Non-invasive vaccine delivery in transfersomes, niosomes and liposomes: a comparative study

Non-invasive vaccine delivery is a top priority for public health agencies because conventional immunization practices are unsafe and associated with numerous limitations. Recently, the skin has emerged as a potential alternative route for non-invasive delivery of vaccine. Topical immunization (TI), introduction of antigen through topical application onto the intact skin, has many practical merits compared to injectable routes of administration. One of the possibilities for increasing the penetration of bioactives through the skin is the use of vesicular systems. Specially designed lipid vesicles are attracting intense attention and can be used for non-invasive antigen delivery. In the present study, elastic vesicle transfersomes, non-ionic surfactant vesicles (niosomes) and liposomes were used to study their relative potential in non-invasive delivery of tetanus toxoid (TT). Transfersomes, niosomes and liposomes were prepared and characterized for shape, size and entrapment efficiency. These vesicles were extruded through polycarbonate filter (50-nm pore size) to assess the elasticity of the vesicles. The immune stimulating activity of transfersomes, niosomes and liposomes were studied by measuring the serum anti-TT IgG titre following topical immunization. The immune response elicited by topical immunization was compared with that elicited by same dose of alum-adsorbed tetanus toxoid (AATT) given intramuscularly. The results indicate that optimal formulations of transfersomes, niosomes and liposomes could entrap 72.7+/-3.4, 42.5+/-2.4 and 41.3+/-2.2% of antigen and their elasticity values were 124.4+/-4.2, 29.3+/-2.4 and 21.7+/-1.9, respectively. In vivo study revealed that topically given TT containing transfersomes, after secondary immunization, could elicit immune response (anti-TT-IgG) that was equivalent to one that produced following intramuscularly alum-adsorbed TT-based immunization. In comparison to transfersomes, niosomes and liposomes elicited weaker immune response. Thus transfersomes hold promise for effective non-invasive topical delivery of antigen(s).     

Innovative bola-surfactant niosomes as topical delivery systems of 5-fluorouracil for the treatment of skin cancer

An innovative niosomal system made up of alpha,omega-hexadecyl-bis-(1-aza-18-crown-6) (Bola), Span 80 and cholesterol (2:5:2 molar ratio) was proposed as a topical delivery system for 5-fluorouracil (5-FU), largely used in the treatment of different forms of skin cancers. Bola-niosomes showed a mean size of approximately 400 nm, which were reduced to approximately 200 nm by a sonication procedure with a polydispersion index value of 0.1. Bola-niosomes showed a loading capacity of approximately 40% with respect to the amount of 5-FU added during the preparation. 5-FU-loaded bola-niosomes were tested on SKMEL-28 (human melanoma) and HaCaT (non-melanoma skin cancer with a specific mutations in the p53 tumor suppressor gene) to assess the cytotoxic activity with respect to the free drug. 5-FU-loaded bola-niosomes showed an improvement of the cytotoxic effect with respect to the free drug. Confocal laser scanning microscopy studies were carried out to evaluate both the extent and the time-dependent bola-niosome-cell interaction. The percutaneous permeation of 5-FU-loaded niosomes was evaluated by using human stratum corneum and epidermis membranes. Bola-niosomes provided an increase of the drug penetration of 8- and 4-folds with respect to a drug aqueous solution and to a mixture of empty bola-niosomes with a drug aqueous solution.     

Comparative study of liposomes,transfersomes and ethosomes as carriers for improving topical delivery of celecoxib

Topical administration of celecoxib proved to be an effective mean of preventing skin cancer development and improving anticancer drugs effectiveness in skin tumors treatment. The aim of this study was the development of an effective topical formulation of celecoxib, able to promote drug skin delivery, providing its in depth penetration through the skin layers. Three kinds of vesicular formulations have been investigated as drug carriers: liposomes containing a surfactant, or transfersomes and ethosomes, containing suitable edge activators. Firstly, the effect of membrane composition variations on the system performance has been evaluated for each vesicle type. Selected formulations were characterized for particle size, polydispersity index and encapsulation efficiency. The best formulations were subjected to ex vivo permeation studies through excised human skin. All vesicular formulations markedly (p < 0.001) improved the drug amount penetrated into the skin with respect to an aqueous suspension, from 2.0 to 6.5, up to 9.0 folds for liposomes, transfersomes and ethosomes, respectively. In particular, ethosomes containing Tween 20 as edge activator not only showed the best vesicle dimensions and homogeneity, and the highest encapsulation efficacy (54.4%), but also enabled the highest increase in drug penetration through the skin, probably due to the simultaneous presence in their composition of ethanol and Tween 20, both acting as permeation enhancers. Therefore, among the various vesicular formulations examined in the study, Tween 20-ethosomes can be considered the most promising one as carrier for topical celecoxib applications aimed to prevent skin cancer development and increase the anticancer drugs effectiveness against skin tumors.     

