Pulmonary Delivery of Curcumin and Beclomethasone Dipropionate in a Multicomponent Nanosuspension for the Treatment of Bronchial Asthma.

Curcumin has shown a potential extraordinary activity as an add-on ingredient in asthma treatment, due to its immunomodulatory and anti-inflammatory mechanism of action. However, its low water solubility and bioavailability lead to a poor therapeutic effect, which can be overcome by its formulation as nanocrystals. The aim of this study was to prepare a multicomponent formulation for the delivery of curcumin (CUR) and beclomethasone dipropionate (BDP) into the lungs as water-based nanosuspensions (NS). Single component formulations (CUR-NS, BDP-NS) and a multicomponent formulation (CUR+BDP-NS) were prepared through a wet ball media milling technique, using P188 as a non-toxic stabilizer. Characterization was carried out in terms of size, size distribution, zeta potential, nanocrystals morphology, and solid-state properties. Moreover, the inhalation delivery efficiency was studied with Next Generation Impactor (NGI, Apparatus E Ph. Eu). CUR-NS was optimized and showed a long-term stability and improved nanocrystals apparent solubility. The three formulations exhibited a nanocrystal mean diameter in the range of 200-240 nm and a homogenous particle size distribution. Aggregation or sedimentation phenomena were not observed in the multicomponent formulation on 90 days storage at room temperature. Finally, the nebulization tests of the three samples showed optimal aerodynamic parameters and MMAD < 5 µm.

Nanocrystals as Effective Delivery Systems of Poorly Water-soluble Natural Molecules.

Natural products are an important source of therapeutically effective compounds throughout the world. Since ancient times, a huge amount of both plant extracts and isolated compounds have been largely employed in treatment and prevention of human disorders and, currently, more than 60% of the world's population trusts on plant medicaments as demonstrated by the increasing quantity of herbal therapeutics in the market. Unfortunately, several promising natural molecules for the treatment of the most diverse ailments are characterized by extremely unfavourable features, such as low water solubility and poor/irregular bioavailability, which hinder their clinical use. To overcome these limitations and to make herbal therapy more effective, different formulative approaches have been employed. Among the different strategies for increasing drug solubility, nanocrystals can be considered one of the most interesting and successful approaches. Drug nanocrystals are nanosized drug particles usually formulated as nanosuspensions, namely submicron dispersions in liquid media where surfactants, polymers, or a mixture of both act as stabilisers. In this review, we described the most significant results and progresses concerning drug nanocrystal formulations for the delivery of natural compounds with a significant pharmacological activity. The text is organized in nine sections, each focusing on a specific poorly water- soluble natural compound (apigenin, quercetin, rutin, curcumin, baicalin and baicalein, hesperetin and hesperidin, resveratrol, lutein, silybin). To foster the clinical translation of these natural nanomedicines, our opinion is that future research should pair the essential pharmacokinetic studies with carefully designed pre-clinical experiments, able to prove the formulation efficacy in relevant animal models in vivo.

Enhancing Topical Delivery of Resveratrol through a Nanosizing Approach.

Resveratrol is a naturally occurring polyphenol with strong antioxidant and free radical scavenging properties, recently proposed as a therapeutic agent for skin diseases. In this study, we investigated the possibility of improving the dermal bioavailability of the poorly water-soluble drug resveratrol by nanocrystal technology. To this purpose, nanosuspensions were prepared by the wet media milling technique, using Poloxamer 188 or Tween 80 as stabilizers, and characterized by means of both solid state and morphological and dimensional studies. All analytical data demonstrated that neither a modification of the drug crystalline pattern nor the isomerization of the trans double bond were observed after the wet media milling particle size reduction process, which produced rounded and smooth nanocrystals with a mean diameter ranging between 0.2-0.3 µm. Resveratrol skin delivery from nanosuspension formulations was evaluated by the pig ear skin model via tape stripping. Results of the experiments showed that after application of nanosuspension formulations, higher amounts of resveratrol could penetrate the skin at deeper levels compared to drug coarse suspensions. The antioxidant activity of resveratrol in nanocrystals was assessed by the DPPH assay, which demonstrated that the size reduction process as well as the formulation compositions did not modify the drug antioxidant activity.

Penetration enhancer-containing vesicles (PEVs) as carriers for cutaneous delivery of minoxidil: in vitro evaluation of drug permeation by infrared spectroscopy.

Recently, we carried out a research on new liposomal systems prepared by using in their composition a few penetration enhancers which differ for chemical structure and physicochemical properties. The penetration enhancer-containing vesicles (PEVs) were prepared by using soy lecithin and different amounts of three penetration enhancers, 2-(2-ethoxyethoxy) ethanol (Transcutol(®)), capryl-caproyl macrogol 8-glyceride (Labrasol(®)), and cineole.To study the influence of the PEVs on (trans)dermal delivery of minoxidil, in vitro diffusion experiments were performed through new born pig skin and the results were compared with that obtained applying the vesicular system without enhancer (control) after pretreatment of the skin with the various enhancers. In this study, Fourier transform infrared spectroscopy (FTIR), attenuated total reflectance FTIR (ATR-FTIR) and FTIR imaging were used to evaluate the effective penetration of minoxidil in the skin layers and to discover the influence of the enhancer on the drug topical delivery. These analytical studies allowed us to characterize the drug formulations and to evaluate the vesicle distribution into the skin. Recorded spectra confirmed that the vesicle formulations with penetration enhancers promoted drug deposition into the skin.

