Abstract

Non-steroidal anti-inflammatory medicines, or NSAIDs, are becoming becoming increasingly common due to their widespread acceptance as necessary medications for the efficient treatment of pain and inflammation. They possess antipyretic, analgesic, and anti-inflammatory characteristics. On the other hand, taking NSAIDs orally can result in a number of adverse effects in gastrointestinal tract, pulmonary, cardiovascular systems. As a result, transdermal NSAIDs application were suggested over the oral NSAID administration for the treatment of pain and inflammation. Medication applied directly to the skin is meant to have either systemic or local effects. Nanovesicles are extremely promising therapeutic agents for the treatment of cancer, inflammatory infections, and degenerative diseases. Phospholipid vesicles known as transfersomes are specifically employed as drug carriers for transdermal delivery, offering a novel therapeutic strategy. The present review article emphasis the composition, penetration mechanisms, production processes, and characterization techniques of transferosomes, as transdermal delivery system of drugs

Keywords

Introduction

Over the past few decades, the pharmaceutical industry has made some incredibly impressive breakthroughs in the areas of drug delivery and therapy. The way medications are currently administered for patient monitoring, targeting, diagnosis, and therapy has altered as a result of this field's discoveries in nanotechnology. Nanovesicles are extremely promising therapeutic agents for the treatment of cancer, inflammatory infections, and degenerative diseases. In the relatively new but rapidly expanding fields of nanomedicine and nano delivery systems, materials in the nanoscale range are used as diagnostic tools or to carefully deliver therapeutic medicines to specific target areas One of the most significant developments in vesicle research has been the ability to reduce the flawed transdermal penetration of several low- and high-molecular-weight medications thanks to a novel vesicular derivative called "transferosomes"[1]. Vesicular carrier systems known as transferosomes are specifically engineered to have an edge activator and at least one interior aqueous compartment surrounded by a lipid bilayer [2]. A schematic diagram of the structure of transferosome is represented in figure 1.

       
           
       
    Figure 1. Structure of transferosome

Transfersomes consist of phospholipids and edge activator (EA), a membrane-softening agent (e.g., Tween 80, Span 80, and sodium cholate) that promotes the ultra-deformable property of the transfersomes. Once the transfersomes reach the skin pores, they can spontaneously change their membrane flexibility and pass through the pores, a phenomenon known as self-optimizing deformability [2]. Due to their high deformability, transfersomes, in conjunction with EAs, produce a transepidermal osmotic gradient; they can also squeeze between stratum corneum cells and transport drugs throughout the skin [3]. Both low and large molecular weight medications, including as albumin, corticosteroids, sex hormone, insulin, gap junction protein, and analgesics, can be carried by transferosomes. They guard against the drug's metabolic breakdown while it is encapsulated. They serve as a depot, progressively discharging their contents. They can be applied topically or systemically to deliver drugs. Simple procedures that don't require complex methods, needless use, or ingredients that are unsuitable for use in pharmaceuticals make them easy to scale up [4] The FDA has approved the class of medications known as nonsteroidal anti-inflammatory medicines (NSAIDs) for use as analgesics, antipyretics, and anti-inflammatory agents [4]. One of the most frequently prescribed drug types for pain and inflammation is NSAIDs [5]. Compared to other drug classes, NSAIDs are used to treat the majority of patients with various etiologies of pain (up to 71.6% of patients with cancer pain) [6]. Historically, the chemical characteristics of nonsteroidal anti-inflammatory medications (NSAIDs) were used to classify them. Most often prescribed NSAIDs can be categorized as primary derivatives of propionic acid, enolic acid, salicylic acid, acetic acid, or anthranilic acid. But as research has progressed, the categorization has also altered due to the degree to which these drugs specifically block their primary targets, the cyclooxygenase/prostaglandin-endoperoxide synthase (PGHS) enzymes. Moreover, NSAIDs are arranged in groups based on a system that was created using information on their half-lives. However, in spite of the differences between classes, their roles are essentially the same [7].

