In vivo biodistribution of venlafaxine-PLGA nanoparticles for brain delivery: plain vs. functionalized nanoparticles

Background: Actually, no drugs provide therapeutic benefit to approximately one-third of depressed patients. Depression is predicted to become the first global disease by 2030. So, new therapeutic interventions are imperative.Research design and methods: Venlafaxine-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) were surface functionalized with two ligands against transferrin receptor to enhance access to brain. An in vitro blood-brain barrier model using hCMEC/D3 cell line was developed to evaluate permeability. In vivo biodistribution studies were performed using C57/bl6 mice. Particles were administered intranasal and main organs were analyzed.Results: Particles were obtained as a lyophilized powder easily to re-suspend. Internalization and permeability studies showed the following cell association sequence: TfRp-NPs>Tf-NPs>plain NPs. Permeability studies also showed that encapsulated VLF was not affected by P-gP pump efflux increasing its concentration in the basolateral side after 24 h. In vivo studies showed that 25% of plain NPs reach the brain after 30 min of one intranasal administration while less than 5% of functionalized NPs get the target.Conclusions: Plain NPs showed the highest ability to reach the brain vs. functionalized NPs after 30 min by intranasal administration. We suggest plain NPs probably travel via direct nose-to-brian route whereas functionalized NPs reach the brain by receptor-mediated endocytosis.

In vivo dual-delivery of glucagon like peptide-1 (GLP-1) and dipeptidyl peptidase-4 (DPP4) inhibitor through composites prepared by microfluidics for diabetes therapy

Oral delivery of proteins is still a challenge in the pharmaceutical field. Nanoparticles are among the most promising carrier systems for the oral delivery of proteins by increasing their oral bioavailability. However, most of the existent data regarding nanosystems for oral protein delivery is from in vitro studies, lacking in vivo experiments to evaluate the efficacy of these systems. Herein, a multifunctional composite system, tailored by droplet microfluidics, was used for dual delivery of glucagon like peptide-1 (GLP-1) and dipeptidyl peptidase-4 inhibitor (iDPP4) in vivo. Oral delivery of GLP-1 with nano- or micro-systems has been studied before, but the simultaneous nanodelivery of GLP-1 with iDPP4 is a novel strategy presented here. The type 2 diabetes mellitus (T2DM) rat model, induced through the combined administration of streptozotocin and nicotinamide, a non-obese model of T2DM, was used. The combination of both drugs resulted in an increase in the hypoglycemic effects in a sustained, but prolonged manner, where the iDPP4 improved the therapeutic efficacy of GLP-1. Four hours after the oral administration of the system, blood glucose levels were decreased by 44%, and were constant for another 4 h, representing half of the glucose area under the curve when compared to the control. An enhancement of the plasmatic insulin levels was also observed 6 h after the oral administration of the dual-drug composite system and, although no statistically significant differences existed, the amount of pancreatic insulin was also higher. These are promising results for the oral delivery of GLP-1 to be pursued further in a chronic diabetic model study.

Isoflavones in food supplements: chemical profile, label accordance and permeability study in Caco-2 cells

Consumers nowadays are playing an active role in their health-care. A special case is the increasing number of women, who are reluctant to use exogenous hormone therapy for the treatment of menopausal symptoms and are looking for complementary therapies. However, food supplements are not clearly regulated in Europe. The EFSA has only recently begun to address the issues of botanical safety and purity regulation, leading to a variability of content, standardization, dosage, and purity of available products. In this study, isoflavones (puerarin, daidzin, genistin, daidzein, glycitein, genistein, formononetin, prunetin, and biochanin A) from food supplements (n = 15) for menopausal symptoms relief are evaluated and compared with the labelled information. Only four supplements complied with the recommendations made by the EC on the tolerable thresholds. The intestinal bioavailability of these compounds was investigated using Caco-2 cells. The apparent permeability coefficients of the selected isoflavonoids across the Caco-2 cells were affected by the isoflavone concentration and product matrix.

Drug-delivery systems of green tea catechins for improved stability and bioavailability

Numerous studies in humans, animal models and cell lines have suggested the potential benefits from the consumption of green tea polyphenols, including prevention of cancer and heart diseases. However these potential effects have been strongly limited by green tea catechins low bioavailability, which hinders the development of therapeutic applications. In this review formulations that are being proposed for delivery of green tea catechins are discussed. New delivery systems are presented as valid alternatives to overcome the limitations such as green tea catechins poor stability or intestinal absorption.

