Luiza Abrahão Frank

Improving drug biological effects by encapsulation into polymeric nanocapsules

This review is based on selected reports from 2004 to 2014 and provides a comprehensive and updated overview of the state of the art related to the drug delivery advantages of polymeric nanocapsules, which are a specific type of polymeric nanoparticles used for improvement of biological effects. Special attention is given to the application of nanocapsules to increase the chemical and photostability of drugs, to modulate the interaction with cells and tissues, to reduce adverse effects of drugs, and to increase the drug efficiency and/or bioavailability. Moreover, this review covers in vitro and in vivo studies, highlighting interesting examples of drugs from several therapeutic classes for which efficacy is improved by encapsulation in different types of nanocapsules, especially in lipid-core nanocapsules. We also briefly present the first results obtained so far attesting to the safety of using polymeric nanocapsules for drug delivery.

Chitosan gel containing polymeric nanocapsules: a new formulation for vaginal drug delivery

The vaginal route of administration is an alternative for several treatments for either local or systemic pharmacological effects. However, the permanence of a drug in this route represents a challenge for formulation development that can be overcome by using nanoencapsulation and chitosan gel. Thus, this work aimed to evaluate the performance of chitosan hydrogels containing cationic and anionic acrylic-based nanocapsules (Eudragit® RS 100 and Eudragit® S 100, respectively) with Nile red as a model of lipophilic substance in the vaginal route of administration, as measured by increases in the residence time and the penetration of these formulations. Several formulations were prepared with increasing chitosan concentrations, and were analyzed in terms of pH and rheological behavior so that the most suitable formulation could be selected. The enhancement of the adhesion (tensile stress test and washability profile) and penetration (confocal laser scanning microscopy and extraction followed by quantification) properties of the formulations, when applied to porcine vaginal mucosa, were evaluated. The nanocapsule suspensions produced presented adequate properties: size of approximately 200 nm (polydispersity index of ≤v0.2); zeta potential around +10 mV for the cationic formulation and -10 mV for the anionic formulation; and pH values of 6.1±0.1 (Eudragit RS 100), 5.3±0.2 (Eudragit S 100), 6.2±0.1 (Nile red loaded Eudragit RS 100), and 5.1±0.1 (Nile red loaded Eudragit S 100). The chitosan formulation presented suitable viscosity for vaginal application and acidic pH (approximately 4.5). The tensile stress test showed that both formulations containing polymeric nanocapsules presented higher mucoadhesion when compared with the formulation without nanocapsules. In the washability experiment, no significant differences were found between formulations. Confocal microscopy and fluorescence quantification after extraction from the mucosa showed higher penetration of Nile red when it was nanoencapsulated, particularly in cationic nanocapsules. The formulations developed based on chitosan gel vehicle at 2.5% weight/weight containing polymeric nanocapsules, especially the cationic nanocapsules, demonstrated applicability for the vaginal delivery of hydrophobic substances.

The use of nanoencapsulation to decrease human skin irritation caused by capsaicinoids.

Capsaicin, a topical analgesic used in the treatment of chronic pain, has irritant properties that frequently interrupt its use. In this work, the effect of nanoencapsulation of the main capsaicinoids (capsaicin and dihydrocapsaicin) on skin irritation was tested in humans. Skin tolerance of a novel vehicle composed of chitosan hydrogel containing nonloaded nanocapsules (CH-NC) was also evaluated. The chitosan hydrogel containing nanoencapsulated capsaicinoids (CH-NC-CP) did not cause skin irritation, as measured by an erythema probe and on a visual scale, while a formulation containing free capsaicinoids (chitosan gel with hydroalcoholic solution [CH-ET-CP]) and a commercially available capsaicinoids formulation caused skin irritation. Thirty-one percent of volunteers reported slight irritation one hour after application of CH-NC-CP, while moderate (46% [CH-ET-CP] and 23% [commercial product]) and severe (8% [CH-ET-CP] and 69% [commercial product]) irritation were described for the formulations containing free capsaicinoids. When CH-NC was applied to the skin, erythema was not observed and only 8% of volunteers felt slight irritation, which demonstrates the utility of the novel vehicle. A complementary in vitro skin permeation study showed that permeation of capsaicinoids through an epidermal human membrane was reduced but not prevented by nanoencapsulation.

