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.

Challenges in neuroprotective nanomedicine development: progress towards noninvasive gene therapy of glaucoma

Over the past decade the application of gene therapy of retinal diseases such as glaucoma has produced promising results. However, optic nerve regeneration and restoration of vision in patients with glaucoma is still far from reality. Neuroprotective approaches in the form of gene therapy may provide significant advantages, but are still limited by many factors both at the organ and cellular levels. In general, gene delivery systems for eye diseases range from simple eye drops and ointments to more advanced bio- and nanotechnology-based systems such as muco-adhesive systems, polymers, liposomes and ocular inserts. Most of these technologies were developed for front-of-the-eye ophthalmic therapies and are not applicable as back-of-the-eye delivery systems. Currently, only the invasive intravitreal injections are capable of successfully delivering genes to the retina. Here we review the challenges and possible strategies for the noninvasive gene therapy of glaucoma including the barriers in the eye and in neural cells, and present a cross-sectional view of gene delivery as it pertains to the prevention and treatment of glaucoma.

Pharmaceutical characterization of solid and dispersed carbon nanotubes as nanoexcipients

Background

Carbon nanotubes (CNTs) are novel materials with considerable potential in many areas related to nanomedicine. However, a major limitation in the development of CNT-based therapeutic nanomaterials is a lack of reliable and reproducible data describing their chemical and structural composition. Knowledge of properties including purity, structural quality, dispersion state, and concentration are essential before CNTs see widespread use in in vitro and in vivo experiments. In this work, we describe the characterization of several commercially available and two in-house-produced CNT samples and discuss the physicochemical profiles that will support their use in nanomedicine.

Methods

Eighteen single-walled and multi-walled CNT raw materials were characterized using established analytical techniques. Solid CNT powders were analyzed for purity and structural quality using thermogravimetric analysis and Raman spectroscopy. Extinction coefficients for each CNT sample were determined by ultraviolet-visible near infrared absorption spectroscopy. Standard curves for each CNT sample were generated in the 0–5 μg/mL concentration range for dispersions prepared in 1,2-dichlorobenzene.

Results

Raman spectroscopy and thermogravimetric analysis results demonstrated that CNT purity and overall quality differed substantially between samples and manufacturer sources, and were not always in agreement with purity levels claimed by suppliers. Absorbance values for individual dispersions were found to have significant variation between individual single-walled CNTs and multi-walled CNTs and sources supplying the same type of CNT. Significant differences (P < 0.01) in extinction coefficients were observed between and within single-walled CNTs (24.9–53.1 mL·cm⁻¹·mg⁻¹) and multi-walled CNTs (49.0–68.3 mL·cm⁻¹·mg⁻¹). The results described here suggest a considerable role for impurities and structural inhomogeneities within individual CNT preparations and the resulting spectroscopic properties of their dispersions.

Conclusion

Raw CNT materials require thorough analytical workup before they can be used as nanoexcipients. This applies especially to the determination of CNT purity, structure, and concentration. The results presented here clearly demonstrate that extinction coefficients must be determined for individual CNT preparations prior to their use.

Amino acid-substituted gemini surfactant-based nanoparticles as safe and versatile gene delivery agents

Gene based therapy represents an important advance in the treatment of diseases that heretofore have had either no treatment or cure. To capitalize on the true potential of gene therapy, there is a need to develop better delivery systems that can protect these therapeutic biomolecules and deliver them safely to the target sites. Recently, we have designed and developed a series of novel amino acid-substituted gemini surfactants with the general chemical formula C(12)H(25) (CH(3))(2)N(+)-(CH(2))(3)-N(AA)-(CH(2))(3)-N(+) (CH(3))(2)-C(12)H(25) (AA= glycine, lysine, glycyl-lysine and, lysyl-lysine). These compounds were synthesized and tested in rabbit epithelial cells using a model plasmid and a helper lipid. Plasmid/gemini/lipid (P/G/L) nanoparticles formulated using these novel compounds achieved higher gene expression than the nanoparticles containing the parent unsubstituted compound. In this study, we evaluated the cytotoxicity of P/G/L nanoparticles and explored the relationship between transfection efficiency/toxicity and their physicochemical characteristics (such as size, binding properties, etc.). An overall low toxicity is observed for all complexes with no significant difference among substituted and unsubstituted compounds. An interesting result revealed by the dye exclusion assay suggests a more balanced protection of the DNA by the glycine and glycyl-lysine substituted compounds. Thus, the higher transfection efficiency is attributed to the greater biocompatibility and flexibility of the amino acid/peptide-substituted gemini surfactants and demonstrates the feasibility of using amino acid-substituted gemini surfactants as gene carriers for the treatment of diseases affecting epithelial tissue.