Skin delivery of 5-fluorouracil from ultradeformable and standard liposomes in-vitro

The potential use of ultradeformable and standard liposomes as skin drug delivery systems was investigated in-vitro. An improved experimental design gave a good measure for skin deposition of drug. This avoided the contamination that can occur due to incomplete washing of the donor before direct determination of the amount of drug in the skin. The design used aqueous ethanolic receptor which is believed to diffuse into skin, disrupting deposited liposomes (if any) and thus releasing both bound and free drug. The receptor fluid was refined by testing different concentrations of ethanol. The applied dose was also optimized. Using the improved design and the optimum dose, an ultradeformable formulation was compared with four traditional liposomes for skin delivery of 5-fluorouracil (5-FU). The best receptor was 50% aqueous ethanol and the optimum dose was 20 microL. The ultradeformable formulation was superior to standard liposomes in the skin delivery of 5-FU. Of the traditional liposomes, the non-rigid preparation was the best. However, stabilization of the liposome membrane with cholesterol abolished the benefit of this non-rigid preparation. It was concluded that ultradeformable vesicles are promising agents for skin delivery of drugs.     

Vesicular carriers containing phenylethyl resorcinol for topical delivery system; liposomes,transfersomes and invasomes

Topical administration of phenylethyl resorcinol (PR) has attracted much attention as skin lightening agent with potent anti-tyrosinase activity. Two novel types of elastic carriers were developed to overcome the limitation of PR as topical delivery by increasing the solubility, stability and decreasing skin irritation compared to conventional liposomes. In addition, it also promotes skin penetration of PR to reach deep skin layer at the target site. The lead formulations were obtained from the invasomes containing 1% (w/v) d-limonene mixed with 10% (v/v) absolute ethanol as the skin enhancer, and transfersomes containing 15% (w/w) sodium deoxycholate (SDC) as edge activator. All formulations gave a vesicle size < 500 nm, polydispersity index (PDI) < 0.3, high zeta potential, entrapment efficiency > 50%, and good stability on storage at 30°C at 75% RH for 4 months. Transfersomes have a lower degree of deformability (6.63%) than invasomes (25.26%). In contrast, the liposomes as rigid vesicles do not show a deformable property. This characteristic affects the skin permeation, and thus, transfersomes with high elastic property provided a significantly higher cumulative amount, steady state flux (J_ss) and permeability coefficient (K_p) compared to other formulations. However, in vitro PR accumulation in full-thickness newborn pig skin demonstrated that the application of elastic carrier formulations gave significantly higher accumulation than liposomes, and gave anti-tyrosinase activity up to 80%. These results are straightforwardly related to the results of cellular level study. Transfersomes and invasomes showed higher tyrosinase inhibition activity and melanin content reduction when compared to liposomes in B16 melanoma cells. In addition, acute irritation test in rabbits confirmed that these formulations are safe for skin application. Therefore, elastic vesicle carriers have the efficiency to deliver PR into the deep skin in both quantity and effectiveness which are better than conventional liposomes and appropriate for a skin lightening product.     