Co-encapsulation of imiquimod and copaiba oil in novel nanostructured systems: promising formulations against skin carcinoma

In this study, two types of cutaneous-directed nanoparticles are proposed for the co-encapsulation of imiquimod (a drug approved for the treatment of basal cell carcinoma) and copaiba oil (oil that exhibits anti-proliferative properties). Nanostructured copaiba capsules (NCCImq) were prepared using the interfacial deposition method, and nanostructured Brazilian lipids (NBLImq) were prepared by high-pressure homogenization. The formulations exhibited average diameter, zeta potential, pH and drug content of approximately 200nm, -12mV, 6 and 1mgmL(-1), respectively. In addition, the formulations exhibited homogeneity regarding particle size, high encapsulation efficiency and stability. Both nanocarriers controlled imiquimod release, and NBLImq exhibited slower drug release (p < 0.05), likely due to increased interaction of the drug with the solid lipid (cupuaçu seed butter). The in vitro evaluation of the imiquimod-loaded nanocarriers was performed using healthy skin cells (keratinocytes, HaCaT); no alteration was observed, suggesting the biocompatibility of the nanocarriers. In addition, in vitro skin permeation/penetration using pig skin was performed, and NCCImq led to increased drug retention in the skin layers and reduced amounts of drug found in the receiver solution. Thus, NCCImq is considered the most promising nanoformulation for the treatment of skin carcinoma.

Gelatin-based membrane containing usnic acid-loaded liposome improves dermal burn healing in a porcine model.

There are a range of products available which claim to accelerate the healing of burns; these include topical agents, interactive dressings and biomembranes. The aim of this study was to assess the effect of a gelatin-based membrane containing usnic acid/liposomes on the healing of burns in comparison to silver sulfadiazine ointment and duoDerme® dressing, as well as examining its quantification by high performance liquid chromatography. The quantification of the usnic acid/liposomes was examined using high performance liquid chromatography (HPLC) by performing separate in vitro studies of the efficiency of the biomembranes in terms of encapsulation, drug release and transdermal absorption. Then, second-degree 5cm2 burn wounds were created on the dorsum of nine male pigs, assigned into three groups (n=3): SDZ - animals treated with silver sulfadiazine ointment; GDU - animals treated with duoDerme®; UAL - animals treated with a gelatin-based membrane containing usnic acid/liposomes. These groups were treated for 8, 18 and 30days. In the average rate of contraction, there was no difference among the groups (p>0.05). The results of the quantification showed that biomembranes containing usnic acid/liposomes were controlled released systems capable of transdermal absorption by skin layers. A macroscopic assay did not observe any clinical signs of secondary infections. Microscopy after 8days showed hydropic degeneration of the epithelium, with intense neutrophilic infiltration in all three groups. At 18days, although epidermal neo-formation was only partial in all three groups, it was most incipient in the SDZ group. Granulation tissue was more exuberant and cellularized in the UAL and GDU groups. At 30days, observed restricted granulation tissue in the region below the epithelium in the GDU and UAL groups was observed. In the analysis of collagen though picrosirius, the UAL group showed greater collagen density. Therefore, the UAL group displayed development and maturation of granulation tissue and scar repair that was comparable to that produced by duoDerme®, and better than that produced by treatment with sulfadiazine silver ointment In addition, the UAL group showed increased collagen deposition compared to the other two groups.

The use of chitosan as cationic coating or gel vehicle for polymeric nanocapsules: Increasing penetration and adhesion of imiquimod in vaginal tissue

&NA; The human papillomavirus (HPV) infection, which is strongly related to cervical cancer, can be reduced by the topical application of imiquimod. Some strategies have been used to increase the adhesion and penetration of drugs through the vaginal mucosa. Two of them are the development of mucoadhesive semisolid formulations and the development of polymeric nanocarriers. In this paper, we hypothesize that the combined use of these two strategies results in a better performance of the formulation to retain imiquimod into the vaginal tissue. Aiming this, two different systems are proposed: (a) chitosan‐coated poly(&egr;‐caprolactone)‐nanocapsules incorporated into hydroxyethylcellulose gel (HEC‐NCimiq‐chit), and (b) poly(&egr;‐caprolactone)‐nanocapsules incorporated into chitosan hydrogel (CHIT‐NCimiq). These formulations were submitted to three main tests: mucoadhesivity by interaction, permeation and washability test (or retention test). We developed an integrative index that allows comparing the global performance of the proposed formulations by considering jointly the results of these three tests. Thus, when considered the integrative indexes for the formulations, our results show that CHIT‐NCimiq presents the best performance for the treatment of HPV. Graphical abstract Figure. No caption available.

Carvedilol-loaded nanocapsules: Mucoadhesive properties and permeability across the sublingual mucosa

&NA; Carvedilol is a drug used to treat heart failure, hypertension, and coronary artery diseases. However, it has low oral bioavailability (25–35%) due to its high first‐pass hepatic metabolism. The objective of this study was to develop carvedilol‐loaded mucoadhesive nanocapsules as delivery systems for the sublingual administration of the drug. Nanocapsules were prepared using poly(&egr;‐caprolactone) (CAR‐LNC) and Eudragit® RS 100 (CAR‐NC) as polymeric wall. In vitro interaction of formulations with mucin was performed to predict their mucoadhesion capacity. The permeability and washability profiles of carvedilol were evaluated using porcine sublingual mucosa. The mean diameter of particles in formulations was in the nanometric range, and particles had low polydispersity and slightly acidic pH. Zeta potential values were positive for CAR‐NC and negative for CAR‐LNC. Encapsulation efficiency was higher than 87% and 99% for CAR‐NC and CAR‐LNC, respectively. Both formulations presented controlled drug release profiles and mucoadhesive properties. Carvedilol was able to permeate through the sublingual mucosa. Nanoencapsulation improved retention time on the mucosa and permeation in presence of simulated salivary flux. This study highlighted the suitability of using CAR‐loaded nanocapsules in the development of innovative sublingual dosage forms. Graphical abstract Figure. No caption available. HighlightsCarvedilol was encapsulated in Eudragit® RS 100 or poly(&egr;)caprolactone nanocapsules.Interaction of nanocapsules with mucin and porcine sublingual mucosa was evidenced.Nanoencapsulated carvedilol was able to cross porcine sublingual mucosa.Nanoencapsulation improved carvedilol permeation in presence of simulated salivary flux.

