Biological activity and characteristics of triamcinolone-acetonide formulated with the self-regulating drug carriers, Transfersomes

Ultra-deformable liposomes containing bleomycin: In vitro stability and toxicity on human cutaneous keratinocyte cell lines

Formulations of ultra-deformable liposomes containing bleomycin (Bleosome) have previously been described and proposed for topical treatment of skin cancer [Lau, K.G., Chopra, S., Maitani, Y., 2003. Entrapment of bleomycin in ultra-deformable liposomes. S. T. P. Pharm. Sci. 13, 237-239]. In this study, the stability of various Bleosome formulations was characterised and a purification process was established to isolate Bleosome for testing on cultures of either human cutaneous keratinocytes (NEB-1) immortalised by human papilloma virus (HPV)-type 16, or a spontaneously immortalised human squamous cell carcinoma (SCC) from a primary tumour. Bleosome facilitated entrapment of high concentrations of active bleomycin and samples purified by gel-filtration chromatography remained stable during 7 days of storage at 4 degrees C or at room temperature. Serially-diluted samples of this purified, high-strength product, 'high dose' were applied onto keratinocyte cell cultures to elucidate Bleosome LD50 profiles. In vitro data revealed that the LD50 of bleomycin encapsulated in Bleosome was approximately three-fold higher than free bleomycin solution for SCC cells, and nearly 30 times higher for NEB-1 cells. However, Bleosome containing 30 microg/ml of active bleomycin killed more than twice as many SCC cells than NEB-1 cells. At that concentration, the potency of liposomal bleomycin on causing cell death of SCC cells was found to be similar to that of free bleomycin solution. This effect was not seen on NEB-1 cells. It seems that SCC cells were particularly susceptible to Bleosome containing high levels of bleomycin. Results from these experiments promote the development of a novel product for the topical treatment of skin cancer.

Developments in the rat adjuvant arthritis model and its use in therapeutic evaluation of novel non-invasive treatment by SOD in Transfersomes

The aim of this study was firstly to refine a rat model of arthritis, the adjuvant arthritis (AA) model, by studying the time course of the disease, introducing new evaluation methods such as haematological and biochemical parameters in order to identify the main stages of the disease. An optimisation of treatment schedule and evaluation criteria was developed. This refinement provided novel non-invasive anti-inflammatory treatment of the AA with SOD by using mixed lipid vesicles specially developed for transdermal delivery, Transfersomes (Tfs), this being the second major aim. The time course of AA includes a first stage: 1 day after the disease induction, the induced paw volume more than doubled and the paw circumference increased by approx. 50%. Two weeks later, another stage occurred where the disease shifted from the local arthritis form towards polyarthritis: an additional increase of volume and circumference of the induced and non-induced paws, occurred. The animals also started to loose weight around day 14 after the disease induction. Radiographic observable lesions increased correspondingly. Treatment of animals, started at day 1 after induction, by epicutaneous application of SOD-Tfs showed that 1 mg SOD/kg body weight is more efficient than 0.66 mg SOD /kg body weight. As a positive control, SOD liposomes intravenously injected were used for comparison and confirmed the biological efficiency of epicutaneously applied SOD in Tfs. SOD solution and empty Tfs epicutaneously applied exerted no effect. In addition, epicutaneous application of SOD-Tfs used prophylactically was able to suppress the induced rat paw oedema. Radiographic images showed less joint lesions in SOD-Tfs treated animals in comparison with control and placebo treated rats. It was shown for the first time that SOD incorporated into Tfs and applied onto a skin area not necessarily close to the inflamed tissue is able to promote non-invasive treatment of induced arthritis.

Effect of edge activators on the formation and transfection efficiency of ultradeformable liposomes

Highly deformable hydrophilic lipid vesicles have been studied for transdermal delivery of therapeutically active small molecules and proteins. Here, we report the effects of edge activators on the formation of ultradeformable liposomes (UL) and transdermal gene delivery. Sodium cholate, sodium deoxycholate, and Tween 80 were tested as edge activators. Of the edge activators, sodium cholate and sodium deoxycholate resulted in the smaller sizes of UL and more positive zeta potentials than did Tween 80. Moreover, sodium deoxycholate-based UL showed the highest positive zeta potentials, which might lead to the firmer binding with negatively charged DNA. Following topical application onto mice, DNA complexed with UL containing either sodium cholate or sodium deoxycholate showed substantial transdermal absorption. In contrast, DNA complexed with Tween 80-based UL did not show in vivo transdermal absorption. These data suggest that UL might be of use as a transdermal delivery system of plasmid DNA, and that the choice of edge activators may play an important role in the transdermal delivery of plasmid DNA via UL.

