α-Cyclodextrin-based poly(pseudo)rotaxane for antifungal drug delivery to the vaginal mucosa.

This work aimed to evaluate poly(pseudo)rotaxanes (PPRs) potential for vaginal antifungal delivery. For this, PPRs containing terbinafine (TB) 2 % were obtained using two small surfactants, Kolliphor® RH40 and Gelucire® 48/16, and different α-cyclodextrin (α-CD) concentrations (5 and 10 %). PPRs were characterized by their physicochemical characteristics, irritation, and mucoadhesion capabilities. Formulations' performance was assessed in a vertical penetration model, which uses ex vivo entire porcine vagina. Conventional penetration experiments with excised vaginal tissue were performed as a control. Results showed all formulations were non-irritant according to the HET-CAM test. Furthermore, PPRs with 10 % αCD showed superior mucoadhesion (p < 0.05). Conventional horizontal penetration studies could not differentiate formulations (p > 0.05). However, PPRs with 10 % αCD presented a better performance in vertical ex vivo studies, achieving higher drug penetration into the vaginal mucosa (p < 0.05), which is probably related to the formulation's prolonged residence time. In addition, the antifungal activity of the formulations was maintained against Candida albicans and C. glabrata cultures. More importantly, the formulation's viscosity and drug delivery control had no negative impact on the antifungal activity. In conclusion, the best performance in a more realistic model evidenced the remarkable potential of PPRs for vaginal drug delivery.

Cyclodextrin inclusion complex of a multi-component natural product by hot-melt extrusion.

This study aimed to investigate whether hot-melt extrusion (HME) processing can promote molecular encapsulation of a multi-component natural product composed of volatile and pungent hydrophobic substances (ginger oleoresin (OR)) with cyclodextrins. 6-Gingerol and 6-shogaol, the biomarkers of ginger OR, were quantified by HPLC. Phase-solubility studies were performed using ß-cyclodextrin (ßCD) and hydroxypropyl-ß-cyclodextrin (HPßCD) for ginger OR complexation. Solid complexes were then prepared by thermal (HME)- and solvent (slurry (SL))-based methods. Morphology, thermal behavior, solubility, in vitro dissolution, and in vivo anti-inflammatory activity were evaluated. HPßCD gave rise to AL-type complexes with ginger OR, whereas ßCD led to materials with limited solubility. Ginger OR was complexed with HPßCD by HME without significant change in gingerol and shogaol content. Additionally, thermogravimetric analysis (TGA) suggested higher volatile retention in HME complexes than in SL ones. Shogaol and gingerol solubility and dissolution significantly increased from SL and HME complexes compared with ginger OR. In turn, 1:2 OR/HPßCD HME complex showed higher 6-shogaol solubility than SL, associated with a gradual release. The carrageenan-induced pleurisy test showed that the anti-inflammatory activity of ginger OR was maintained after complexation with HPßCD. The complexes significantly decrease the levels of IL-1ß and inhibit cell migration. HME complex showed performance equivalent to the positive control and superior to the SL material. Taken together, these results indicate that HME can be useful for promoting the molecular encapsulation of complex natural products that contain volatile and thermolabile substances. HME complexes showed better in vivo and in vitro performance than complexes prepared using the solvent-based method.

Poly(pseudo)rotaxanes formed by mixed micelles and α-cyclodextrin enhance terbinafine nail permeation to deeper layers.

