Ultradeformable Liposomes Research Articles

Sunlight triggered photodynamic ultradeformable liposomes against Leishmania braziliensis are also leishmanicidal in the dark

Being independent of artificial power sources, self administered sunlight triggered photodynamic therapy could be a suitable alternative treatment for cutaneous leishmaniasis, that avoids the need for injectables and the toxic side effects of pentavalent antimonials. In this work we have determined the in vitro leishmanicidal activity of sunlight triggered photodynamic ultradeformable liposomes (UDL). ZnPc is a hydrophobic Zn phthalocyanine that showed 20% anti-promastigote activity (APA) and 20% anti-amastigote activity (AA) against Leishmania braziliensis (strain 2903) after 15 min sunlight irradiation (15 J/cm 2). However, when loaded in UDL as UDL-ZnPc (1.25 μM ZnPc–1 mM phospholipids) it elicited 100% APA and 80% AA at the same light dose. In the absence of host cell toxicity, UDL and UDL-ZnPc also showed non-photodynamic leishmanicidal activity. Confocal laser scanning microscopy of cryosectioned human skin mounted in non-occlusive Saarbrücken Penetration Model, showed that upon transcutaneous administration ZnPc penetrated nearly 10 folds deeper as UDL-ZnPc than if loaded in conventional liposomes (L-ZnPc). Quantitative determination of ZnPc confirmed that UDL-ZnPc penetrated homogeneously in the stratum corneum, carrying 7 folds higher amount of ZnPc 8 folds deeper than L-ZnPc. It is envisioned that the multiple leishmanicidal effects of UDL-ZnPc could play a synergistic role in prophylaxis or therapeutic at early stages of the infection.

Skin hydration and possible shunt route penetration in controlled estradiol delivery from ultradeformable and standard liposomes.

Human skin delivery of estradiol from ultradeformable and traditional liposomes was explored, comparing occlusive and open application, with the aim of examining the role of skin hydration. Partially hydrated epidermis was used for open hydration, but fully hydrated membranes were used for occluded studies. In addition, we developed a novel technique to investigate the role of shunt route penetration in skin delivery of liposomal estradiol. This compared delivery through epidermis with that through a stratum corneum (SC)/epidermis sandwich from the same skin with the additional SC forming the top layer of the sandwich. This design was based on the fact that orifices of shunts only occupy 0.1% of skin surface area and thus for SC/epidermis sandwiches there will be a negligible chance for shunts to superimpose. The top SC thus blocks most shunts available on the bottom membrane. If shunts play a major role then the delivery through sandwiches should be much reduced compared with that through epidermis, taking into consideration the expected reduction owing to increased membrane thickness. After open application, both ultradeformable and traditional liposomes improved estradiol skin delivery, with the ultradeformable liposomes being superior. Occlusion reduced the delivering efficiency of both vesicle types, supporting the theory that a hydration gradient provides the driving force. Shunt route penetration was found to play only a very minor role in liposomal delivery. In conclusion, full hydration of skin reduces estradiol delivery from liposomes and the shunt route is not the main pathway for this delivery.

Human skin sandwich for assessing shunt route penetration during passive and iontophoretic drug and liposome delivery.

This work explored the role of skin appendages (shunt route) in passive and iontophoretic drug and liposome penetration. The technique used an epidermis and stratum corneum sandwich from the same skin donor with the additional stratum corneum forming the top layer of the sandwich. Penetration was monitored during occluded passive and iontophoretic (0.5 mA cm(-2)) delivery of mannitol and estradiol solutions, and ultradeformable liposomes containing estradiol. The shunt route had a significant role during passive penetration of mannitol (hydrophilic compound), but was negligible during penetration of estradiol (lipophilic drug) and liposomes. In iontophoresis, the shunt route significantly contributed to the overall flux of all preparations, being highest for mannitol. However, shunts were not the only pathway for iontophoretic drug delivery and evidence was observed for the creation of new aqueous pathways via disorganization of the intercellular lipid domain of stratum corneum. The skin sandwich technique should prove valuable for general studies on routes of skin penetration.