Hydrocortisone and dexamethasone in very deformable drug carriers have increased biological potency, prolonged effect, and reduced therapeutic dosage

We characterised biological properties of novel formulations of two low-potency glucocorticosteroids, dexamethasone and hydrocortisone, which have an equivalent dose ratio of 1:50 in vasoconstriction tests. The rate of such carrier-mediated, mainly non-diffusive glucocorticosteroids transport with very deformable lipid vesicles (Transfersomes) through the skin, and the corresponding cutaneous drug biodistribution data, were complemented with the drug bio-efficacy studies. The minimum effective drug dose that reduces arachidonic acid-induced murine ear oedema by 50% was used as one bioactivity indicator. The minimum drug amount ensuring such an effect in mouse skin decreases appreciably when a corticosteroid is applied epicutaneously with very deformable vesicles rather than a lotion or a crème. Specifically, the minimum effective dose for hydrocortisone in very deformable carriers is 2-3 microg cm(-2) whereas for the crème- or lotion-like preparations at least 10 microg cm(-2) is required. Such three- to fivefold relative increase of hydrocortisone potency is accompanied by at least 13%, and more often >20%, absolute drug potency enhancement. The delivery of hydrocortisone with very deformable carriers moreover prolongs the suppression of the drug-induced oedema nearly 2-fold (to approximately 24 h per application). The effective dose of dexamethasone delivered with very deformable vesicles into murine skin is reduced >10 times compared with the crème- or lotion-based products. Specifically, less than 0.1 microg cm(-2) dexamethasone in very deformable vesicles suppresses the arachidonic acid-induced murine ear oedema >50%, on the average. Dexamethasone use on the skin in such vesicles extends the duration of drug action fourfold, compared with a commercial crème, i.e. to >48 h per application. Epicutaneous use of glucocorticosteroids in very deformable vesicles also diminishes such drug's abrasion sensitivity and may increase the general robustness of drug effect. Lower frequency of skin treatment, which ensures adequate biological response, is a result of this. Topical corticosteroid delivery with very deformable vesicles, Transfersomes, thus improves the therapeutic risk-benefit ratio, arguably due to better targeting into and longer drug presence in the skin.

Lipid vesicles and other colloids as drug carriers on the skin

Colloids from an aqueous suspension can cross the skin barrier only through hydrophilic pathways. Various colloids have a different ability to do this by penetrating narrow pores of fixed size in the skin, or the relevant nano-pores in barriers modelling the skin. Such ability is governed by colloid adaptability, which must be high enough to allow penetrant deformation to the size of a pore in such barrier: for a 100 nm colloid trespassing the skin this means at least 5-fold deformation/elongation. (Lipid) Bilayer vesicles are normally more adaptable than the comparably large (lipid coated) fluid droplets. One of the reasons for this, and an essential condition for achieving a high bilayer adaptability and pore penetration, is a high bilayer membrane elasticity. The other reason is the relaxation of changing colloid's volume-to-surface constraint during pore penetration; it stands to reason that such relaxation requires a concurrent, but only transient and local, bilayer permeabilisation. Both these phenomena are reflected in bilayer composition sensitivity, which implies non-linear pressure dependency of the apparent barrier penetrability, for example. Amphipats that acceptably weaken a membrane (surfactants, (co)solvents, such as certain alcohols, etc.) consequently facilitate controlled, local bilayer destabilisation and increase lipid bilayer flexibility. When used in the right quantity, such additives thus lower the energetic expense for elastic bilayer deformation, associated with pore penetration. Another prerequisite for aggregate transport through the skin is the colloid-induced opening of the originally very narrow ( approximately 0.4 nm) gaps between cells in the barrier to pores with diameter above 30 nm. Colloids incapable of enforcing such widening-and simultaneously of self-adapting to the size of 20-30 nm without destruction-are confined to the skin surface. All relatively compact colloids seem to fall in this latter category. This includes mixed lipid micelles, solid (nano)particles, nano-droplets, biphasic vesicles, etc. Such colloids, therefore, merely enter the skin through the rare wide gaps between groups of skin cells near the organ surface. Transdermal drug delivery systems based on corresponding drug formulations, therefore, rely on simple drug diffusion through the skin; the colloid then, at best, can modulate drug transport through the barrier. In contrast, the adaptability-and stability-optimised mixed lipid vesicles (Transfersomes, a trademark of IDEA AG) can trespass much narrower pathways between most cells in the skin; such highly adaptable colloids thus mediate drug transport through the skin. Sufficiently stable ultra-adaptable carriers, therefore, can ensure targeted drug delivery deep below the application site. This has already been shown in numerous preclinical tests and several phase I and phase II clinical studies. Drug delivery by means of highly adaptable drug carriers, moreover, allows highly efficient and well-tolerated drug targeting into the skin proper. Sustained drug release through the skin into systemic blood circulation is another field of ultradeformable drug carrier application.