Novel patch-based systems for the localised delivery of ALA-esters

Photodynamic therapy with 5-aminolevulinate patch for the treatment of superficial basal cell carcinomas

5-Aminolevulinate (ALA) patches with red light (630-nm light source and a total light dose of 37 J/cm² ) is an effective treatment indicated by food and drug administration (FDA) and european medicines agency (EMA) only for grade I to II actinic keratosis located on the scalp and face. Currently, there are no efficacy data on their use in the treatment of other types of epithelial neoplasms. We analyzed the efficacy of ALA patches in seven superficial basal cell carcinomas (sBCCs) that occurred in four patients. All lesions were treated with topical ALA patches. A complete response of all sBCCs was achieved at week 24 after treatment. Our study suggests that ALA patches for sBCCs have good efficacy rates and excellent safety profile.

5-Aminolaevulinic acid patch photodynamic therapy for the treatment of actinic keratoses: preliminary results from an Italian study in the real-life setting

BACKGROUND

Photodynamic therapy (PDT) is recommended for both lesion and field therapy of actinic keratoses (AKs). The 5-aminolaevulinic acid (5-ALA) patch PDT is indicated for the treatment of isolated mild AKs (≤1.8 cm) on the face and bald scalp. It was demonstrated to be effective and safe in clinical trials with a good tolerability profile.

METHODS

In this retrospective multicenter real-life study, 33 patients with a total of 99 AKs of the scalp, face, ears, and/or hands and 2 actinic cheilitis were treated with one treatment session of 5-ALA patch PDT with a red light source (total dose of 37 J/cm2).

RESULTS

Overall, 12 weeks after treatment, 68/99 (69%) lesions were completely cleared. Complete response was obtained in 82% of AKs on the ears, 78% on the face, 57% on the hands, and 56% on the scalp and in the two actinic cheilitis. The treatment was very effective on grade I AKs, cleared in 87% of the cases and less efficient on grade II-III lesions, cleared in 47% of the cases. 5-ALA patch PDT was well tolerated with a good to excellent cosmetic outcome in 97% of the patients and with 94% of the patients being satisfied or very satisfied with the treatment.

CONCLUSIONS

Our results confirm that 5-ALA patch PDT is a good option for AK treatment in clinical practice, it is easy to use, effective and well tolerated even in difficult-to-treat-areas. Moreover, it has an excellent cosmetic outcome.

Branched poly (lactic acid) microparticles for enhancing the 5-aminolevulinic acid phototoxicity

An innovative microcarrier based on a carboxy-enriched and branched polylactic acid derivative was developed to enhance the in vitro phototoxicity of the photosensitizer and prodrug 5-aminolevulinic. Microparticles, prepared by double emulsion technique and loaded with the prodrug were carefully characterized and the effect of the polymer structure on the chemical, physical and biological properties of the final product was evaluated. Results showed that microparticles have a spherical shape and ability to allocate up to 30 μg of the photosensitizer per mg of carrier despite their difference in solubility. Release studies performed in various simulated physiological conditions demonstrate the influence of the branched structure and the presence of the additional carboxylic groups on the release rate and the possibility to modulate it. In vitro assays conducted on human epithelial adenocarcinoma cells proved the not cytotoxicity of the carriers in a wide range of concentrations. The hemocompatibility and surface proteins adsorption were evaluated at different microparticles concentrations to evaluate the safety and estimate the possible microparticles residential time in the bloodstream. The advantages, of loading 5-aminolevulinic acid in the prepared carrier has been deeply described in terms of enhanced phototoxicity, compared to the free 5-aminolevulinic acid formulation after irradiation with light at 635 nm. The obtained results demonstrate the advantages of the prepared derivative compared to the linear polylactide for future application in photodynamic therapy based on the photosensitizer 5-aminolevulinic acid.