Hesperetin-loaded lipid-core nanocapsules in polyamide: a new textile formulation for topical drug delivery

Chronic venous insufficiency is characterized by chronic reflux disorder of blood from the peripheral to the central vein, with subsequent venous hypertension and resulting changes in the skin. Traditionally, nonsurgical treatments relied on the use of compression therapy, and more recently a variety of flavonoids have been shown to have positive effects. There have also been developments of more effective drug delivery systems using various textiles and nanotechnology to provide new therapeutic options. Our objective was to use nanotechnology to develop a new formulation containing hesperetin (Hst), a substance not previously used in the treatment of chronic venous insufficiency, impregnated into textile fibers as a possible alternative treatment of venous diseases. We prepared the nanocapsules using the interfacial deposition of preformed polymer method with an Hst concentration of 0.5 mg/mL and then characterized the size and distribution of particles. To quantify the Hst in the samples, we developed an analytical method using high-performance liquid chromatography. Studies of encapsulation efficiency (98.81%±0.28%), microscopy, drug release (free-Hst: 104.96%±12.83%; lipid-core nanocapsule-Hst: 69.90%±1.33%), penetration/permeation, drug content (0.46±0.01 mg/mL) and the effect of washing the textile after drug impregnation were performed as part of the study. The results showed that nanoparticles of a suitable size and distribution with controlled release of the drug and penetration/permeation into the skin layers were achieved. Furthermore, it was established that polyamide was able to hold more of the drug, with a 2.54 times higher content than the cotton fiber; after one wash and after five washes, this relation was 2.80 times higher. In conclusion, this is a promising therapeutic alternative to be further studied in clinical trials.

Production, characterization and application of nanotechnology-based vegetable multi-component theospheres in nonwovens: A women's intimate hygiene approach

The main objective of this work was to develop a nanotechnology-based component containing substances of vegetable origin, such as butters and essential oils, whose properties may help balance the vulvovaginal microbiota and be applied in nonwovens for feminine hygiene products. The high-pressure homogenization technique was used to obtain the aqueous dispersion of these nanoparticles containing tea tree oil, alpha-bisabolol, resveratrol, grape seed oil and citric acid, namely VM-Theospheres (theospheres are nanoparticles formed by Theobroma grandiflorum butter). The average particle size range was 274 ± 5 nm. The stability tests indicated that formulation status remained stable at room temperature for 28 days. In vitro analysis of skin penetration and irritation showed that the VM-Theospheres can be considered safe for use in feminine hygiene products. The production of an absorbent layer was performed by impregnation of VM-Theospheres in nonwovens. The results revealed that spraying was the most effective method, without the need to treat the samples first.

An Inhalable Powder Formulation Based on Micro- and Nanoparticles Containing 5-Fluorouracil for the Treatment of Metastatic Melanoma

Melanoma is the most aggressive and lethal type of skin cancer, with a poor prognosis because of the potential for metastatic spread. The aim was to develop innovative powder formulations for the treatment of metastatic melanoma based on micro- and nanocarriers containing 5-fluorouracil (5FU) for pulmonary administration, aiming at local and systemic action. Therefore, two innovative inhalable powder formulations were produced by spray-drying using chondroitin sulfate as a structuring polymer: (a) 5FU nanoparticles obtained by piezoelectric atomization (5FU-NS) and (b) 5FU microparticles of the mucoadhesive agent Methocel™ F4M for sustained release produced by conventional spray drying (5FU-MS). The physicochemical and aerodynamic were evaluated in vitro for both systems, proving to be attractive for pulmonary delivery. The theoretical aerodynamic diameters obtained were 0.322 ± 0.07 µm (5FU-NS) and 1.138 ± 0.54 µm (5FU-MS). The fraction of respirable particles (FR%) were 76.84 ± 0.07% (5FU-NS) and 55.01 ± 2.91% (5FU-MS). The in vitro mucoadhesive properties exhibited significant adhesion efficiency in the presence of Methocel™ F4M. 5FU-MS and 5FU-NS were tested for their cytotoxic action on melanoma cancer cells (A2058 and A375) and both showed a cytotoxic effect similar to 5FU pure at concentrations of 4.3 and 1.7-fold lower, respectively.