Topical delivery of liposomally encapsulated interferon evaluated by in vitro diffusion studies

Dual-stimuli responsive liposomes using pH- and temperature-sensitive polymers for controlled transdermal delivery

The use of skin environment-sensitive liposomes for transdermal penetration is beneficial for improving cosmetic efficacy.

In vivo sustained dermal delivery and pharmacokinetics of interferon alpha in biphasic vesicles after topical application

Biphasic vesicles, a novel nanostructured lipid-based delivery system show potential for topical application of interferon alpha (IFN α) for the treatment of human papillomavirus (HPV) infections (anogenital warts). Dermal delivery of IFN α encapsulated in biphasic vesicles (BPV-IFN α), applied topically to the skin, was characterized in a guinea pig model. BPV-IFN α (1g, 2 MIU/g) was topically applied either as a single or multiple treatments on the skin of guinea pigs. As a comparison with currently used regimens, IFN α solution was administered intravenously or intradermally. Skin and serum samples were collected over 96 h, IFN α levels were determined by an antiviral assay, and half-life (t₁/₂) and elimination (k) rates were calculated. Topical BPV-IFN α treatment resulted in maximum skin levels (about 100,000 U/100 cm(2)) of IFN α within 6h and maintained for 72-96 h. Clearance from the skin after intradermal injections was initially fast (t₁/₂ 0.62 h, k 1.1179 h(-1)), followed by a slower steady decrease after 6h. After intravenous and intradermal administration, IFN α was rapidly cleared from the serum, t₁/₂ 0.75 h, k 0.9271 h(-1) and t₁/₂ 1.28 h, k 0.5421 h(-1), respectively, whereas after topical application, IFN α levels remained below 100 U/mL. Topical application of BPV- IFN α resulted in sustained delivery of biologically active IFN α locally into skin with minimal systemic exposure.

Biologic activities of molecular chaperones and pharmacologic chaperone imidazole-containing dipeptide-based compounds: natural skin care help and the ultimate challenge: implication for adaptive responses in the skin

Accumulation of molecular damage and increased molecular heterogeneity are hallmarks of photoaged skin and pathogenesis of human cutaneous disease. Growing evidence demonstrates the ability of molecular chaperone proteins and of pharmacologic chaperones to decrease the environmental stress and ameliorate the oxidation stress-related and glycation disease phenotypes, suggesting that the field of chaperone therapy might hold novel treatments for skin diseases and aging. In this review, we examine the evidence suggesting a role for molecular chaperone proteins in the skin and their inducer and protecting agents: pharmacologic chaperone imidazole dipeptide-based agents (carcinine and related compounds) in cosmetics and dermatology. Furthermore, we discuss the use of chaperone therapy for the treatment of skin photoaging diseases and other skin pathologies that have a component of increased glycation and/or free radical-induced oxidation in their genesis. We examine biologic activities of molecular and pharmacologic chaperones, including strategies for identifying potential chaperone compounds and for experimentally demonstrating chaperone activity in in vitro and in vivo models of human skin disease. This allows the protein to function and traffic to the appropriate location in the skin, thereby increasing protein activity and cellular function and reducing stress on skin cells. The benefits of imidazole dipeptide antioxidants with transglycating activity (such as carcinine) in skin care are that they help protect and repair cell membrane damage and help retain youthful, younger-looking skin. All skin types will benefit from daily, topical application of pharmacologic chaperone antioxidants, anti-irritants, in combination with water-binding protein agents that work to mimic the structure and function of healthy skin. General strategies are presented addressing ground techniques to improve absorption of usually active chaperone proteins and dipeptide compounds, include encapsulation into hydrophobic carriers, a combination with penetration enhancers, active electrical transport, or chemical modification to increase hydrophobicity.

