Andreia Almeida

Development and characterization of crosslinked hyaluronic acid polymeric films for use in coating processes.

The aim of this work was to develop and characterize new hyaluronic acid-based responsive materials for film coating of solid dosage forms. Crosslinking of hyaluronic acid with trisodium trimetaphosphate was performed under controlled alkaline aqueous environment. The films were produced through casting process by mixing crosslinked or bare biopolymer in aqueous dispersion of ethylcellulose, at different proportions. Films were further characterized regarding morphology by scanning electron microscopy, robustness by permeation to water vapor transmission, and ability to hydrate in simulated gastric and intestinal physiological fluids. The safety and biocompatibility of films were assessed against Caco-2 and HT29-MTX intestinal cells. The permeation to water vapor transmission was favored by increasing hyaluronic acid content in the final formulation. When in simulated gastric fluid, films exhibited lower hydration ability compared to more extensive hydration in simulated intestinal fluids. Simultaneously, in simulated intestinal fluids, films partially lost weight, revealing ability for preventing drug release at gastric pH, but tailoring the release at higher intestinal pH. The physiochemical characterization suggests thermal stability of films and physical interaction between compounds of formulation. Lastly, cytotoxicity tests demonstrated that films and individual components of the formulations, when incubated for 4h, were safe for intestinal cells Overall, these evidences suggest that hyaluronic acid-based responsive films, applied as coating material of oral solid dosage forms, can prevent the premature release of drugs in harsh stomach conditions, but control the release it in gastrointestinal tract distal portion, assuring safety to intestinal mucosa.

Elucidation of the impact of cell culture conditions of Caco-2 cell monolayer on barrier integrity and intestinal permeability

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The role of non-endothelial cells on the penetration of nanoparticles through the blood brain barrier.

HighlightsThe blood brain barrier (BBB) protects the central nervous system (CNS) from harmful substances, including therapeutic agents.Alternative ways to deliver drugs to the CNS, overcoming the BBB are required, to improve the efficacy of brain target drugs.Nanoparticles have demonstrate ability to increase the bioavailability of drugs in the CNS.The influence of non‐endothelial may have on the BBB translocation of nanoparticles is discussed in this review.The influence of macrophages and/or monocytes as nanoparticle delivery carriers to the CNS are also approached. ABSTRACT The blood brain barrier (BBB) is a well‐established cell‐based membrane that circumvents the central nervous system (CNS), protecting it from harmful substances. Due to its robustness and cell integrity, it is also an outstanding opponent when it comes to the delivery of several therapeutic agents to the brain, which requires the crossing through its highly‐organized structure. This regulation and cell‐cell communications occur mostly between astrocytes, pericytes and endothelial cells. Therefore, alternative ways to deliver drugs to the CNS, overcoming the BBB are required, to improve the efficacy of brain target drugs. Nanoparticles emerge here as a promising drug delivery strategy, due to their ability of high drug loading and the capability to exploit specific delivery pathways that most drugs are unable to when administered freely, increasing their bioavailability in the CNS. Thus, further attempts to assess the possible influence of non‐endothelial may have on the BBB translocation of nanoparticles are here revised. Furthermore, the use of macrophages and/or monocytes as nanoparticle delivery cells are also approached. Lastly, the temporarily disruption of the overall organization and normal structure of the BBB to promote the penetration of nanoparticles aimed at the CNS is described, as a synergistic path.

Pharmacological and toxicological assessment of innovative self-assembled polymeric micelles as powders for insulin pulmonary delivery

AIM Explore the use of polymeric micelles in the development of powders intended for pulmonary delivery of biopharmaceuticals, using insulin as a model protein. MATERIALS & METHODS Formulations were assessed in vitro for aerosolization properties and in vivo for efficacy and safety using a streptozotocin-induced diabetic rat model. RESULTS Powders presented good aerosolization properties like fine particle fraction superior to 40% and a mass median aerodynamic diameter inferior of 6 μm. Endotracheally instilled powders have shown a faster onset of action than subcutaneous administration of insulin at a dose of 10 IU/kg, with pharmacological availabilities up to 32.5% of those achieved by subcutaneous route. Additionally, micelles improved the hypoglycemic effect of insulin. Bronchoalveolar lavage screening for toxicity markers (e.g., lactate dehydrogenase, cytokines) revealed no signs of lung inflammation and cytotoxicity 14 days postadministration. CONCLUSION Developed powders showed promising safety and efficacy characteristics for the systemic delivery of insulin by pulmonary administration.