Biphasic vesicles for topical delivery of interferon alpha in human volunteers and treatment of patients with human papillomavirus infections

PURPOSE. Topical biphasic vesicle delivery system encapsulating interferon alpha (IFN α) was developed as an alternative to injections used to treat human papillomavirus (HPV) infections. METHODS. Biphasic lipid vesicles encapsulating increasing doses of IFN α (biphasic IFN α) were characterized for encapsulation efficiency, size, zeta potential and vesicle structure by centrifugation, dynamic light scattering, confocal microscopy and small-angle x-ray scattering. Biphasic IFN-α delivery into human skin in vivo and topical efficacy in patients with genital warts were evaluated. RESULTS. Average encapsulation efficiency of IFN α was 81-91%. The average particle size was 1000-1100 nm and zeta potential +70 to +78 mV. After application of 5, 15 and 40MU/g biphasic IFN α formulation in a topical patch on the upper inner arm in healthy volunteers, skin IFN α levels increased to 120±30, 380±60 and 400±80 IU/mg protein in skin homogenates (n=5, 5, and 7), respectively. Topical application of biphasic IFN α (1 MU/dose) twice daily for two weeks in a pilot study with 12 patients with external condylomata acuminata resulted in a decrease in lesion size, in 2',5'-oligoadenylate synthetase activity and in tissue viral load. CONCLUSIONS. Biphasic vesicles delivered clinically significant levels of IFN α across intact human skin and elicited marked therapeutic effect in patients.

Drug delivery through the skin: molecular simulations of barrier lipids to design more effective noninvasive dermal and transdermal delivery systems for small molecules, biologics, and cosmetics

The delivery of drugs through the skin provides a convenient route of administration that is often preferable to injection because it is noninvasive and can typically be self-administered. These two factors alone result in a significant reduction of medical complications and improvement in patient compliance. Unfortunately, a significant obstacle to dermal and transdermal drug delivery alike is the resilient barrier that the epidermal layers of the skin, primarily the stratum corneum, presents for the diffusion of exogenous chemical agents. Further advancement of transdermal drug delivery requires the development of novel delivery systems that are suitable for modern, macromolecular protein and nucleotide therapeutic agents. Significant effort has already been devoted to obtain a functional understanding of the physical barrier properties imparted by the epidermis, specifically the membrane structures of the stratum corneum. However, structural observations of membrane systems are often hindered by low resolutions, making it difficult to resolve the molecular mechanisms related to interactions between lipids found within the stratum corneum. Several models describing the molecular diffusion of drug molecules through the stratum corneum have now been postulated, where chemical permeation enhancers are thought to disrupt the underlying lipid structure, resulting in enhanced permeability. Recent investigations using biphasic vesicles also suggested a possibility for novel mechanisms involving the formation of complex polymorphic lipid phases. In this review, we discuss the advantages and limitations of permeation-enhancing strategies and how computational simulations, at the atomic scale, coupled with physical observations can provide insight into the mechanisms of diffusion through the stratum corneum.

