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Rivastigmine is an acetylcholinesterase (AchE) and butyrylcholinesterase (BchE) inhibitor drug approved by the US Food and Drug Administration (FDA) for the treatment of mild to moderate dementia of Alzheimer's type. However, its first-pass metabolism and gastrointestinal side effects negatively affect the tolerability and efficacy of oral therapy. These adverse effects could be avoided with the use of a sustained -release formulation as an intramuscular (IM) administration system. The objective of this work was to develop polylactic co-glycolic acid (PLGA) microparticles for the sustained release of rivastigmine and to evaluate its stability during storage, tissue tolerance, in vitro release, and in vivo pharmacokinetics after its IM administration. The microparticles were made by the solvent evaporation emulsion method. A series of formulation parameters (the type of polymer used, the amount of polymer used, the initial amount of rivastigmine, and the volume of PVA 0.1% w/v) were studied to achieve an encapsulation efficiency (EE) and a rivastigmine load of 54.8 ± 0.9% and 3.3 ± 0.1%, respectively. The microparticles, whose size was 56.1 ± 2.8 μm, had a spherical shape and a smooth surface. FT-IR analysis showed that there is no chemical interaction between rivastigmine and the polymer. PLGA microparticles maintain rivastigmine retained and stable under normal (5 ± 3 °C) and accelerated storage (25 ± 2 °C and 60 ± 5 % RH) conditions for at least 6 months. The microparticles behaved as a sustained release system both in vitro and in vivo compared to non-encapsulated rivastigmine. The IM administration of the formulation in rats did not produce significant tissue damage. However, it is necessary to reproduce the experiments with multiple doses to rule out a negative effect in terms of tolerability in chronic treatment. To the best of our knowledge, this study is the only one that has obtained the sustained release of rivastigmine from PLGA microparticles after IM administration in an in vivo model. [Display omitted] [ABSTRACT FROM AUTHOR]

In previous work, we reported on the design of biodegradable rhein-loaded PLGA microparticles for the treatment of osteoarthritis. Considering that a formulation designed for intra-articular administration must meet sterility requirements to guarantee its safety, in this study the effect of gamma radiation sterilization on these microparticles was evaluated. The size, morphology, and surface characteristics of the microparticles and the encapsulation efficiency of rhein were not affected by the sterilization process. Although DSC and PXRD analyses suggested otherwise, rhein release profiles were not altered by gamma radiation. The release of rhein from the microparticles was fitted to a Gompertz model. In conclusion, the results of this study suggest that gamma radiation is a suitable method for the sterilization of rhein-loaded PLGA microparticles to enable their intra-articular administration in order to provide a therapeutic solution to patients suffering from chronic joint diseases. [ABSTRACT FROM AUTHOR]

[Display omitted] Epigallocatechin-3-gallate (EGCG) exhibits several pharmacological activities with potential benefits for human health, however, it has low oral bioavailability. A promising approach is to transport EGCG in a nanostructured system to protect it until it reaches the site of action and also allow combining chemotherapy with phototherapy to improve its therapeutic efficiency. The aim of this work was to synthesize GNR@mSiO 2 -NH 2 /EGCG and characterize the adsorption process, its antioxidant activity, properties and photothermal stability, for its potential use in chemo-photothermal therapy. The nanosystem presented good encapsulation efficiency (19.2 %) and EGCG loading capacity (6.0 %). The DPPH• free radical scavenging capacity (RSA) and chelating activity of the nanosystem was 60.7 ± 6.9 % and 71.0 ± 6.4 % at an EGCG equivalent concentration of 1 µg/mL and 30 µg/mL, respectively. The core–shell NPs presented a good photothermal transduction efficiency of 17 %. EGCG free, as well as its RSA and chelating activity, remained stable after NIR irradiation (808 nm, 7 W/cm2). The morphology of GNR@mSiO 2 remained intact after being irradiated with NIR, however, ultrasmall gold NPs could be observed, probably a product of photocracking of GNR. In summary, the nanosystem has good antioxidant activity, photothermal stability, and photothermal transduction ability making it potentially useful for chemo-photothermal therapy. [ABSTRACT FROM AUTHOR]

Grape canes (Vitis vinifera L.) are an important source of bioactive stilbenes, but they are considered a pruning residue. Despite the potential advantages for human health, the low aqueous solubility and stability limits their usage in commercial goods. This research aimed to improve knowledge about the solubility and stability of the main stilbenes present in important residues of the wine industry, such as grape canes (V. vinifera L. cv. Pinot Noir), through the formation of inclusion complexes with cyclodextrins (CDs) and subsequent polymeric microencapsulation. The formation of inclusion complexes between stilbenes presents in grape cane extracts and 15 mM hydroxypropyl-β-cyclodextrin (HP-β-CD) increased the aqueous solubility of (E)-resveratrol, (E)-ε-viniferin and (E)-piceatannol by 2.8, 5.4 and 1.9 times, respectively. The microencapsulation (by spray drying) of the inclusion complexes using maltodextrin (MD) (10% w/v) allowed us to improve the stability of the stilbenes, obtaining a retention percentage of 81.9 ± 2.2% after 60 min of UV irradiation (254 nm). The lower size microparticles (MPs) formulation was 10.9 ± 0.9 µm and had a stilbene loading of 0.61 ± 0.01 mg/100 mg of MPs. The prototype tablets and capsules made from the MPs presented suitable characteristics for their eventual use. The microencapsulation of inclusion complexes between stilbenes presents in grape cane extracts and HP-β-CD, using MD as a matrix component, is useful to increase the solubility and stability of stilbenes. The prepared MPs can be used for the development of nutraceutical products. [ABSTRACT FROM AUTHOR]