Comparative study of liposomes,transfersomes, ethosomes and cubosomes for transcutaneous immunisation: characterisation and in vitro skin penetration

Objectives Lipid colloidal vaccines, including liposomes, transfersomes, ethosomes and cubosomes, were formulated, characterised and investigated for their ability to enhance penetration of a peptide vaccine through stillborn piglet skin in vitro. Methods Liposomes and transfersomes were formulated using a film‐hydration method, ethosomes using a modified reverse phase method and cubosomes using a lipid precursor method. The size, zeta potential, peptide loading and interfacial behaviour of the formulations were characterised. Skin penetration studies were performed using Franz diffusion cells with piglet skin as the membrane. The localization of peptide in the skin was examined using confocal laser scanning microscopy. Key finding The various formulations contained negatively charged particles of similar size (range: 134–200 nm). Addition of the saponin adjuvant Quil A to the formulations destabilised the monolayers and reduced peptide loading. Cubosomes and ethosomes showed superior skin retention compared with the other systems. Confocal laser scanning microscopy showed greater peptide penetration and accumulation in the skin treated with cubosomes and ethosomes. With the other systems peptide was only located in the vicinity of the hair follicles and within the hair shaft. Conclusions We conclude from the in‐vitro studies that cubosomes and ethosomes are promising lipid carriers for transcutaneous immunisation.     

Elastic liposomes mediated transdermal delivery of an anti-jet lag agent: preparation, characterization and in vitro human skin transport study

In order to get across the intact skin, drug-laden carriers have to pass through narrow, confining pores of 50 nm or less diameter, under the influence of a suitable transdermal gradient. Novel ultradeformable carriers, the elastic liposomes achieve this target via its deforming and self-optimizing property. The main goal of this work was to prepare and characterize, elastic liposomes bearing melatonin, an anti-jet lag agent for its efficient transdermal delivery. Elastic liposomes bearing melatonin were prepared by modified extrusion method and characterized for shape, lamellarity, size distribution, percent drug loading, turbidity profile by Transmission electron microscopy (TEM), Dynamic light scattering (DLS), Mini-column centrifugation and Nephelometric techniques. The effect of different formulation variables like type of surfactant and concentration of surfactant on the deformability of vesicles, turbidity changes, transdermal flux across human cadaver skin, amount of drug deposited into the skin were investigated. Confocal laser scanning (CLS) micrographs revealed that probe (Rhodamine Red) loaded elastic liposomes were able to penetrate much deeper than the probe loaded conventional rigid liposomes. Out of the three surfactants utilized namely, Span 80, Sodium cholate and Sodium dodecylsulphate, formulation bearing Span 80 at an optimum lipid: surfactant ratio of 85:15% w/w proved to be the best in all parameters studied. The optimum skin permeation profile including greater transdermal flux and lower lag time of melatonin from optimized elastic liposomes via human cadaver skin was observed. Our results of the present study demonstrated the feasibility of elastic liposomal system for transdermal delivery of this anti- jet lag agent, which provides better transdermal flux, higher entrapment efficiency, greater skin drug deposition and possesses the ability of a self-penetration enhancer as compared to conventional liposomes.     

Formulation of tretinoin-loaded topical proniosomes for treatment of acne: in-vitro characterization,skin irritation test and comparative clinical study

Abstract

Tretinoin (TRT) is a widely used retinoid for the topical treatment of acne, photo-aged skin, psoriasis and skin cancer which makes it a good candidate for topical formulation. Yet side effects, like redness, swelling, peeling, blistering and, erythema, in addition to its high lipophilicity make this challenging. Therefore, the aim of this study was the development of TRT-loaded proniosomes to improve the drug efficacy and to increase user acceptability and compliance by reducing its side effects. Nine formulae were prepared according to 3² factorial design and were evaluated for their morphology, vesicle size, entrapment efficiency (EE %), and% of drug released after 5?h. Hydrogel of the candidate formula, N8G (proniosomes prepared with 0.025% TRT, and Span60: cholesterol molar ratio of 3:1 and incorporated in 1% carbopol gel) was developed and evaluated for skin irritation test and clinical study in acne patients compared to marketed product. Candidate formula showed higher efficacy and very low irritation potential when compared to marketed product in human volunteers.     

