Influence of different surfactants on the physicochemical properties of elastic liposomes

Paclitaxel-loaded elastic liposomes synthesised by microfluidics technique for enhance transdermal delivery

The inherent flexibility of elastic liposomes (EL) allows them to penetrate the small skin pores and reach the dermal region, making them an optimum candidate for topical drug delivery. Loading chemotherapy in ELs could improve chemotherapy's topical delivery and localise its effect on skin carcinogenic tissues. Chemotherapy-loaded EL can overcome the limitations of conventional administration of chemotherapies and control the distribution to specific areas of the skin. In the current studies, Paclitaxel was utilised to develop Paclitaxel-loaded EL. As an alternative to the conventional manufacturing methods of EL, this study is one of the novel investigations utilising microfluidic systems to examine the potential to enhance and optimise the quality of Els by the microfluidics method. The primary aim was to achieve EL with a size of < 200 nm, high homogeneity, high encapsulation efficiency, and good stability. A phospholipid (DOPC) combined with neutral and anionic edge activators (Tween 80 and sodium taurocholate hydrate) at various lipid-to-edge activator ratios, was used for the manufacturing of the ELs. A preliminary study was performed to study the size, polydispersity (PDI), and stability to determine the optimum microfluidic parameters and lipid-to-edge activator for paclitaxel encapsulation. Furthermore, physiochemical characterisation was performed on the optimised Paclitaxel-loaded EL using a variety of methods, including Dynamic Light Scattering, Fourier Transform Infrared Spectroscopy, Atomic force microscopy, elasticity, encapsulation efficiency, and In vitro release. The results reveal the microfluidics' significant impact in enhancing the EL characteristics of EL, especially small and controllable size, Low PDI, and high encapsulation efficiency. Moreover, the edge activator type and concentration highly affect the EL characteristics. The Tween 80 formulations with optimised concentration provide the most suitable size and higher encapsulation efficiency. The release profile of the formulations showed more immediate release from the EL with higher edge activator concentration and a higher % of the released dug from the Tween 80 formulations.

On the deformability of additivated phosphatidylcholine liposomes: Molecular dynamic regimes and membrane elasticity

Liposomes with enhanced elasticity have been proven to increase the efficiency of drug transport across the skin. The understanding of the background physicochemical processes driving the liposome viscoelastic properties is an essential feature for the design of effective formulations involving different lipids and additive molecules. In this work we use field-cycled nuclear magnetic resonance relaxometry to analyze both the mechanical properties of liposome membranes, and their relationship with the involved molecular dynamics. Different liposomal formulations were considered. We show a correlation between the molecular dynamical regime and mesoscopic physical parameters that define the expected deformability of the vesicles. Results strongly suggest that the purity of the used lipids may influence the elastic properties of the membranes in an appreciable way. Common features in the behaviour of the involved dynamic variables were identified by comparing formulations with surfactants of similar molecular weight.

The technology of transdermal delivery nanosystems: from design and development to preclinical studies

Transdermal administration has gained much attention due to the remarkable advantages such as patient compliance, drug escape from first-pass elimination, favorable pharmacokinetic profile and prolonged release properties. However, the major limitation of these systems is the limited skin penetration of the stratum corneum, the skin's most important barrier, which protects the body from the insertion of substances from the environment. Transdermal drug delivery systems are aiming to the disruption of the stratum corneum in order for the active pharmaceutical ingredients to enter successfully the circulation. Therefore, nanoparticles are holding a great promise because they can act as effective penetration enhancers due to their small size and other physicochemical properties that will be analyzed thoroughly in this report. Apart from the investigation of the physicochemical parameters, a comparison between the different types of nanoparticles will be performed. The complexity of skin anatomy and the unclear mechanisms of penetration should be taken into consideration to reach some realistic conclusions regarding the way that the described parameters affect the skin permeability. To the best of the authors knowledge, this is among the few reports on the literature describing the technology of transdermal delivery systems and how this technology affects the biological activity.

