An EPR spin probe study of the interactions between PC liposomes and stratum corneum membranes

Clinical evaluation of liposome-based gel formulation containing glycolic acid for the treatment of photodamaged skin

Background: Long contact of UV causes skin damage. Glycolic acid (GA) as an alpha hydroxy acid is used to treat photodamaged skin. However, GA leads to side effects including; burning, erythema and peeling.Purpose: The aim of this study was to develop a controlled delivery systems loading GA in order to increasing its efficacy and lowering its side effects.Methods: Liposomes were evaluated for encapsulation efficiency, size and morphology. Optimized formulation was dispersed in HPMC gel bases and drug release kinetics were also studied. Clinical efficacy and safety of GA-loaded liposomal gel and GA gel formulation were evaluated in patients with photodamaged skin.Results: The EE% and average particle size of liposomes were 64 ±2.1 % and 317±3.6 nm, respectively. SEM image showed that liposomes were spherical in shape. In vitro release kinetics of GA from both formulations followed Weibull model. Clinical evaluation revealed that GA-loaded liposomal gel was more effective than GA gel formulation. Treatment with GA-loaded liposomal gel resulted in a statistically significant reduction in the scores of hyperpigmentation, fine wrinkling and lentigines. Moreover, liposomal gel formulation was able to minimize side effects of GA.Conclusion: According to the obtained results, the liposome-based gel formulation can be used as potential drug delivery system to enhance permeation of GA through skin layers and also reduce its side effects.

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.

Hyaluronic acid-conjugated liposomes loaded with dexamethasone: a promising approach for the treatment of inflammatory diseases

Dexamethasone is a well-known anti-inflammatory drug readily used to treat many lung diseases. However, its side effects and poor lower airway deposition and retention are significant limitations to its usage. In this work, we developed lipid nanoparticulate platforms loaded with dexamethasone and evaluated their behavior in inflammatory lung models in vitro and in vivo. Dexamethasone-loaded liposomes with an average diameter below 150 nm were obtained using a solvent injection method. Three different formulations were produced with a distinct surface coating (polyethylene glycol, hyaluronic acid, or a mixture of both) as innovative strategies to cross the pulmonary mucus layer and/or target CD44 expressed on alveolar proinflammatory macrophages. Interestingly, while electron paramagnetic spectroscopy showed that surface modifications did not induce any molecular changes in the liposomal membrane, drug loading analysis revealed that adding the hyaluronic acid in the bilayer led to a decrease of dexamethasone loading (from 3.0 to 1.7w/w%). In vitro experiments on LPS-activated macrophages demonstrated that the encapsulation of dexamethasone in liposomes, particularly in HA-bearing ones, improved its anti-inflammatory efficacy compared to the free drug. Subsequently, in vivo data revealed that while intratracheal administration of free dexamethasone led to an important inter-animals variation of efficacy, dexamethasone-loaded liposomes showed an improved consistency within the results. Our data indicate that encapsulating dexamethasone into lipid nanoparticles is a potent strategy to improve its efficacy after lung delivery.

Pre-clinical safety of topically administered sunitinib-loaded lipid and polymeric nanocarriers targeting corneal neovascularization

Three different types of sunitinib-loaded (SUN-loaded) nanocarriers were compared, aiming at the topical treatment of corneal neovascularization (CNV): polymeric nanospheres (NS), liposomes (LIP), and solid lipid nanoparticles (SLN). Three out of eleven formulations prepared for an optimization study - the best SUN-loaded nanocarrier of each assessed type (NS, LIP, and SLN) - were selected, based on their size, polydispersity index (PdI), drug load (DL), and encapsulation efficiency (EE). These three optimal formulations were further characterized by nanoparticle tracking analysis (NTA), electron paramagnetic resonance (EPR) spectroscopy, and zeta potential. In vitro SUN release profiles were obtained for the optimal formulations, along with ex vivo corneal permeability/retention studies, and ocular tolerance assays, namely: the bovine corneal opacity and permeability (BCOP) assay, the HET-CAM test (hen's egg test - chorioallantoic membrane), and hemolytic potential (HP) assay. None of the optimal formulations exhibited toxicity or potential for ocular irritation. SLN showed higher surface fluidity, drug release more suitable for topical ocular applications, besides greater SUN corneal retention. Our results suggest that SLN are the best CNV-targeting SUN-loaded nanocarriers for clinical translation when compared to their NS and LIP analogues.