Potential of microneedles in enhancing delivery of photosensitising agents for photodynamic therapy

Photodynamic therapy can be used in the treatment of pre-malignant and malignant diseases. It offers advantages over other therapies currently used in the treatment of skin lesions including avoidance of damage to surrounding tissue and minimal or no scarring. Unfortunately, systemic delivery of photosensitising agents can result in adverse effects, such as prolonged cutaneous photosensitivity; while topical administration lacks efficacy in the clearance of deeper skin lesions and those with a thick overlying keratotic layer. Therefore, enhancement of conventional photosensitiser delivery is desired. However, the physicochemical properties of photosensitising agents, such as extreme hydrophilicity or lipophilicity and large molecular weights make this challenging. This paper reviews the potential of microneedles as a viable method to overcome these delivery-limiting physicochemical characteristics and discusses the current benefits and limitations of solid, dissolving and hydrogel-forming microneedles. Clinical studies in which microneedles have successfully improved photodynamic therapy are also discussed, along with benefits which microneedles offer, such as precise photosensitiser localisation, painless application and reduction in waiting times between photosensitiser administration and irradiation highlighted.

High aspect ratio elongated microparticles for enhanced topical drug delivery in human volunteers

Delivery of therapeutics into skin is hindered by the epidermal barriers. To overcome these barriers for the treatment of skin diseases, a cutaneous delivery method capable of field treatment using silica-elongated microparticles is developed. The microparticles are massaged into the skin using a 3D-printed microtextured applicator resulting in significant field-directed drug delivery enhancement.

Design, characterization and ex vivo evaluation of chitosan film integrating of insulin nanoparticles composed of thiolated chitosan derivative for buccal delivery of insulin

The purpose of this study is to optimize and characterize of chitosan buccal film for delivery of insulin nanoparticles that were prepared from thiolated dimethyl ethyl chitosan (DMEC-Cys). Insulin nanoparticles composed of chitosan and dimethyl ethyl chitosan (DMEC) were also prepared as control groups. The release of insulin from nanoparticles was studied in vitro in phosphate buffer solution (PBS) pH 7.4. Optimization of chitosan buccal films has been carried out by central composite design (CCD) response surface methodology. Independent variables were different amounts of chitosan and glycerol as mucoadhesive polymer and plasticizer, respectively. Tensile strength and bioadhesion force were considered as dependent variables. Ex vivo study was performed on excised rabbit buccal mucosa. Optimized insulin nanoparticles were obtained with acceptable physicochemical properties. In vitro release profile of insulin nanoparticles revealed that the highest solubility of nanoparticles in aqueous media is related to DMEC-Cys nanoparticles. CCD showed that optimized buccal film containing 4% chitosan and 10% glycerol has 5.81 kg/mm(2) tensile strength and 2.47 N bioadhesion forces. Results of ex vivo study demonstrated that permeation of insulin nanoparticles through rabbit buccal mucosa is 17.1, 67.89 and 97.18% for chitosan, DMEC and DMEC-Cys nanoparticles, respectively. Thus, this study suggests that DMEC-Cys can act as a potential enhancer for buccal delivery of insulin.

In vitro evaluation of 5-aminolevulinic acid (ALA) loaded PLGA nanoparticles

Background

5-Aminolevulinic acid (ALA) is a prodrug for topical photodynamic therapy. The effectiveness of topical ALA can be limited by its bioavailability. The aim of this study was to develop a novel ALA delivery approach using poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs).

Methods

A modified double emulsion solvent evaporation method was used to prepare ALA loaded PLGA NPs (ALA PLGA NPs). The characteristics, uptake, protoporphyrin IX fluorescence kinetics, and cytotoxicity of ALA PLGA NPs toward a human skin squamous cell carcinoma cell line were examined.