Topical delivery of interferon alpha by biphasic vesicles: evidence for a novel nanopathway across the stratum corneum

Noninvasive delivery of macromolecules across intact skin is challenging but would allow for needle-free administration of many pharmaceuticals. Biphasic vesicles, a novel lipid-based topical delivery system, have been shown to deliver macromolecules into the skin. Investigation of the delivery mechanism of interferon alpha (IFN alpha), as a model protein, by biphasic vesicles could improve understanding of molecular transport through the stratum corneum and allow for the design of more effective delivery systems. The interaction of biphasic vesicles with human skin and isolated stratum corneum membrane was investigated by confocal microscopy, differential scanning calorimetry (DSC) and small- and wide-angle X-ray scattering (SAXS and WAXS). Confocal microscopy revealed that biphasic vesicles delivered IFN alpha intercellularly, to a depth of 70 microm, well below the stratum corneum and into the viable epidermis. DSC and SAXS/WAXS data suggest that the interaction of biphasic vesicles with SC lipids resulted in the formation of a three-dimensional cubic Pn3m polymorphic phase by the molecular rearrangement of intercellular lipids. This cubic phase could be an intercellular permeation nanopathway that may explain the increased delivery of IFN alpha by biphasic vesicles. Liposomes and submicrometer emulsion (the individual building blocks of biphasic vesicles) separately and methylcellulose gel, an alternative topical vehicle, did not induce a cubic phase and delivered low amounts of IFN alpha below the stratum corneum. Molecular modeling of the cubic Pn3m phase and lamellar-to-cubic phase transitions provides a plausible mechanism for transport of IFN alpha. It is hypothesized that induction of a Pn3m cubic phase in stratum corneum lipids could make dermal and transdermal delivery of other macromolecules also possible.

Advancing nonviral gene delivery: lipid- and surfactant-based nanoparticle design strategies

Gene therapy is a technique utilized to treat diseases caused by missing, defective or overexpressing genes. Although viral vectors transfect cells efficiently, risks associated with their use limit their clinical applications. Nonviral delivery systems are safer, easier to manufacture, more versatile and cost effective. However, their transfection efficiency lags behind that of viral vectors. Many groups have dedicated considerable effort to improve the efficiency of nonviral gene delivery systems and are investigating complexes composed of DNA and soft materials such as lipids, polymers, peptides, dendrimers and gemini surfactants. The bottom-up approach in the design of these nanoparticles combines components essential for high levels of transfection, biocompatibility and tissue-targeting ability. This article provides an overview of the strategies employed to improve in vitro and in vivo transfection, focusing on the use of cationic lipids and surfactants as building blocks for nonviral gene delivery systems.

Evidence for lymphatic transport of insulin by topically applied biphasic vesicles

The cutaneous delivery pathway through the lymphatics of a novel transdermal lipid-based delivery system (biphasic vesicles), which was previously shown to deliver sustained physiological levels of basal insulin in a pain-free manner across the skin, was evaluated in a diabetic rat model. Transdermal patches (one per rat) containing insulin in biphasic vesicles (1–10 mg recombinant human insulin dose) were applied to the shaved abdominal skin of streptozotocin-induced diabetic rats for 73 h. Blood glucose was monitored approximately every 2–10 h using a Lifescan glucose meter. Inguinal lymph node insulin levels were analysed by ELISA. Insulin in the lymph nodes increased in a dose- and time-dependent manner. Maximal transdermal insulin concentrations in the lymph nodes were observed with both 140 IU (5 mg: 43.0 + 18.0 μIU mg−1 (mean + s.e.m., n = 4)) and 280 IU (10 mg: 48.0 + 19.6 μIU mg−1 (mean + s.e.m., n = 4)) doses of recombinant insulin at t = 73 h. The level of insulin in the lymph nodes after subcutaneous injection of 1 mg insulin at the peak blood glucose response was 35.8 μIU mg−1 (n = 2), before falling to 0.35 μIU mg−1 by t = 48 h (n = 2). The lymphatics is involved in the transdermal insulin delivery by biphasic vesicles. This is the first report on the lymphatic transport of a protein after non-invasive topical application on the skin.