The relationship between Candida species charge density and chitosan activity evaluated by ion-exchange chromatography

Chitosan, a natural biopolymer presents antifungal activity that seems to be dependent on the interaction of its cationic amino groups and yeast cell surface. In this work we used ion-exchange chromatography to assess the surface charge density of Candida species and subsequently to relate this with their sensitivity profile to chitosan. The ability of several strains from distinct Candida species to interact with strong anionic and cationic exchangers was tested and the yeasts charge surface was assessed by measuring the zeta potential. Our results showed that all the yeast cells tested presented no interaction with the cationic resin and a species-related pattern of interaction was observed with the anionic resin. Specifically, regarding the Q-Sepharose support, Candida glabrata showed the lower retention affinity, followed by Candida albicans, presenting Candida tropicalis an intermediate profile; Candida parapsilosis and Candida guilliermondii revealed a stronger ionic interaction. The yeasts retention synergy in the anionic resin corroborates with the zeta potential outcomes. The behavior observed fit with sensitivity patterns to chitosan as the most susceptible species to chitosan presented higher affinity to the anionic resin in contrast to the less sensitive ones (C. albicans and C. glabrata). This data confirms and reinforces that chitosan activity is probably mediated by an ionic reaction between its amino free groups and ionic charges at the cell surface.

Insulin-loaded nanoparticles are prepared by alginate ionotropic pre-gelation followed by chitosan polyelectrolyte complexation

Alginate nanoparticles were prepared from dilute alginate sol by inducing a pre-gel with calcium counter ions, followed by polyelectrolyte complex coating with chitosan. Particles in the nanometer size range were obtained with 0.05% alginate and 0.9 mM Ca2+. The mean particle size was influenced by time and stirring speed of nanoparticle preparation, by alginate guluronic acid content and chitosan molecular weight and by the initial alginate:chitosan mass ratio. The association efficiency of insulin into alginate nanoparticles, as well as loading capacity were mainly influenced by the alginate:chitosan mass ratio. Under optimized size conditions, the association efficiency and loading capacities were as high as 92% and 14.3%, respectively. Approximately 50% of the protein was partially retained by the nanoparticles in gastric pH environment up to 24 hours while a more extensive release close to 75% was observed under intestinal pH conditions. Mild formulation conditions, optimum particle size range obtained, high insulin entrapment efficiency, and resistance to gastrointestinal release seem to be synergic and promising factors toward development of an oral insulin delivery form.

Alginate/chitosan nanoparticles are effective for oral insulin delivery

PURPOSE

To evaluate the pharmacological activity of insulin-loaded alginate/chitosan nanoparticles following oral dosage in diabetic rats.

METHODS

Nanoparticles were prepared by ionotropic pre-gelation of an alginate core followed by chitosan polyelectrolyte complexation. In vivo activity was evaluated by measuring the decrease in blood glucose concentrations in streptozotocin induced, diabetic rats after oral administration and flourescein (FITC)-labelled insulin tracked by confocal microscopy.

RESULTS

Nanoparticles were negatively charged and had a mean size of 750 nm, suitable for uptake within the gastrointestinal tract due to their nanosize range and mucoadhesive properties. The insulin association efficiency was over 70% and insulin was released in a pH-dependent manner under simulated gastrointestinal conditions. Orally delivered nanoparticles lowered basal serum glucose levels by more than 40% with 50 and 100 IU/kg doses sustaining hypoglycemia for over 18 h. Pharmacological availability was 6.8 and 3.4% for the 50 and 100 IU/kg doses respectively, a significant increase over 1.6%, determined for oral insulin alone in solution and over other related studies at the same dose levels. Confocal microscopic examinations of FITC-labelled insulin nanoparticles showed clear adhesion to rat intestinal epithelium, and internalization of insulin within the intestinal mucosa.

CONCLUSION

The results indicate that the encapsulation of insulin into mucoadhesive nanoparticles was a key factor in the improvement of its oral absorption and oral bioactivity.

Probing insulin's secondary structure after entrapment into alginate/chitosan nanoparticles

The aim of the present study was to probe the structural integrity of insulin after being entrapped into chitosan/alginate nanoparticles produced by ionotropic polyelectrolyte pre-gelation. By manipulating the alginate:chitosan mass ratio and the pH during nanoparticle production, desired nanoparticles with a mean size of 850 (+/-88)nm and insulin association efficiency of 81 (+/-2)% were obtained. Insulin secondary structure was assessed by Fourier transform infrared (FTIR) and circular dichroism (CD) after entrapment into nanoparticles and after release from the particles under gastrointestinal simulated conditions. FTIR second-derivative spectra and area-overlap compared to an insulin standard confirmed that no significant conformational changes of insulin occurred in terms of alpha-helix and beta-sheet content. Far-UV-CD spectra corroborated the preservation of insulin structure during the nanoparticle production procedure. The presented nanoparticulate system is a promising carrier for insulin oral delivery since it preserves insulin structure and therefore also, potentially, its bioactivity.