MECHANISM OF ACTION

The inhibition of the cyclooxygenase (COX) enzyme is the primary mode of action of NSAIDs. Arachidonic acid cannot be converted into thromboxanes, prostaglandins, or prostacyclins without cyclooxygenase [8]. Cyclooxygenase exist in two forms; COX 1 and COX 2. COX 1 serves physiological housekeeping functions while the another one normally present in minute quantities. Most of the NSAIDs inhibit COX-1 and COX-2 nonselectively, but now some selective COX-2 inhibitors have been produced NSAID use is related to gastrointestinal toxicity, which may adversely affect the lower gastrointestinal tract (NSAID-induced enteropathy) as well as the upper gastrointestinal tract (peptic ulcer disease) [9]. It is estimated that between 10% and 50% of patients cannot handle NSAID medication due to adverse effects such as upset stomach, diarrhea, and abdominal pain. gastrointestinal ulcers and bleeding occur with long-term NSAID use [10]. Ultra-deformable vesicles can be used for transdermal administration of nsaids to eliminate the side effects. Studies have been carried out on Diclofenac and Ketoprofen. Ketoprofen in a Transfersome formulation gained marketing approval by the Swiss regulatory agency (SwissMedic) in 2007; the product is expected to be marketed under the trademark Diractin. Further therapeutic products based on the transfersome technology, according to IDEA AG, are in clinical development (Schatzlein, 1998; Gamal, 1999; Wearner, 1988).

Methodologies for the preparation of transferosomes

Thin film hydration method

In a round-bottom flask, the phospholipids and edge activator (the components that form vesicles) are dissolved using a mixture of volatile organic solvents (such as methanol and chloroform in an appropriate (v/v) ratio). The following step can include the addition of the lipophilic drugs. A rotary vacuum evaporator is used to evaporate the organic solvent above the lipid transition temperature under reduced pressure in order to generate a thin layer. Maintain it under vacuum to get rid of any remaining solvent residue [6]. After the thin film has been formed, it is hydrated by rotating it for the required quantity of time at the appropriate temperature using a buffer solution with a correct pH (example, pH 7.4). At this point, the hydrophilic drug inclusion can be done. For the production of small vesicles, the resultant vesicles are sonicated in a bath or probe sonicator after being swelled at ambient temperature. Extrusion across a sandwich of 200 nm to 100 nm polycarbonate membranes homogenizes the sonicated vesicles.

Modified hand shaking method

A 1:1 mixture of ethanol and chloroform was utilized to dissolve the medication, lecithin (PC), and edge activator. Organic solvent was removed by evaporation while hand shaking above lipid transition temperature (43°C).  With rotation, a thin lipid coating developed inside the flask wall. The thin coating was left overnight to allow the solvent to completely evaporate. After that, the film was hydrated for 15 minutes at the appropriate temperature using phosphate buffer (pH 7.4) and light shaking. Up to an hour at 2–8 0C, the transfersome suspension is further hydrated [11].

Vortexing-Sonication Method

The phospholipids, edge activator and the drugs are mixed in a phosphate buffer. The mixture is then vortexed until milky transdermal suspension is obtained. It is then sonicator, for a respective time at room temperature and then extruded through polycarbonate membranes [12 13].

Ethanol injection method

This approach involves heating the drug and aqueous solution while stirring continuously and maintaining a constant temperature throughout the process. Phospholipids and edge activators are added to an ethanolic solution, which is then dropped gradually into an aqueous solution. When the solution makes touch with lipid molecules precipitate and form bilayered structures in aqueous environments. Compared to other approaches, this one has greater benefits.

Freeze thaw method

Using this technique, a suspension of produced multilamellar vesicles is subjected to repeated cycles of extremely low temperature for freezing and then extremely high temperature subjection.After the suspension is ready, it is poured into a tube and submerged for 30 seconds in a nitrogen bath (-30° C). It is placed in a water bath at a high temperature after freezing. This is done up to eight times over.