Turbiscan Lab ® Expert analysis of the stability of ethosomes ® and ultradeformable liposomes containing a bilayer fluidizing agent

The stability of vesicular drug carriers containing linoleic acid, as a model of bilayer fluidizing agent, was evaluated using a Turbiscan optical analyzer, an innovative analytical instrument able to determine the long-time stability of colloidal systems. Ethosomes ® and ultradeformable liposomes were prepared using Phospholipon 100G ® as the lecithin component, while ethanol and sodium cholate were used for the specific preparation of ethosomes ® and ultradeformable liposomes, respectively. The advantages of the Turbiscan optical analyzer are: (i) its ability to measure reversible (creaming and sedimentation) and irreversible (coalescence and segregation) destabilization phenomena directly in the sample without any dilution and (ii) to detect these phenomena much earlier and easier than other apparatuses. Turbiscan data showed that both colloidal vesicles demonstrate a good stability during the 3 h of the experiment. No modification of Turbiscan backscattering profiles of colloidal suspensions occurred when different amounts of linoleic acid were used to prepare ethosomes ® and ultradeformable liposomes. No coalescence, sedimentation, flocculation or clarification occurred. The results were very encouraging and confirmed the fact that the Turbiscan optical analyzer can be used to study the stability of colloidal formulations even in the presence of deformable agents.

Avoiding failed reconstitution of ultradeformable liposomes upon dehydration

Although freeze-drying is an ordinarily used technique to dehydrate conventional liposomes, we have found that ultradeformable liposomes (UDLs) suffered irreversible aggregation when rehydrated upon freeze-drying (99.4% water elimination), even in high sugar content (4/1 sucrose/lipid mass ratio). When dehydrated by speed vac and vacuum drying, two alternative techniques that rendered less pronounced dehydration (94.27 and 96.2% water elimination, respectively) and avoid ice formation, however, UDL could only be successfully rehydrated when vacuum dried in 4/1 sucrose/lipid mass ratios. Conventional liposomes, on the other hand, were successfully reconstituted upon dehydrated by the three methods in lower sugar content (2/1 sucrose/lipid mass ratio). These results indicated that the 27% mole sodium cholate within the UDL lipid matrix was responsible for a greater and differential mechanical sensitivity of the bilayers to the different dehydration stress, as compared to conventional liposomes.

Formulation and Clinical Evaluation Of Ultradeformable Liposomes in the Topical Treatment of Psoriasis

Ultradeformable liposomes of Methotrexate (MTX) were formulated to enhance its transdermal delivery in the treatment of psoriasis. Formulations were characterized for particle size, polydispersity index, morphology employing TEM and residual solvent analysis. The efficacy of topical liposomal MTX gel was compared with the commercially available plain MTX gel by clinically investigating the reduction in PASI score in psoriasis patients. Allergic contact sensitization potential of placebo ultradeformable liposomal gel was evaluated which showed that the placebo gel did not produce any reaction in the induction as well as challenge phase in 12 human volunteers. Open label, randomized parallel study was conducted in 25 patients. Baseline PASI score in the group receiving liposomal gel (0.25%) was 5.3 ± 1.027 and at the 10th week was reduced to 2.4 ± 0.625. In the case of the group applying plain MTX gel (1%), the baseline PASI score was 6.2 ± 0.17, reduced to 2.9 ± 0.79 at the 10th week. It was observed that liposomal MTX gel of 0.25% improved palmoplantar psoriasis in comparison with 1% plain MTX gel. Therefore, reducing the dose by entrapping MTX in liposomes improved the efficacy and patient compliance.