Idebenone-loaded solid lipid nanoparticles for drug delivery to the skin: in vitro evaluation.

Idebenone (IDE), a synthetic derivative of ubiquinone, shows a potent antioxidant activity that could be beneficial in the treatment of skin oxidative damages. In this work, the feasibility of targeting IDE into the upper layers of the skin by topical application of IDE-loaded solid lipid nanoparticles (SLN) was evaluated. SLN loading different amounts of IDE were prepared by the phase inversion temperature method using cetyl palmitate as solid lipid and three different non-ionic surfactants: ceteth-20, isoceteth-20 and oleth-20. All IDE loaded SLN showed a mean particle size in the range of 30-49 nm and a single peak in size distribution. In vitro permeation/penetration experiments were performed on pig skin using Franz-type diffusion cells. IDE penetration into the different skin layers depended on the type of SLN used while no IDE permeation occurred from all the SLN under investigation. The highest IDE content was found in the epidermis when SLN contained ceteth-20 or isoceteth-20 as surfactant while IDE distribution into the upper skin layers depended on the amount of IDE loaded when oleth-20 was used as surfactant. These results suggest that the SLN tested could be an interesting carrier for IDE targeting to the upper skin layers.

Transcutol containing vesicles for topical delivery of minoxidil.

The aim of this work was to evaluate the ability of Transcutol (Trc) to produce elastic vesicles with soy lecithin (SL) and study the influence of the obtained vesicles on in vitro (trans)dermal delivery of minoxidil. To this purpose, so-called penetration enhancer-containing vesicles (PEVs) were prepared using Trc aqueous solutions (5-10-20-30% v/v) as hydrophilic phase. SL liposomes, without Trc, were used as control. Prepared formulations were characterized in terms of size distribution, morphology, zeta potential, deformability, and rheological behavior. The influence of the obtained PEVs on (trans)dermal delivery of minoxidil was studied by in vitro diffusion experiments through pig skin. Results showed that all prepared PEVs were able to give good entrapment efficiency (E%≈67) similar to that of conventional liposomes. Trc-containing PEVs showed to be more deformable than liposomes only when minoxidil was loaded in 5 and 10% Trc-containing vesicles. Rheological studies showed that PEVs have higher fluidity than conventional liposomes. All PEVs showed a higher stability than liposomes as shown by studying zeta potential and size distribution during three months. Results of in vitro diffusion experiments showed that Trc-containing PEVs are able to deliver minoxidil to deep skin layers without any transdermal permeation.

Penetration enhancer-containing vesicles (PEVs) as carriers for cutaneous delivery of minoxidil.

The aim of this work was to evaluate the ability of a few different penetration enhancers to produce elastic vesicles with soy lecithin and the influence of the obtained vesicles on in vitro (trans)dermal delivery of minoxidil. To this purpose, so-called Penetration Enhancer-containing Vesicles (PEVs) were prepared as dehydrated-rehydrated vesicles by using soy lecithin and different amounts of three penetration enhancers, 2-(2-ethoxyethoxy)ethanol (Transcutol), capryl-caproyl macrogol 8-glyceride (Labrasol), and cineole. Soy lecithin liposomes, without penetration enhancers, were used as control. Prepared formulations were characterized in terms of size distribution, morphology, zeta potential, and vesicle deformability. The influence of PEVs on (trans)dermal delivery of minoxidil was studied by in vitro diffusion experiments through newborn pig skin in comparison with traditional liposomes and ethanolic solutions of the drug also containing each penetration enhancer. A skin pre-treatment study using empty PEVs and conventional liposomes was also carried out. Results showed that all the used penetration enhancers were able to give more deformable vesicles than conventional liposomes with a good drug entrapment efficiency and stability. In vitro skin penetration data showed that PEVs were able to give a statistically significant improvement of minoxidil deposition in the skin in comparison with classic liposomes and penetration enhancer-containing drug ethanolic solutions without any transdermal delivery. Moreover, the most deformable PEVs, prepared with Labrasol and cineole, were also able to deliver to the skin a higher total amount of minoxidil than the PE alcoholic solutions thus suggesting that minoxidil delivery to the skin was strictly correlated to vesicle deformability, and therefore to vesicle composition.

Phycocyanin liposomes for topical anti-inflammatory activity: in-vitro in-vivo studies.