Reverse-Phase Evaporation Method

In a round-bottom flask, the phospholipids and edge activator are combined with an organic solvent mixture (diethyl ether and chloroform, for example) and dissolved. At this stage the lipophilic drug can incorporated.The lipid films are then obtained by utilizing a rotary evaporator to evaporate the solvent. The organic phase, which mainly consists of isopropyl ether and/or diethyl ether, is where the lipid films are redissolved. The organic phase is then combined with the aqueous phase to create a two-phase system. At this point, the hydrophilic drug inclusion can be completed. After that, this system is sonicated with a bath sonicator until a uniform w/o (water in oil) emulsion forms. Using a rotary evaporator, the organic solvent is gradually evaporated to create a thick gel that subsequently turns into a vesicular suspension [14 15].

Characterization of Transferosomes

Vesicle size, shape and charge[16 17 18]

Phase contrast microscopy, dynamic light scattering method, and photon correlation spectroscopy  can all be used to determine the size of the vesicles. Prior to measurement, transfersomes are diluted with distilled water and filtered through a 0.2 mm membrane filter. Transmission electron microscopy (TEM) and optical microscopy can be used to view the morphology of the vesicles. For TEM measurement, 1% phototungustic acid is employed as a negative stain. Using an optical microscope and phase contrast microscopy, transfersomes without sonication can be visualized.After applying a cover slip and spreading a thin layer of transfersomes on a slide, the morphology of the vesicles is examined under an optical microscope. Zetasizer may be used to calculate the surface charge and charge density of transfersomes .

Entrapment efficiency

Entrapment efficiency (EE) of transfersomes is determined by ultracentrifugation. Vesicles are separated in an cooling centrifuge at 10,000 to 20,000 rpm for particular time interval [19]. The supernatant liquid is then collected and, after appropriate dilution, it is measured in uv spectrophotometer or high performance liquid chromatography (HPLC) to determine  the unencapsulated drug  to calculate the EE. From the unentrapped drug, amount of medication entrapped in the vesicles is estimated using the following formula

?=(Total amount of drug taken-free drug)/(Total amount of drug taken)*100

NO. of vesicles per cubic mm

In order to optimize the composition and other process variables, this parameter is crucial. Transfersome formulations that are not sonicated are diluted five times using a 0.9% sodium chloride solution. Then, for further investigation, an optical microscope and hemocytometer might be employed. The following formula is used to count and compute the Transfersomes in 80 small squares.

Total no.of transferosome per cubic mm=Total no.of transferosomes counted*dilution factor*4000Total no.of squares counted

Degree of deformability

This parameter significant because it has an impact on how well the transfersomal formulation penetrates. Pure water is used as the a standard in the present study. The mixture is run through many microporous filters with known pore diameters ranging from 50 to 400 nm. DLS measurements are used to measure the particle size and size distribution following each pass [20 21 22]. The expression for the degree of deformability is:

D=J*rv/rp                                          [3]

Where, D = degree of deformability,

 J = amount of suspension extruded during 5 min, rv is size of the vesicle and

rp = pore size of the barrier.

In vitro drug release

A scientific method to optimize the transfersomal formulation can be made possible by the in vitro drug release profile, which can offer essential information on the formulation design as well as information on the release mechanism and kinetics. The in vitro drug release study is performed using Franz diffusion cell method [23].The transferosomal formulation is placed on a cellophane membrane between the donor and receptor compartment, which constitutes the buffer. Samples are taken at specific intervals and replaced with fresh buffer each time to maintain sink conditions. The absorbance of the samples is measured, and the amount of drug released is computed.