P102. Development of ultradeformable liposome entrapped with nitrosyl ruthenium complex for PDT application

P102. Development of ultradeformable liposome entrapped with nitrosyl ruthenium complex for PDT application

Innovative Drug Delivery Systems for the Administration of Natural Compounds

The use of natural compounds has recently been reconsidered in modern clinical practice. A further advancement of these compounds is represented by the possibility of using innovative drug delivery systems that can improve the biopharmaceutical features of the delivered compounds. This review examines the recent developments in the field of delivery of natural drugs belonging to several therapeutic classes. In particular, the examined therapeutic classes are: antitumoral drugs, i.e. paclitaxel, doxorubicin, tea catechins and hypericin; anti-infective drugs, i.e. Melaleuca alternifolia and Artemisia arborescens L.; and antinflammatory/antioxidant drugs, i.e. cannabinoids and glycyrrhizinates used for topical application. In this review we highlight the utility of a suitable drug delivery system to improve the biopharmaceutical aspects of these drugs. The examined carriers are: vesicular carriers (liposomes, Ethosomes®, ultradeformable liposomes), nano- and microparticles, innovative gels, microemulsions. Keywords: Natural compounds, antitumoral drugs, anti-infective drugs, antiinflammatory drugs, drug delivery systems, vesicles, nanoparticles, microemulsions, cyclodextrins

Photodynamic ultradeformable liposomes: Design and characterization

Hydrophobic ([tetrakis(2,4-dimetil-3-pentyloxi)-phthalocyaninate]zinc(II)) (ZnPc) and hydrophilic ([tetrakis( N, N, N-trimethylammoniumetoxi)-phthalocyaninate]zinc(II) tetraiodide) (ZnPcMet) phthalocyanines were synthesized and loaded in ultradeformable liposomes (UDL) of soybean phosphatidylcholine and sodium cholate (6:1, w/w, ratio), resulting 100 nm mean size vesicles of negative Zeta potential, with encapsulation efficiencies of 85 and 53%, enthalpy of phase transition of 5.33 and 158 J/mmol for ZnPc and ZnPcMet, respectively, indicating their deep and moderate partition into UD matrices. Matrix elasticity of UDL-phthalocyanines resulted 28-fold greater than that of non-UDL, leaking only 25% of its inner aqueous content after passage through a nanoporous barrier versus 100% leakage for non-UDL. UDL-ZnPc made ZnPc soluble in aqueous buffer while kept the monomeric state, rendering singlet oxygen quantum yield ( Φ Δ ) similar to that obtained in ethanol (0.61), whereas UDL-ZnPcMet had a four-fold higher Φ Δ than that of free ZnPcMet (0.21). Free phthalocyanines were non-toxic at 1 and 10 μM, both in dark or upon irradiation at 15 J/cm 2 on Vero and J-774 cells (MTT assay). Only liposomal ZnPc at 10 μM was toxic for J-774 cells under both conditions. Aditionally, endo-lysosomal confinement of the HPTS dye was kept after irradiation at 15 J/cm 2 in the presence of UDL-phtalocyanines. This could lead to improve effects of singlet oxygen against intra-vesicular pathogen targets inside the endo-lysosomal system.

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 °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™ LD 50 profiles. In vitro data revealed that the LD 50 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 μg/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.

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.

Electrically assisted skin delivery of liposomal estradiol; phospholipid as damage retardant

This work investigated transdermal penetration of a model lipophilic drug (estradiol) through human epidermis from phosphatidylcholine (PC)-based liposomes and saturated aqueous estradiol solution (control). Representative examples of cholate-containing ultradeformable (Transfersomes), non-rigid (pure PC) and membrane-stabilized (cholesterol-containing) vesicles were used. The unilamellar vesicles' diameters and zeta potentials were determined. Transdermal penetration studies involved occluded passive penetration for 12 h and cathodic iontophoresis (0.8 mA/cm 2) for 8 h for all systems. Combined electroporation (5 pulses, 100 V, 100 ms, 1 min spacing) and iontophoresis (0.8 mA/cm 2, for 2 h) was also employed for ultradeformable vesicles and control. Estradiol penetration parameters (flux and skin deposition) from different formulations were compared. All vesicles had essentially the same particle size, with ultradeformable liposomes showing the highest negative zeta potential (−29 mV). Occluded passive penetration improved estradiol skin penetration from liposomes relative to control. Iontophoretic studies revealed the superiority of ultradeformable vesicles regarding drug skin penetration and deposition compared to traditional liposomes. Combination of electroporation and iontophoresis did not markedly improve estradiol penetration for ultradeformable vesicles. The combination results implied repair of the skin barrier due to the penetration retarding effect of PC monomers released from liposomes.