Designation of imidazole-containing dipeptides as pharmacological chaperones

We review the dichotomous regulatory roles of natural imidazole-containing peptidomimetics (N-acetylcarnosine [NAC], carcinine, non-hydrolized carnosine) in maintaining skin homeostasis that determines whether keratinocytes survive or undergo apoptosis in response to various insults and in the development of skin diseases. General strategies addressing common ground techniques to improve absorption of usually active chaperone proteins or their dipeptide inducer (usually poorly absorbed) compounds include encapsulation into hydrophobic carriers, combination with penetration enhancers, active electrical transport or chemical modification to increase hydrophobicity. A growing evidence is presented that demonstrates the ability of NAC (lubricant eye drops) or carcinine to act as pharmacological chaperones, or being synergistically coupled in patented formulations with another imidazole-containing peptidomimetic (such as, Leucyl-histidylhydrazide), to decrease oxidative stress and ameliorate oxidative and excessive glycation stress-related eye disease phenotypes, suggesting that the field of chaperone therapy might hold novel treatments for age-related cataracts, glaucoma, age-related macular degeneration (AMD), and ocular complications of diabetes (OCD). Current efforts are being directed towards exploring therapeutic approaches of pharmacological targeting and human drug delivery for chaperone molecules based on innovative patented strategies.

Can drug-bearing liposomes penetrate intact skin?

Using liposomes to deliver drugs to and through human skin is controversial, as their function varies with type and composition. Thus they may act as drug carriers controlling release of the medicinal agent. Alternatively, they may provide a localized depot in the skin so minimizing systemic effects or can be used for targeting delivery to skin appendages (hair follicles and sweat glands). Liposomes may also enhance transdermal drug delivery, increasing systemic drug concentrations. With such a multiplicity of functions, it is not surprising that mechanisms of liposomal delivery of therapeutic agents to and through the skin are unclear. Accordingly, this article provides an overview of the modes and mechanisms of action of different vesicles as drug delivery vectors in human skin. Our conclusion is that vesicles, depending on the composition and method of preparation, can vary with respect to size, lamellarity, charge, membrane fluidity or elasticity and drug entrapment. This variability allows for multiple functions ranging from local to transdermal effects. Application to dissimilar skins (animal or human) via diverse protocols may reveal different mechanisms of action with possible vesicle skin penetration reaching different depths, from surface assimilation to (rarely) the viable tissue and subsequent systemic absorption.

Novel Delivery Systems for Interferons

Interferons, IFNs, are among the most widely studied and clinically used biopharmaceuticals. Despite their invaluable therapeutic roles, the widespread use of IFNs suffers from some inherent limitations, mainly their relatively short circulation lifespan and their unwanted effects on some non-target tissues. Therefore, both these constraints have become the central focus points for the research efforts on the development of a variety of novel delivery systems for these therapeutic agents with the ultimate goal of improving their therapeutic end-points. Generally, the delivery systems currently under investigation for IFNs can be classified as particulate delivery systems, including micro- and nano-particles, liposomes, minipellets, cellular carriers, and non-particulate delivery systems, including PEGylated IFNs, other chemically conjugated IFNs, immunoconjugated IFNs, and genetically conjugated IFNs. All these strategies and techniques have their own possibilities and limitations, which should be taken into account when considering their clinical application. In this article, currently studied delivery systems/techniques for IFN delivery have been reviewed extensively, with the main focus on the pharmacokinetic consequences of each procedure.

Lipid vesicles for skin delivery of drugs: reviewing three decades of research

Since liposomes were first shown to be of potential value for topical therapy by Mezei and Gulasekharam in 1980, studies continued towards further investigation and development of lipid vesicles as carriers for skin delivery of drugs. Despite this long history of intensive research, lipid vesicles are still considered as a controversial class of dermal and transdermal carriers. Accordingly, this article provides an overview of the development of lipid vesicles for skin delivery of drugs, with special emphasis on recent advances in this field, including the development of deformable liposomes and ethosomes.