Novel carbopol-based transfersomal gel of 5-fluorouracil for skin cancer treatment: in vitro characterization and in vivo study

Abstract

5-fluorouracil (5-Fu) is an antineoplastic drug, topically used for the treatment of actinic keratosis and nonmelanoma skin cancer. It shows poor percutaneous permeation through the conventionally applicable creams and thus inefficient for the treatment of deep-seated skin cancer. In the present article, transfersomal gel containing 5-Fu was investigated for the treatment of skin cancer. Different formulation of tranfersomes was prepared using Tween-80 and Span-80 as edge activators. The vesicles were characterized for particle size, shape, entrapment efficiency, deformability and in vitro skin permeation. Optimized formulation was incorporated into 1% carbopol 940 gel and evaluated for efficacy in the treatment of skin cancer. 5-Fu-loaded transfersomes (TT-2) has the size of 266.9?±?2.04?nm with 69.2?±?0.98% entrapment efficiency and highest deformability index of 27.8?±?1.08. Formulation TT-2 showed maximum skin deposition (81.3%) and comparable transdermal flux of 21.46?µg/cm²?h. The TT-2-loaded gel showed better skin penetration and skin deposition of the drug than the marketed formulation. Composition of the transfersomal gel has been proved nonirritant to the skin. We concluded that the developed 5-Fu-loaded transfersomal gel improves the skin absorption of 5-Fu and provide a better treatment for skin cancer.     

Targeted gene delivery to skin cells in vivo: a comparative study of liposomes and polymers as delivery vehicles

Liposomes are microscopic lipid membrane vesicles that provide a current strategy for topical, dermal delivery of biologically active molecules. They have been successfully used for the delivery of various low and high molecular weight molecules into the skin, and as an alternative to virus-mediated delivery systems, have opened the field of dermal gene therapy. The present study was undertaken on 6-day-old rat pups to determine in vivo the efficacy of several liposome and nonliposome formulations, including phospholipid liposomes and their cationic or pegylated variants, nonionic liposomes and their cationic variant, PINC polymer (Protective, Interactive, Noncondensing polymers), and a propylene glycol:alcohol:water mixture (delivery vehicle for minoxidil) in delivering beta-galactosidase and luciferase reporter genes into skin cells. Based upon our observations of the expression of beta-galactosidase and luciferase reporter genes in skin cells, we report here that nonionic liposomes are the most efficient vehicle for transdermal delivery followed by nonionic/cationic and phospholipid (pegylated) liposomes. The propylene glycol:ethanol:water mixture and the PINC polymer were relatively inefficient in the delivery of beta-galactosidase or luciferase DNAs. This simple, noninvasive technique of using nonionic liposomes to deliver biomolecules provides an efficient delivery strategy for gene therapy and drug delivery to the dermal organ site.     

Fractional laser-assisted topical delivery leads to enhanced,accelerated and deeper cutaneous 5-fluorouracil uptake

Background: Topical 5-Fluorouracil (5-FU) exhibits suboptimal efficacy for non-melanoma skin cancer, attributed to insufficient intracutaneous penetration. This study investigates the impact of ablative fractional laser (AFXL) at different laser-channel depths on cutaneous 5-FU pharmacokinetics and biodistribution.

Methods: In vitro porcine skin underwent AFXL-exposure using a fractional 10,600 nm CO₂-laser, generating microscopic ablation zones (MAZ) reaching the dermoepidermal junction (MAZ-ED), superficial-(MAZ-DS), or mid-dermis(MAZ-DM). 5-FU in AFXL-exposed and control skin was measured in Franz diffusion cells at 4 and 24 hours (n = 55). HPLC quantified 5-FU in full-thickness skin, specific skin depths of 100μm-1500μm, and transcutaneous receiver-compartments. Qualitative matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) visualized 5-FU in selected samples.

Results: Overall, AFXL enhanced and accelerated 5-FU uptake versus unexposed controls, with increased accumulation in deep skin layers (p < 0.01). While total, 24-hour 5-FU uptake in control skin was 0.096 mg/cm³ (0.19% of applied concentration), AFXL delivered up to 4.707 mg/cm³ (MAZ-DM; 9.41% uptake, 49-fold enhancement) (p = 0.002; 24 hours). Indicating accelerated delivery, 5-FU in laser-exposed samples at 4 hours was at least 10-fold that of 24-hour controls (p = 0.002). Deeper laser-channels increased delivery throughout the skin (MAZ-ED vs. MAZ-DM; p<0.01). MALDI-MSI confirmed enhanced, accelerated, deeper and more uniform 5-FU distribution after AFXL versus controls.

