Vesicular carrier constructs for topical immunisation

Nanovesicle Formulation Enhances Anti-inflammatory Property and Safe Use of Piroxicam

BACKGROUND

Enhanced utilization of certain drugs may be possible through the development of alternative delivery forms. It has been observed that NSAIDs have adverse gastrointestinal tract effects such as irritation and ulceration during anti-inflammatory therapy. This challenge may be overcome through nano topical formulations.

OBJECTIVE

This study aimed to explore the potentials of a transdermal nanovesicular formulation for safe and enhanced delivery of piroxicam (PRX), a poorly water-soluble NSAID.

METHODS

Preformulation studies were conducted using DSC and FTIR. Ethosomal nanovesicular carrier (ENVC) was prepared by thin-film deposition technique using Phospholipon® 90 H (P90H) and ethanol and then converted into gel form. The formulation was characterized using a commercial PRX gel as control. Permeation studies were conducted using rat skin and Franz diffusion cell. Samples were assayed spectrophotometrically, and the obtained data was analyzed by ANOVA using GraphPad Prism software.

RESULTS

The preformulation studies showed compatibility between PRX and P90H. Spherical vesicles of mean size 343.1 ± 5.9 nm, and polydispersity index 0.510 were produced, which remained stable for over 2 years. The optimized formulation (PE30) exhibited pseudoplastic flow, indicating good consistency. The rate of permeation increased with time in the following order: PE30 > Commercial, with significant difference (p< 0.05). It also showed higher inhibition of inflammation (71.92 ± 9.67%) than the reference (64.12 ± 7.92%).

CONCLUSION

ENVC gel of PRX was formulated. It showed potentials for enhanced transdermal delivery and anti-inflammatory activity relative to the reference. This may be further developed as a safe alternative to the oral form.

Design considerations for liposomal vaccines: influence of formulation parameters on antibody and cell-mediated immune responses to liposome associated antigens

Liposomes (phospholipid bilayer vesicles) are versatile and robust delivery systems for induction of antibody and T lymphocyte responses to associated subunit antigens. In the last 15 years, liposome vaccine technology has matured and now several vaccines containing liposome-based adjuvants have been approved for human use or have reached late stages of clinical evaluation. Given the intensifying interest in liposome-based vaccines, it is important to understand precisely how liposomes interact with the immune system and stimulate immunity. It has become clear that the physicochemical properties of liposomal vaccines - method of antigen attachment, lipid composition, bilayer fluidity, particle charge, and other properties - exert dramatic effects on the resulting immune response. Here, we present a comprehensive review of the physicochemical properties of liposomal vaccines and how they influence immune responses. A discussion of novel and emerging immunomodulators that are suitable for inclusion in liposomal vaccines is also presented. Through a comprehensive analysis of the body of liposomal vaccine literature, we enumerate a series of principles that can guide the rational design of liposomal vaccines to elicit immune responses of a desired magnitude and quality. We also identify major unanswered questions in the field, pointing the direction for future study.

Physicochemical properties and antioxidant activity of gamma-oryzanol-loaded liposome formulations for topical use

The objective of this study is to prepare the gamma-oryzanol-loaded liposomes and investigate their physicochemical properties and antioxidant activity intended for cosmetic applications. Liposomes, Composing phosphatidylCholine (PC) and Cholesterol (Chol), CHAPS or sodium taurocholate (NaTC) were prepared by sonication method. Gamma-oryzanol-loaded liposomes were prepared by using 3, 5 and 10% gamma-oryzanol as an initial concentration. The formulation factors in a particular type and composition of lipid and initial drug loading on the physicochemical properties (i.e., particle size, zeta potential, entrapment efficiency, drug release) and antioxidant activity were studied. The particle sizes of bare liposomes were in nanometer range. The gamma-oryzanol-loaded liposomes in formulations of PC/CHAPS and PC/NaTC liposomes were smaller than PC/Chol liposomes. The incorporation efficiency of 10% gamma-oryzanol-loaded PC/Chol liposomes was less than gamma-oryzanol-loaded PC/CHAPS liposomes and PC/NaTC liposomes allowing higher in vitro release rate due to higher free gamma-oryzanol in buffer solution. The antioxidant activity of gamma-oryzanol-loaded liposomes was not different from pure gamma-oryzanol. Both gamma-oryzanol-loaded PC/CHAPS liposomes and PC/NaTC liposomes were showed to enhance the antioxidant activity in NHF cells. gamma-oryzanol-loaded PC/Chol liposomes demonstrated the lowest cytotoxicity in NHF cells. It was conceivably concluded that liposomes prepared in this study are suitable for gamma-oryzanol incorporation without loss of antioxidant activity.