This work aimed to develop water-based formulations for onychomycosis topical treatment using micelles of small pegylated surfactants associated with α-cyclodextrin (αCD) to deliver terbinafine to the nail. Kolliphor® RH40 (RH40) and Gelucire® 48/16 (GEL) single and mixed micelles (RH40:GEL 1:1) were prepared. αCD was added to the surfactants dispersions to form poly(pseudo)rotaxanes (PPR). Formulations were characterized in terms of drug solubilization (3 to 34-fold increase), particle size (9-11 nm) and Z-potential (+0.3 - +1.96 mV), blood compatibility (non-hemolytic), rheological behavior (solid-like viscoelastic properties after 5-10% αCD addition), drug release and interaction with the nail plate. GEL micelles and surfactant-10% αCD PPRs notably hydrated the nail plate. The high viscosity of PPR led to a slower drug release, except for RH40:GEL +10% αCD that surprisingly released terbinafine faster. The RH40:GEL +10% αCD formulation delivered twice more amount of terbinafine to deeper regions of nail plate compared to other formulations. The results evidenced the potential of PPR formed by small pegylated surfactants as a water-based formulation for nail drug delivery.

Preformulation and characterization of raloxifene-loaded lipid nanoparticles for transdermal administration.

Transdermal administration of raloxifene hydrochloride (RLX)-loaded nanostructured lipid carriers (NLCs) has been proposed to circumvent its low oral bioavailability (2%). Preformulation studies were carried out to evaluate drug-excipient compatibility of various adjuvants commonly used for NLC preparation (waxes, cholesterol, compritol, gelucire, span 60, span 80, span 85, tween 80, poloxamer 188, oleic acid, caprylic/capric triglyceride, and castor oil). It was used differential scanning calorimetry (DSC), isothermal stress testing (IST), and solubility studies. The most promising excipients were chosen for NLC obtention, and full characterization was done, including in vitro skin permeation. DSC curves suggested drug-excipient interaction among some compounds, and the IST study showed incompatibility of RLX with waxes, compritol, cholesterol, span 60, and poloxamer 188. Solubility studies helped select gelucire, caprylic/capric triglyceride, span 80, and tween 80 for NLC production. Twelve NLCs were obtained (NLC1 to NLC12), but NLC7 and NLC8 were the most promising ones. In vitro release studies demonstrated that NLC7 and NLC8 were able to control RLX release (14.74 and 9.07% at 24 h, respectively) compared with the unloaded drug (> 90% at 24 h). Unloaded RLX did not permeate the diffusion cells' receptor medium and showed higher drug skin retention (11-fold) than RLX-loaded NLC. NLC reduced RLX skin retention, favoring drug permeation to deeper skin layers. NLC7 increased drug flux is 2.4-fold. NLC7 is a promising formulation for RLX transdermal drug delivery.

Enhanced nail delivery of voriconazole-loaded nanomicelles by thioglycolic acid pretreatment: A study of protein dynamics and disulfide bond rupture.

This work aimed to select an effective penetration enhancer (PE) for nail pretreatment, develop voriconazole (VOR)-loaded nanomicelles, and evaluate their ability to deliver VOR to the nail. A complete analysis of nail protein dynamics, bond rupture, and microstructure was performed. Alternative methods as electron paramagnetic resonance (EPR) and the Ellman's reagent (DTNB) assay were also evaluated. Nanomicelles were produced and characterized. The PE hydrated the hooves, following the order: urea ≈ cysteine ≈ glycolic acid < thioglycolic acid (TGA) < NaOH. SEM images and methylene blue assay showed enlarged pores and roughness of porcine hooves after incubation with NaOH and TGA. EPR was demonstrated to be the most sensitive technique. DTNB assay quantified higher thiol groups for samples treated with TGA (p < 0.05). A stratigraphic analysis with Raman spectroscopy demonstrated that hooves treated with TGA presented a higher SH/SS ratio at the edges, affecting protein secondary structure. In vitro permeation studies demonstrated significant VOR permeation (29.44 ± 6.13 µg/cm2), 10-fold higher than previous studies with lipid nanoparticles. After TGA pretreatment, VOR permeation was further enhanced (3-fold). TGA pretreatment followed by VOR-loaded nanomicelles demonstrates a promising approach for onychomycosis treatment. The novel methods for protein analysis were straightforward and helpful.

Thymol-Loaded Biogenic Silica Nanoparticles in an Aquatic Environment: The Impact of Particle Aggregation on Ecotoxicity.