Results

The mean particle size of spherical ALA PLGA NPs was 65.6 nm ± 26 nm with a polydispersity index of 0.62. The encapsulation efficiency was 65.8% ± 7.2% and ALA loading capacity was 0.62% ± 0.27%. When ALA was dispersed in PLGA NPs, it turned into an amorphous phase. ALA PLGA NPs could be taken up by squamous cell carcinoma cells and localized in the cytoplasm. The protoporphyrin IX fluorescence kinetics and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay showed that ALA PLGA NPs were more effective than free ALA of the same concentration.

Conclusion

PLGA NPs provide a promising ALA delivery strategy for topical ALA-photodynamic therapy of skin squamous cell carcinoma.

5-aminolevulinic acid-incorporated nanoparticles of methoxy poly(ethylene glycol)-chitosan copolymer for photodynamic therapy

Purpose

The aim of this study was to make 5-aminolevulinic acid (5-ALA)-incorporated nanoparticles using methoxy polyethylene glycol/chitosan (PEG-Chito) copolymer for application in photodynamic therapy for colon cancer cells.

Methods

5-ALA-incorporated (PEG-Chito-5-ALA) nanoparticles were prepared by ion complex formation between 5-ALA and chitosan. Protoporphyrin IX accumulation in the tumor cells and phototoxicity induced by PEG-Chito-5-ALA nanoparticles were assessed using CT26 cells in vitro.

Results

PEG-Chito-5-ALA nanoparticles have spherical shapes with sizes diameters 200 nm. More specifically, microscopic observation revealed a core-shell structure of PEG-Chito-5-ALA nanoparticles. 1H NMR spectra showed that 5-ALA was incorporated in the core of the nanoparticles. In the absence of light irradiation, all components such as 5-ALA, empty nanoparticles, and PEG-Chito-5-ALA nanoparticles did not affect the viability of cells. However, 5-ALA or PEG-Chito-5-ALA nanoparticles induced tumor cell death under light irradiation, and the viability of tumor cells was dose-dependently decreased according to the increase in irradiation time. In particular, PEG-Chito-5-ALA nanoparticles induced increased phototoxicity and higher protoporphyrin IX accumulation into the tumor cells than did 5-ALA alone. Furthermore, PEG-Chito-5-ALA nanoparticles accelerated apoptosis/necrosis of tumor cells, compared to 5-ALA alone.

Conclusion

PEG-Chito-5-ALA nanoparticles showed superior delivery capacity of 5-ALA and phototoxicity against tumor cells. These results show that PEG-Chito-5-ALA nanoparticles are promising candidates for photodynamic therapy of colon cancer cells.

Photodynamic therapy based on 5-aminolevulinic acid and its use as an antimicrobial agent

Exogenous 5-aminolevulinic acid (ALA) is taken up directly by bacteria, yeasts, fungi, and some parasites, which then induces the accumulation of protoporphyrin IX (PPIX). Subsequent light irradiation of PPIX leads to the inactivation of these organisms via photodamage to their cellular structures. ALA uptake and light irradiation of PPIX produced by host cells leads to the inactivation of other parasites, along with some viruses, via the induction of an immune response. ALA-mediated PPIX production by host cells and light irradiation result in the inactivation of other viruses via either the induction of a host cell response or direct photodynamic attack on viral particles. This ALA-mediated production of light-activated PPIX has been extensively used as a form of photodynamic therapy (PDT) and has shown varying levels of efficacy in treating conditions that are associated with microbial infection, ranging from acne and verrucae to leishmaniasis and onychomycosis. However, for the treatment of some of these conditions by ALA-based PDT, the role of an antimicrobial effect has been disputed and in general, the mechanisms by which the technique inactivates microbes are not well understood. In this study, we review current understanding of the antimicrobial mechanisms used by ALA-based PDT and its role in the treatment of microbial infections along with its potential medical and nonmedical applications.