Conclusions: AFXL offers laser-channel depth-dependent, enhanced and accelerated 5-FU uptake, with increased deposition in deep skin layers.     

Polyacrylic acid polymers hydrogels intended to topical drug delivery: preparation and characterization

Abstract

Context: Bioadhesiviness of polyacrylic acid polymers make them promising hydrogels to design topical drug delivery systems, allowing a close contact with biological substrate as well as an enhanced local concentration gradient, both factors that may improve the biological performance of the drugs.

Aim: Texture and bioadhesive properties of hydrogels were assessed by using texture analyzer and they were correlated with their rheological behavior and performance as drug delivery systems.

Methods: Aqueous dispersions of both polymers were prepared at 0.5%, 1.0% and 1.5% w/v. Hardness, compressibility, adhesiveness, cohesiveness, bioadhesion, continuous flow, oscillatory dynamic test and in vitro drug release were evaluated.

Results: Rheological and texture parameters were dependent on polymer concentration and C974P polymer built the strongest structures. Both 1.5% hydrogels presented high bioadhesion values. About 50% of the metronidazole (MTZ) was sustained released from hydrogels within 2?h with an initial burst release at early stage. After, the release rates were decreased and 10% of the MTZ was released in the next 10?h. The drug release process was driven by Fickian diffusion and complex mechanism for PP and C974P hydrogels, respectively.

Conclusion: The set of results demonstrated that these hydrogels are promising to be used as topical controlled drug delivery system.     

Mannich base derivatives of theophylline and 5-fluorouracil: syntheses,properties and topical delivery characteristics

Mannich base prodrugs of theophylline and 5-fluorouracil have been prepared and tested for their ability to deliver their parent drugs through hairless mouse skin. The Mannich base derivatives were more effective than the previously described N-acyloxyalkyl derivatives. In the case of theophylline the Mannich base derivative was also found to be as effective as the previously described N-hydroxymethyl derivative. All of the Mannich bases reverted to their parent compounds in water, but some were relatively stable in aprotic solvents such as isopropyl myristate which was therefore used as a vehicle for the diffusion experiments with the prodrugs.     

Utilization of PEGylated cerosomes for effective topical delivery of fenticonazole nitrate: in-vitro characterization,statistical optimization,and in-vivo assessment

In this investigation, we focused on ceramide IIIB, a skin component whose depletion tends to augment multiple skin disorders and fungal infections. Ceramide IIIB was included into PEGylated surfactant-based vesicular phospholipid system to formulate ‘PEGylated cerosomes’ (PCs) loaded with fenticonazole nitrate (FTN). FTN is a potent antifungal agent adopted in the treatment of mixed mycotic and bacterial infections. The ceramide content of the vesicles may provide protective and regenerative skin activity whereas Brij^®; the PEGylated surfactant, can enhance drug deposition and skin hydration. Both components are expected to augment the topical effect of FTN. PCs were prepared by thin-film hydration technique. A 2³ full-factorial design was applied to study the effect of ceramide amount (X₁), Brij type (X₂) and Brij amount (X₃) on the physicochemical properties of the formulated PCs namely; entrapment efficiency (EE%;Y₁), particle size (PS;Y₂), polydispersity index (PDI;Y₃) and zeta potential (ZP;Y₄). The optimal formula was selected for further in-vivo dermatokinetic and histopathological study. The optimal FTN-loaded PC (PC6) showed nanosized cerosomes (551.60 nm) with high EE% (83.00%w/w), and an acceptable ZP value of 20.90 mV. Transmission electron micrographs of the optimal formula illustrated intertwined tubulation form deviated from the conventional spherical vesicles. Finally, the dermatokinetic study of PC6 showed higher drug concentration and localization of FTN in skin layers when compared with FTN suspension and the histopathological study confirmed its safety for topical application. The overall findings of our study verified the effectiveness of utilizing PEGylated cerosomes to augment the activity of FTN as a topical antifungal agent.     