Transfersomes for transdermal drug delivery

Transfersomes (Idea AG) are a form of elastic or deformable vesicle, which were first introduced in the early 1990s. Elasticity is generated by incorporation of an edge activator in the lipid bilayer structure. The original composition of these vesicles was soya phosphatidyl choline incorporating sodium cholate and a small concentration of ethanol. Transfersomes are applied in a non-occluded method to the skin and have been shown to permeate through the stratum corneum lipid lamellar regions as a result of the hydration or osmotic force in the skin. They have been used as drug carriers for a range of small molecules, peptides, proteins and vaccines, both in vitro and in vivo. It has been claimed by Idea AG that intact Transfersomes penetrate through the stratum corneum and the underlying viable skin into the blood circulation. However, this has not been substantiated by other research groups who have extensively probed the mechanism of penetration and interaction of elastic vesicles in the skin. Structural changes in the stratum corneum have been identified, and intact elastic vesicles visualised within the stratum corneum lipid lamellar regions, but no intact vesicles have been ascertained in the viable tissues. Using the principle of incorporating an edge-activator agent into a bilayer structure, a number of other elastic vesicle compositions have been evaluated. This review describes the research into the development and evaluation of Transfersomes and elastic vesicles as topical and transdermal delivery systems.

Skin localization of cow's milk proteins delivered by a new ready-to-use atopy patch test

PURPOSE

Atopy patch tests (APTs) allow the detection of delayed allergies at the skin level. The localization of beta-lactoglobulin delivered into the skin by an innovative ready-to-use APT (E-patch was investigated and the efficacy and safety of this device were assessed.

METHODS

The E-patch containing beta-lactoglobulin was placed for 24 h in contact with hairless rat skin mounted in a Franz diffusion cell. Transdermal passage was monitored by measurement of beta-lactoglobulin A-[methyl-(14)C] or by two-site enzyme immunoassay. An iterative skin stripping allowed measurement of the beta-lactoglobulin penetrating the first external skin layers.

RESULTS

After 24 h, 92% of beta-lactoglobulin remained on the skin. The iterative skin strippings showed a 135-fold higher concentration of beta-lactoglobulin in the stratum corneum than that found in the epidermis-dermis. Analysis of the solution in the receiver compartment by radioactivity assays or immunoassays indicates that intact protein did not cross the skin.

CONCLUSIONS

The E-patch system allows native beta-lactoglobulin to concentrate in the stratum corneum, in the vicinity of immunological cells, but does not lead to its systemic delivery. Therefore, it is suggested that this delivery system creates ideal conditions for promoting a positive topical response with reduced risk of systemic anaphylactic reactions caused by the native form of the beta-lactoglobulin A.

Hydroxyzine from topical phospholipid liposomal formulations: evaluation of peripheral antihistaminic activity and systemic absorption in a rabbit model

Hydroxyzine, an effective but sedating H1-antihistamine is given orally to treat allergic skin disorders. This study was performed to assess the peripheral H(1)-antihistaminic activity and extent of systemic absorption of hydroxyzine from liposomes applied to the skin. Using L-alpha-phosphatidylcholine (PC), small unilamellar vesicles (SUVs) and multilamellar vesicles (MLVs) containing hydroxyzine were prepared. Hydroxyzine in Glaxal Base (GB) was used as the control. Using a randomized, crossover design, each formulation, containing 10 mg of hydroxyzine, was applied to the shaved backs of 6 rabbits (3.08 +/- 0.05 kg). Histamine-induced wheal tests and blood sampling were performed at designated time intervals up to 24 hours. Compared with baseline, hydroxyzine from all formulations significantly suppressed histamine-induced wheal formation by 75% to 95% for up to 24 hours. Mean maximum suppression, 85% to 94%, occurred from 2 to 6 hours, with no differences among the formulations. The areas of plasma hydroxyzine concentration versus time area under the curve (AUCs) from PC-SUV and PC-MLV, 80.1 +/- 20.8 and 78.4 +/- 33.9 ng/mL/h, respectively, were lower than that from GB, 492 +/- 141 ng/mL/h (P < or =.05) over 24 hours. Plasma concentrations of cetirizine arising in-vivo as the active metabolite of hydroxyzine, from PC-SUV, PC-MLV, and GB, were similar with AUCs of 765 +/- 50, 1035 +/- 202, and 957 +/- 227 ng/mL/h, respectively (P < or =.05). Only 0.02% to 0.06% of the initial hydroxyzine dose remained on the skin after 24 hours. In this model, hydroxyzine from SUV and MLV had excellent topical H1-antihistaminic activity, and minimal systemic exposure occurred. Cetirizine formed in-vivo contributed to some of H1-antihistaminic activity.