Besifloxacin liposomes with positively charged additives for an improved topical ocular delivery

Topical ophthalmic antibiotics show low efficacy due to the well-known physiological defense mechanisms of the eye, which prevents the penetration of exogenous substances. Here, we aimed to incorporate besifloxacin into liposomes containing amines as positively charged additives and to evaluate the influence of this charge on drug delivery in two situations: (i) iontophoretic and (ii) passive treatments. Hypothesis are (i) charge might enhance the electromigration component upon current application improving penetration efficiency for a burst drug delivery, and (ii) positive charge might prolong formulation residence time, hence drug penetration. Liposomes elaborated with phosphatidylcholine (LP PC) or phosphatidylcholine and spermine (LP PC: SPM) were stable under storage at 6 ºC for 30 days, showed mucoadhesive characteristics, and were non-irritant, according to HET-CAM tests. Electron paramagnetic resonance spectroscopy measurements showed that neither the drug nor spermine incorporations produced evident alterations in the fluidity of the liposome's membranes, which retained their structural stability even under iontophoretic conditions. Mean diameter and zeta potential were 177.2 ± 2.7 nm and − 5.7 ± 0.3 mV, respectively, for LP PC; and 175.4 ± 1.9 nm and + 19.5 ± 1.0 mV, respectively, for LP PC:SPM. The minimal inhibitory concentration (MIC) and the minimal bactericide concentration (MBC) of the liposomes for P. aeruginosa showed values lower than the commercial formulation (Besivance). Nevertheless, both formulations presented a similar increase in permeability upon the electric current application. Hence, liposome charge incorporation did not prove to be additionally advantageous for iontophoretic therapy. Passive drug penetration was evaluated through a novel in vitro ocular model that simulates the lacrimal flow and challenges the formulation resistance in the passive delivery situation. As expected, LP PC: SPM showed higher permeation than the control (Besivance). In conclusion, besifloxacin incorporation into positively charged liposomes improved passive topical delivery and can be a good strategy to improve topical ophthalmic treatments.

Iontophoresis enhances voriconazole antifungal potency and corneal penetration

Strategies to enhance corneal penetration of voriconazole (VOR) could improve the treatment of fungal keratitis. Here, we evaluated the use of iontophoresis for ocular VOR delivery from either: (i) a cyclodextrin inclusion complex (CD VOR), (ii) a liposome (LP VOR), and (iii) a chitosan-coated liposome (LP VOR CS). LP VOR CS presented mean diameter of 139.2 ± 1.3 nm and zeta potential equal to + 3.3 ± 1.5 mV compared to 134.6 ± 1.7 and -8.2 ± 3.0 mV of LP VOR, which, together with mucin mucoadhesion study, confirmed chitosan-coating. Both drug and liposomal formulations were stable under the influence of an applied electric current. Interestingly, in vitro studies in Candida glabrata culture indicated a decrease in VOR MIC values following iontophoresis (from 0.28 to 0.14 µg/mL). Iontophoresis enhanced drug penetration into the cornea. After 10 min of a 2 mA/cm² applied current, corneal retained amounts were 45.4 ± 11.2, 30.4 ± 2.1 and 30.6 ± 2.9 µg/cm² for, respectively, CD VOR, LP VOR, and LP VOR CS. In conclusion, iontophoresis increases drug potency and enhances drug penetration into the cornea, showing potential to be used as "an emergency burst delivery approach".

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.