Gellan Gum/Pectin Beads Are Safe and Efficient for the Targeted Colonic Delivery of Resveratrol

This work addresses the establishment and characterization of gellan gum:pectin (GG:P) biodegradable mucoadhesive beads intended for the colon-targeted delivery of resveratrol (RES). The impact of the polymer carrier system on the cytotoxicity and permeability of RES was evaluated. Beads of circular shape (circularity index of 0.81) with an average diameter of 914 μm, Span index of 0.29, and RES entrapment efficiency of 76% were developed. In vitro drug release demonstrated that beads were able to reduce release rates in gastric media and control release for up to 48 h at an intestinal pH of 6.8. Weibull’s model correlated better with release data and b parameter (0.79) indicated that the release process was driven by a combination of Fickian diffusion and Case II transport, indicating that both diffusion and swelling/polymer chains relaxation are processes that contribute equally to control drug release rates. Beads and isolated polymers were observed to be safe for Caco-2 and HT29-MTX intestinal cell lines. RES encapsulation into the beads allowed for an expressive reduction of drug permeation in an in vitro triple intestinal model. This feature, associated with low RES release rates in acidic media, can favor targeted drug delivery from the beads in the colon, a promising behavior to improve the local activity of RES.

Development and characterization of lipid-polymeric nanoparticles for oral insulin delivery

ABSTRACT Introduction: The oral route is widely accepted as the most physiological path for exogenous administration of insulin, as it closely mimic the endogenous insulin pathway. Thus, in this work it is proposed an innovative lipid-polymeric nanocarrier to delivery insulin orally. Areas covered: Nanoparticles were produced through a modified solvent emulsification-evaporation method, using ethyl palmitate and hydroxypropylmethylcellulose acetate succinate as matrix. Lipid-polymeric nanoparticles were around 300 nm in size, negatively charged (−20 mV) and associated insulin with efficiency higher than 80%. Differential scanning calorimetry suggested thermal stability of nanoparticles. In vitro release assays under simulated gastrointestinal conditions resulted in 9% and 14% of insulin released at pH 1.2 during 2 h and at pH 6.8 for 6 h, respectively, demonstrating the ability of those nanoparticles to protect insulin against premature degradation. Importantly, nanoparticles were observed to be safe at potential therapeutic concentrations as did not originate cytotoxicity to intestinal epithelial cells. Lastly, the permeability of nanoencapsulated insulin through Caco-2 monolayers and a triple Caco-2/HT29-MTX/Raji B cell model correlated well with slow release kinetics, and fosters the effectiveness of nanoparticles to promote intestinal absorption of peptidic drugs. Expert opinion: Lipid-polymeric nanoparticles were developed to encapsulate and carry insulin through intestine. Overall, nanoparticles provide insulin stability and intestinal permeability.

Mucoadhesive nanostructured polyelectrolytes complexes modulate the intestinal permeability of methotrexate

ABSTRACT Nanostructured polyelectrolytes complexes (nano PECs) loaded with methotrexate (MTX) were obtained by the polyelectrolyte complexation of chitosan (CS) and hyaluronic acid (HA), further incorporating hypromellose phthalate (HP). The mean diameter of nano PECs ranged from 325 to 458 nm, with a narrow size distribution. Zeta potential was close to +30 mV, decreasing to +21 mV after the incorporation of HP, a range of values that favour the physical stability of system as the interaction with cationic biological membranes. The electrostatic interactions between the different components were indicated by the FTIR data. The mucoadhesiveness of nano PECs was demonstrated and MTX and HP influenced this property. The cell viability assays showed the biosafety of the isolated polymers and nano PECs in intestinal HT29‐MTX and Caco‐2 cell lines at 4 h of test. The permeability values of MTX loaded in CS/HA nano PECs were 7.6 and 4‐fold higher than those of CS/HA/HP nano PECS and free drug, respectively, in the Caco‐2 monoculture. In mucus secreting co‐culture cell model these values were 3 and 6.5 fold, respectively. Such features indicate that nano PECs developed in this work can be promising carriers for MTX in the treatment of local or systemic diseases. Graphical abstract Figure. No Caption available.

Micellar-Based Nanoparticles for Cancer Therapy and Bioimaging

Micelles are versatile nanosized systems composed by amphiphilic molecules. Their small size and capacity to encapsulate both hydrophilic and hydrophobic compounds, as well as their easier functionalization, are some of the characteristics responsible for their multifunctionality, and their potential use in different clinical settings. In fact, micelles have important applications in cancer therapy because of their capacity to deliver hydrophobic anticancer drugs to tumor sites. In recent years, applications beyond the delivery of hydrophobic drugs have been explored. In this chapter, we will discuss the main features of micelles that make them good candidates in the development of systems for cancer therapy and bioimaging. The state-of-the-art and recent advances in academic research and in clinical applications will be discussed