In vitro skin permeation studies

The purpose of this study is to evaluate the transdermal flux of the medicines, which is commonly expressed in units of ?g/cm2 /h, [24] as well as the transport efficiencies of the transdermal delivery systems. The data gathered for this investigation can also be utilized to optimize the formulation before carrying out more costly in-vivo research and to forecast in vivo behaviors from various transdermal administration techniques. The ideal method for assessing a proposed formulation's ability to permeate is to use human skin. However, the human skin is less desirable for the permeation study because to its restricted availability, ethical issues, and religious boundaries. Many animal models have been proposed as more approachable alternatives to human skin, including ape, porcine, rat, mouse, guinea pig, and snake skins. It should be remembered, too, that percutaneous absorption through different animal skin types may vary greatly from the findings using human skin models [25 26].

Turbidity measurement

Turbidity of the drug can be measured by using nephelometer.

Stability studies

By following the guidelines from International Conference on Harmonization (ICH), stability testing of new drug substances and products is subject to general cases for storage conditions. These cases include 25 ± 2 ?/60% relative humidity (RH) 5% RH or 30 ± 2 ?/65% RH ±5% for a period of 12 months, and 40 ± 2 ?/75% RH 5% for accelerated testing. It is recommended that drug items meant for refrigeration undergo long-term storage at 5 ±3? for a duration of 12 months, followed by an accelerated study at 25± 2 ?/60% RH ± 5% RH for a period of 6 months. Failure to meet the drug product's standards is considered a significant alteration [27]

APPLICATIONS OF TRANSFERSOMES

Insulin Delivery:

The effective noninvasive therapeutic application of such high molecular weight medications on the skin is facilitated by transfersomes. Insulin is usually injected subcutaneously, which is a troublesome method. Insulin encapsulation within Transfersomes.(Transfersulin) solves all of these issues. Depending on the particular carrier composition, the first signs of systemic hypoglycemia can appear 90 to 180 minutes after transfersulin injection on the intact skin.[28]

Interferon Delivery:

medicines can be released under regulated conditions and the stability of labile medicines is increased by transferosomes. They serve as transporters for interferone (INF-?), a leukocyte product with immunomodulatory and antiviral properties.In addition to providing immune treatment and regulated release of the active component to boost the stability of labile medicines, transferosomes also capture INF[29].

Transport of Proteins:

Large and bulky biogenic molecules, such peptides and body proteins, are exceedingly difficult to transfer into the body. Such a chemical exhibits gastrointestinal tract breakdown when taken orally. The most effective method for delivering any form of protein into the body is through transfersomes. It has been noted that the molecules transported by transfersomes have a similar bioavailability to the medication given by subcutaneous injection. Strong immunogenic response was demonstrated by the protein preparation, such as bovine serum albumin (immunogenic adjuvant), which was given repeatedly during the epicutaneous transfersome preparation process[30].

Delivery of Corticosteroids:

In 2003 and 2004, Cevc and Blume investigated the biological activity and properties of halogenated corticosteroid triamcinolone-acetonide-loaded transferosomes made using the traditional thin-film hydration method. The outcomes demonstrated that transferosomes had a longer-lasting and higher biological potency in addition to requiring a lower therapeutic dosage[31].

Transdermal immunization:

 The most significant use of transferosomes is in transdermal immunization, which involves the use of transferosomes containing soluble proteins such as gap junction protein, human serum albumin, and integral membrane protein. These methods present  have at least two benefits: they can be used without an injection, and they also result in a rather high titer and potentially high IgA levels. Corticosteroids have also been delivered using transferosomes. By maximizing the medication dose applied topically, transferosomes enhance the site specificity and overall drug safety of corticosteroid delivery into skin.

CONCLUSION

Transfersomes are a novel drug delivery system and are special types of liposomes. They provide improved drug penetration via the skin; their ingredients are safe and authorized for use in cosmetic and pharmaceutical products.They can handle therapeutic molecules with a broad range of solubility; they can boost the transdermal flow, prolonging the release and enhancing the site specificity of bioactive compounds. Therefore, the future of transfersomes in transdermal medication administration appears bright and promising.

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