Long-circulating poly(ethylene glycol)-grafted gelatin nanoparticles customized for intracellular delivery of noscapine: preparation, in-vitro characterization, structure elucidation, pharmacokinetics, and cytotoxicity analyses

Noscapine, the tubulin-binding anticancer agent, when administered orally, requires high ED(50) (300-600 mg/kg), whereas intravenous administration (10 mg/kg) results in rapid elimination of the drug with a half-life of 0.39 h. Hence, the development of long-circulating injectable nanoparticles can be an interesting option for designing a viable formulation of noscapine for anticancer activity. Noscapine-enveloped gelatin nanoparticles and poly(ethylene glycol)-grafted gelatin nanoparticles were constructed and characterized. Data indicate that smooth and spherical shaped nanoparticles of 127 ± 15 nm were engineered with maximum entrapment efficiency of 65.32 ± 3.81%. Circular dichroism confirms that nanocoacervates retained the α-helical content of gelatin in ethanol whereas acetone favored the formation of a random coil. Moreover, the Fourier transform infrared and powder X-ray diffraction pattern prevents any significant change in the noscapine-loaded gelatin nanoparticles in comparison with individual components. In-vitro release kinetic data suggest a first-order release of noscapine (85.1%) from gelatin nanoparticles with a release rate constant of 7.611×10(-3). It is to be noted that there is a 1.43-fold increase in the area under the curve up to the last sampling point for the noscapine-loaded poly(ethylene glycol)-grafted gelatin nanoparticles over the noscapine-loaded gelatin nanoparticles and a 13.09-fold increase over noscapine. Cytotoxicity analysis of the MCF-7 cell line indicated that the IC(50) value of the noscapine-loaded poly(ethylene glycol)-grafted gelatin nanoparticles was equivalent to 20.8 μmol/l, which was significantly (P<0.05) lower than the IC(50) value of the noscapine-loaded gelatin nanoparticles (26.3 μmol/l) and noscapine (40.5 μmol/l).Noscapine-loaded poly(ethylene glycol)-grafted gelatin nanoparticles can be developed as a promising therapeutic agent for the management of breast cancer.     

Transdermal delivery of an analgesic agent using elastic liposomes: preparation, characterization and performance evaluation

The aim of the present study was to prepare and characterize novel vesicular carrier elastic liposomes, of most commonly used non-steroidal anti-inflammatory agent diclofenac for its sustained and targeted delivery. Elastic liposomes of diclofenac were prepared and characterized in vitro and in vivo. The effect of different formulation variables like type of surfactant, concentration of surfactant and dose of drug on transdermal flux, amount of drug deposited into the skin, muscle and plasma concentration was investigated. The biological activity of optimized formulation was evaluated using carrageenan induced rat paw edema model and results were compared with commercial hydrogel formulation. The elastic liposomal formulations achieved muscle drug concentration between 2.2+/-0.14 to 5.3+/-0.22 microg/g at 12 hr. The same dose of commercial hydrogel formulation produced drug levels between 0.41+/-0.07 to 1.1+/-0.09 microg/g in the muscle. Plasma concentration study showed regiospecificity of elastic liposomal formulation. The results of in vivo study revealed that incorporation of diclofenac in elastic liposomes increased its biological activity two fold as compared to commercial hydrogel formulation. The results of the present study demonstrated greater effectiveness of dermaly applied diclofenac elastic liposomal formulation in comparison to conventional delivery system. The optimized elastic liposomal formulation offers a promising means for the non-invasive treatment of local pain and inflammation by topical application.     

Cholesterol succinyl chitosan anchored liposomes: preparation,characterization, physical stability,and drug release behavior

The purpose of this study was to prepare cholesterol succinyl chitosan anchored liposomes (CALs) and to investigate their characterization, physical stability, and drug release behavior in vitro. Three cholesterol succinyl chitosan (CHCS) conjugates with different substitution degrees (DS) of the cholesterol moiety were synthesized and used as the anchoring materials to coating on the liposome surface by the incubation method. CALs were almost spherical and had a classic shell-core structure. Compared with plain liposomes and chitosan-coated liposomes (CCLs), CALs had larger sizes, higher zeta potentials, and better physical stability after storage at 4 ± 2°C and 25 ± 2°C. Epirubicin, as a model drug, was effectively loaded into CALs and exhibited the more sustained release in both phosphate buffer solution (pH 7.4) and 1% (vol/vol) aqueous fetal bovine serum compared to plain liposomes and CCLs.From the Clinical EditorCholesterol succinyl chitosan anchored liposomes (CAL) as delivery vehicles are characterized in this work, including their physical stability and drug release behavior in vitro. Epirubicin as a model drug, was effectively loaded into CALs, and exhibited sustained release behavior both in phosphate buffer solution (PBS, pH 7.4) and 1% (V/V) aqueous fetal bovine serum (FBS).     