OBJECTIVES: The aim of this work was to investigate the anti-inflammatory activity of C-phycocyanin (C-PC) on skin inflammation after topical administration and the influence of liposomal delivery on its pharmacokinetic properties. METHODS: Liposomes of different size and structure were prepared with different techniques using soy phosphatidylcholine and cholesterol. Vesicular dispersions were characterised by transmission electron microscopy, optical and fluorescence microscopy for vesicle formation and morphology, dynamic laser light scattering for size distribution, and Zetasizer for zeta-potential. C-PC skin penetration and permeation experiments were performed in vitro using vertical diffusion Franz cells and human skin treated with either free or liposomal drug dispersed in a Carbopol gel. KEY FINDINGS: The protein was mainly localised in the stratum corneum, while no permeation of C-PC through the whole skin thickness was detected. Two percent C-PC-encapsulating liposomes showed the best drug accumulation in the stratum corneum and the whole skin, higher than that of the corresponding free 2% C-PC gel. Moreover, skin deposition of liposomal C-PC was dose dependent since skin accumulation values increased as the C-PC concentration in liposomes increased. The topical anti-inflammatory activity of samples was evaluated in vivo as inhibition of croton oil-induced or arachidonic acid-induced ear oedema in rats. CONCLUSIONS: The results showed that C-PC can be successfully used as an anti-inflammatory drug and that liposomal encapsulation is effective in improving its anti-inflammatory activity.

SLN as a topical delivery system for Artemisia arborescens essential oil: in vitro antiviral activity and skin permeation study.

The effect of SLN incorporation on transdermal delivery and in vitro antiherpetic activity of Artemisia arborescens essential oil was investigated. Two different SLN formulations were prepared using the hot-pressure homogenization technique, Compritol 888 ATO as lipid, and Poloxamer 188 and Miranol Ultra C32 as surfactants. Formulations were examined for their stability for two years by monitoring average size distribution and zeta potential values. The antiviral activity of free and SLN incorporated essential oil was tested in vitro against Herpes Simplex Virus-1 (HSV-1) by a quantitative tetrazolium-based colorimetric method (MTT), while the effects of essential oil incorporation into SLN on both the permeation through and the accumulation into the skin strata was investigated by using in vitro diffusion experiments through newborn pig skin and an almond oil Artemisia essential oil solution as a control. Results showed that both SLN formulations were able to entrap the essential oil in high yields and that the mean particle size increased only slightly after two years of storage, indicating a high physical stability. In vitro antiviral assays showed that SLN incorporation did not affect the essential oil antiherpetic activity. The in vitro skin permeation experiments demonstrated the capability of SLN of greatly improving the oil accumulation into the skin, while oil permeation occurred only when the oil was delivered from the control solution.

Liposomes as carriers for dermal delivery of tretinoin: in vitro evaluation of drug permeation and vesicle-skin interaction.

The influence of liposome composition, size, lamellarity and charge on the (trans)dermal delivery of tretinoin (TRA) was studied. For this purpose we studied both multilamellar (MLV) or unilamellar (UV) liposomes. Positively or negatively charged liposomes were obtained using either hydrogenated (Phospholipon90H) or non-hydrogenated soy phosphatidylcholine (Phospholipon90) and cholesterol, in combination with stearylamine or dicetylphosphate. Liposomal formulations were characterized by transmission electron microscopy (TEM) and optical and light polarized microscopy for vesicle formation and morphology, and by dynamic laser light scattering for size distribution. In order to obtain more information about the stability and the thermodynamic activity of the liposomal tretinoin, TRA diffusion through a lipophilic membrane was investigated. The effect of the vesicular incorporation of tretinoin on its accumulation into the newborn pig skin was also studied. The experiments were performed in vitro using Franz cells in occlusive conditions and were compared to three different controls. The tretinoin amount delivered through and accumulated in the several skin layers was detected by HPLC. Furthermore, TEM in combination with osmium tetroxide was used to visualize the skin structure after the liposomal administration. Overall obtained results showed that liposomes may be an interesting carrier for tretinoin in skin disease treatment, when appropriate formulations are used. In particular, negatively charged liposomes strongly improved newborn pig skin hydration and TRA retention, though no evidence of intact vesicle penetration was found.

Liposomal incorporation of Artemisia arborescens L. essential oil and in vitro antiviral activity.

The effect of liposomal inclusion on the in vitro antiherpetic activity of Artemisia arborescens L. essential oil was investigated. In order to study the influence of vesicle structure and composition on the antiviral activity of the vesicle-incorporated oil, multilamellar (MLV) and unilamellar (SUV) positively charged liposomes were prepared by the film method and sonication. Liposomes were obtained from hydrogenated (P90H) and non-hydrogenated (P90) soy phosphatidylcholine. Formulations were examined for their stability for over one year, monitoring the oil leakage from vesicles and the average size distribution. The antiviral activity was studied against Herpes simplex virus type 1 (HSV-1) by a quantitative tetrazolium-based colorimetric method. Results showed that Artemisia essential oil can be incorporated in good amounts in the prepared vesicular dispersions. Stability studies pointed out that vesicle dispersions were very stable for at least six months and neither oil leakage nor vesicle size alteration occurred during this period. After one year of storage oil retention was still good, but vesicle fusion was present. Antiviral assays demonstrated that the liposomal incorporation of A. arborescens essential oil enhanced its in vitro antiherpetic activity especially when vesicles were made with P90H. On the contrary, no significant difference in antiviral activity was observed between the free and SUV-incorporated oil.