Thymol, a monoterpene phenol, is used as a natural biocide. To circumvent its chemical instability, we propose use of thymol-loaded biogenic silica nanoparticles (BSiO2 #THY NPs); however, the toxicity of this system for aquatic organisms is unknown. Thus, the present study aimed to evaluate the toxicogenetic effects induced by thymol, BSiO2 NP, and BSiO2 #THY on Artemia salina and zebrafish (Danio rerio) early life stages. We also investigated the impact of BSiO2 aggregation in different exposure media (saline and freshwater). Based on the median lethal concentration at 48 h (LC5048h ), BSiO2 #THY (LC5048h = 1.06 mg/L) presented similar toxic potential as thymol (LC5048h = 1.03 mg/L) for A. salina, showing that BSiO2 had no influence on BSiO2 #THY toxicity. Because BSiO2 aggregated and sedimented faster in A. salina aqueous medium than in the other medium, this NP had lower interaction with this microcrustacean. Thus, BSiO2 #THY toxicity for A. salina is probably due to the intrinsic toxicity of thymol. For zebrafish early life stages, BSiO2 #THY (LC5096h = 13.13 mg/L) was more toxic than free thymol (LC5096h = 25.60 mg/L); however, BSiO2 NP has no toxicity for zebrafish early life stages. The lower aggregation of BSiO2 in the freshwater medium compared to the saline medium may have enhanced thymol's availability for this aquatic organism. Also, BSiO2 #THY significantly induced sublethal effects as thymol, and both were genotoxic for zebrafish. In conclusion, although BSiO2 #THY still needs improvements to ensure its safety for freshwater ecosystems, BSiO2 NP seems to be a safe nanocarrier for agriculture. Environ Toxicol Chem 2021;40:333-341. © 2020 SETAC.

Development of carvedilol-loaded lipid nanoparticles with compatible lipids and enhanced skin permeation in different skin models.

The study aimed to develop lipid nanoparticles using excipients compatible with carvedilol (CARV) for enhanced transdermal drug delivery. Nanostructured lipid carriers (NLC) were successfully obtained and fully characterised. Franz diffusion cells were used for release and in vitro permeation studies in the porcine epidermis (EP) and full-thickness rat skin. NLC4 and NLC5 (0.5 mg/mL of CARV) presented small size (80.58 ± 1.70 and 116.80 ± 12.23 nm, respectively) and entrapment efficiency of 98.14 ± 0.79 and 98.27 ± 0.99%, respectively. CARV-loaded NLC4 and NLC5 controlled drug release. NLC4 allowed CAR permeation through porcine EP in greater amounts than NLC5, i.e. 11.83 ± 4.71 µg/cm2 compared to 3.06 ± 0.79 µg/cm2. NLC4 increased CARV permeation by 2.5-fold compared to the unloaded drug in rat skin studies (13.73 ± 4.12 versus 5.31 ± 1.56 µg/cm2). NLC4 seems to be a promising carrier for the transdermal delivery of CARV.

SLN- and NLC-encapsulating antifungal agents: skin drug delivery and their unexplored potential for treating onychomycosis.

BACKGROUND: Lipid nanoparticles have been extensively studied for drug delivery of antifungal drugs, especially for dermatophytosis treatments. They can accumulate in skin appendages and release drugs in a controlled manner and also increase skin moisture, due to the formation of an occlusive film. Since moisture heavily influences nail and skin permeability, these systems seem to pose great potential for antifungal drug delivery. METHODS: We therefore compare skin and nail physiopathological structure and discuss the potential use of lipid nanoparticles in managing skin and nail mycoses, highlighting their unexplored use in onychomycosis. RESULTS: Structural features become particularly relevant when treating local skin/nail disorders. Nail plate represents the most resistant barrier to the penetration of molecules. In recent years, at least 55 researches have been reported about lipid nanoparticles and, antifungal drugs. They have focused on production methods and nanoparticle ingredients influence on entrapment efficiency, fungal activity in vitro, stability, and drug release. Lipid nanoparticles such as SLN and NLC have shown great results in permeating the skin. Currently, however, there is just one study published using NLC applied directly to the nail plate. NLC containing voriconazole had a noteworthy impact on the penetration depth of a nanoencapsulated drug, which allowed its deeper penetration into porcine hooves than the unloaded drug. CONCLUSION: Evidence of the success of SLN and NLC in achieving high encapsulation efficiencies of antifungals and promoting cutaneous delivery indicates the potential of the systems in enhancing nail hydration and drug penetration into the nail plate.