Retained topical delivery of 5-aminolevulinic acid using cationic ultradeformable liposomes for photodynamic therapy

5-Aminolevulinic acid (5-ALA), inducing photodynamic protoporphyrin (PpIX), is a hydrophilic molecule, resulting in leashing the capacity to cross tissue barriers like stratum corneum (SC) of skin. Here, we aimed to develop 5-ALA loaded ultradeformable liposomes (UDL) with different surface charges, and to investigate their physicochemical characteristics and capability for the skin penetration and retention of 5-ALA for topical photodynamic therapy (PDT). The effects of surface charges of UDL on in vitro permeation of 5-ALA and in vivo accumulation of 5-ALA-induced PpIX in viable skin were determined and then compared with conventional neutral liposomes (nLiposome). All UDL showed smaller particle size and better deformability than nLiposome. However, entrapment efficiency of 5-ALA was similar to each vesicle. Among vesicles, the cationic UDL (cUDL) demonstrated higher stability and permeability, and could deliver 5-ALA into deep skin tissue by topical application. Moreover, the 5-ALA loaded in cUDL was long retained, and induced more amount of PpIX in viable skin than those in other UDL and nLiposome. Considering that the conversion of 5-ALA into PpIX occurs preferentially in epidermis, these results suggested that topical delivery of 5-ALA loaded in cUDL could be an interesting proposal to optimize PDT related to 5-ALA.

Mucoadhesive buccal patches based on interpolymer complexes of chitosan-pectin for delivery of carvedilol

The study was designed to develop bioadhesive patches of carvedilol hydrochloride using chitosan (CH) and pectin (PE) interpolymer complexes and to systematically evaluate their in vitro and in vivo performances. Mucoadhesive buccal patches of carvedilol were prepared using solvent casting method. The physicochemical interaction between CH and PE was investigated by FTIR and DSC studies. The patches were evaluated for their physical characteristics like mass variation, content uniformity, folding endurance, ex vivo mucoadhesion strength, ex vivo mucoadhesion time, surface pH, in vitro drug release, in situ release study, and in vivo bioavailability study. The swelling index of the patches was found to be proportional to the PE concentration. The surface pH of all the formulated bioadhesive patches was found to lie between 6.2 and 7.2. The optimized bioadhesive patch (C1, CH:PE 20:80) showed bioadhesive strength of 22.10 ± 0.20 g, in vitro release of 98.73% and ex vivo mucoadhesion time of 451 min with in a period of 8 h. The optimized patch demonstrated good in vitro and in vivo results. The buccal delivery of carvedilol in rabbits showed a significant improvement in bioavailability of carvedilol from patches when compared to oral route.

Oil components modulate the skin delivery of 5-aminolevulinic acid and its ester prodrug from oil-in-water and water-in-oil nanoemulsions

The study evaluated the potential of nanoemulsions for the topical delivery of 5-aminolevulinic acid (ALA) and methyl ALA (mALA). The drugs were incorporated in oil-in-water (O/W) and water-in-oil (W/O) formulations obtained by using soybean oil or squalene as the oil phase. The droplet size, zeta potential, and environmental polarity of the nanocarriers were assessed as physicochemical properties. The O/W and W/O emulsions showed diameters of 216-256 and 18-125 nm, which, respectively, were within the range of submicron- and nano-sized dispersions. In vitro diffusion experiments using Franz-type cells and porcine skin were performed. Nude mice were used, and skin fluorescence derived from protoporphyrin IX was documented by confocal laser scanning microscopy (CLSM). The loading of ALA or mALA into the emulsions resulted in slower release across cellulose membranes. The release rate and skin flux of topical drug application were adjusted by changing the type of nanocarrier, the soybean oil O/W systems showing the highest skin permeation. This formulation increased ALA flux via porcine skin to 180 nmol/cm(2)/h, which was 2.6-fold that of the aqueous control. The CLSM results showed that soybean oil systems promoted mALA permeation to deeper layers of the skin from ∼100 μm to ∼140 μm, which would be beneficial for treating subepidermal and subcutaneous lesions. Drug permeation from W/O systems did not surpass that from the aqueous solution. An in vivo dermal irritation test indicated that the emulsions were safe for topical administration of ALA and mALA.