Electroporation and ultradeformable liposomes; human skin barrier repair by phospholipid

This work investigated the effect of electroporation on human epidermal penetration of a model neutral lipophilic compound (estradiol) from saturated aqueous solution and when encapsulated in ultradeformable liposomes. Total amount penetrated and skin deposition were compared with values obtained from passive diffusion. The effect of electrical pulsing on liposome size was investigated. The action of phosphatidylcholine on skin that was structurally altered by such pulses was determined. Electroporation did not affect liposome size. Skin pulsing considerably increased estradiol penetration and skin deposition from solution, relative to passive delivery, with subsequent partial recovery of skin resistance to molecular penetration. Surprisingly, with liposomes, electroporation did not markedly affect estradiol skin penetration. Importantly, liposomal phosphatidylcholine applied during or after pulsing accelerated skin barrier repair, i.e. provided an anti-enhancer or retardant effect.

Iontophoretic estradiol skin delivery and tritium exchange in ultradeformable liposomes

This work evaluated the in vitro transdermal iontophoretic delivery of tritiated estradiol from ultradeformable liposomes compared with saturated aqueous solution (control). Effects of current density and application time on tritium exchange with water were also determined. Penetration studies used three Protocols. Protocol I involved occluded passive steady state estradiol penetration from ultradeformable liposomes and control. The effect of current densities on drug penetration rates was also assessed (Protocol II). In Protocol III, three consecutive stages of drug penetration (first passive, iontophoresis and second passive) through the same human epidermal membranes were monitored. Such an experimental design investigated the possible effect of high current density (0.8 mA/cm 2) on skin integrity. The tritium exchange study showed that extent of exchange correlated well with current density and time of application, with some shielding of estradiol by the liposomal structure. Liposomes enhanced estradiol passive penetration after occlusion. Protocol II showed that estradiol flux increased linearly with current density, although being delivered against electroosmotic flow. In Protocol III, reduction in flux of the second passive stage to near that of the first reflected a reversibility of the structural changes induced in skin by current.

Oestradiol skin delivery from ultradeformable liposomes: refinement of surfactant concentration

The aims of this study were to refine ultradeformable liposomes for oestradiol skin delivery and to evaluate Span 80 and Tween 80 as edge activators compared with sodium cholate. Vesicles containing phosphatidylcholine (PC) mixed with edge activators and oestradiol were prepared. Entrapment efficiency and vesicle size were determined. Interactions between activators and vesicles were investigated using differential scanning calorimetry. Transepidermal permeation of oestradiol from vesicles was studied compared to saturated aqueous control in vitro. The maximum flux ( J max) and its time ( T max) were calculated from the flux curves and skin deposition was assessed. The compositions of refined formulations were predicted, liposomes prepared, and tested against control. Entrapment efficiency depended on PC concentration with some contribution from sodium cholate and Tween 80. Vesicle sizes ranged from 124 to 135 nm. Edge activators interacted with lipid bilayers and disrupted packing. The refined edge activator concentrations in PC vesicles were 14.0, 13.3 and 15.5% w/w for sodium cholate, Span 80 and Tween 80, respectively; they increased J max by 18, 16 and 15-fold and skin deposition by 8, 7 and 8-fold compared with control. Ultradeformable vesicles thus improved skin delivery of oestradiol compared to control and Span 80 and Tween 80 were equivalent to sodium cholate as edge-activators.

Reversible Skin Permeabilization for Transdermal Delivery of Macromolecules

Great advances in transdermal delivery of macromolecules have been made within the last few years using ultradeformable liposomes, electroporation, and low-frequency ultrasound, each of which has been shown to deliver macromolecules at clinically useful rates. Until recently, delivery of high-molecular-weight compounds across the skin was not a realistic option, since the skin's great barrier properties prevent transport of macromolecules across human skin at therapeutically relevant rates. An overview of chemical (liposomes and chemical enhancers) and physical (iontophoresis, electroporation, and ultrasound) methods of enhancement is presented, with emphasis on work published within the last two years. Key experimental results and their mechanistic interpretation are provided for each enhancement technique.