Voriconazole-loaded nanostructured lipid carriers (NLC) for drug delivery in deeper regions of the nail plate.

Voriconazole-loaded nanostructured lipid carriers (VOR-NLC) were developed and drug penetration evaluated in porcine hooves in vitro. Synergistic effect of urea (Ur), selected among other known chemical enhancers according to hoof hydration potential, was also evaluated. VOR-NLC presented a high encapsulation efficiency (74.52±2.13%), approximate mean diameter of 230nm and were positively charged (+27.32±2.74mV). Stability studies indicated they were stable under refrigeration (4±2°C) for up to 150days. SEM images revealed hooves treated with VOR-NLC and VOR-NLC-Ur suffered a disturbance on the surface depicting high roughness and porosity. Permeation data showed a substantial VOR amount retained in superficial hooves sections independent of the formulation used (2.42±0.26; 2.52±0.36 and 2.41±0.60µg/cm2 for unloaded VOR, VOR-NLC and VOR-NLC-Ur, respectively, p>0.05). Still, successive extractions, revealed the amount of VOR retained in deeper regions was significantly higher when VOR-NLC or VOR-NLC-Ur was used (0.17±0.04, 0.47±0.14 and 0.36±0.07µg/cm2 for unloaded VOR, VOR-NLC and VOR-NLC-Ur, respectively, p<0.05). Such results indicate NLC are promising formulations for the management of onychomycosis. Further studies in diseased nail plates are necessary.

Improved tacrolimus skin permeation by co-encapsulation with clobetasol in lipid nanoparticles: Study of drug effects in lipid matrix by electron paramagnetic resonance.

Combined therapy with corticosteroids and immunosuppressant-loaded nanostructured lipid carriers (NLC) could be useful in the treatment of skin diseases. To circumvent NLC loading capacity problems, loaded drugs should have different physicochemical characteristics, such as tacrolimus (TAC) and clobetasol (CLO). Therefore, in the present study, TAC and CLO were encapsulated in NLC (TAC-NLC, CLO-NLC and TAC+CLO-NLC), coated or otherwise with chitosan. Electron paramagnetic resonance (EPR) spectroscopy of different spin labels was used to investigate the impact of drug and oil incorporation on the lipid dynamic behavior of the lipid matrices. In addition, the impact of co-encapsulation on drug release and skin permeation was evaluated. Entrapment efficiency was greater than 90% for both drugs, even when the maximum drug loading achieved for TAC-NLC and CLO-NLC was kept at TAC+CLO-NLC, because TAC is more soluble in the solid lipid and CLO in the liquid lipid. EPR data indicated that both drugs reduced the lipid fluidity near the polar surface of the lipid matrix, which suggests their presence in this region. In addition, EPR data showed that liquid lipid is also present in more superficial regions of the nanoparticle matrix. CLO was released faster than TAC from TAC+CLO-NLC, probably because it is more soluble in the liquid lipid. TAC skin penetration was affected by CLO. A 5-fold increase in TAC penetration was observed from TAC+CLO-NLC when compared to TAC-NLC formulations. Coating also increased TAC and CLO permeation to deeper skin layers (1.8-fold and 1.6-fold, respectively). TAC+CLO-NLC seems to be an effective strategy for topical delivery of TAC and CLO, and thus constitutes promising formulations for the treatment of skin diseases.