Biomedical potentialities of cationic geminis as modulating agents of liposome in drug delivery across biological barriers and cellular uptake

Hydroxyethyl bearing gemini surfactants, alkanediyl-α,ω-bis(N-hexadecyl-N-2-hydroxyethyl-N-methylammonium bromide), 16-s-16(OH), were used to augment phosphatidylcholine based liposomes to achieve higher stability and enhanced cellular uptake and penetration. The developed liposomes were loaded with rhodamine B, doxorubicin hydrochloride, pralidoxime chloride to investigate release properties, cytotoxicity in vitro, as well as ability to cross the blood-brain barrier. At molar ratio of 35:1 (lipid:surfactant) the formulation was found to be of low toxicity, stable for two months, and able to deliver rhodamine B beyond the blood-brain barrier in rats. In vivo, pharmacokinetics of free and formulated 2-PAM in plasma and brain were evaluated, liposomal 2-PAM was found to reactivate 27% of brain acetylcholinesterase, which is, to our knowledge, the first example of such high degree of reactivation after intravenous administration of liposomal drug.

Coarse-grained molecular dynamics simulations of the effect of edge activators on the skin permeation behavior of transfersomes

Transfersomes (TRS) can provide sustained drug delivery and themselves are biocompatible, biodegradable and nontoxic. Edge activators (EAs) are key factors for increasing the deformability of TRS, and this active deformation mechanism is of commercial interest, especially at the molecular level. Accordingly, in this paper, the deformability of pure dipalmitoyl phosphatidylcholine (DPPC) vesicles, TRS with sodium cholate as an EA, and DPPC vesicles containing pogostone (POG) were compared via umbrella sampling technology. The DPPC conformation and membrane fluidity of these three types of bilayer systems were evaluated, and the changes in the membrane properties of vesicles caused by EAs were studied. EAs could increase the deformability of TRS by decreasing the deformation energy barrier due to their amphiphilic structures, which was similar to those of DPPC molecules. The membrane properties also changed via treatment with EAs including altering the tail chain angle, disturbing the ordered tail chain arrangement and prompting lateral diffusion of DPPC molecules. In addition, the impact of EAs on DPPC bilayers was further demonstrated to be concentration dependent. An ideal concentration was identified for the lowest amount of EA that offered a gel-liquid-crystalline phase transition of DPPC bilayers. Importantly, POG, a lipophobic transdermal drug, can also affect the skin permeation behavior of vesicles but had weaker effects than EA.

Formulation and optimisation of novel transfersomes for sustained release of local anaesthetic

Objective

To investigate the effect of formulation parameters on the preparation of transfersomes as sustained-release delivery systems for lidocaine and to develop and validate a new high-performance liquid chromatography (HPLC) method for analysis.

Method

Taguchi design of experiment (DOE) was used to optimise lidocaine-loaded transfersomes in terms of phospholipid, edge activator (EA) and phospholipid : EA ratio. Transfersomes were characterised for size, polydispersity index (PDI), charge and entrapment efficiency (%EE). A HPLC method for lidocaine quantification was optimised and validated using a mobile phase of 30%v/v PBS (0.01 m) : 70%v/v Acetonitrile at a flow rate of 1 ml/min, detected at 255 nm with retention time of 2.84 min. The release of lidocaine from selected samples was assessed in vitro.

Key findings

Transfersomes were 200 nm in size, with PDI ~ 0.3. HPLC method was valid for linearity (0.1–2 mg/ml, R2 0.9999), accuracy, intermediate precision and repeatability according to ICH guidelines. The %EE was between 44% and 56% and dependent on the formulation parameters. Taguchi DOE showed the effect of factors was in the rank order : lipid : EA ratio ˃ EA type ˃ lipid type. Optimised transfersomes sustained the release of lidocaine over 24 h.

Conclusion

Sustained-release, lidocaine-loaded transfersomes were successfully formulated and optimised using a DOE approach, and a new HPLC method for lidocaine analysis was developed and validated.