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.

Transdermal immunisation with an integral membrane component, gap junction protein, by means of ultradeformable drug carriers, transfersomes

Molecules greater than 500 Da normally do not cross the skin. This prevents epicutaneous delivery of the high molecular weight therapeutics as well as non-invasive transcutaneous immunisation. Extremely deformable vesicles prepared by the judicious combination of several materials provide a solution to this problem: the resulting agent carriers, transfersomes, are the only tested colloidal system that can transport even large macromolecules spontaneously through the skin in immunologically active form. Gap junction proteins (GJP) incorporated into transfersomes and applied to the intact skin surface thus give rise to specific antibody titres marginally higher than those elicited by subcutaneous injections of GJP in transfersomes, mixed lipid micelles or liposomes. The latter two carrier systems give no significant biological response after epicutaneous administration. Transcutaneous protein delivery by means of transfersomes also appears to increase the relative concentration of anti-GJP IgA in the serum.

Transdermal iontophoretic delivery of enkephalin formulated in liposomes

Transdermal iontophoretic transport of a liposomal formulation of [Leu5]enkephalin, across human cadaver skin, was investigated. Franz (vertical) cells were supplied with 0.5 mA/cm2 current density via silver/silver chloride electrodes from a Scepter power supply. Enkephalin spiked with [3H]enkephalin was transported across skin from anode or cathode, depending on the charge on the molecule. Liposomes or their constituents were shown to penetrate into the skin. Enkephalin, when delivered iontophoretically at its isoelectric point, from liposomes carrying positive or negative charge on their surface, resulted in permeation of radioactivity which was same or less than that of the controls when analyzed by liquid scintillation counting. When analyzed by radiochromatography detector on HPLC, degradation of enkephalin during transport was observed, with several degradation peaks in the chromatogram. The degradation was less in liposome formulations, as compared to controls. This is the first report of the combined use of liposomes and iontophoresis for transdermal delivery.

Application of liposomes as potential cutaneous drug delivery systems. In vitro and in vivo investigation with radioactively labelled vesicles

The potential application of liposomes as dermal delivery systems was investigated, with regard to vesicle composition and size. Liposomes were made up of phospholipids or skin lipids, referred to as phospholipid-based liposomes and stratum corneum lipid-based liposomes, respectively. A stripping procedure from stratum corneum to dermis by means of adhesive tape was carried out to evaluate the extent of accumulation in the superficial layers of the skin. The various liposomes were radiolabelled both in the bilayer structures with [3H]cholesterol, [14C]dipalmitoylphosphatidylcholine and [14C]palmitic acid, depending on vesicle type, and in the aqueous compartments with [14C]inulin. Inulin absorption and elimination was also evaluated. Stratum corneum lipid-based liposomes could permeate the stratum corneum to a greater extent than phospholipid-based liposomes. Stratum corneum lipid-based liposomes could deliver a greater amount of aqueous radiolabelled marker ([14C]inulin) to the deeper skin strata (epidermis and dermis), while avoiding systemic absorption and, hence, organ distribution and renal elimination of [14C]inulin. Another important parameter in determining the extent of absorption is the vesicle size: the greater the mean size of liposomes, the poorer the permeation through stratum corneum layers. When fluid liposomes made up of unsaturated lecithins were used, a percutaneous absorption was obtained instead of dermal delivery. Stratum corneum lipid-based unilamellar liposomes may be suitable devices for dermal delivery.

A single intrauterine infusion of sustained recombinant ovine interferon-τ extends corpus luteum lifespan in cyclic ewes