Enhancement of immunoprotective effect of CpG-ODN by formulation with polyphosphazenes against E. coli septicemia in neonatal chickens

Synthetic oligodeoxynucleotides (ODN) containing CpG motifs (CpG-ODN) have been shown to be effective immunoprotective agents and vaccine adjuvants in a variety of bacterial and protozoan diseases in different animal species. The objective of this study was to investigate the immunoprotective effect of formulated CpG-ODN with polyphosphazene, liposome or oil-in-water emulsion against E. coli infections in neonatal chickens. Eighteen-day-old embryonating eggs were inoculated with 50 microg CpG-ODN or formulated CpG-ODN with polyphophazene, liposome or oil-in-water emulsion. Four days after exposure to formulated CpG-ODN or day-1 post-hatch, 1 x 10(4) or 1 x l0(5) cfu of a virulent isolate of E. coli was inoculated by the subcutaneous route in the neck. Clinical signs, pathology, bacterial isolations from the air sacs, and mortality were observed for eight days following challenge with E. coli. The survival rate of birds following E. coli infection was 0% in groups receiving either non-CpG-ODN or saline. In contrast, birds receiving either CpG-ODN or CpG-ODN formulated with polyphosphazene had significantly higher survival of 55% (P<0.0001). The relative risk of mortality was significantly reduced for birds treated with CpG-ODN formulated in PCPP (0.25), in PCEP (0.33), or unformulated CpG-ODN (0.39) in comparison to the group treated with saline (p<0.01). Although formulation of CpG-ODN with liposomes or oil-in-water emulsion did not increase the immunoprotective effect against E. coli infection, no adverse reactions or poor hatchability were observed in embryos. This is the first time that CpG-ODN formulated with polyphosphazene has been demonstrated to have an immunoprotective effect against an extra cellular bacterial infection in neonatal broiler chickens following in ovo delivery.

Pathogenesis and therapeutic approaches for improved topical treatment in localized scleroderma and systemic sclerosis

SSc is a chronic progressive disorder of unknown aetiology characterized by excess synthesis and deposition of collagen and other extracellular matrix components in a variety of tissues and organs. Localized scleroderma (LS) differs from SSc in that with LS only skin and occasionally subcutaneous tissues are involved. Although rarely life threatening, LS can be disfiguring and disabling and, consequently, can adversely affect quality of life. There is no known effective treatment for LS, and various options, including, as examples, corticosteroids and other immunomodulatory agents, ultraviolet radiation and vitamin D analogues, are of unproven efficacy. Clinical trials evaluating combination therapy such as corticosteroids with MTX or UVA1 exposure with psoralens have not been established as consistently effective. New immunomodulators such as tacrolimus and thalidomide are also being evaluated. A better understanding of the molecular and cellular mechanisms of LS has led to evaluation of new treatments that modulate profibrotic cytokines such as TGF-beta and IL-4, regulate assembly and deposition of extracellular matrix components, and restore Th1/Th2 immune balance by administering IL-12 or IFN-gamma. IFN-gamma acts by directly inhibiting collagen synthesis and by restoring immune balance. In this review, we evaluate current and future treatment options for LS and cutaneous involvement in SSc. Recent advances in therapy focus mainly on anti-fibrotic agents. Delivery of these drugs into the skin as the target tissue might be a key factor in developing more effective and safer therapy.

Gemini surfactants: a new family of building blocks for non-viral gene delivery systems

Gemini surfactants provide a significant opportunity in the development of new non-viral delivery systems designed for gene therapy applications. This review summarizes the wide range of gemini surfactant structures that have been employed for DNA transfection in vitro. A general observation is that those structures capable of inducing a wide variety of polymorphic structures (lamellar, hexagonal, or cubic phases) demonstrate higher transfection efficiencies. Those compounds whose structures result in pH-dependent changes in aggregate structure similarly show higher levels of transfection. In vivo transfection using gemini surfactants has been demonstrated in only three cases, and in a recent study the transfection was linked to a specific therapeutic response.