less than 10 min.

Transferosmes has also been used for the topical analgesics, anaesthetics agents, NSAIDS and anti-cancer agents.

List of Drugs used for transfersomes-

Drug Inference

Norgesterol Improved transdermal flux

Tamoxifen Improved transdermal flux

Oestradiol Improved transdermal flux

Topical analgesic andanesthetic agent (Tetracaine,lignocaine)

Suitable means for the non-invasive treatment of local pain ondirect topical drug application .

Corticosteroids

Hydrocortosone

Triamcinolone acetonide.

Improved site specificity and overall drug safety.Biologically active at dose several times lower than currentlyused formulation.Used for both local and systemic delivery.

Insulin High encapsulation efficiency.Transfer across the skin with an efficiency of >50%.Provide noninvasive means of therapeutic use.

[cont..]Interferon-αInterleukin-2

Efficient delivery means (because delivery other route isdifficult). Controlled release. Overcome stability problem.

Soluble proteins

Human serum albuminIntegral membrane protein

Permits non-invasive immunization through normal skin.Antibody titer is similar or even slightly higher thansubcutaneous injection.

ColchicineVincristine

Increase skin penetration

REFRENCES-Asian Journal of Biochemical and Pharmaceutical Research Issue 2 (Vol. 1) 2011 G. Cevc, G. Blume, A. Sehatzlein, D. Gebauer and A. Paul., Advance Drug Delivery Reviews.,1996, 18, 349.K. A. Walters and J. Hadgraft., Drug and Pharmaceutical Science., Marcel Dekker., 1993, 59, 383.. A. Bhatia and R. Kumar., Journal of Pharmaceutical sciences., 2004, 7(2), 252.10. H. E. J. Hofland, J. A. Bouwstra, F. Spies, G. Gooris, J. F. Nagelkerke; Journal of PharmaceuticalSciences., 1994, 83, 1192. A. Jadou and V. Preat., International Journal of Pharmaceutics., 1997, 154, 229. S. Jain, D. Mishra, A. Kuksal, A. K. Tiwary and N. K. Jain., Vesicular approach for drug deliveryinto or across the skin: current status and future prospects; Cited on 10th April 2011,http//www.Pharmainfo.net.

Transfersome., Cited on 12th April 2011, http//www.wikipedia/Transfersome

THANK YOU.