An investigation into the combination of low frequency ultrasound and liposomes on skin permeability

Antigen application onto skin that has been pre-treated with low frequency ultrasound leads to immunisation, and it was hypothesised that immunisation could be enhanced if antigens were entrapped within liposomes, the latter being known vaccine adjuvants. However, it has been suggested that liposomes can repair skin damage, which could limit antigen permeation and transcutaneous immunisation. The aim of the present work was therefore to investigate the influence of liposome application on subsequent: (i) in vitro antigen permeation through, and (ii) in vivo barrier properties of, ultrasound-treated skin. Sonication was conducted using either phosphate buffered saline (PBS) or an aqueous solution of sodium dodecyl sulphate (SDS) as the coupling medium, and rats were used as the animal models. Liposome application to sonicated skin reduced antigen penetration and transepidermal water loss (TEWL, used as an indication of skin integrity) when the skin had been sonicated using PBS coupling medium. The influence of liposome was evident within 5min of its application, and smaller liposomes were more effective at repairing skin disruption caused by sonication. Such skin repair did not, however, take place when the skin had been sonicated in the presence of SDS (which caused greater skin disruption), and changes in in vitro antigen permeation and in vivo TEWL were negligible. Skin repair by liposomes seems to depend on the extent of the disruption caused by ultrasound application.

Cutaneous delivery of prophylactic and therapeutic vaccines: historical perspective and future outlook

The skin has long been recognized as an attractive target for vaccine administration. A number of clinical studies have tested the epidermal and dermal routes of delivery using a variety of vaccines over the years. In many cases, cutaneous administration has been associated with immunological benefits, such as the induction of greater immune responses compared with those elicited by conventional routes of delivery. Furthermore, there is a growing body of evidence to suggest that such benefits may be particularly important for certain higher-risk populations, such as the elderly, the immunocompromised and cancer patients. Despite the potential advantages of vaccination via the skin, results have sometimes been conflicting and the full benefits of this approach have not been fully realized, partly due to the lack of delivery devices that accurately and reproducibly administer vaccines to the skin. The 5-year outlook, however, appears quite promising as new cutaneous delivery systems advance through clinical trials and become available for more widespread clinical and commercial use.

Efficient tumor targeting of hydroxycamptothecin loaded PEGylated niosomes modified with transferrin

The aim of the present report was to exploit the possibility of combination of the stealth action by polyethylene glycol cyanoacrylate-co-hexadecyl cyanoacrylate (PEG-PHDCA) modified niosomes and active targeting function of transferrin (Tf) by transferrin receptor-mediated endocytosis to promote drug delivery to solid tumor following intravenous administration with hydroxycamptothecin (HCPT) as model drug. HCPT-loaded PEG-niosomes (PEG-NS) were prepared by thin-film hydration and ultrasound method; the periodate-oxidated Tf was coupled to terminal amino group of PEG to produce the active targeting vesicles with average diameters of 116 nm. The uptake of Tf-PEG-NS into KB cells was concentration and time dependent, which could be inhibited by low temperature and free Tf, indicating that the endocytosis process was energy-driven and receptor specific. Compared with HCPT injection, non-stealth niosomes and PEG-NS, Tf-PEG-NS demonstrated the strongest cytotoxicity to three carcinomatous cell lines (KB, K562 and S180 cells), the greatest intracellular uptake especially in nuclei, the highest tumor concentration and largest area under the intratumoral hydroxycamptothecin concentration curve, as well as the most powerful anti-tumor activity with the inhibition rate of 71% against S180 tumor in mice. The results showed that the transferrin modified PEGylated niosomes could be one of the promising solutions to the delivery of anti-tumor drugs to tumor.