Delivery carriers were developed to permit sustained release of recombinant ovine tau-interferon (roIFN-tau) to increase corpus luteum (CL) lifespan in cyclic ewes following a single intrauterine administration on Day 10 post estrus. A single infusion with 1.7 mg roIFN-tau covalently bound to carboxymethyl biogel agarose (carbodiimide coupling) significantly increased the interestrus interval (P < 0.01) in treated (n = 4) versus control animals (n = 6), whereas liposomally encapsulated roIFN-tau administered to experimental ewes (n = 8) versus control ewes (n = 6) was less effective (P < 0.05). RoIFN-tau covalently bound to trisacryl (glutaraldehyde coupling) was also effective in cyclic ewes (n = 6), but covalent binding to Eupergit C through oxirane bonds yielded ineffective preparations. Ewes that were given 1.7 mg soluble roIFN-tau (n = 8) displayed slight extension of the CL lifespan compared with ewes that were given 1.7 mg soluble BSA (n = 6), but this extension lacked significance in the Mann-Whitney U-test (P > 0.05). These results are consistent with previous data from experiments performed with daily intrauterine infusion of soluble, native or recombinant oIFN-tau. In addition, because CL maintenance requires only a single administration, these methods are efficient and simple to use since they avoid animal catheterization and allow for reduced injection frequency. Moreover, they may permit the use of smaller amounts of IFN. It is concluded that the use of oIFN-tau sustained in some delivery systems may allow for the development of an experimental sheep pseudopregnancy model.

Comparison of absorption of aqueous lidocaine and liposome lidocaine following topical application on rabbit vessels

Liposomes are small particles that encapsulate lidocaine to form topical drug carriers. Forty rabbits were used to compare the absorption of aqueous lidocaine with that of liposome lidocaine after application of each on femoral and iliac vessels. Both agents entered the circulation rapidly. The serum levels of lidocaine were significantly lower and the peaks in concentration appeared later after the use of liposome lidocaine than after the use of aqueous lidocaine. This phenomenon was due to local accumulation of liposome lidocaine and slow release of lidocaine from the liposome. As a topical spasmolytic agent, liposome lidocaine may be superior to the aqueous form due to a lower serum concentration and less total absorption.

Topical delivery of liposomally encapsulated gamma-interferon

The extent of uptake of gamma interferon (gamma-IFN) in various strata of hairless mouse, human and hamster skin upon application of a liposomal formulation and an aqueous solution were determined by in vitro diffusion cell experiments. For each of the animal species studied, 70-80% of the liposomally entrapped IFN was deposited onto or penetrated into the skin as determined 24 h after in vitro application. However, a significant fraction of this total amount (approximately 0.25-0.30) is either adsorbed to or associated with the stratum corneum. The drug content found in the deeper skin strata, where the receptor sites reside, suggests that drug deposition is strongly influenced by the skin species tested. The percent of applied drug found in this strata 24 h after application followed the order: hamster (6.1) much greater than human (0.9) greater than hairless mouse (0.3), although the amounts of drug in the total skin of each species tested were approximately the same. This indicates that the deposition of drug into the living epidermis and/or dermis cannot be predicted by determination of the amount of drug in the total skin. The amounts in the deeper skin strata were also in the order of increasing number of follicles/hair in the skin species, suggesting that the transfollicular route is an important pathway for liposomal topical therapeutics.

Adsorption of fluorescein dyes on albumin microspheres

The surface characteristics of bovine and egg albumin microspheres were examined using four anionic dyes; sodium fluorescein, eosin, erythrosin, rose bengal, and the cationic dye rhodamine B. The adsorption isotherms of the dyes on unloaded albumin microspheres exhibited Langmuir behavior for dilute solutions of rose bengal, erythrosin, and eosin, suggesting monolayer formation in the initial stages of the sorption process. The adsorption capacity of the microspheres for the dyes (k2) and the affinity constants of the dyes for the microspheres (k1) were found to depend on both the polarizability and the hydrophobic properties of the dye, presumably reflecting the heterogeneous character of the microsphere surface. Further, the extent of sorption at higher dye concentrations was found to depend on the ability of the dye to form stable aggregates inside the microspheres and on environmental long-range forces acting at these sites. At both low and high dye concentrations, the amount adsorbed to the microsphere surface increased with increasing hydrophobicity of the dyes. The lowest adsorption was observed for the nonsubstituted dye fluorescein, whereas the most hydrophobic dye used, rose bengal, was completely adsorbed onto the microsphere surface. The data suggest that the bovine albumin microsphere surfaces are highly hydrophobic and less porous than egg albumin microsphere surfaces.