Nanoparticles based on the complex of chitosan and polyaspartic acid sodium salt: preparation, characterization and the use for 5-fluorouracil delivery.

New nonstoichiometric polyelectrolyte complex nanoparticles were prepared based on chitosan (CS) and polyaspartic acid sodium salt (PAsp). The physicochemical properties of the complexes were investigated by means of turbidity, dynamic light scattering, transmission electron microscopy and zeta potential. The results indicated that the slow dropwise addition of chitosan into PAsp allowed to elaborate either anionic or cationic particles in the size range of 85-300 nm with proper CS and PAsp unit molar ratios. Investigation of structural changes during the addition of CS revealed that the microstructure of the nanoparticles depended strongly on the unit molar ratio of CS to PAsp. Nanoparticles containing a hydrophilic drug, 5-fluorouracil (5FU), were prepared by mixing and absorption method. In vitro and in vivo experiment indicated that the drug-loaded CS-PAsp nanoparticles presented a sustained release of 5FU compared to the 5FU solution and the areas under curve (AUC) were increased by about four times.     

The microsponge delivery system of benzoyl peroxide: preparation, characterization and release studies

Benzoyl peroxide (BPO) is commonly used in topical formulations for the treatment of acne and athletes foot. Skin irritation is a common side effect, and it has been shown that controlled release of BPO from a delivery system to the skin could reduce the side effect while reducing percutaneous absorption. Therefore, the aim of the present study was to produce ethylcellulose microparticles containing BPO which were able to control the release of BPO to the skin. In order to optimize the microparticle formulation, factors affecting the physical properties of microparticles were also investigated. Benzoyl peroxide microparticles were prepared using an emulsion solvent diffusion method by adding an organic internal phase containing benzoyl peroxide, ethyl cellulose and dichloromethane into a stirred aqueous phase containing polyvinyl alcohol. Drug content, particle size analysis and loading yield were determined in the prepared microparticles. BPO microparticles were then incorporated into standard vehicles for release studies. Scanning electron microscopy was used to study the shape and morphology of the microsponges. The micrograph of microsponges showed that they were spherical in shape and contained pores. These pores resulted from the diffusion of solvent from the surface of the microparticles and thus the particles were designated as microsponges. It was shown that the drug:polymer ratio, stirring rate, volume of dispersed phase influenced the particle size and drug release behavior of the formed microsponges and that the presence of emulsifier was essential for microsponge formation. The results showed that, generally, an increase in the ratio of drug:polymer resulted in a reduction in the release rate of BPO from microsponges which was attributed to a decreased internal porosity of the microsponges.     

Nanoparticles of 5-fluorouracil (5-FU) loaded N-succinyl-chitosan (Suc-Chi) for cancer chemotherapy: preparation, characterization--in-vitro drug release and anti-tumour activity

N-Succinyl-chitosan has favourable properties as a drug carrier, such as biocompatibility, low toxicity and long-term retention in the body. It is a good candidate for cancer chemotherapy as a polymeric drug carrier. This study describes the preparation and characterization of 5-fluorouracil-loaded N-succinyl-chitosan nanoparticles (5-FU-Suc-Chi/NP) by an emulsification solvent diffusion method. The influence of the initial 5-FU concentration on the nanoparticle characteristics and release behaviour in phosphate-buffered saline solution (PBS) was evaluated. The Suc-Chi nanoparticles had a particle diameter (Z-average) in the range 202 approximately 273 nm and a negative zeta-potential (approx. -27 to -18 mV). The formulation with an initial 5-FU concentration of 1000 microg mL-1 provided the highest loading capacity (19%) and the highest extent of release (61% at 24 h). The 5-FU-Suc-Chi/NP showed good anti-tumour activity against Sarcoma 180 solid tumour and mild toxicity. According to the data obtained, this Suc-Chi-based nanotechnology opens new and interesting perspectives for cancer chemotherapy.